Composite structure with variable dimensions and method of forming the same

Abstract

A composite structure with a variable specification and a method of forming the composite structure are disclosed. In one example, a composite structure with a variable specification is described. The composite structure includes: a first end with a first specification, a second end with a second specification smaller than the first specification, a plurality of continuous layers, and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer includes a terminal end having a blunt end shape. Each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end. The plurality of subtractive layers are separated from each other by at least one continuous layer of the plurality of continuous layers.

Description

Technical Field

[0001] The present disclosure relates generally to composite structures and, more particularly, to composite structures and methods of forming composite structures having variable gages. Background Art

[0002] Composite structures are used in a wide variety of applications due to their high strength-to-weight ratio, corrosion resistance, and other favorable attributes, including in the manufacture of aircraft, spacecraft, rotorcraft, watercraft, automobiles, trucks, and other vehicles and structures. In general, a composite structure is a structure formed from two or more constituent materials having different physical and / or chemical properties that, when combined, produce a composite material having properties that differ from those of the individual constituent materials.

[0003] For example, one type of composite material is carbon fiber reinforced plastic ("CFRP"). CFRP typically includes one or more composite layers or plies laminated together to form a sheet, laminate, or layup. Each composite layer or ply may include a reinforcement material and a matrix material. The matrix material surrounds, binds, and supports the reinforcement material. The reinforcement material provides structural strength to the matrix material and the CFRP. The matrix material is typically a non-conductive polymer such as an epoxy resin. The reinforcement material is typically composed of conductive carbon fiber bundles. Summary of the invention

[0004] In an example, a composite structure having a variable gauge is described. The composite structure includes: a first end having a first gauge, a second end having a second gauge less than the first gauge, a plurality of continuous layers, and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer includes a terminal end having a blunt end shape. Each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end. The plurality of subtractive layers are separated from each other by at least one continuous layer of the plurality of continuous layers.

[0005] In another example, a method of forming a composite structure having a variable specification is described. The method includes: forming a plurality of continuous layers and forming a plurality of subtractive layers. Forming the plurality of subtractive layers includes: for each subtractive layer, forming an end of the subtractive layer having a blunt end shape. The method also includes: positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having a first end and a second end. The first end has a first specification, and the second end has a second specification, which is smaller than the first specification. Positioning the plurality of continuous layers and the plurality of subtractive layers includes: (a) positioning the plurality of continuous layers so that each continuous layer extends from the first end to the second end; and (b) positioning the plurality of subtractive layers so that (i) each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end, and (ii) the plurality of subtractive layers are separated from each other by at least one of the plurality of continuous layers.

[0006] In another example, a composite structure with variable specifications is described. The composite structure includes: a first section with a first specification, a second section with a second specification less than the first specification, and a transition section between the first section and the second section. The transition section includes: a first end at the first section and having the first specification, a second end at the second section and having the second specification, a first outer surface extending from the first end to the second end, and a second outer surface extending from the first end to the second end. The transition section also includes a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) stacked between the first outer surface and the second outer surface.

[0007] The plurality of layers include: (a) a plurality of continuous layers, wherein each continuous layer extends from a first end to a second end; and (b) at least one subtractive layer. Each subtractive layer includes a terminal end having a blunt end shape. Each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end. Each subtractive layer is sandwiched between and abuts against corresponding two continuous layers in the plurality of continuous layers.

[0008] The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples, further details of which can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The novel features believed to be characteristic of the exemplary examples are set forth in the appended claims. However, the illustrative examples together with the preferred modes of use, further objects and description thereof will be best understood by reference to the following detailed description of illustrative examples of the disclosure when read in conjunction with the accompanying drawings, in which:

[0010] Figure 1 A composite structure according to an example is depicted.

[0011] Figure 2 A composite structure according to another example is depicted.

[0012] Figure 3 A composite structure according to another example is depicted.

[0013] Figure 4 Depicted is a simplified block diagram of a composite structure according to another example.

[0014] Figure 5A Depicted according to another example includes Figure 1 A side view of a composite stringer of a composite structure.

[0015] Figure 5B Depicted according to another example includes Figure 3 Side view of a composite stringer of a composite structure.

[0016] Figure 6 A flow chart of an example process for forming a composite structure having variable specifications according to an example is shown.

[0017] Figure 7 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Figure 6 Use with the processing shown.

[0018] Figure 8 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Figure 6 Use with the processing shown.

[0019] Fig. 9 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Figure 8 Use with the processing shown.

[0020] Fig.10 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig. 9 Use with the processing shown.

[0021] Fig.11 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig. 9 Use with the processing shown.

[0022] Fig.12 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.11 Use with the processing shown.

[0023] Fig.13 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Figure 6 Use with the processing shown.

[0024] Fig.14 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Figure 6 Use with the processing shown.

[0025] Fig.15 A flow chart of an example process for forming a composite structure having variable specifications according to an example is shown.

[0026] Fig.16 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.15 Use with the processing shown.

[0027] Fig.17 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.16 Use with the processing shown.

[0028] Fig.18 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.16 Use with the processing shown.

[0029] Fig.19 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.16 Use with the processing shown.

[0030] Fig. 20 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.16 Use with the processing shown.

[0031] Fig.21 A flowchart showing an example process for forming a composite structure having variable specifications that can be used with Fig.16 Use with the processing shown. DETAILED DESCRIPTION

[0032] The disclosed examples will now be described more fully below with reference to the accompanying drawings, in which some, but not all, of the disclosed examples are shown. In fact, several different examples may be described, and these different examples should not be construed as limited to the examples set forth herein. Rather, these examples are described so that the present disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art.

[0033] With respect to quantities or measurements described herein, the terms "about" or "substantially" mean that the recited characteristic, parameter or value need not be achieved precisely, but rather deviations or changes in the amount that do not interfere with the function that the characteristic is intended to provide include, for example, tolerances, measurement errors, measurement precision limitations, and other factors known to those skilled in the art.

[0034] As used herein, the terms "greater than" and "less than" are intended to have their ordinary meanings. Thus, a first value is greater than a second value if it is greater than a second value by any amount. Similarly, a first value is less than a second value if it is less than a second value by any amount.

[0035] As used herein, the term "composite structure" refers to a structure that is manufactured, made, or assembled in whole or in part from one or more composite materials.

[0036] As described above, composite structures are widely used in a variety of applications due to their high strength-to-weight ratio, corrosion resistance, and other favorable attributes, including in the manufacture of aircraft, spacecraft, rotorcraft, watercraft, flying cars, trains, automobiles, trucks, and other vehicles (e.g., passenger cabins or cargo containers). Additionally or alternatively, composite structures may be used in buildings, bridges, swimming pools, storage tanks, robotic frame structures, energy structures (e.g., wind blades, turbine blades, propeller blades, and / or solar panels), sporting goods (e.g., bicycle frames, sleds, snowboards, surfboards, paddles), homes, office buildings, and / or medical panels.

[0037] In some embodiments, different portions of a composite structure may have different specifications. As used herein, the term "spec" refers to the thickness between two opposing sides of a composite structure. For a variety of reasons, it may be desirable to change the specifications from one portion of a composite structure relative to another portion of the composite structure. For example, the stiffness and / or strength of a composite structure may be related to the specifications of the composite structure. In some cases, it may be desirable to change the stiffness and / or strength of a composite structure from a first portion of a composite structure to a second portion of the composite structure. For example, it may be desirable that a first portion of a composite structure is subjected to a relatively large amount of load and / or force applied compared to a second portion of the composite structure. Thus, it may be desirable that the specifications of the first portion of a composite structure be greater than the specifications of the second portion of the composite structure.

[0038] In other examples, it may be desirable to vary the specifications of the composite structure additionally or alternatively based on other design criteria, such as, for example, aesthetics, weight distribution, space constraints, load variations, and / or damage protection.

[0039] One method of transitioning from one specification to another involves forming a composite structure from a multilayer composite material, the multilayer composite material including a plurality of continuous plies and one or more drop-off plies. Typically, each continuous ply extends from a first end to a second end of the composite structure. In contrast, each drop-off ply extends from the first end to a corresponding position of the tip of the drop-off ply between the first end and the second end. In this arrangement, the second end has fewer layers relative to the first end. Therefore, by positioning the tip of the drop-off ply between the first end and the second end, the specification decreases from the first end to the second end, thereby making the transition from one specification to another.

[0040] Existing methods of transitioning from one specification to another have some disadvantages. For example, in existing composite structures with variable specifications, the ends of the reduced layers have a blunt-end shape and are arranged in groups close to each other. This can result in relatively large resin pockets in the area at or near the ends of the reduced layers. In some cases, the relatively large resin pockets can cause delamination in this area under certain thermal and / or mechanical loads. In addition, for example, arranging the ends of the reduced layers in groups can increase the risk of layer kinking and / or wrinkling, which can reduce the strength of the laminate.

[0041] As an example, Figure 1 An example composite structure 100 having variable specifications is depicted according to an example. Figure 1 As shown, the composite structure 100 includes a first end 110A having a first dimension 112A and a second end 110B having a second dimension 112B, the second dimension 112B being smaller than the first dimension 112A of the first end 110A. The composite structure 100 also includes a first outer surface 114 extending from the first end 110A to the second end 110B and a second outer surface 116 extending from the first end 110A to the second end 110B.

[0042] Likewise Figure 1 As shown, the composite structure 100 includes a plurality of layers 118 of composite material stacked and arranged between the second outer surface 116 and the first outer surface 114. i＝1 Up to 118 i＝n (hereinafter collectively referred to as "layer 118 i ”), where n is an integer greater than or equal to 2. Figure 1 In the embodiment, the composite structure 100 includes a total of 18 layers 118 i (ie, n=18). However, in other examples, the composite structure 100 may include a fewer or greater number of layers 118 i .

[0043] In this arrangement, the first dimension 112A of the first end 110A and the second dimension 112B of the second end 110B have respective thicknesses between the first outer surface 114 and the second outer surface 116 at the first end 110A and the second end 110B, respectively. i The second specification 112B is related to the layer 118 at the second end 110B. i For example, in Figure 1 In the first end 110A, the layer 118 i The number of layers 118 is greater than that of the layer 118 at the second end 110B i The number of first specifications 112A makes it larger than the second specifications 112B.

[0044] Specifically, in order to change the layer 118 between the first end 110A and the second end 110B i Number of layers of composite material 118 i It includes a plurality of continuous layers 118A and a plurality of subtractive layers 118B. Figure 1 In the embodiment, each continuous layer 118A extends from the first end 110A to the second end 110B. However, each subtractive layer 118B includes a terminal end 120, and each subtractive layer 118B extends from the first end 110A to a corresponding position between the first end 110A and the second end 110B.

[0045] Thus, the continuous layer 118A is present at the first end 110A and the second end 110B, but the subtractive layer 118B is present at the first end 110A and not at the second end 110B. In this way, the subtractive layer 118B can contribute to the first specification 112A at the first end 110A, while not contributing to the second specification 112B at the second end 110B because the subtractive layer 118B terminates before the second end 110B (i.e., the end 120 is located at a corresponding position between the first end 110A and the second end 110B).

[0046] For the sake of clarity, in Figure 1 In the embodiment, the representative subset of the continuous layer 118A is labeled with the reference number 118A, and the representative subset of the reduced layer 118B is labeled with the reference number 118B. However, each layer 118 extending completely from the first end 110A to the second end 110B i is one of the continuous layers 118A, and each layer 118 terminates between the first end 110A and the second end 110B. i is a layer in the subtraction layer 118B. Specifically, Figure 1 Middle, Floor 118 i＝1-3，9-18 is a continuous layer 118A, and layer 118 i＝4-8It is the subtracted layer 118B.

[0047] like Figure 1 As shown, the end 120 of each reduction layer 118B has a blunt end shape, and the reduction layers 118B are stacked (e.g., in groups) next to each other. Generally, this method of transitioning from one specification to another may be effective. However, it has been found that using the following reference Figures 2 to 3 One or more techniques described in detail may improve the performance of the composite structure 100 .

[0048] For example, using a subtractive layer 118B having a blunt-end shaped end 120 and / or arranging the subtractive layers 118B in groups may result in relatively large resin pockets in a region 122 at or near the end 120 of the subtractive layer 118B. In some cases, under certain thermal and / or mechanical loads, the relatively large resin pockets in the region 122 may result in delamination in the region 122. In addition, for example, arranging the ends 120 of the subtractive layers 118B in groups may increase the risk of layer kinking and / or wrinkling, which may reduce laminate strength. Furthermore, in some cases, arranging the ends 120 of the subtractive layers at an eccentric position (e.g., closer to the first outer surface 114 than the second outer surface 116) may also increase the risk of layer kinking and / or wrinkling, and the layers may have reduced static strength and / or reduced fatigue strength due to potential deformation under thermal and / or mechanical loads.

[0049] In the examples, composite structures with variable specifications are described that can improve upon composite structure 100 in one or more aspects. For example, in some examples, end 120 of subtractive layer 118B can have a tapered shape and / or layer 118 i The arrangements may be arranged according to one or more patterns that may enhance the load bearing properties of the composite structure, reduce re-curing, simplify processing requirements for forming the composite structure, reduce material handling costs, and / or reduce the weight of the composite structure.

[0050] Now refer to Figure 2 , a composite structure 200 having variable specifications is depicted according to an example. Figure 2 As shown, the composite structure 200 includes a first end 210A having a first dimension 212A and a second end 210B having a second dimension 212B, the second dimension 212B being smaller than the first dimension 212A of the first end 210A. Figure 2 As shown, the composite structure 200 includes a first outer surface 214 extending from the first end 210A to the second end 210B, and a second outer surface 216 extending from the first end 210A to the second end 210B.

[0051] Likewise Figure 2As shown, the composite structure 200 includes a plurality of layers 218 of composite material stacked between the second outer surface 216 and the first outer surface 214. i＝1 To 218 i＝n (hereinafter collectively referred to as "layer 218 i ”), where n is an integer greater than or equal to 2. Figure 2 In the embodiment, the composite structure 200 includes a total of 28 layers 218 i (ie, n=28). However, in other examples, composite structure 200 may include a fewer number or a greater number of layers 218 i .

