Composite structures having variable gauge and methods for forming composite structures having variable gauge - Patents.com

Abstract

To provide a composite structure having a variable gage.SOLUTION: A composite structure 200 includes a first end 210A having a first gage 212A, a second end 210B having a second gage 212B, which is less than the first gage 212A, a plurality of continuous plies 218A, and a plurality of drop-off plies 218B. Each continuous ply 218A extends from the first end 210A to the second end 210B. Each drop-off ply 218B includes a tip 220 having a tapered shape. Each drop-off ply 218B extends from the first end 210A to a respective position of the tip 220 of the drop-off ply 218B between the first end 210A and the second end 210B. The drop-off plies 218B are separated from each other by at least one of the continuous plies 218A.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to composite structures and, more particularly, to composite structures and methods for forming composite structures having variable gauge. [Background technology]

[0002] Due to their high strength-to-weight ratio, corrosion resistance, and other favorable properties, composite structures are used in a wide range of applications, including the manufacture of aircraft, spacecraft, rotorcraft, ships, automobiles, trucks, and other vehicles and structures. Generally, a composite structure is a structure formed from two or more component materials having different physical and / or chemical properties that, when combined, produce a composite material having properties that differ from the material properties of the individual components.

[0003] As an example, one type of composite material is carbon fiber reinforced plastic (CFRP). CFRP generally includes one or more composite layers or plies that are stacked 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, bonds, and supports the reinforcement material. The reinforcement material provides structural strength to the matrix material and the CFRP. The matrix material is generally a non-conductive polymer, such as an epoxy resin. The reinforcement material generally consists of strands of conductive carbon fibers. Summary of the Invention

[0004] In an embodiment, 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 plies, and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a tapered or blunt-end shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. The plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies.

[0005] In another example, a method of forming a composite structure having variable gauge is described. The method includes forming a plurality of continuous plies and forming a plurality of drop-off plies. Forming the plurality of drop-off plies includes forming a tip of the drop-off ply having a tapered or blunt shape for each drop-off ply. The method also includes positioning the plurality of continuous plies and the plurality of drop-off plies in a stack having a first end and a second end. The first end has a first gauge and the second end has a second gauge smaller than the first gauge. Positioning the plurality of continuous plies and the plurality of drop-off plies includes (a) positioning the plurality of continuous plies such that each continuous ply extends from the first end to the second end, and (b) positioning the plurality of drop-off plies such that (i) each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end, and (ii) the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies.

[0006] In another example, a composite structure having a variable gauge is described. The composite structure includes a first segment having a first gauge, a second segment having a second gauge smaller than the first gauge, and a transition segment between the first and second segments. The transition segment includes a first end of the first segment having the first gauge, a second end of the second segment having the second gauge, 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 segment also includes a plurality of plies (i) extending between the first and second ends and (ii) arranged in a stack between the first and second outer surfaces.

[0007] The plurality of plies includes (a) a plurality of continuous plies each extending from a first end to a second end, and (b) at least one drop-off ply. Each drop-off ply includes a tip having a tapered or blunt shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. Each drop-off ply is sandwiched between and abuts respective two continuous plies of the plurality of continuous plies.

[0008] The foregoing features, functions, and advantages may be realized individually in various examples or may be combined in yet other examples, further details of which may be understood by reference to the following description and drawings.

[0009] The novel features believed characteristic of the illustrated embodiments are set forth in the appended claims, however the embodiments as well as the preferred mode of use and further objects and explanations thereof will best be understood by reading the following detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0010] [Figure 1] 1 shows a composite structure according to an embodiment. [Diagram 2] 4 illustrates a composite structure according to another embodiment. [Diagram 3] 4 illustrates a composite structure according to another embodiment. [Figure 4] 4 shows a simplified block diagram of a composite structure according to another embodiment. [Figure 5A] 2 illustrates a side view of a composite stringer including the composite structure of FIG. 1 according to another embodiment. [Figure 5B] 4 illustrates a side view of a composite stringer including the composite structure of FIG. 3 according to another embodiment. [Figure 6] 1 illustrates a flowchart of an exemplary process for forming a composite structure having variable gauge, according to an embodiment. [Figure 7] 7 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 6. [Figure 8] 7 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 6. [Figure 9] 9 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. [Figure 10] 10 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. [Figure 11] 10 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. [Figure 12] 12 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 11 . [Figure 13] 7 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 6. [Figure 14]7 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 6. [Figure 15] 1 illustrates a flowchart of an exemplary process for forming a composite structure having variable gauge, according to an embodiment. [Figure 16] 16 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 15. [Figure 17] 17 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 16. [Figure 18] 17 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 16. [Figure 19] 17 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 16. [Figure 20] 17 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 16. [Figure 21] 17 shows a flowchart of an exemplary process for forming a composite structure with variable gauge that can be used in the process shown in FIG. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the disclosed embodiments will be described more comprehensively with reference to the attached drawings, which show some, but not all, of the disclosed embodiments. In fact, several different embodiments may be described, and these embodiments should not be construed as being limited to the embodiments set forth herein. Rather, such embodiments are described so that this disclosure is comprehensive and comprehensive, and the scope of the disclosure is fully conveyed to those skilled in the art.

[0012] The words "about" or "substantially" in connection with quantities or measurements described herein mean that the described characteristic, parameter, or value need not be precisely achieved, but rather that deviations or variations, including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those of skill in the art, of a magnitude that does not render the effect that the characteristic is intended to provide impossible, may occur.

[0013] As used herein, the terms "greater than" and "less than" are intended to have their general meaning. Thus, if a first bulb is any larger than a second bulb, then the first bulb is greater than the second bulb. Similarly, if a first bulb is any smaller than a second bulb, then the first bulb is less than the second bulb.

[0014] As used herein, the term "composite structure" means a structure that is fabricated, manufactured or assembled, in whole or in part, from one or more composite materials.

[0015] As noted above, composite structures can be used in a variety of applications, including the manufacture of aircraft, spacecraft, rotorcraft, ships, flying taxis, trains, automobiles, trucks, and other vehicles (e.g., passenger capsules or cargo containers) due to their high strength-to-weight ratio, corrosion resistance, and other favorable properties. Additionally or alternatively, composite structures can be used in buildings, bridges, swimming pools, storage tanks, robotic frame structures, energy structures (e.g., wind blades, turbine blades, propulsion blades, and / or solar panels), sporting goods (e.g., bicycle frames, skis, snowboards, surfboards, paddles, etc.), residential homes, office buildings, and / or medical board frames.

[0016] In some embodiments, different portions of a composite structure may have different gauges. As used herein, the term "gauge" refers to the thickness between two opposing sides of a composite structure. For various reasons, it may be desirable to change the gauge from one portion of a composite structure to another portion of the composite structure. For example, the stiffness and / or strength of the composite structure may be related to the gauge of the composite structure. In some instances, it may be desirable to change the stiffness and / or strength of the composite structure from a first portion of the composite structure to a second portion of the composite structure. For example, the first portion of the composite structure may be expected to receive a relatively larger amount of load and / or applied force than the second portion of the composite structure. Thus, it may be desirable for the first portion of the composite structure to have a gauge that is greater than the gauge of the second portion of the composite structure.

[0017] In other examples, it may be desirable to additionally or alternatively vary the gauge of a composite structure based on other design criteria such as, for example, aesthetics, weight distribution, space constraints, load variations, and / or damage protection.

[0018] One approach to transitioning from one gauge to another involves forming a composite structure from multiple plies of composite material, including multiple continuous plies and one or more drop-off plies. Generally, 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 respective location of the tip of the drop-off ply between the first end and the second end. In this arrangement, fewer plies are disposed at the second end than at the first end. Thus, by positioning the tip of the drop-off ply between the first end and the second end, the gauge is reduced from the first end to the second end to transition from one gauge to another.

[0019] Existing approaches for transitioning from one gauge to another have several drawbacks. For example, in existing composite structures with variable gauge, the tips of the drop-off plies have a blunt shape and are placed immediately adjacent to each other in a cluster. This results in relatively large resin pockets in or near the area of ​​the tips of the drop-off plies. In some instances, the relatively large resin pockets may cause delamination in areas subject to thermal and / or mechanical loading. In addition, for example, placing the tips of the drop-off plies in a cluster may increase the risk of ply kinking and / or wrinkling, reducing the strength of the laminate.