[0052] In this arrangement, the first dimension 212A of the first end 210A and the second dimension 212B of the second end 210B have corresponding thicknesses between the first outer surface 214 and the second outer surface 216 at the first end 210A and the second end 210B, respectively. In addition, as described above, the first dimension 212A and the layer 218 at the first end 210A i The second specification 212B is related to the layer 218 at the second end 210B. i For example, in Figure 2 In the first end 210A, the layer 218 i The number is greater than that of the layer 218 at the second end 210B i The number of first specifications 212A makes it larger than the second specifications 212B.

[0053] As described above, the layer 218 of the composite material i resulting in variable specifications of the composite structure 200, the layers 218 i The plurality of continuous layers 218A and the plurality of subtractive layers 218B are stacked and arranged between the second outer surface 216 and the first outer surface 214. Figure 2 In the embodiment of the present invention, each continuous layer 218A extends from the first end 210A to the second end 210B. However, each subtractive layer 218B extends from the first end 210A to a terminal end 220 of the subtractive layer 218B at a corresponding position between the first end 210A and the second end 210B. Therefore, the first specification 212A is based on the number of continuous layers 218A and the number of subtractive layers 218B, while the second specification 212B is based on the number of continuous layers 218A (without the number of subtractive layers 218B).

[0054] For the sake of clarity, in Figure 2 In the embodiment, the representative subset of the continuous layer 218A is labeled with the reference number 218A, and the representative subset of the reduced layer 218B is labeled with the reference number 218B. However, each layer 218 extending completely from the first end 210A to the second end 210B iis one of the continuous layers 218A, and each layer 218 terminates between the first end 210A and the second end 210B. i is a layer in the subtraction layer 218B. Specifically, Figure 2 Middle, Floor 218 i＝1-6 ,8, 10 , 12 , 14 , 15 , 17 , 19 , 21 , 23 , 25-28 is a continuous layer 218A, while layer 218 i＝7，9，11，13，16，18，20，22，24 It is the subtracted layer 218B.

[0055] like Figure 2 As shown, the end 220 of each subtractive layer 218B has a tapered shape. More specifically, for example, the end 220 of each subtractive layer 218B may gradually reduce the thickness in a direction from the first end 210A toward the end 220 of the second end 210B. Because the end 220 has a tapered shape, the end 220 may be more closely abutted against the layer 218B. i The adjacent layers (e.g. Figure 1 In this way, the end 220 having a tapered shape can reduce (or can minimize) the resin pocket at the end 220 of the reduction layer 218B, which can help improve (or can maximize) the interlaminar strength of the composite structure 200. Therefore, the tapered shape of the end 220 of the reduction layer 218B can help improve the load-bearing performance of the composite structure 200 with variable specifications for transitioning from a portion with a first specification 212A to a portion with a second specification 212B.

[0056] In an example, the tapered shape of the tip 220 of the subtractive layer 218B can be formed by cutting each subtractive layer 218B at an angle less than about 85 degrees relative to the longitudinal axis of the subtractive layer 218B. In contrast, for example, the tapered shape of the tip 220 of the subtractive layer 218B can be formed by cutting each subtractive layer 118B at an angle of about 90 degrees relative to the longitudinal axis of the subtractive layer 118B. Figure 1 The distal end 120 of the reduced layer 118B is shown as having a blunt end shape.

[0057] As described above, the load-bearing performance of the composite structure 200 may be enhanced additionally or alternatively based on the pattern in which the layers 218i are arranged in the composite structure 200. For example, Figure 2 In the embodiment, the subtractive layers 218B may be separated from each other by at least one of the continuous layers 218A. More particularly, in Figure 2In the embodiment, each subtractive layer 218B can be sandwiched and abutted between corresponding two continuous layers 218A in the plurality of continuous layers 218A. By separating the subtractive layers 218B from each other and / or sandwiching the subtractive layers 218B between continuous layers 218A, the subtractive layers 218B can be more evenly distributed between the second outer surface 216 and the first outer surface 214 (with the subtractive layers 218B being more uniformly distributed between the second outer surface 216 and the first outer surface 214). Figure 1 This may help reduce (or may prevent) ply kinking and / or wrinkling, reduce (or may prevent) resin pockets, and / or increase (or may maximize) inter-ply strength of composite structure 200.

[0058] As mentioned above, in Figure 2 Middle, Floor 218 i＝1-6，8，10，12，14，15，17，21，23，25-28 is a continuous layer 218A, while layer 218 i＝7，9，11，13，13，16，18，20，22，24 is the subtracted layer 218B. Therefore, Figure 2 218 in each floor i＝7，9，11，11，13，16，18，20，22，24 At least one layer 218 i＝1-6，8，10，12，14，15，17，19，21，23，25-28 Separated from each other, and each layer 218 i＝7，9，11，13，16，18，20，22，24 Sandwiched between and close to layer 218 i＝1-6，8，10，12，14，15，17，19，21，23，25-28 For example, between the corresponding two layers in Figure 2 Middle, Floor 218 i＝7 Pass level 218 i＝8 With layer 218 i＝9 Separate, and layer 218 i＝7 Sandwiched in layer 218 i＝6 With layer 218 i＝8 In addition, for example, layer 218 i＝9 Pass level 218 i＝10 With layer 218 i＝11 Separated by layer 218 i＝8 With layer 218 i＝7 Separated and sandwiched between layers 218 i＝8 With layer 218 i＝10 In addition, for example, layer 218 i＝16 Pass level 218 i＝14，15 With layer 218 i＝13 Separated by layer 218 i＝17 With layer 218 i＝18 Separated and sandwiched between layers 218 i＝15 With layer 218 i＝17 Between. For Figure 2 The remaining subtracted layer 218B (ie, layer 218 i＝11，13，18，20，22，24 ) has a similar relationship. As described above, the layer 218 i Arranged in a pattern having properties of subtractive layers 218B interleaved with continuous layers 218A (e.g., as Figure 2) may help reduce (or may prevent) ply kinking and / or wrinkling, reduce (or may prevent) resin pockets, and / or increase (or may maximize) inter-ply strength of the composite structure 200.

[0059] In an example, the pattern of the ends 220 of the reduced layers 218B may additionally or alternatively include one or more of the following characteristics: (i) the ends 220 are arranged in a pattern in the front half of the composite structure 200 that is substantially a mirror image or a mirror image of the pattern of the ends 220 in the back half of the composite structure 200, (ii) the ends 220 are staggered relative to each other, and / or (iii) the ends 220 are spaced apart relative to each other by at least a threshold distance (e.g., from one or more layers 218B). i Each of these characteristics, alone or in combination, can help arrange the subtractive layers 218B into a pattern that can reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength.

[0060] Figure 2 The end 220 is shown arranged in a substantially mirrored or mirrored pattern relative to a central portion 224 of the composite structure 200 according to one example. The central portion 224 may include one or more layers 218 i , floor 218 i A reference frame is provided to characterize the pattern of ends 220 of reduced layers 218B on opposite sides of central portion 224. Generally, central portion 224 is (i) between second outer surface 216 and first outer surface 214, and (ii) extends from first end 210A to second end 210B.

[0061] exist Figure 2 In the embodiment, the central portion 224 may include the layer 218 i＝15，16 Therefore, in Figure 2 In the embodiment, the central portion 224 may include a single subtractive layer 218B (ie, layer 218 i＝16 ) and a single continuous layer 218A (ie, layer 218 i＝15 ). However, in another example, the center portion 224 may include two subtractive layers 218B and at least one continuous layer 218A. In yet another example, the center portion 224 may consist of only a single subtractive layer 218B. In another example, the center portion 224 may consist of one or more continuous layers 218A and omit the subtractive layer 218B. More generally, the center portion 224 may include one or more continuous layers 218A and / or one or more subtractive layers 218B.

[0062] As described above, the ends 220 of the subtractive layers 218B can be arranged in a substantially mirror image or mirrored pattern relative to the central portion 224. For example, a first subset of the subtractive layers 218B can be between the first outer surface 214 and the central portion 224, while a second subset of the subtractive layers 218B can be between the central portion 224 and the second outer surface 216. In this arrangement, the ends 220 of the first subset of subtractive layers 218B are arranged in a substantially mirrored pattern as the pattern of the ends 220 of the second subset of subtractive layers 218B. In other words, with reference to the central portion 224, the corresponding locations of the ends 220 of the first subset of subtractive layers 218B are (i) oppositely and (ii) similarly (or identically) arranged compared to the corresponding locations of the ends 220 of the second subset of subtractive layers 218B.

[0063] For example, in Figure 2 In the embodiment, the central portion 224 may include the layer 218 i＝15，16 , minus the first subset of layers 218B may include layers 218 i＝7，9，11，13 , and the second subset minus layer 218B may include layer 218 i＝18，20，22，24 .like Figure 2 As shown, the pattern of the ends 220 of the first subset of subtractive layers 218B is substantially mirrored with the pattern of the ends 220 of the second subset of subtractive layers 218B. For example, with reference to the central portion 224, the corresponding positions of the ends 220 of the first subset are oppositely and similarly arranged compared to the corresponding positions of the ends 220 of the second subset.

[0064] In addition, if Figure 2 As shown, the pattern of the end 220 of the subtractive layer 218B can be a monotonically outward pattern. Figure 2 , the first subset of reduced layers 218B may be ordered from the reduced layers 218B closest to the center portion 224 (eg, layers 218 i＝13 ) to the reduced layer 218B (ie, layer 218) closest to the first outer surface 214 i＝7 ). The pattern of the end 220 of the first subset of the reduction layers 218B may include: the relative distance between the end 220 of the reduction layer 218B and the second end 210B of each reduction layer 218B in the sequence decreases successively. Figure 2 Medium, (i) layer 218 i＝13 The end 220 of the layer 218 is at a first distance from the second end 210B, (ii) i＝11 The end 220 of the layer 218 is at a second distance from the second end 210B (the second distance is less than the first distance), (iii) the layer 218 i＝9 The end 220 of the layer 218 is at a third distance from the second end 210B (the third distance is less than the second distance), and (iv) the layer 218 i＝7The end 220 is at a fourth distance from the second end 210B (the fourth distance is less than the third distance).

[0065] Similarly, the order of the second subset of subtracted layers 218B may be ordered from the subtracted layer 218B closest to the center portion 224 (eg, layer 218 i＝18 ) to the reduced layer 218B (eg, layer 218) closest to the second outer surface 216 i＝24 ). The pattern of the end 220 of the second subset of the reduction layers 218B includes: the relative distance between the end 220 of the reduction layer 218B and the second end 210B of each reduction layer 218B in the sequence decreases successively. Figure 2 Middle, (v) layer 218 i＝18 The end 220 of the layer 218 is at a fifth distance from the second end 210B. i＝20 The end 220 of the layer 218 is at a sixth distance from the second end 210B (the sixth distance is less than the fifth distance), (vii) the layer 218 i＝22 The end 220 of the layer 218 is at a seventh distance from the second end 210B (the seventh distance is less than the sixth distance), and (viii) the layer 218 i＝24 The end 220 is at an eighth distance from the second end 210B (the eighth distance is less than the seventh distance).

[0066] Therefore, in Figure 2 In the monotonically outward pattern of the ends 220 shown, the ends 220 of the reduced layers 218B generally appear to expand outward from the center portion 224 in a direction from the first end 210A to the second end 210B. The monotonically outward pattern of the ends 220 can help to more gradually and / or smoothly transition from the first dimension 212A at the first end 210A to the second dimension 212B at the second end 210B. In addition, for example, relative to, for example Figure 1 With the arrangement of the tips 120 in FIG. 1 (which are grouped near the first outer surface 114 ), the monotonous outward pattern of the tips 220 can help achieve a relatively greater degree of symmetry.

[0067] according to Figure 2 In addition or alternative aspects of the monotonically outward pattern shown, the reduction layers 218B can be arranged into multiple pairs of reduction layers 218B, which define a sequence of the reduction layers 218B decreasing in the direction from the first end 210A toward the second end 210B (i.e., the sequence of the corresponding positions of the end 220 in the direction from the first end 210A toward the second end 210B). In particular, each pair of reduction layers 218B can include a corresponding one of the first subset of reduction layers 218B and a corresponding one of the second subset of reduction layers 218B.

[0068] For example, in Figure 2 The first pair includes layer 218 i＝13，18, the second pair includes layer 218 i＝11，20 , the third pair includes layer 218 i＝9，22 , and the fourth pair includes layer 218 i＝7，24 .like Figure 2 As shown, in the direction from the first end 210A to the second end 210B, the reduction layers 218B decrease in order from the first pair to the fourth pair. In other words, the end 220 of the first pair of reduction layers 218B is closest to the first end 210A, the end 220 of the second pair of reduction layers 218B is second closest to the first end 210A, the end 220 of the third pair of reduction layers 218B is third closest to the first end 210A, and the end 220 of the fourth pair of reduction layers 218B is farthest from the first end 210A.

[0069] Additionally, for example, for each pair of reduction layers 218B, a corresponding one of the reduction layers 218B of the first subset and a corresponding one of the reduction layers 218B of the second subset may be substantially equidistant from the central portion 224 in a dimension between the first outer surface 214 and the second outer surface 216. Figure 2 As shown, the first pair of subtractive layers 218B are spaced from the central portion 224 by a distance equal to that of the single layer 218 i The first pair of reduction layers 218B are each spaced a distance equal to three times the layer thickness 226 from the center portion 224; the second pair of reduction layers 218B are each spaced a distance equal to five times the layer thickness 226 from the center portion 224; and the fourth pair of reduction layers 218B are each spaced a distance equal to seven times the layer thickness 226 from the center portion 224. Arranging the reduction layers 218B in pairs, with the reduction layers 218B (i) decreasing in order from the first end 210A to the second end 210B, and / or (ii) equidistant from the center portion 224, can additionally facilitate a gradual and / or smooth transition from the first specification 212A at the first end 210A to the second specification 212B at the second end 210B, and / or achieve a smooth transition from, for example, the first specification 212A at the first end 210A to the second specification 212B at the second end 210B. Figure 1 The arrangement of the tips 120 in (the tips 120 are grouped near the first outer surface 114) has a relatively greater degree of symmetry.