[0020] By way of example, Figure 1 illustrates an exemplary composite structure 100 having a variable gauge, according to an embodiment. As shown in Figure 1, the composite structure 100 includes a first end 110A having a first gauge 112A and a second end 110B having a second gauge 112B that is smaller than the first gauge 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.

[0021] As also shown in FIG. 1 , the composite structure 100 includes a plurality of plies 118 of composite material disposed in a stack between the second exterior surface 116 and the first exterior surface 114. i=1 ~118 i=n (Hereafter collectively referred to as "Ply118 i In FIG. 1 , the composite structure 100 includes a total of eighteen plies 118. i (i.e., n=18). However, in other examples, the composite structure 100 may include plies 118 i Fewer or more plies may be included.

[0022] In this configuration, the first gauge 112A at the first end 110A and the second gauge 112B at the second end 110B are the thickness 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 gauge 112B is related to the amount of ply 118 at the second end 110B. i For example, in FIG. 1, the amount of ply 118 at the first end 110A is i The amount of ply 118 at the second end 110B is such that the first gauge 112A is greater than the second gauge 112B. i greater than the amount of

[0023] In particular, the ply 118 between the first end 110A and the second end 110B. i To change the amount of composite plies 118 i 1 includes a plurality of continuous plies 118A and a plurality of drop-off plies 118B. In FIG. 1, each continuous ply 118A extends from a first end 110A to a second end 110B, while each drop-off ply 118B includes a tip 120, and each drop-off ply 118B extends from the first end 110A to a respective location of the tip 120 of the drop-off ply 118B between the first end 110A and the second end 110B.

[0024] Thus, the continuous ply 118A is present at the first end 110A and the second end 110B, while the drop-off ply 118B is present at the first end 110A and absent at the second end 110B. In this manner, the drop-off ply 118B may contribute to the first gauge 112A at the first end 110A, but does not contribute to the second gauge 112B at the second end 110B because the drop-off ply 118B terminates before the second end 110B (i.e., the tip 120 is at a respective position between the first end 110A and the second end 110B).

[0025] For clarity of illustration, a representative subset of continuous plies 118A is labeled with reference numeral 118A and a representative subset of drop-off plies 118B is labeled with reference numeral 118B in FIG. i Each of the plies 118 is one of the continuous plies 118A and terminates between the first end 110A and the second end 110B. i Each of plies 118B is one of the drop-off plies 118B. i=1-3,9-18 is continuous ply 118A, ply 118 i=4-8 is a drop off ply 118B.

[0026] As shown in Figure 1, the tip 120 of each drop-off ply 118B has a blunt shape, and the drop-off plies 118B are placed immediately adjacent to one another in a stack (e.g., in a cluster). Generally, this approach to transitioning from one gauge to another can be effective. However, it has been found that the performance of the composite structure 100 can be improved using one or more of the techniques described in detail below with reference to Figures 2-3.

[0027] For example, using drop-off plies 118B with blunt tips 120 and / or clustering the drop-off plies 118B may result in relatively large resin pockets at and near the tips 120 of the drop-off plies 118B in the region 122. In some instances, the relatively large resin pockets in the region 122 may cause delamination in the region 122 where thermal and / or mechanical loads are applied. Additionally, for example, clustering the tips 120 of the drop-off plies 118B may increase the risk of ply kinking and / or wrinkling, reducing the strength of the laminate. Furthermore, in some instances, off-center placement of the drop-off ply tips 120 (e.g., closer to the first exterior surface 114 than to the second exterior surface 116) may also increase the risk of ply kinking and / or wrinkling, thereby reducing static strength and / or fatigue strength due to potential distortion under thermal and / or mechanical loads.

[0028] Examples are described that have a composite structure having a variable gauge, which may improve the composite structure 100 in one or more respects. For example, in some examples, the tip 120 of the drop-off ply 118B may have a tapered shape and / or the tip 120 of the ply 118B may have a tapered shape. i The can be arranged according to one or more patterns that can, among other things, improve the load-bearing properties of the composite structure, reduce rehardening, simplify tooling requirements for forming the composite structure, reduce material handling costs, and / or reduce the weight of the composite structure.

[0029]

[0023] Referring now to Figure 2, a composite structure 200 having a variable gauge is shown, according to an embodiment. As shown in Figure 2, the composite structure 200 includes a first end 210A having a first gauge 212A and a second end 210B having a second gauge 212B that is smaller than the first gauge 212A of the first end 210A. Additionally, as shown in Figure 2, 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.

[0030] As also shown in FIG. 2 , the composite structure 200 includes a plurality of plies 218 of composite material disposed in a stack between the second exterior surface 216 and the first exterior surface 214. i=1 ~218 i=n (Hereafter, collectively, "Ply218 i In FIG. 2, the composite structure 200 includes a total of 28 plies 218. i (i.e., n=28). However, in other examples, the composite structure 200 may include plies 218 i Fewer or more plies may be included.

[0031] In this configuration, the first gauge 212A at the first end 210A and the second gauge 212B at the second end 210B are the thickness between the first outer surface 214 and the second outer surface 216 at the first end 210A and the second end 210B, respectively. Further, as described above, the first gauge 212A is the thickness between the plies 218 at the first end 210A and the second outer surface 216 at the second end 210B. i The second gauge 212B is related to the amount of ply 218 at the second end 210B. i For example, in FIG. 2, the amount of ply 218 at first end 210A is i The amount of ply 218 at the second end 210B is such that the first gauge 212A is greater than the second gauge 212B. i greater than the amount of

[0032] As described above, the variable gauge of the composite structure 200 is formed by stacking plies 218 of composite material including a plurality of continuous plies 218A and a plurality of drop-off plies 218B disposed between the second exterior surface 216 and the first exterior surface 214. i2, each continuous ply 218A extends from a first end 210A to a second end 210B, while each drop-off ply 218B extends from a first end 210A to a respective location of a tip 220 of the drop-off ply 218B between the first end 210A and the second end 210B. Thus, the first gauge 212A is based on the amount of continuous plies 218A and the amount of drop-off plies 218B, and the second gauge 212B is based on the amount of continuous plies 218A (and not the amount of drop-off plies 218B).

[0033] For clarity of illustration, a representative subset of continuous plies 218A is labeled with reference numeral 218A and a representative subset of drop-off plies 218B is labeled with reference numeral 218B in FIG. i Each of the plies 218 is one of the continuous plies 218A and terminates between the first end 210A and the second end 210B. i Each of plies 218B is one of the drop-off plies 218B. i=1-6,8,10,12,14,15,17,19,21,23,25-28 is continuous ply 218A, ply 218 i=7,9,11,13,16,18,20,22,24 is a drop-off ply 218B.

[0034] 2, the tip 220 of each drop-off ply 218B has a tapered shape. More specifically, for example, the thickness of the tip 220 of each drop-off ply 218B may be gradually reduced in thickness in a direction along the tip 220 from the first end 210A to the second end 210B. Because the tip 220 has a tapered shape, the tip 220 may be gradually reduced in thickness from the first end 210A to the second end 210B. i1 , which terminates relatively abruptly). Thus, the tapered tip 220 may reduce (or minimize) resin pockets at the tip 220 of the drop-off ply 218B and help improve (or maximize) the interlaminar strength of the composite structure 200. Thus, the tapered tip 220 of the drop-off ply 218B may help improve the load-bearing capabilities of the composite structure 200 having a variable gauge for the transition from the section having the first gauge 212A to the section having the second gauge 212B.

[0035] Within the scope of the embodiment, the tapered shape of the tips 220 of the drop-off plies 218B may be formed by cutting each drop-off ply 218B at an angle of approximately 85 degrees less relative to the longitudinal axis of the drop-off ply 218B. In contrast, the blunt shape of the tips 120 of the drop-off plies 118B shown in FIG. 1 may be formed, for example, by cutting each drop-off ply 118B at an angle of approximately 90 degrees relative to the longitudinal axis of the drop-off ply 118B.

[0036] As discussed above, the load-bearing capacity of the composite structure 200 may additionally or alternatively be improved by the ply 218. i2, the drop-off plies 218B are separated from one another by at least one of the continuous plies 218A. More specifically, in FIG. 2, each drop-off ply 218B is sandwiched between and abuts two respective continuous plies 218A of the plurality of continuous plies 218A. By separating the drop-off plies 218B from one another and / or sandwiching the drop-off plies 218B between the continuous plies 218A, the drop-off plies 218B can be more evenly distributed between the second exterior surface 216 and the first exterior surface 214 (compared to the clustered arrangement of the drop-off plies 118B shown in FIG. 1). This can help (or prevent) reducing ply kinks and / or wrinkling, reducing resin pockets, and / or reducing interlaminar strength of the composite structure 200.