[0070] In an example, each reduction layer 218B may have a layer angle of between about -30 degrees and +30 degrees relative to the longitudinal axis (e.g., longitudinal axis 348) of the composite structure 200. This may help achieve a desired stiffness with a relatively small (or minimized) number of layers 218i, and thus reduce (or may minimize) the weight and / or cost of manufacturing the composite structure 200. In an example, for each pair, the layer angles of the reduction layers 218B in the pair are approximately the same. This may help improve (or may maximize) the symmetry of the composite structure 200.

[0071] according to Figure 2In addition or alternatively to the monotonically outward pattern shown, the monotonically outward pattern may include: the ends 220 of the first subset of reduced layers 218B alternate with the ends 220 of the second subset of reduced layers 218B in a direction from the first end 210A to the second end 210B. Figure 2 , from the first end 210A to the second end 210B, the order of the end 220 of the subtracted layers 218B is as follows: (i) the layers 218 from the second subset i＝18 end 220, (ii) layer 218 from the first subset i＝13 end 220, (iii) layer 218 from the second subset i＝20 end 220, (iv) layer 218 from the first subset i＝11 end 220, (v) layer 218 from the second subset i＝22 end 220, (vi) layer 218 from the first subset i＝9 end 220, (vii) layer 218 from the second subset i＝24 end 220 of the first subset, and (viii) layer 218 from the first subset i＝7 Alternating the respective positions of the ends 220 of the subtractive layers 218B may additionally or alternatively facilitate a more gradual and / or smooth transition from the first dimension 212A at the first end 210A to the second dimension 212B at the second end 210B.

[0072] As described above, arranging the reduction layers 218B such that the ends 220 of the reduction layers 218B are staggered relative to each other may additionally or alternatively help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlayer strength. Figure 2 , the respective positions of the ends 220 of the subtractive layers 218B can be staggered from the first end 210A to the second end 210B. "Staggered" means that the ends 220 of the subtractive layers 218B are respectively at respective distances from the second end 210B, and the respective distances between the ends 220 and the second end 210B are all different from each other (i.e., no two ends of the subtractive layers are equidistant from the second end 210B). Staggering the ends 220 of the subtractive layers 218B can help alleviate some or all of the challenges associated with the above-described clustered arrangement of subtractive layers.

[0073] Moreover, as described above, spacing the ends 220 relative to each other by at least a threshold distance may additionally or alternatively help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength. In an example, for each reduction layer 218B, the distance 228 between the end 220 of the reduction layer 218B and the end 220 of an adjacent one of the reduction layers 218B may be at least ten times greater than the layer thickness 226 of the reduction layer 218B. In this example, for each reduction layer 218B, an adjacent one of the reduction layers 218B is adjacent to the reduction layer 218B in the dimension extending between the first outer surface 214 and the second outer surface 216. That is, two reduction layers 218B are adjacent to each other only if there is no other reduction layer 218B between the two reduction layers 218B in the dimension extending between the first outer surface 214 and the second outer surface 216. Thus, for example, the layers 218B may be spaced apart from each other by at least one threshold distance. i＝18 With layer 218 i＝16 and layer 218 i＝20 adjacent to the other subtractive layer 218B (ie, layer 218 i＝7，9，11，13，22，24 ) are not adjacent.

[0074] exist Figure 2 The layers 218 adjacent to each other are depicted in i＝18 The end 220 and the layer 218 i＝16 A representation of the distance 228 between the ends 220 of Figure 2 As shown, layer 218 i＝18 The end 220 and the layer 218 i＝16 The distance between the ends 228 is greater than that of the layer 218 i＝18 The layer thickness 226 is at least ten times greater. Similarly, Figure 2 2, the ends 220 of other adjacent subtractive layers of the subtractive layer 218B are separated by a respective distance 228, which is at least ten times greater than the layer thickness 226. As described above, arranging the subtractive layers 218B such that the ends 220 of adjacent subtractive layers of the subtractive layer 218B are separated by a distance 228 (the distance 228 is at least ten times the layer thickness 226) can help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength.

[0075] Additionally or alternatively, for example, the distance 230 between non-adjacent subtraction layers of the subtraction layer 218B may be at least three times greater than the layer thickness 226 of each subtraction layer 218B. Figure 2 Layer 218 is depicted in i＝18 The end 220 and the layer 218 i＝13 A representation of the distance 230 between the ends 220 of the layer 218 i＝18 With layer 218 i＝13 are not adjacent to each other (for example, because layer 218i＝16 On level 218 i＝18 With layer 218 i＝13 between). Figure 2 As shown, layer 218 i＝18 The distance 230 between the end 220 of the layer 218i=13 is greater than that of the layer 218 i＝18 226. Similarly, the ends 220 of other non-adjacent subtraction layers in subtraction layers 218B are separated by respective distances 230, which are at least three times greater than the layer thickness 226. As described above, arranging subtraction layers 218B such that the ends 220 of non-adjacent subtraction layers of subtraction layers 218B are separated by distances 228 (distance 228 is at least three times the layer thickness 226) can help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength.

[0076] exist Figure 2 For all layers 218 i , the layer thickness 226 is the same. However, in another example, one or more layers 218i may have a thickness different from another layer 218 i In some embodiments, layer 218 i Providing different layer thicknesses can help provide relatively greater flexibility in achieving manufacturing quality goals.

[0077] In addition, Figure 2 In the embodiment, the ends 220 of the subtractive layer 218B all have a tapered shape. However, in another example, one or more ends 220 of the subtractive layer 218B may have Figure 1 Although a tapered shape may be beneficial for at least the reasons described above, a subtractive layer 218B including a tip 120 having a blunt tip shape and having the above Figure 2 The composite structure of a pattern describing one or more characteristics can provide Figure 1 The composite structure 100 shown in FIG. Figure 1 The composite structure of the reduced layer 118B arranged in the mode shown, but with the end 220 having a tapered shape, can provide Figure 1 Thus, in an example, the subtractive layers 118B, 218B may have a tapered end 220 and / or a blunt end 120, and the subtractive layers 118B, 218B may be arranged in a clustered pattern (e.g. Figure 1 shown) and / or having the above Figure 2 The pattern of one or more of the characteristics described.

[0078] As described, arranging the ends 220 of the reduction layers 218B in a pattern having one or more of the above-described characteristics may facilitate relative to, for example, Figure 1 The arrangement of the ends 120 in the composite structure 200 achieves a relatively large degree of symmetry (e.g., about the center portion 224). As used herein, the term "symmetric" is intended to be a relative term and does not mean perfect symmetry. For example, Figure 2 As shown, the composite structure 200 includes 14 layers 218 between the central portion 224 and the first outer surface 214. i , and 12 layers 218 between the central portion 224 and the second outer surface 216 i However, in the context of this disclosure, relative to Figure 1 The composite structure 100 shown, Figure 2 The composite structure 200 is shown to have a greater degree of symmetry.

[0079] In an example, providing the composite structure 200 with a relatively greater degree of symmetry about the center portion 224 may help increase (or may maximize) interlaminar strength. Additionally or alternatively, providing the composite structure 200 with a relatively greater degree of symmetry about the center portion 224 may help reduce (or may minimize) re-solidification, processing, material handling costs, and / or weight.

[0080] As mentioned above, Figure 2 Composite structure 200 showing reduced ply 218B arranged in an exemplary pattern of one or more properties may facilitate improved performance, reduced resolidification, reduced tooling, reduced material handling costs, and / or reduced weight of composite structure 200. Other exemplary patterns of one or more properties are possible.

[0081] For example, Figure 3 A composite structure 300 having variable specifications is shown according to another example. Figure 3 As shown, the composite structure 300 includes a first end 310A having a first dimension 312A and a second end 310B having a second dimension 312B, wherein the second dimension 312B is smaller than the first dimension 312A of the first end 310A. Figure 3 As shown, the composite structure 300 includes a first outer surface 314 extending from the first end 310A to the second end 310B, and a second outer surface 316 extending from the first end 310A to the second end 310B.

[0082] Likewise Figure 3 As shown, the composite structure 300 includes a plurality of layers 318 of composite material stacked between the second outer surface 316 and the first outer surface 314. i＝1 To 318 i＝n (hereinafter collectively referred to as "layer 318i ”), where n is an integer greater than or equal to 2. Figure 3 In the embodiment, the composite structure 300 includes a total of 28 layers 318 i (ie, n=28). However, in other examples, composite structure 300 may include a fewer number or a greater number of layers 318 i .

[0083] In this arrangement, the first dimension 312A of the first end 310A and the second dimension 312B of the second end 310B have respective thicknesses between the second outer surface 316 and the first outer surface 314 at the first end 310A and the second end 310B, respectively. i The second specification 312B is related to the number of layers 318 at the second end 310B. i For example, in Figure 3 In the first end 310A, the layer 318 i The number of layers 318 at the second end 310B is greater than i The number of first specifications 312A makes it larger than the second specifications 312B.

[0084] As described above, the layer 318 of the composite material i Resulting in a variable thickness of the composite structure 300, the layer 318i includes a plurality of continuous layers 318A and a plurality of reduced layers 318B arranged in a stacked manner between the second outer surface 316 and the first outer surface 314. Figure 3 In the embodiment, each continuous layer 318A extends from the first end 310A to the second end 310B. However, each subtractive layer 318B includes an end 320, and each subtractive layer 318B extends from the first end 310A to a corresponding position between the first end 310A and the second end 310B.

[0085] For the sake of clarity, in Figure 3 In the embodiment, the representative subset of continuous layers 318A is labeled with reference numeral 318A, while the representative subset of reduced layers 318B is labeled with reference numeral 318B. However, each layer 318 extending completely from the first end 310A to the second end 310B i is one of the continuous layers 318A, and each layer 318 terminates between the first end 310A and the second end 310B. i is a layer in the subtraction layer 318B. Specifically, Figure 3 Middle, floor 318 i＝1-4，6，8，10，12，14，15，17，19，21，23，25-28 is a continuous layer 318A, and layer 318 i＝5，7，9，11，13，16，18，20，22，24 It is the subtracted layer 318B.

[0086] like Figure 3As shown, the end 320 of each subtractive layer 318B has the above Figure 2 Thus, the tapered end 320 may reduce (or minimize) the resin pocket at the end 320 of the reduction layer 318B, which may help improve (or maximize) the interlaminar strength of the composite structure 300. However, in other examples, one or more reduction layers 318B may have Figure 1 Blunt tip shape shown.

[0087] As described above, additionally or alternatively, layer 318 may be used. i The pattern arranged in the composite structure 300 enhances the load-bearing performance of the composite structure 300. For example, Figure 3 In the embodiment, the subtractive layers 218B can be separated from each other by at least one of the continuous layers 318A. For example, each subtractive layer 318B can be sandwiched between and against corresponding two continuous layers 318A in the plurality of continuous layers 318A. By separating the subtractive layers 318B from each other and / or sandwiching the subtractive layers 318B between the continuous layers 318A, the subtractive layers 318B can be more evenly distributed between the second outer surface 316 and the first outer surface 314 (with the subtractive layers 318B being more uniformly distributed between the second outer surface 316 and the first outer surface 314). Figure 1 This may help reduce (or may prevent) ply kinking and / or wrinkling, reduce (or may prevent) resin pockets, and / or increase (or may maximize) inter-ply strength of composite structure 300.

[0088] In an example, the pattern of the ends 320 of the subtractive layers 218B may additionally or alternatively include one or more of the following characteristics: (i) the pattern of the ends 320 in the front half of the composite structure 300 is arranged in a pattern that is a mirror image of the pattern of the ends 320 in the back half of the composite structure 300, (ii) the staggered arrangement of the ends 320 relative to each other, and / or (iii) the ends 320 are spaced apart relative to each other by at least a threshold distance. As described above, each of these characteristics may contribute, alone or in combination, to arranging the subtractive layers 318B in a pattern that may reduce (or may prevent) ply kinking and / or wrinkling, may reduce (or may prevent) resin pockets, and / or increase (or may maximize) inter-ply strength.

[0089] Figure 3 The ends 320 are shown arranged in a mirrored pattern relative to a center portion 324 of the composite structure 300 according to another example. The center portion 324 may include one or more layers 318. i , layer 318 iA reference frame is provided to characterize the pattern of ends 320 of reduced layers 318B on opposite sides of central portion 324. Central portion 324 is (i) between second outer surface 316 and first outer surface 314, and (ii) extends from first end 310A to second end 310B.

[0090] exist Figure 3 In the embodiment, the central portion 324 may include layer 318 i＝14，15 Therefore, in Figure 3 In one embodiment, the center portion 324 may include two continuous layers 318A. However, in another example, the center portion 324 may include two subtractive layers 318B and at least one continuous layer 318A. In yet another example, the center portion 324 may consist of only a single subtractive layer 318B. In another example, the center portion 324 may consist of at least one continuous layer 318A and omit the subtractive layer 318B. More generally, the center portion 324 may include one or more continuous layers 318A and / or one or more subtractive layers 318B.

[0091] In addition, if Figure 3 As shown, the ends 320 of the subtractive layers 318B can be arranged in a substantially mirror image or mirrored pattern relative to the central portion 324. For example, a first subset of the subtractive layers 318B can be between the first outer surface 314 and the central portion 324, while a second subset of the subtractive layers 318B can be between the central portion 324 and the second outer surface 316. In this arrangement, the ends 320 of the first subset of subtractive layers 318B are arranged in a substantially mirrored pattern as the pattern of the ends 320 of the second subset of subtractive layers 318B. In other words, with reference to the central portion 324, the corresponding locations of the ends 320 of the first subset of subtractive layers 318B are (i) oppositely and (ii) similarly (or identically) arranged compared to the corresponding locations of the ends 320 of the second subset of subtractive layers 318B.