[0037] As shown above, in Figure 2, ply 218 i=1-6,8,10,12,14,15,17,19,21,23,25-28 is continuous ply 218A, ply 218 i=7,9,11,13,16,18,20,22,24 is the drop-off ply 218B. Thus, in FIG. i=7,9,11,13,16,18,20,22,24 Each of the plies is 218 i=1-6,8,10,12,14,15,17,19,21,23,25-28 and plies 218 are separated from each other by at least one of i=7,9,11,13,16,18,20,22,24 Each of the plies is 218 i=1-6,8,10,12,14,15,17,19,21,23,25-28 For example, in FIG. 2, ply 218 i=7 Ply 218 i=8 By Ply 218 i=9 Separated from ply 218 i=7 Ply 218 i=6 and Ply 218 i=8 In addition, for example, ply 218 i=9 Ply 218 i=10 By ply218 i=11 Separated from ply 218 i=8 By ply218 i=9 Separated from ply 218 i=8 and Ply 218i=10 Further, for example, ply 218 i=16 Ply 218 i=14,15 By ply218 i=13 Separated from ply 218 i=17 By ply218 i=18 Separated from ply 218 i=15 and Ply 218 i=17 A similar relationship exists between the remainder of the drop-off ply 218B in FIG. i=11,13,18,20,22,24 As noted above, the plies 218 are arranged in a pattern having the characteristics of continuous plies 218A alternating with drop-off plies 218B (e.g., as shown in FIG. 2). i Arranging the ply may help reduce (or prevent) kinking and / or wrinkling, may help reduce (or prevent) resin pockets, and / or may help increase (or maximize) the interlaminar strength of the composite structure 200.

[0038] Within the scope of the embodiment, the pattern of tips 220 of the drop-off plies 218B may additionally or alternatively include one or more of the following characteristics: (i) an arrangement of tips 220 in a front half of the composite structure 200 in a pattern that substantially mirrors or mirrors the pattern of tips 220 in a back half of the composite structure 200; (ii) an offset arrangement of tips 220 relative to one another; and / or (iii) at least one threshold distance (e.g., between plies 218B and the tip 220). i , at least one distance relative to the respective positions and / or respective thicknesses of one or more of the tips 220. Each of these characteristics, alone or in combination, can contribute to arranging the drop-off plies 218B in a pattern that can reduce (or prevent) kinking and / or wrinkling of the ply, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength.

[0039] 2 illustrates tips 220 arranged in a substantially mirror or mirror pattern relative to a central portion 224 of a composite structure 200, according to one example. The central portion 224 includes one or more plies 218B that provide a frame of reference for characterizing the pattern of tips 220 of the drop-off plies 218B on either side of the central portion 224. i Generally, central portion 224 (i) is between second outer surface 216 and first outer surface 214, and (ii) extends from first end 210A to second end 210B.

[0040] In FIG. 2, the central portion 224 is i=15,16 Thus, in FIG. 2, the central portion 224 may include a single drop-off ply 218B (i.e., ply 218 i=16 ) and a single continuous ply 218A (i.e., ply 218 i=15 ) in one embodiment. However, in another embodiment, the central portion 224 can include two drop-off plies 218B and at least one continuous ply 218A. In yet another embodiment, the central portion 224 can consist of only a single drop-off ply 218B. In another embodiment, the central portion 224 can include one or more continuous plies 218A and can include a drop-off ply 218B. More specifically, the central portion 224 can include one or more of the continuous plies 218A and / or one or more of the drop-off plies 218B.