[0092] For example, in Figure 3 In the embodiment, the central portion 324 may include layer 318 i＝14，15 , minus the first subset of layers 318B may include layers 318 i＝5，7，9，11，13 , and the second subset minus layer 318B may include layer 318 i＝16，18，20，22，24 .like Figure 3 As shown, the pattern of the ends 320 of the first subset of subtracted layers 318B is substantially mirrored with the pattern of the ends 320 of the second subset of subtracted layers 318B. For example, referring to the central portion 334, the corresponding positions of the ends 330 of the first subset are oppositely and similarly arranged compared to the corresponding positions of the ends 330 of the second subset.

[0093] As mentioned above, Figure 2 The pattern of the end 220 of the reduced layer 218B is shown to be a monotonically outward pattern. Figure 3 The ends 320 of the reduction layers 318B are shown arranged in a monotonically inward pattern according to an example. In a first sequence of the first subset of the reduction layers 318B from the first outer surface 314 toward the central portion 324, the relative distances between the ends 220 of the reduction layers 318B and the second end 310B of the respective reduction layers 318B in the first sequence are sequentially reduced. Moreover, in a second sequence of the second subset of the reduction layers 318B from the second outer surface 316 toward the central portion 324, the relative distances between the ends 220 of the reduction layers 318B and the second end 310B of the respective reduction layers 318B in the second sequence are sequentially reduced.

[0094] In this way, Figure 3 Medium, (i) layer 318 i＝5 The end 320 of the layer 318 is at a first distance from the second end 310B, (ii) i＝7 The end 320 of the layer 318 is at a second distance from the second end 310B (the second distance is less than the first distance), (iii) the layer 318 i＝9 The end 320 of the layer 318 is at a third distance from the second end 310B (the third distance is less than the second distance), i＝11 The end 320 of the layer 318 is at a fourth distance from the second end 310B (the fourth distance is less than the third distance), and (v) the layer 318 i＝13 The end 320 of is at a fifth distance from the second end 310B (the fifth distance is less than the fourth distance). Figure 3 Middle, (vi) layer 318 i＝24 The end 320 of the layer 318 is at a sixth distance from the second end 310B. i＝22 The end 320 of the layer 318 is at a seventh distance from the second end 310B (the seventh distance is less than the sixth distance), (viii) i＝20 The end 320 of the layer 318 is at an eighth distance from the second end 310B (the eighth distance is less than the seventh distance), i＝18 The end 320 of the (x) layer 318 is at a ninth distance from the second end 310B (the ninth distance is less than the eighth distance), and i＝16 The end 320 is at the tenth distance from the second end 310B (the tenth distance is less than the ninth distance).

[0095] Therefore, in Figure 3In the monotonically inward pattern of the ends 320 shown, the ends 320 of the reduced layers 318B generally appear to converge inwardly from the first outer surface 314 and the second outer surface 316 in a direction from the first end 310A to the second end 310B toward the central portion 324. The monotonically inward pattern of the ends 320 can facilitate a more gradual and / or smooth transition from the first gauge 312A at the first end 310A to the second gauge 312B at the second end 310B. Additionally, for example, with respect to, for example Figure 1 With the arrangement of the tips 120 in FIG. 1 (which are grouped near the first outer surface 114 ), the monotonically inward pattern of the tips 320 can help achieve a relatively greater degree of symmetry.

[0096] according to Figure 3 In addition or alternative aspects of the monotonically inward pattern shown, the reduction layers 318B can be arranged into a plurality of pairs of reduction layers 318B that define a sequence of the reduction layers 318B decreasing in a direction from the first end 310A toward the second end 310B (i.e., the sequence of the corresponding positions of the end 320 in a direction from the first end 310A toward the second end 310B). In particular, each pair of reduction layers 318B can include a corresponding one of the first subset of reduction layers 318B and a corresponding one of the second subset of reduction layers 318B.

[0097] For example, in Figure 3 The first pair includes layer 318 i＝5，24 , the second pair includes layer 318 i＝7，22 , the third pair includes layer 318 i＝9，20 , the fourth pair includes layer 318 i＝11，18 , and the fifth pair includes layer 318 i＝13，16 .like Figure 3 As shown, in the direction from the first end 310A to the second end 310B, the reduction layers 318B decrease in order from the first pair to the fifth pair. In other words, the end 320 of the first pair of reduction layers 318B is closest to the first end 310A, the end 320 of the second pair of reduction layers 318B is second closest to the first end 310A, the end 320 of the third pair of reduction layers 318B is third closest to the first end 310A, the end 320 of the fourth pair of reduction layers 318B is second farthest from the first end 310A, and the end 320 of the fifth pair of reduction layers 318B is farthest from the first end 310A.

[0098] Additionally, for example, for each pair of subtractive layers 318B, the dimension between the first outer surface 314 and the second outer surface 316, a corresponding one of the subtractive layers 318B of the first subset and a corresponding one of the subtractive layers 318B of the second subset may be equidistant from the central portion 324. Figure 3 As shown, each layer in the first pair of subtractive layers 318B is spaced from the central portion 324 by an amount equal to that of a single layer 318 iThe second pair of reduction layers 318B are each spaced apart from the center portion 324 by a distance equal to eight times the layer thickness 326; the third pair of reduction layers 318B are each spaced apart from the center portion 324 by a distance equal to six times the layer thickness 326, the fourth pair of reduction layers 318B are each spaced apart from the center portion 324 by a distance equal to two times the layer thickness 326, and the fifth pair of reduction layers 318B are each immediately adjacent to and abutting the center portion 324. Arranging the reduction layers 318B in pairs, with the reduction layers 318B (i) decreasing in pairs in order from the first end 310A to the second end 310B, and / or (ii) equidistant relative to the center portion 324, can additionally facilitate a more gradual and / or smooth transition from the first gauge 312A at the first end 310A to the second gauge 312B at the second end 310B, and / or achieve a smoother transition relative to, for example, the first gauge 312A at the first end 310A to the second gauge 312B at the second end 310B. Figure 1 The arrangement of the tips 120 in (the tips 120 are grouped near the first outer surface 114) has a relatively greater degree of symmetry.

[0099] according to Figure 3 In addition or alternatively to the monotonically inward pattern shown, the monotonically inward pattern may include: the ends 320 of the first subset of reduced layers 318B alternate with the ends 320 of the second subset of reduced layers 318B in a direction from the first end 310A to the second end 310B. Figure 3 , from the first end 310A to the second end 310B, the order of the end 320 of the subtracted layers 318B is as follows: (i) the layers 318 from the first subset i＝5 end 320, (ii) layer 318 from the second subset i＝24 end 320, (iii) layer 318 from the first subset i＝7 end 320, (iv) layer 318 from the second subset i＝22 The end 320 of (v) layer 318 from the first subset i＝9 end 320, (vi) layer 318 from the second subset i＝20 end 320, (vii) layer 318 from the first subset i＝11 end 320, (viii) layer 318 from the second subset i＝18 end 320, (ix) layer 318 from the first subset i＝13 end 320 of, and (x) layer 318 from the second subset i＝16 Alternating the respective positions of the ends 320 of the subtractive layers 318B may additionally or alternatively facilitate a more gradual and / or smooth transition from the first dimension 312A at the first end 310A to the second dimension 312B at the second end 310B.

[0100] As described above, arranging the reduction layers 318B such that the ends 320 of the reduction layers 318B are staggered relative to each other may additionally or alternatively help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlayer strength. Figure 3 , the respective positions of the ends 320 of the subtractive layers 318B can be staggered from the first end 310A to the second end 310B. "Staggered" means that the ends 320 of the subtractive layers 318B are respectively at respective distances from the second end 310B, and the respective distances between the ends 320 and the second end 310B are all different from each other (i.e., no two ends of the subtractive layers are equidistant from the second end 310B). Staggering the ends 320 of the subtractive layers 318B can help alleviate some or all of the challenges associated with the above-described clustered arrangement of subtractive layers.

[0101] Moreover, as described above, spacing the ends 320 relative to each other by at least a threshold distance may additionally or alternatively help reduce (or may prevent) layer kinking and / or wrinkling, reduce (or may prevent) resin pockets, and / or increase (or may maximize) inter-layer strength. In an example, for each reduction layer 318B, a distance 328 between the end 320 of the reduction layer 318B and the end 320 of an adjacent one of the reduction layers 318B may be at least ten times greater than the layer thickness 326 of the reduction layer 318B. In this example, for each reduction layer 318B, an adjacent one of the reduction layers 318B is adjacent to the reduction layer 318B in the dimension extending between the first outer surface 314 and the second outer surface 316. For example, as described above, two reduction layers 318B are adjacent to each other only if there is no other reduction layer 318B between them in the dimension extending between the first outer surface 314 and the second outer surface 316. Thus, for example, the layers 318B may be spaced apart from each other by at least a threshold distance. i＝7 With layer 318 i＝5 and layer 318 i＝9 adjacent to the other subtractive layer 318B (ie, layer 318 i＝11，13，16，18，20，22，24 ) are not adjacent.

[0102] exist Figure 3 The layers 318 adjacent to each other are depicted in i＝7 The end 320 and the layer 318 i＝5 A representation of the distance 328 between the ends 320 of Figure 3 As shown, layer 318 i＝7 The end 320 and the layer 318 i＝5 The distance between the ends of 328 is greater than that of layer 318 i＝7 The layer thickness 326 of is at least ten times greater. Similarly, Figure 33, the ends 320 of other adjacent subtractive layers of the subtractive layer 318B are separated by a respective distance 328, which is at least ten times greater than the layer thickness 326. As described above, arranging the subtractive layers 318B such that the ends 320 of adjacent subtractive layers of the subtractive layer 318B are separated by a distance 328 (the distance 328 is at least ten times the layer thickness 326) can help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength.

[0103] Additionally or alternatively, for example, the distance 330 between non-adjacent subtraction layers of the subtraction layer 318B may be at least three times greater than the layer thickness 326 of each subtraction layer 318B. Figure 3 Layer 318 is depicted in i＝7 The end 320 and the layer 318 i＝22 A representation of the distance 330 between the ends 320 of the layer 318 i＝7 With layer 318 i＝22 are not adjacent to each other (for example, because layer 318 i＝9，11，13，16，18，20 On level 318 i＝7 and layer 318i=22). Figure 3 As shown, layer 318 i＝7 The end 320 and the layer 318 i＝22 The distance between the ends of 330 is greater than that of layer 318 i＝7 326. Similarly, the ends 320 of other non-adjacent subtractive layers in subtractive layers 318B are separated by respective distances 330, which are at least three times greater than the layer thickness 326. As described above, arranging subtractive layers 318B such that the ends 320 of non-adjacent subtractive layers of subtractive layers 318B are separated by distances 328 (distance 328 is at least three times the layer thickness 326) can help reduce (or prevent) layer kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) inter-layer strength.

[0104] exist Figure 3 For all layers 318 i , the layer thickness 326 is the same. However, in another example, one or more layers 318i may have a thickness different from another layer 318i. i In some embodiments, layer 218 i Providing different layer thicknesses can help provide relatively greater flexibility in achieving manufacturing quality goals.

[0105] In addition, Figure 3 In the embodiment, the ends 320 of the subtractive layer 318B all have a tapered shape. However, in another example, one or more ends 320 of the subtractive layer 318B may have Figure 1The blunt end shape of the tip 120 shown. Although a tapered shape may be beneficial for at least the reasons described above, the subtractive layer 318B including the tip 120 having a blunt end shape and having the above Figure 3 The composite structure of a pattern describing one or more characteristics can provide Figure 1 An improvement to the composite structure 100 is shown.

[0106] exist Figures 1 to 3 , a composite structure 100, 200, 300 having a shape that is curved between a first end 110A, 210A, 310A and a second end 110B, 210B, 310B is shown. However, in other examples, the composite structure 100, 200, 300 may have a different shape, such as, for example, a planar shape, a scalloped shape, a corrugated shape, a uniform shape, a non-uniform shape, a polygonal shape, and / or a non-polygonal shape.

[0107] In some examples, the first end 110A, 210A, 310A and / or the second end 110B, 210B, 310B may form an outer surface of the composite structure 100, 200, 300. However, in other examples, the first end 110A, 210A, 310A and / or the second end 110B, 210B, 310B may be connected to corresponding sections of other sections of a larger composite structure. For example, Figures 1 to 3 The illustrated composite structures 100 , 200 , 300 may provide a transition section of a composite structure for transitioning from one specification to another within the composite structure.

[0108] Reference Figure 4 , shows a simplified block diagram of a composite structure 400 with variable specifications according to another example. Figure 4 As shown, composite structure 400 includes a first section 440, a second section 442, and a transition section 444 between first section 440 and second section 442. First section 440 has a first dimension 412A, and second section 442 has a second dimension 412B that is smaller than first dimension 412A. Figure 4 Composite structure 400 is depicted as having three segments (ie, first segment 440 , transition segment 444 , and second segment 442 ), but in other examples, composite structure 400 may include a fewer or greater number of segments.

[0109] The transition section 444 may have a variable specification for transitioning between the first specification 412A and the second specification 412B. For example, the transition section 444 may include one or more continuous layers and one or more reduced layers, which are configured as described above with respect to Figures 1 to 3The composite structure 100 , 200 , 300 is shown transitioning between a first dimension 412A and a second dimension 412B.

[0110] For example, Figure 4 As shown, the transition section 444 includes a first end 410A at the first section 440 and having a first dimension 412A, a second end 410B at the second section 442 and having a second dimension 412B, a first outer surface 414 extending from the first end 410A to the second end 410B, and a second outer surface 416 extending from the first end 410A to the second end 410B. Thus, the first end 410A can provide a connection between the first section 440 and the transition section 444, and the second end 410B can provide a connection between the second section 442 and the transition section 444.

[0111] The transition section 444 also includes a plurality of layers 418 that (i) extend between the first end 410A and the second end 410B and (ii) are stacked and arranged between the first outer surface 414 and the second outer surface 416. Figure 4 As shown, the layer 418 includes a plurality of continuous layers 418A and at least one subtractive layer 418B. As described above, each continuous layer 418A extends from the first end 410A to the second end 410B, each subtractive layer 418B includes a terminal end 420, and each subtractive layer 418B extends from the first end 410A to the terminal end 420 of the subtractive layer 418B at a corresponding position between the first end 410A and the second end 410B. In an example, the terminal end 420 of the subtractive layer 418B may have a tapered shape (e.g., as shown in FIG. 1 ). Figures 2 to 3 ) and / or a blunt-ended shape (e.g., Figure 1 shown).

[0112] In some examples, each subtractive layer 418B is sandwiched between and abuts against corresponding two continuous layers 418A in the plurality of continuous layers 418A. Additionally or alternatively, the ends 420 of the subtractive layers 418B may be arranged in a monotonically outward pattern (e.g., as Figure 2 ), a monotonous inward pattern (e.g. Figure 3 ), staggered mode (e.g. Figures 2 to 3 ) and / or substantially mirrored patterns (e.g., as Figures 2 to 3 as shown), as described above.

[0113] For example, in an embodiment where the ends 420 are arranged in a monotonically inward pattern, (i) a first subset of the reduction layers 418B are between the first outer surface 414 and the central portion of the stack, and a second subset of the reduction layers 418B are between the central portion and the second outer surface 416, (ii) in a first sequence of the first subset of the reduction layers 418B from the first outer surface 414 toward the central portion, the relative distances between the ends 420 of the reduction layers 418B and the second ends 410B in the first sequence decrease sequentially, and (iii) in a second sequence of the second subset of the reduction layers 418B from the second outer surface 416 toward the central portion, the relative distances between the ends 420 of the reduction layers 418B and the second ends 410B in the second sequence decrease sequentially.

[0114] In addition, for example, in an embodiment where the ends 420 are arranged in a monotonically outward pattern, (i) a first subset of the reduction layers 418B is between the first outer surface 414 and the center portion of the stack, and a second subset of the reduction layers 418B is between the center portion and the second outer surface 416, (ii) in a first sequence of the first subset of the reduction layers 418B from the center portion toward the first outer surface 414, the relative distances between the ends 420 of the reduction layers 418B and the second ends 410B of the reduction layers 418B in the first sequence decrease sequentially, and (iii) in a second sequence of the second subset of the reduction layers 418B from the center portion toward the second outer surface 416, the relative distances between the ends 420 of the reduction layers 418B and the second ends 410B in the second sequence decrease sequentially.

[0115] Additionally or alternatively, for each reduction layer 418B, the distance between the end 420 of the reduction layer 418B and the end 420 of an adjacent one of the reduction layers 418B may be at least ten times greater than the thickness of the reduction layer 418B. Additionally or alternatively, the distance between non-adjacent reduction layers of the reduction layer 418B may be at least three times greater than the thickness of each reduction layer 418B.

[0116] In the example, the above Figures 1 to 4 The composite structures 100, 200, 300, 400 described above can be used to form various structures. As an example, an aircraft, a spacecraft, a rotorcraft, a watercraft, an automobile, a truck, and / or another type of vehicle (e.g., a passenger cabin or a cargo container) can include the composite structures 100, 200, 300, 400 described above. In addition, for example, a building, a bridge, a swimming pool, a storage tank, a robot frame structure, an energy structure (e.g., a wind blade, a turbine blade, a propulsion blade, and / or a solar panel), a sporting goods (e.g., a bicycle frame, a sled, a snowboard, a surfboard, a paddle), a residence, an office building, and / or a medical panel rack can include the composite structures 100, 200, 300, 400 described above.

[0117] As an example, FIG. 5A to FIG. 5B A composite stringer 550 is depicted, which may include the composite stringer 550 described above. Figures 1 to 4 One or more of the composite structures 100, 200, 300, 400 described. Typically, a composite stringer 550 is an elongated member that can be coupled to one or more skin panels to help carry and / or transfer loads from the skin panels of an aircraft to another structure (e.g., a frame, ribs, and / or spar of the aircraft). In this way, the composite stringer 550 can help prevent bending under compressive or shear loads on the skin panels, and / or reduce bending of the skin panels. For these and other reasons, aircraft typically include one or more composite stringers 550 in the fuselage, wing assemblies, and / or tail of the aircraft.

[0118] Typically, the composite stringer 550 includes one or more flanges 552A to 552C and one or more webs 554A to 554B. FIG. 5A to FIG. 5B In FIG. 5 , the composite stringer 550 includes a skin flange 552A configured to be coupled to a support structure 556 (eg, a skin panel of an aircraft), an upper flange 552B, and a web 554A extending between the skin flange 552A and the upper flange 552B. FIG. 5A to FIG. 5B In the embodiment, the composite stringer 550 is in the form of a hat-shaped stringer. Thus, the web 554A may extend from a first side of the upper flange 550B, and the composite stringer 550 may further include a second skin flange 552C configured to be coupled to the support structure 556 and a second web 554B extending between the second skin flange 552C and the second side of the upper flange 552B.

[0119] In an example, the composite stringer 550 may further include one or more corner portions, each corner portion providing a transition section between two other sections of the composite stringer 550 (i.e., between the skin flange 552A, the web 554A, the upper flange 552B, the second web 554B, and the second skin flange 552C). FIG. 5A to FIG. 5B , the corner portions of the composite stringer 550 may include (i) a first corner portion 558A extending from the skin flange 552A to the web 554A, (ii) a second corner portion 558B extending from the web 554A to the upper flange 552B, (iii) a third corner portion 558C extending from the second skin flange 552C to the second web 554B, and / or (iv) a fourth corner portion 558D extending from the second web 554B to the upper flange 552B.

[0120] Moreover, in FIG. 5A to FIG. 5BIn the example, the upper flange 552B has a first dimension 512A. The skin flange 552A, the second skin flange 552C, the web 554A and the second web 554B all have a second dimension 512B. In this example, the first dimension 512A is greater than the second dimension 512B.

[0121] In this arrangement, the second corner portion 558B and the fourth corner portion 558D can be a composite structure with variable specifications. For example, the upper flange 552B can be a first section (e.g., the first section 440), and the web 554A can be a second section (e.g., Figure 4 442 in the second section), and the second corner portion 558B can be a transition section between the upper flange 552B and the web 554A (e.g., Figure 4 Similarly, for example, the upper flange 552B may be a first segment (e.g., the first segment 440), and the second web 554B may be a second segment (e.g., Figure 4 442 in the second section), and the fourth corner portion 558D may be a transition section between the upper flange 552B and the second web 554B (eg, Figure 4 Transition section 444 in.

[0122] In particular, Figure 5A In the embodiment, the second corner portion 558B and the fourth corner portion 558D each include Figure 1 The composite structure 100 shown. Figure 5B In the embodiment, the second corner portion 558B and the fourth corner portion 558D each include Figure 3 The composite structure 300 shown. FIG. 5A to FIG. 5B As shown, Figure 3 The composite structure 300 includes a subtractive layer 318B having a tapered end 320 arranged in a monotonically inward pattern, with Figure 1 Compared to the composite structure 100 including the reduced layers 118B having the blunt-end shaped tips 120 arranged in groups at or near the first outer surface 114, Figure 3 The composite structure 300 provides a smoother and relatively more symmetrical transition from the first dimension 512A to the second dimension 512B.

[0123] As mentioned above, FIG. 5A to FIG. 5B One example of a structure that may include the composite structures 100, 200, 300, 400 described herein is depicted. However, as described above, the composite structures 100, 200, 300, 400 may be incorporated into other structures. FIG. 5A to FIG. 5B In structures other than the composite stringer 550 shown.

[0124] Now refer to Figure 6, a flow chart of a process 600 for forming a composite structure having variable specifications is described according to an example. Figure 6 As shown, at block 610, process 600 includes forming a plurality of continuous layers. At block 612, process 600 includes forming a plurality of subtractive layers. Forming a plurality of subtractive layers at block 612 may include, at block 614, for each subtractive layer, forming a tip of the subtractive layer having a tapered shape.

[0125] At block 616, process 600 includes positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having a first end and a second end. The first end has a first specification. The second end has a second specification that is smaller than the first specification. Figure 6 As shown, positioning the plurality of continuous layers and the plurality of subtractive layers at block 616 may include: positioning the plurality of continuous layers at block 618 so that each continuous layer extends from the first end to the second end. Positioning the plurality of continuous layers and the plurality of subtractive layers at block 616 may also include: positioning the plurality of subtractive layers at block 620 so that (i) each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end, and (ii) the plurality of subtractive layers are separated from each other by at least one continuous layer of the plurality of continuous layers.

[0126] Figures 7 to 14 Additional aspects of process 600 are depicted according to other examples. Figure 7 As shown, process 600 may also include, at block 622 , curing the plurality of continuous layers and the plurality of subtractive layers after positioning the plurality of continuous layers and the plurality of subtractive layers in a stack at block 616 .

[0127] like Figure 8 As shown, positioning the plurality of continuous layers and the plurality of subtractive layers in a stack at block 616 may also include forming a first outer surface extending from the first end to the second end at block 624, and forming a second outer surface extending from the first end to the second end at block 626. The first specification and the second specification may be respective thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0128] like Fig. 9 As shown, positioning the plurality of continuous layers and the plurality of subtractive layers in a stack at block 616 may include positioning a first subset of the plurality of subtractive layers between the first outer surface and the central portion at block 628. The central portion (i) is between the first outer surface and the second outer surface, and (ii) extends from the first end to the second end. Also, at block 628, Fig. 9 In the embodiment, positioning the plurality of continuous layers and the plurality of subtractive layers in a stack at block 616 may include positioning a second subset of the plurality of subtractive layers between the central portion and the second outer surface at block 630 .

[0129] like Fig.10As shown, positioning a first subset of the plurality of subtracted layers at block 628 and positioning a second subset of the plurality of subtracted layers at block 630 may include, at block 632, positioning the plurality of subtracted layers such that ends of the first subset of the plurality of subtracted layers are arranged in a pattern that is substantially mirror image of a pattern of ends of the second subset of the plurality of subtracted layers.

[0130] like Fig.11 As shown, positioning the plurality of subtractive layers at block 620 may include, at block 634 , positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0131] like Fig.12 As shown, positioning the first subset of the plurality of reduction layers at box 628 may include: (i) at box 636, positioning the first subset of the plurality of reduction layers in an order from a reduction layer closest to the central portion to a reduction layer closest to the first outer surface, and (ii) at box 638, positioning the first subset of the plurality of reduction layers such that the pattern of the ends of the first subset of the plurality of reduction layers includes: the relative distances between the ends of the reduction layers and the second ends of the respective reduction layers in the order decrease in sequence.

[0132] Moreover, if Fig.12 As shown, positioning the second subset of the plurality of reduction layers at box 630 may include: (i) at box 640, positioning the second subset of the plurality of reduction layers includes: positioning the second subset of the plurality of reduction layers in an order from a reduction layer closest to the central portion to a reduction layer closest to the second outer surface, and (ii) at box 642, positioning the second subset of the plurality of reduction layers so that the pattern of the ends of the second subset of the plurality of reduction layers includes: the relative distances between the ends of the reduction layers and the second end of the respective reduction layers in the order decrease sequentially.

[0133] like Fig.13 As shown, positioning the plurality of subtraction layers at block 620 may include positioning the plurality of subtraction layers at block 644 such that, for each subtraction layer, a distance between an end of the subtraction layer and an end of an adjacent one of the plurality of subtraction layers is at least ten times greater than a thickness of the subtraction layer. For each subtraction layer, an adjacent one of the plurality of subtraction layers is adjacent to the subtraction layer in a dimension extending between the first outer surface and the second outer surface.

[0134] like Fig.14 As shown, positioning the plurality of subtraction layers at block 620 may include, at block 646 , positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0135] Now refer to Fig.15 , a flowchart of a process 1500 for forming a composite structure having variable specifications is described according to an example. Fig.15As shown, at block 1510, process 1500 includes: forming a plurality of continuous layers. At block 1512, process 1500 includes: forming a plurality of subtractive layers. Forming a plurality of subtractive layers at block 1512 may include: at block 1514, for each subtractive layer, forming a tip of the subtractive layer having a tapered shape.

[0136] At block 1516, process 1500 may include positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having (i) a first end, (ii) a second end, (iii) a first exterior surface extending from the first end to the second end, and (iv) a second exterior surface extending from the first end to the second end. The first end has a first dimension. The second end has a second dimension that is smaller than the first dimension.

[0137] exist Fig.15 In the embodiment of the present invention, positioning the plurality of continuous layers and the plurality of subtractive layers at block 1516 may include positioning the plurality of continuous layers such that each continuous layer extends from the first end to the second end at block 1518. Additionally, positioning the plurality of continuous layers and the plurality of subtractive layers at block 1516 may further include positioning the plurality of subtractive layers such that each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end at block 1520. A first subset of the plurality of subtractive layers is between the first outer surface and the central portion of the stack, and a second subset of the plurality of subtractive layers is between the central portion and the second outer surface.

[0138] Figures 16 to 21 Additional aspects of process 1500 are depicted according to other examples. Fig.16 As shown, positioning multiple continuous layers and multiple subtractive layers in a stack at box 1516 may also include: at box 1522, arranging the multiple subtractive layers in a monotonically inward pattern, including (i) in a first subset of the multiple subtractive layers in a first order from the first outer surface toward the central portion, the relative distance between the end and the second end of each subtractive layer in the first order decreases sequentially, and (ii) in a second subset of the multiple subtractive layers in a second order from the second outer surface toward the central portion, the relative distance between the end and the second end of each subtractive layer in the second order decreases sequentially.

[0139] like Fig.17 As shown, after positioning the plurality of continuous layers and the plurality of subtractive layers in a stack at block 1516 , process 1500 may include, at block 1524 , curing the plurality of continuous layers and the plurality of subtractive layers.

[0140] like Fig.18 As shown, positioning the plurality of continuous layers and the plurality of subtractive layers at block 1516 may include, at block 1526 , positioning the plurality of continuous layers and the plurality of subtractive layers such that the plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0141] like Fig.19 As shown, positioning the plurality of subtractive layers at block 1520 may include, at block 1528 , positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0142] like Fig. 20 As shown, positioning the plurality of subtraction layers at block 1520 may include: positioning the plurality of subtraction layers at block 1530 such that, for each subtraction layer, a distance between an end of the subtraction layer and an end of an adjacent one of the plurality of subtraction layers is at least ten times greater than a thickness of the subtraction layer. For each subtraction layer, an adjacent one of the plurality of subtraction layers is adjacent to the subtraction layer in a dimension extending between the first outer surface and the second outer surface.

[0143] like Fig.21 As shown, positioning the plurality of subtraction layers at block 1520 may include, at block 1532 , positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0144] Figures 6 to 21 One or more boxes shown in can represent a module, segment or part of a program code, which includes one or more instructions, which can be executed by a processor to implement a specific logical function or step in the process. The program code can be stored on any type of computer-readable medium or data storage (for example, a storage device including a disk or hard disk drive). In addition, the program code can be encoded on a computer-readable storage medium in a machine-readable format, or encoded on other non-transient media or products. The computer-readable medium may include a non-transient computer-readable medium or memory, for example, a computer-readable medium such as a register memory, a processor cache, and a random access memory (RAM) that stores data for a short time. The computer-readable medium may also include a non-transient medium, for example, such as an auxiliary or permanent long-term memory (such as a read-only memory (ROM), an optical disk or a disk, a CD-ROM read-only memory (CD-ROM)). The computer-readable medium may also be any other volatile or non-volatile storage system. For example, a computer-readable medium may be considered to be a tangible computer-readable storage medium.

[0145] In some cases, components of the devices and / or systems described herein may be configured to perform a function such that the components are actually configured and constructed (with hardware and / or software) to achieve such performance. Then, an example configuration includes one or more processors that execute instructions to cause the system to perform a function. Similarly, components of a device and / or system may be configured such that, for example, when operating in a particular manner, the components of the device and / or system are configured or adapted to be capable of or suitable for performing a function.

[0146] In addition, this disclosure includes examples according to the following clauses:

[0147] Clause 1: A composite structure having a variable gauge, the composite structure comprising a first end having a first gauge and a second end having a second gauge, the second gauge being smaller than the first gauge. The composite structure further comprises a plurality of continuous layers and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer comprises a terminal end having a tapered shape. Each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end. The plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0148] Clause 2: The composite structure of clause 1, further comprising: a first outer surface extending from the first end to the second end, and a second outer surface extending from the first end to the second end. The plurality of continuous layers and the plurality of reduced layers are stacked and arranged between the first outer surface and the second outer surface. The first specification and the second specification are the respective thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0149] Clause 3: The composite structure of clause 2, wherein a first subset of the plurality of subtractive layers is between the first exterior surface and the central portion. The central portion (i) is between the first exterior surface and the second exterior surface, and (ii) extends from the first end to the second end. A second subset of the plurality of subtractive layers is between the central portion and the second exterior surface. The ends of the first subset of the plurality of subtractive layers are arranged in a pattern that is substantially a mirror image of the pattern of the ends of the second subset of the plurality of subtractive layers.

[0150] Clause 4: The composite structure of Clause 3, wherein the central portion comprises a single reduced layer of the plurality of reduced layers.

[0151] Clause 5: The composite structure of Clause 3, wherein the central portion comprises two subtractive layers of the plurality of subtractive layers and at least one continuous layer of the plurality of continuous layers between the two subtractive layers.

[0152] Clause 6: The composite structure of any one of clauses 1 to 5, wherein the respective positions of the ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0153] Clause 7: The composite structure of clause 6, wherein a first subset of the plurality of reduction layers is in an order from a reduction layer closest to the central portion to a reduction layer closest to the first outer surface. The pattern of the ends of the first subset of the plurality of reduction layers includes: the relative distance between the ends of the reduction layers and the second end of each reduction layer in the order decreases in sequence. The second subset of the plurality of reduction layers is in an order from a reduction layer closest to the central portion to a reduction layer closest to the second outer surface. The pattern of the ends of the second subset of the plurality of reduction layers includes: the relative distance between the ends of the reduction layers and the second end of each reduction layer in the order decreases in sequence.

[0154] Clause 8: A composite structure according to any one of clauses 2 to 7, wherein, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0155] Clause 9: The composite structure of any one of clauses 1 to 8, wherein a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0156] Item 10: A method of forming a composite structure having a variable specification, the method comprising: forming a plurality of continuous layers and forming a plurality of subtractive layers. Forming the plurality of subtractive layers comprises: for each subtractive layer, forming an end of the subtractive layer having a tapered shape. The method further comprises: positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having a first end and a second end. The first end has a first specification. The second end has a second specification, the second specification being smaller than the first specification. Positioning the plurality of continuous layers and the plurality of subtractive layers comprises: (a) positioning the plurality of continuous layers such that each continuous layer extends from the first end to the second end; and (b) positioning the plurality of subtractive layers such that (i) each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end, and (ii) the plurality of subtractive layers are separated from each other by at least one of the plurality of continuous layers.

[0157] Clause 11: The method of clause 10, further comprising, after positioning the plurality of continuous layers and the plurality of subtractive layers in the stack, curing the plurality of continuous layers and the plurality of subtractive layers.

[0158] Clause 12: The method of any one of clauses 10 to 11, wherein positioning the plurality of continuous layers and the plurality of subtractive layers in a stack further comprises: forming a first outer surface extending from a first end to a second end, and forming a second outer surface extending from the first end to the second end. The first specification and the second specification are respective thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0159] Clause 13: The method of clause 12, wherein positioning the plurality of continuous layers and the plurality of subtractive layers in the stack comprises positioning a first subset of the plurality of subtractive layers between the first outer surface and the central portion. The central portion (i) is between the first outer surface and the second outer surface, and (ii) extends from the first end to the second end. Positioning the plurality of continuous layers and the plurality of subtractive layers in the stack further comprises positioning a second subset of the plurality of subtractive layers between the central portion and the second outer surface. Positioning the first subset of the plurality of subtractive layers and positioning the second subset of the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that the ends of the first subset of the plurality of subtractive layers are arranged in a pattern that is substantially mirror image of the pattern of the ends of the second subset of the plurality of subtractive layers.

[0160] Clause 14: The method of clause 13, wherein the central portion comprises a single subtractive layer of the plurality of subtractive layers.

[0161] Clause 15: The method of clause 13, wherein the central portion comprises two subtractive layers of the plurality of subtractive layers and at least one continuous layer of the plurality of continuous layers between the two subtractive layers.

[0162] Clause 16: The method of any one of clauses 10 to 15, wherein positioning the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0163] Clause 17: The method according to clause 16, wherein positioning the first subset of the plurality of reduction layers comprises: (i) positioning the first subset of the plurality of reduction layers in order from the reduction layer closest to the central portion to the reduction layer closest to the first outer surface, and (ii) positioning the first subset of the plurality of reduction layers such that the pattern of the ends of the first subset of the plurality of reduction layers includes: the relative distances between the ends of the reduction layers and the second ends of the reduction layers in the order sequentially decrease. Positioning the second subset of the plurality of reduction layers comprises: (a) positioning the second subset of the plurality of reduction layers comprises: positioning the second subset of the plurality of reduction layers in order from the reduction layer closest to the central portion to the reduction layer closest to the second outer surface, and (b) positioning the second subset of the plurality of reduction layers such that the pattern of the ends of the second subset of the plurality of reduction layers includes: the relative distances between the ends of the reduction layers and the second ends of the reduction layers in the order sequentially decrease.

[0164] Clause 18: The method of any one of clauses 10 to 17, wherein the plurality of reduction layers are positioned such that, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0165] Clause 19: The method of any one of clauses 10 to 18, wherein positioning the plurality of subtraction layers comprises positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0166] Clause 20: A composite structure having a variable specification. The composite structure includes a first section having a first specification and a second section having a second specification, the second specification being smaller than the first specification. The composite structure also includes a transition section between the first section and the second section. The transition section includes: a first end at the first section and having the first specification, a second end at the second section and having the second specification, a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) stacked and arranged between the first outer surface and the second outer surface. The plurality of layers include: (a) a plurality of continuous layers, wherein each continuous layer extends from the first end to the second end; and (b) at least one subtractive layer, wherein each subtractive layer includes an end having a tapered shape, wherein each subtractive layer extends from the first end to a corresponding position of the end of the subtractive layer between the first end and the second end. Each subtractive layer is sandwiched between and abuts against corresponding two continuous layers of the plurality of continuous layers.

[0167] Clause 21: A composite structure having a variable specification, the composite structure comprising a first end having a first specification and a second end having a second specification, the second specification being smaller than the first specification. The composite structure also comprises a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) arranged in a stacked arrangement between the first outer surface and the second outer surface. The plurality of layers comprises a plurality of continuous layers and a plurality of reduced layers. Each continuous layer extends from the first end to the second end. Each reduced layer comprises an end having a tapered shape. Each reduced layer extends from the first end to a corresponding position of the end of the reduced layer between the first end and the second end. A first subset of the plurality of reduced layers is between the first outer surface and a central portion of the stack, and a second subset of the plurality of reduced layers is between the central portion and the second outer surface. The ends of the plurality of reduction layers are arranged in a monotonically inward pattern, including (i) in a first sequence of a first subset of the plurality of reduction layers from the first outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the first sequence decrease in sequence, and (ii) in a second sequence of a second subset of the plurality of reduction layers from the second outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the second sequence decrease in sequence.

[0168] Clause 22: The composite structure of Clause 21, wherein the plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0169] Clause 23: The composite structure of any of clauses 21 to 22, wherein the first dimension and the second dimension are respective thicknesses between the first and second exterior surfaces at the first and second ends, respectively.

[0170] Clause 24: A composite structure according to any one of clauses 21 to 23, wherein the central portion comprises at least one continuous layer of the plurality of continuous layers.

[0171] Clause 25: The composite structure of any one of clauses 21 to 24, wherein the respective positions of the ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0172] Clause 26: The composite structure of clauses 21 to 25, wherein the monotonically inward pattern further comprises: ends of the first subset of the plurality of reduced layers alternating with ends of the second subset of the plurality of reduced layers in a direction from the first end to the second end.

[0173] Clause 27: A composite structure according to any one of clauses 21 to 26, wherein the plurality of reduction layers are arranged into a plurality of pairs of reduction layers. Each pair of reduction layers comprises a respective one reduction layer of the first subset and a respective one reduction layer of the second subset. For each pair of reduction layers, a respective one reduction layer of the first subset and a respective one reduction layer of the second subset are substantially equidistant from the central portion in a dimension between the first outer surface and the second outer surface.

[0174] Clause 28: The composite structure of any of clauses 21 to 27, wherein each subtractive ply has a ply angle relative to the longitudinal axis of the composite structure that is between approximately -30 degrees and +30 degrees.

[0175] Clause 29: The composite structure of clause 28, wherein, for each pair, the ply angles of the plurality of reduced plies in the pair are approximately the same.

[0176] Clause 30: A composite structure according to any one of clauses 21 to 29, wherein, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0177] Clause 31: The composite structure of any of Clauses 21 to 30, wherein a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0178] Clause 32: A method of forming a composite structure having a variable specification, the method comprising: forming a plurality of continuous layers and forming a plurality of subtractive layers. Forming the plurality of subtractive layers comprises: for each subtractive layer, forming an end of the subtractive layer having a tapered shape. The method further comprises: positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having (i) a first end, (ii) a second end, (iii) a first outer surface extending from the first end to the second end, and (iv) a second outer surface extending from the first end to the second end. The first end has a first specification and the second end has a second specification, the second specification being less than the first specification. Positioning the plurality of continuous layers and the plurality of subtractive layers comprises: positioning the plurality of continuous layers such that each continuous layer extends from the first end to the second end; and positioning the plurality of subtractive layers such that each subtractive layer extends from the first end to a corresponding position of the end of the subtractive layer between the first end and the second end. A first subset of the plurality of subtractive layers is between the first outer surface and a center portion of the stack, and a second subset of the plurality of subtractive layers is between the center portion and the second outer surface. Positioning the plurality of continuous layers and the plurality of subtractive layers in a stack further includes arranging the plurality of subtractive layers in a monotonically inward pattern, including (a) in a first sequence of a first subset of the plurality of subtractive layers from the first outer surface toward the central portion, the relative distances between the ends of the subtractive layers and the second ends in the first sequence decrease in sequence, and (b) in a second sequence of a second subset of the plurality of subtractive layers from the second outer surface toward the central portion, the relative distances between the ends of the subtractive layers and the second ends in the second sequence decrease in sequence.

[0179] Clause 33: The method of clause 32, further comprising: curing the plurality of continuous layers and the plurality of subtractive layers after positioning the plurality of continuous layers and the plurality of subtractive layers in the stack.

[0180] Clause 34: The method of any one of clauses 32 to 33, wherein positioning the plurality of continuous layers and the plurality of subtractive layers comprises positioning the plurality of continuous layers and the plurality of subtractive layers such that the plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0181] Clause 35: The method of any one of clauses 32 to 34, wherein the central portion comprises at least one continuous layer of a plurality of continuous layers.

[0182] Clause 36: The method of any one of clauses 32 to 35, wherein positioning the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0183] Clause 37: The method of any one of clauses 32 to 36, wherein the plurality of reduction layers are positioned such that, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0184] Clause 38: The method of any one of clauses 32 to 37, wherein positioning the plurality of subtraction layers comprises positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0185] Clause 39: A composite structure having a variable specification. The composite structure includes a first section having a first specification and a second section having a second specification, the second specification being smaller than the first specification. The composite structure also includes a transition section between the first section and the second section. The transition section includes a first end at the first section and having the first specification, a second end at the second section and having the second specification, a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) arranged in a stacked arrangement between the first outer surface and the second outer surface. The plurality of layers includes a plurality of continuous layers and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer includes an end having a tapered shape. Each subtractive layer extends from the first end to a corresponding position of an end of the subtractive layer between the first end and the second end. A first subset of the plurality of subtractive layers is between the first outer surface and a central portion of the stack, and a second subset of the plurality of subtractive layers is between the central portion and the second outer surface. The ends of the plurality of reduction layers are arranged in a monotonically inward pattern, including (a) in a first sequence of a first subset of the plurality of reduction layers from the first outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the first sequence decrease in sequence, and (b) in a second sequence of a second subset of the plurality of reduction layers from the second outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the second sequence decrease in sequence.

[0186] Clause 40: The composite structure of Clause 39, wherein the first section is a flange of the composite stringer and the second section is a web of the composite stringer.

[0187] Clause 41: A composite structure having a variable gauge, the composite structure comprising a first end having a first gauge and a second end having a second gauge, the second gauge being smaller than the first gauge. The composite structure further comprises a plurality of continuous layers and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer comprises a terminal end having a blunt end shape. Each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end. The plurality of subtractive layers are separated from each other by at least one continuous layer of the plurality of continuous layers.

[0188] Clause 42: The composite structure of clause 41, further comprising a first outer surface extending from the first end to the second end, and a second outer surface extending from the first end to the second end. The plurality of continuous layers and the plurality of reduced layers are stacked and arranged between the first outer surface and the second outer surface. The first specification and the second specification are the respective thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0189] Clause 43: The composite structure of clause 42, wherein a first subset of the plurality of subtractive layers is between the first exterior surface and the central portion. The central portion (i) is between the first exterior surface and the second exterior surface, and (ii) extends from the first end to the second end. A second subset of the plurality of subtractive layers is between the central portion and the second exterior surface. The ends of the first subset of the plurality of subtractive layers are arranged in a pattern that is substantially a mirror image of the pattern of the ends of the second subset of the plurality of subtractive layers.

[0190] Clause 44: The composite structure of Clause 43, wherein the central portion comprises a single reduced layer of the plurality of reduced layers.

[0191] Clause 45: The composite structure of Clause 43, wherein the central portion comprises two subtractive layers of the plurality of subtractive layers and at least one continuous layer of the plurality of continuous layers between the two subtractive layers.

[0192] Clause 46: The composite structure of any of Clauses 41 to 45, wherein the respective positions of the ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0193] Clause 47: A composite structure according to clause 46, wherein a first subset of the plurality of reduction layers is in an order from a reduction layer closest to the central portion to a reduction layer closest to the first outer surface. The pattern of the ends of the first subset of the plurality of reduction layers includes: the relative distance between the end of the reduction layer and the second end of each reduction layer in the order decreases in sequence. The second subset of the plurality of reduction layers is in an order from a reduction layer closest to the central portion to a reduction layer closest to the second outer surface. The pattern of the ends of the second subset of the plurality of reduction layers includes: the relative distance between the end of the reduction layer and the second end of each reduction layer in the order decreases in sequence.

[0194] Clause 48: A composite structure according to any one of clauses 42 to 47, wherein, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0195] Clause 49: The composite structure of any of Clauses 41 to 48, wherein a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0196] Item 50: A method of forming a composite structure having a variable specification, the method comprising: forming a plurality of continuous layers and forming a plurality of subtractive layers. Forming the plurality of subtractive layers comprises: for each subtractive layer, forming an end of the subtractive layer having a blunt end shape. The method further comprises: positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having a first end and a second end. The first end has a first specification. The second end has a second specification, the second specification being smaller than the first specification. Positioning the plurality of continuous layers and the plurality of subtractive layers comprises: (a) positioning the plurality of continuous layers such that each continuous layer extends from the first end to the second end; and (b) positioning the plurality of subtractive layers such that (i) each subtractive layer extends from the first end to a terminal end of the subtractive layer at a corresponding position between the first end and the second end, and (ii) the plurality of subtractive layers are separated from each other by at least one of the plurality of continuous layers.

[0197] Clause 51: The method of clause 50, further comprising, after positioning the plurality of continuous layers and the plurality of subtractive layers in the stack, curing the plurality of continuous layers and the plurality of subtractive layers.

[0198] Clause 52: The method of any of clauses 50 to 51, wherein positioning the plurality of continuous layers and the plurality of subtractive layers in a stack further comprises: forming a first outer surface extending from a first end to a second end, and forming a second outer surface extending from the first end to the second end. The first specification and the second specification are respective thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0199] Clause 53: The method of clause 52, wherein positioning the plurality of continuous layers and the plurality of subtractive layers in a stack comprises positioning a first subset of the plurality of subtractive layers between the first outer surface and the central portion. The central portion (i) is between the first outer surface and the second outer surface, and (ii) extends from the first end to the second end. Positioning the plurality of continuous layers and the plurality of subtractive layers in a stack further comprises positioning a second subset of the plurality of subtractive layers between the central portion and the second outer surface. Positioning the first subset of the plurality of subtractive layers and positioning the second subset of the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that the ends of the first subset of the plurality of subtractive layers are arranged in a pattern that is substantially mirror image of the pattern of the ends of the second subset of the plurality of subtractive layers.

[0200] Clause 54: The method of clause 53, wherein the central portion comprises a single subtractive layer of the plurality of subtractive layers.

[0201] Clause 55: The method of clause 53, wherein the central portion comprises two subtractive layers of the plurality of subtractive layers and at least one continuous layer of the plurality of continuous layers between the two subtractive layers.

[0202] Clause 56: The method of any one of clauses 50 to 55, wherein positioning the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0203] Clause 57: A method according to clause 56, wherein positioning the first subset of the plurality of reduction layers comprises: (i) positioning the first subset of the plurality of reduction layers in an order from a reduction layer closest to the central portion to a reduction layer closest to the first outer surface, and (ii) positioning the first subset of the plurality of reduction layers such that a pattern of ends of the first subset of the plurality of reduction layers includes: a relative distance between the ends of the reduction layers and the second ends of the reduction layers in the order decreases in sequence. Positioning the second subset of the plurality of reduction layers comprises: (a) positioning the second subset of the plurality of reduction layers comprises: positioning the second subset of the plurality of reduction layers in an order from a reduction layer closest to the central portion to a reduction layer closest to the second outer surface, and (b) positioning the second subset of the plurality of reduction layers such that a pattern of ends of the second subset of the plurality of reduction layers includes: a relative distance between the ends of the reduction layers and the second ends of the reduction layers in the order decreases in sequence.

[0204] Clause 58: The method of any one of clauses 50 to 57, wherein the plurality of reduction layers are positioned such that, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0205] Clause 59: The method of any one of clauses 50 to 58, wherein positioning the plurality of subtraction layers comprises positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0206] Clause 60: A composite structure having a variable specification. The composite structure includes a first section having a first specification and a second section having a second specification, the second specification being smaller than the first specification. The composite structure also includes a transition section between the first section and the second section. The transition section includes: a first end at the first section and having the first specification, a second end at the second section and having the second specification, a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) stacked and arranged between the first outer surface and the second outer surface. The plurality of layers include: (a) a plurality of continuous layers, wherein each continuous layer extends from the first end to the second end; and (b) at least one subtractive layer, wherein each subtractive layer includes an end having a blunt end shape, wherein each subtractive layer extends from the first end to a corresponding position of the end of the subtractive layer between the first end and the second end. Each subtractive layer is sandwiched between and abuts against corresponding two continuous layers of the plurality of continuous layers.

[0207] Clause 61: A composite structure having a variable specification, the composite structure comprising a first end having a first specification and a second end having a second specification, the second specification being smaller than the first specification. The composite structure also comprises a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) arranged in a stacked arrangement between the first outer surface and the second outer surface. The plurality of layers comprises a plurality of continuous layers and a plurality of reduced layers. Each continuous layer extends from the first end to the second end. Each reduced layer comprises an end having a blunt end shape. Each reduced layer extends from the first end to a corresponding position of the end of the reduced layer between the first end and the second end. A first subset of the plurality of reduced layers is between the first outer surface and a central portion of the stack, and a second subset of the plurality of reduced layers is between the central portion and the second outer surface. The ends of the plurality of reduction layers are arranged in a monotonically inward pattern, including (i) in a first sequence of a first subset of the plurality of reduction layers from the first outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the first sequence decrease in sequence, and (ii) in a second sequence of a second subset of the plurality of reduction layers from the second outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the second sequence decrease in sequence.

[0208] Clause 62: The composite structure of Clause 61, wherein the plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0209] Clause 63: The composite structure of any of clauses 61 to 62, wherein the first dimension and the second dimension are respective thicknesses between the first and second exterior surfaces at the first and second ends, respectively.

[0210] Clause 64: A composite structure according to any of clauses 61 to 63, wherein the central portion comprises at least one continuous layer of the plurality of continuous layers.

[0211] Clause 65: The composite structure of any of clauses 61 to 64, wherein the respective positions of the ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0212] Clause 66: The composite structure of clauses 61 to 65, wherein the monotonically inward pattern further comprises: ends of the first subset of the plurality of reduced layers alternating with ends of the second subset of the plurality of reduced layers in a direction from the first end to the second end.

[0213] Clause 67: A composite structure according to any one of clauses 61 to 66, wherein the plurality of reduction layers are arranged into a plurality of pairs of reduction layers. Each pair of reduction layers comprises a respective one reduction layer of the first subset and a respective one reduction layer of the second subset. For each pair of reduction layers, the respective one reduction layer of the first subset and the respective one reduction layer of the second subset are substantially equidistant from the central portion in a dimension between the first outer surface and the second outer surface.

[0214] Clause 68: The composite structure of any of clauses 61 to 67, wherein each subtractive ply has a ply angle relative to the longitudinal axis of the composite structure that is between approximately -30 degrees and +30 degrees.

[0215] Clause 69: The composite structure of clause 68, wherein, for each pair, the ply angles of the plurality of reduced plies in the pair are approximately the same.

[0216] Clause 70: A composite structure according to any one of clauses 61 to 69, wherein, for each reduction layer, the distance between the end of the reduction layer and the end of an adjacent one of the plurality of reduction layers is at least ten times greater than the thickness of the reduction layer. For each reduction layer, the adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first exterior surface and the second exterior surface.

[0217] Clause 71: The composite structure of any of Clauses 61 to 70, wherein a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0218] Clause 72: A method of forming a composite structure having a variable specification, the method comprising: forming a plurality of continuous layers and forming a plurality of subtractive layers. Forming the plurality of subtractive layers comprises: for each subtractive layer, forming an end of the subtractive layer having a blunt end shape. The method further comprises: positioning the plurality of continuous layers and the plurality of subtractive layers in a stack having (i) a first end, (ii) a second end, (iii) a first outer surface extending from the first end to the second end, and (iv) a second outer surface extending from the first end to the second end. The first end has a first specification and the second end has a second specification, the second specification being less than the first specification. Positioning the plurality of continuous layers and the plurality of subtractive layers comprises: positioning the plurality of continuous layers such that each continuous layer extends from the first end to the second end; and positioning the plurality of subtractive layers such that each subtractive layer extends from the first end to a corresponding position of the end of the subtractive layer between the first end and the second end. A first subset of the plurality of subtractive layers is between the first outer surface and a center portion of the stack, and a second subset of the plurality of subtractive layers is between the center portion and the second outer surface. Positioning the plurality of continuous layers and the plurality of subtractive layers in a stack further includes arranging the plurality of subtractive layers in a monotonically inward pattern, including (a) in a first sequence of a first subset of the plurality of subtractive layers from the first outer surface toward the central portion, the relative distances between the ends of the subtractive layers and the second ends in the first sequence decrease in sequence, and (b) in a second sequence of a second subset of the plurality of subtractive layers from the second outer surface toward the central portion, the relative distances between the ends of the subtractive layers and the second ends in the second sequence decrease in sequence.

[0219] Clause 73: The method of clause 72, further comprising: curing the plurality of continuous layers and the plurality of subtractive layers after positioning the plurality of continuous layers and the plurality of subtractive layers in the stack.

[0220] Clause 74: The method of any one of clauses 72 to 73, wherein positioning the plurality of continuous layers and the plurality of subtractive layers comprises positioning the plurality of continuous layers and the plurality of subtractive layers such that the plurality of subtractive layers are separated from one another by at least one continuous layer of the plurality of continuous layers.

[0221] Clause 75: The method of any one of clauses 72 to 74, wherein the central portion comprises at least one continuous layer of a plurality of continuous layers.

[0222] Clause 76: The method of any one of clauses 72 to 75, wherein positioning the plurality of subtractive layers comprises positioning the plurality of subtractive layers such that respective positions of ends of the plurality of subtractive layers are staggered from the first end to the second end.

[0223] Clause 77: The method of any one of clauses 72 to 76, wherein positioning the plurality of reduction layers comprises positioning the plurality of reduction layers such that, for each reduction layer, a distance between an end of the reduction layer and an end of an adjacent one of the plurality of reduction layers is at least ten times greater than a thickness of the reduction layer. For each reduction layer, an adjacent one of the plurality of reduction layers is adjacent to the reduction layer in a dimension extending between the first outer surface and the second outer surface.

[0224] Clause 78: The method of any one of clauses 72 to 77, wherein positioning the plurality of subtraction layers comprises positioning the plurality of subtraction layers such that a distance between non-adjacent subtraction layers in the plurality of subtraction layers is at least three times greater than a thickness of each subtraction layer.

[0225] Clause 79: A composite structure having a variable gauge. The composite structure includes a first section having a first gauge and a second section having a second gauge, the second gauge being smaller than the first gauge. The composite structure also includes a transition section between the first section and the second section. The transition section includes a first end at the first section and having the first gauge, a second end at the second section and having the second gauge, a first outer surface extending from the first end to the second end, a second outer surface extending from the first end to the second end, and a plurality of layers, the plurality of layers (i) extending between the first end and the second end, and (ii) arranged in a stacked arrangement between the first outer surface and the second outer surface. The plurality of layers includes a plurality of continuous layers and a plurality of subtractive layers. Each continuous layer extends from the first end to the second end. Each subtractive layer includes an end having a blunt end shape. Each subtractive layer extends from the first end to a corresponding position of an end of the subtractive layer between the first end and the second end. A first subset of the plurality of subtractive layers is between the first outer surface and a central portion of the stack, and a second subset of the plurality of subtractive layers is between the central portion and the second outer surface. The ends of the plurality of reduction layers are arranged in a monotonically inward pattern, including (a) in a first sequence of a first subset of the plurality of reduction layers from the first outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the first sequence decrease in sequence, and (b) in a second sequence of a second subset of the plurality of reduction layers from the second outer surface toward the central portion, the relative distances between the ends of the reduction layers and the second ends in the second sequence decrease in sequence.

[0226] Clause 80: The composite structure of Clause 79, wherein the first section is a flange of the composite stringer and the second section is a web of the composite stringer.

[0227] For the purpose of illustration and description, descriptions of different advantageous arrangements have been given, and are not intended to be exhaustive or limited to examples of the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. In addition, different advantageous examples may describe different advantages compared to other advantageous examples. The selected one or more examples are selected and described in order to explain the principles of the examples, practical applications, and to enable other persons of ordinary skill in the art to understand the disclosure of various examples with various modifications to suit the particular purpose under consideration.

Claims

1. A composite structure (100, 200, 300, 400) with variable specifications, the composite structure (100, 200, 300, 400) comprising: A first end (110A, 210A, 310A, 410A) having a first specification (112A, 212A, 312A, 412A); a second end (110B, 210B, 310B, 410B) having a second dimension (112B, 212B, 312B, 412B), the second dimension (112B, 212B, 312B, 412B) being smaller than the first dimension (112A, 212A, 312A, 412A); a plurality of continuous layers (118A, 218A, 318A, 418A), wherein each continuous layer extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B); a plurality of subtractive layers (118B, 218B, 318B, 418B), wherein each subtractive layer (118B, 218B, 318B, 418B) comprises a tip (120, 220, 320, 420) having a blunt-end shape, wherein each subtractive layer (118B, 218B, 318B, 418B) extends from the first end (110A, 210A, 310A, 410A) to a corresponding position of the tip (120, 220, 320, 420) of the subtractive layer (118B, 218B, 318B, 418B) between the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B); a first outer surface (114, 214, 314, 414) extending from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B); and a second outer surface (116, 216, 316, 416) extending from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein the plurality of subtractive layers (118B, 218B, 318B, 418B) are separated from each other by at least one continuous layer of the plurality of continuous layers (118A, 218A, 318A, 418A), wherein the plurality of continuous layers (118A, 218A, 318A, 418A) and the plurality of reduced layers (118B, 218B, 318B, 418B) are stacked and arranged between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416), wherein the first specification (112A, 212A, 312A, 412A) and the second specification (112B, 212B, 312B, 412B) are the respective thicknesses between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416) at the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), wherein a first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) is between the first outer surface (114, 214, 314, 414) and a center (220, 320), wherein the center (220, 320) (i) is between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416), and (ii) extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein a second subset (118B, 218B, 318B, 418B) of the plurality of subtractive layers is between the center (220, 320) and the second outer surface (116, 216, 316, 416), wherein the ends (120, 220, 320, 420) of the first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) are arranged in a pattern that is substantially a mirror image of a pattern of the ends (120, 220, 320, 420) of the second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B), wherein respective positions of the ends (120, 220, 320, 420) of the plurality of reduction layers (118B, 218B, 318B, 418B) are staggered from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) are in order from the reduction layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the reduction layer (118B, 218B, 318B, 418B) closest to the first outer surface (114, 214, 314, 414), The pattern of the ends (120, 220, 320, 420) of the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: a relative distance between the ends (120, 220, 320, 420) of the reduction layers (118B, 218B, 318B, 418B) and the second ends (110B, 210B, 310B, 410B) of the reduction layers (118B, 218B, 318B, 418B) in the order decreases in sequence, wherein the second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) is in order from the subtractive layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the subtractive layer (118B, 218B, 318B, 418B) closest to the second outer surface (116, 216, 316, 416), The pattern of the end (120, 220, 320, 420) of the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: the relative distance between the end (120, 220, 320, 420) of each reduction layer (118B, 218B, 318B, 418B) and the second end (110B, 210B, 310B, 410B) in the order decreases in sequence, and wherein the center (220, 320) comprises a single subtractive layer (118B, 218B, 318B, 418B) of the plurality of subtractive layers (118B, 218B, 318B, 418B).

2. The composite structure (100, 200, 300, 400) according to claim 1, wherein: A distance (230, 330) between non-adjacent subtractive layers in the plurality of subtractive layers (118B, 218B, 318B, 418B) is at least three times greater than a thickness (226, 326) of each subtractive layer (118B, 218B, 318B, 418B).

3. A method of forming a composite structure (100, 200, 300, 400) having variable dimensions, the method comprising the steps of: forming a plurality of continuous layers (118A, 218A, 318A, 418A); forming a plurality of subtractive layers (118B, 218B, 318B, 418B), wherein forming the plurality of subtractive layers (118B, 218B, 318B, 418B) comprises: for each subtractive layer (118B, 218B, 318B, 418B), forming a tip (120, 220, 320, 420) of the subtractive layer (118B, 218B, 318B, 418B) having a blunt end shape; and positioning the plurality of continuous layers (118A, 218A, 318A, 418A) and the plurality of subtractive layers (118B, 218B, 318B, 418B) in a stack having a first end (110A, 210A, 310A, 410A) and a second end (110B, 210B, 310B, 410B), wherein the first end (110A, 210A, 310A, 410A) has a first specification (112A, 212A, 312A, 412A), wherein the second end (110B, 210B, 310B, 410B) has a second specification (112B, 212B, 312B, 412B), the second specification (112B, 212B, 312B, 412B) being smaller than the first specification (112A, 212A, 312A, 412A), Wherein, the step of positioning the plurality of continuous layers (118A, 218A, 318A, 418A) and the plurality of reduced layers (118B, 218B, 318B, 418B) comprises: positioning the plurality of consecutive layers (118A, 218A, 318A, 418A) such that each consecutive layer extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), and positioning the plurality of subtractive layers (118B, 218B, 318B, 418B) such that (i) each subtractive layer (118B, 218B, 318B, 418B) extends from the first end (110A, 210A, 310A, 410A) to a respective position of a distal end (120, 220, 320, 420) of the subtractive layer (118B, 218B, 318B, 418B) between the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), (ii) the plurality of subtractive layers (118B, 218B, 318B, 418B) are separated from each other by at least one continuous layer of the plurality of continuous layers (118A, 218A, 318A, 418A), and (iii) respective positions of the ends (120, 220, 320, 420) of the plurality of subtractive layers (118B, 218B, 318B, 418B) are staggered from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), Wherein, the step of positioning the plurality of continuous layers (118A, 218A, 318A, 418A) and the plurality of subtractive layers (118B, 218B, 318B, 418B) in the stack further comprises: forming a first outer surface (114, 214, 314, 414) extending from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B); and forming a second outer surface (116, 216, 316, 416) extending from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein the first specification (112A, 212A, 312A, 412A) and the second specification (112B, 212B, 312B, 412B) are the respective thicknesses between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416) at the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), Wherein, the step of positioning the plurality of continuous layers (118A, 218A, 318A, 418A) and the plurality of subtractive layers (118B, 218B, 318B, 418B) in the stack further comprises: positioning a first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) between the first outer surface (114, 214, 314, 414) and a center (220, 320), wherein the center (220, 320) (i) is between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416) and (ii) extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), and positioning a second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) between the center (220, 320) and the second outer surface (116, 216, 316, 416), wherein positioning the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) and positioning the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B) include positioning the plurality of reduction layers such that the ends (120, 220, 320, 420) of the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) are arranged in a pattern that is substantially mirror image of a pattern of the ends (120, 220, 320, 420) of the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B), and Wherein, locating the first subset of the plurality of subtracted layers (118B, 218B, 318B, 418B) further comprises: positioning the first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) in order from the subtractive layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the subtractive layer (118B, 218B, 318B, 418B) closest to the first outer surface (114, 214, 314, 414), and The pattern of positioning the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) so that the end (120, 220, 320, 420) of the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: the relative distance between the end (120, 220, 320, 420) of each reduction layer (118B, 218B, 318B, 418B) and the second end (110B, 210B, 310B, 410B) in the order decreases in sequence, Wherein, locating the second subset of the plurality of subtracted layers (118B, 218B, 318B, 418B) further comprises: positioning the second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) in order from the subtractive layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the subtractive layer (118B, 218B, 318B, 418B) closest to the second outer surface (116, 216, 316, 416), and The pattern of positioning the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B) so that the end (120, 220, 320, 420) of the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: the relative distance between the end (120, 220, 320, 420) of each reduction layer (118B, 218B, 318B, 418B) and the second end (110B, 210B, 310B, 410B) in the order decreases successively, wherein the center (220, 320) comprises a single subtractive layer (118B, 218B, 318B, 418B) of the plurality of subtractive layers (118B, 218B, 318B, 418B).

4. A composite structure (100, 200, 300, 400) with variable specifications, the composite structure (100, 200, 300, 400) comprising: A first section, the first section having a first specification (112A, 212A, 312A, 412A); a second section, the second section having a second specification (112B, 212B, 312B, 412B), the second specification (112B, 212B, 312B, 412B) being smaller than the first specification (112A, 212A, 312A, 412A); as well as A transition section, the transition section is between the first section and the second section, wherein the transition section comprises: a first end (110A, 210A, 310A, 410A), the first end (110A, 210A, 310A, 410A) being at the first section and having the first dimension (112A, 212A, 312A, 412A), a second end (110B, 210B, 310B, 410B), the second end (110B, 210B, 310B, 410B) being at the second section and having the second specification (112B, 212B, 312B, 412B), a first outer surface (114, 214, 314, 414), wherein the first outer surface (114, 214, 314, 414) extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), a second outer surface (116, 216, 316, 416), wherein the second outer surface (116, 216, 316, 416) extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), and a plurality of layers (118i, 218i, 318i, 418), the plurality of layers (118i, 218i, 318i, 418) (i) extending between the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), and (ii) stacked between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416), Wherein, the plurality of layers (118i, 218i, 318i, 418) include: (i) a plurality of continuous layers (118A, 218A, 318A, 418A), wherein each continuous layer extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), and (ii) a plurality of subtractive layers (118B, 218B, 318B, 418B), wherein each subtractive layer (118B, 218B, 318B, 418B) comprises a tip (120, 220, 320, 420) having a blunt-end shape, wherein each subtractive layer (118B, 218B, 318B, 418B) extends from the first end (110A, 210A, 310A, 410A) to a corresponding position of the tip (120, 220, 320, 420) of the subtractive layer (118B, 218B, 318B, 418B) between the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), wherein each subtractive layer (118B, 218B, 318B, 418B) is sandwiched between and abuts against corresponding two continuous layers (118A, 218A, 318A, 418A) of the plurality of continuous layers (118A, 218A, 318A, 418A), wherein the first specification (112A, 212A, 312A, 412A) and the second specification (112B, 212B, 312B, 412B) are the respective thicknesses between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416) at the first end (110A, 210A, 310A, 410A) and the second end (110B, 210B, 310B, 410B), wherein a first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) is between the first outer surface (114, 214, 314, 414) and a center (220, 320), wherein the center (220, 320) (i) is between the first outer surface (114, 214, 314, 414) and the second outer surface (116, 216, 316, 416), and (ii) extends from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein a second subset (118B, 218B, 318B, 418B) of the plurality of subtractive layers is between the center (220, 320) and the second outer surface (116, 216, 316, 416), wherein the ends (120, 220, 320, 420) of the first subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) are arranged in a pattern that is substantially a mirror image of a pattern of the ends (120, 220, 320, 420) of the second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B), wherein respective positions of the ends (120, 220, 320, 420) of the plurality of reduction layers (118B, 218B, 318B, 418B) are staggered from the first end (110A, 210A, 310A, 410A) to the second end (110B, 210B, 310B, 410B), wherein the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) are in order from the reduction layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the reduction layer (118B, 218B, 318B, 418B) closest to the first outer surface (114, 214, 314, 414), The pattern of the ends (120, 220, 320, 420) of the first subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: a relative distance between the ends (120, 220, 320, 420) of the reduction layers (118B, 218B, 318B, 418B) and the second ends (110B, 210B, 310B, 410B) of the reduction layers (118B, 218B, 318B, 418B) in the order decreases in sequence, wherein the second subset of the plurality of subtractive layers (118B, 218B, 318B, 418B) is in order from the subtractive layer (118B, 218B, 318B, 418B) closest to the center (220, 320) to the subtractive layer (118B, 218B, 318B, 418B) closest to the second outer surface (116, 216, 316, 416), The pattern of the end (120, 220, 320, 420) of the second subset of the plurality of reduction layers (118B, 218B, 318B, 418B) comprises: the relative distance between the end (120, 220, 320, 420) of each reduction layer (118B, 218B, 318B, 418B) and the second end (110B, 210B, 310B, 410B) in the order decreases in sequence, and wherein the center (220, 320) comprises a single subtractive layer (118B, 218B, 318B, 418B) of the plurality of subtractive layers (118B, 218B, 318B, 418B).

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