[0041] As discussed above, the tips 220 of the drop-off plies 218B may be arranged in a substantially mirror or mirror pattern with respect to the central portion 224. For example, a first subset of the drop-off plies 218B may be between the first exterior surface 214 and the central portion 224, and a second subset of the drop-off plies 218B may be between the central portion 224 and the second exterior surface 216. In this arrangement, the tips 220 of the first subset of the drop-off plies 218B are arranged in a pattern that substantially mirrors the pattern of the tips 220 of the second subset of the drop-off plies 218B. In essence, the respective positions of the tips 220 of the first subset of the drop-off plies 218B are arranged (i) oppositely and (ii) similarly (or equally) with respect to the central portion 224, as compared to the respective positions of the tips 220 of the second subset of the drop-off plies 218B. For example, in FIG. 2, the central portion 224 may be arranged in a substantially mirror or mirror pattern with respect to the plies 218. i=15,16 a first subset of the drop-off plies 218B may include plies 218 i=7,9,11,13 and a second subset of drop-off plies 218B may include plies 218 i=18,20,22,24 2, the pattern of tips 220 of the first subset of drop-off plies 218B substantially mirrors the pattern of tips 220 of the second subset of drop-off plies 218B. For example, with respect to the central portion 224, the location of each of the tips 220 of the first subset is oppositely and similarly positioned compared to the location of each of the tips 220 of the second subset.

[0042] In addition, as shown in FIG. 2, the pattern of the tips 220 of the drop-off plies 218B can be a monotonically outward pattern. For example, in FIG. 2, a first subset of the drop-off plies 218B includes the drop-off plies 218B closest to the center portion 224 (e.g., plies 218 i=13 ) to the drop-off ply 218B closest to the first outer surface 214 (i.e., ply 218 i=72 , (i) plies 218B, (ii) plies 218B, and (iii) plies 218B, and (iv) plies 218B, and (v) plies 218B, and (vi) plies 218B, and (vii) plies 218B, and (v ... i=13 (ii) the tip 220 of the ply 218 is a first distance from the second end 210B; i=11 (iii) the tip 220 of the ply 218 is at a second distance from the second end 210B that is less than the first distance; i=9 (iv) the tip 220 of the ply 218 is at a third distance from the second end 210B that is less than the second distance; i=7 The tip 220 is a fourth distance from the second end 210B that is less than the third distance.

[0043] Similarly, a second subset of the drop-off plies 218B may include the drop-off plies 218B closest to the center portion 224 (e.g., plies 218 i=18 ) to the drop-off ply 218B closest to the second outer surface 216 (e.g., ply 218 i=24 ) to the second end 210B. The pattern of the tips 220 of the second subset of drop-off plies 218B includes a decreasing relative distance between the tips 220 of the drop-off plies 218B and the second end 210B with each successive drop-off ply 218B placed in the sequence. Thus, in FIG. 2, (v) plies 218 i=18 (vi) the tip of ply 218 is a fifth distance from second end 210B; i=20 (vii) the tip 220 of the ply 218 is at a sixth distance from the second end 210B that is less than the fifth distance; i=22 (viii) the tip 220 of the ply 218 is at a seventh distance from the second end 210B that is less than the sixth distance; i=24 The tip 220 is at an eighth distance from the second end 210B which is less than the seventh distance.

[0044] 2, the tips 220 of the drop-off ply 218B appear to generally radiate outward from the central portion 224 in a direction from the first end 210A to the second end 210B. The monotonically outward pattern of the tips 220 can facilitate a more gradual and / or smooth transition from the first gauge 212A at the first end 210A to the second gauge 212B at the second end 210B. Additionally, for example, the monotonically outward pattern of the tips 220 can facilitate achieving greater symmetry with respect to, for example, the arrangement of the tips 120 of FIG. 1 (which are clustered near the first exterior surface 114).

[0045] 2, the drop-off plies 218B may be arranged in pairs of drop-off plies 218B that define an order in which the drop-off plies 218B descend in a direction from the first end 210A toward the second end 210B (i.e., an order of the respective positions of the tips 220 in a direction from the first end 210A toward the second end 210B). In particular, each pair of drop-off plies 218B may include one respective drop-off ply 218B of the first subset and one respective drop-off ply 218B of the second subset.

[0046] For example, in FIG. 2, the first pair is ply 218 i=13,18 and the second pair includes ply 218 i=11,20 and the third pair includes ply 218. i=9,22 and the fourth pair includes ply 218 i=7,242, in a direction from the first end 210A to the second end 210B, the drop-off plies 218B drop off in order from the first pair to the fourth pair. In other words, the tips 220 of the first pair of drop-off plies 218B are closest to the first end 210A, the tips 220 of the second pair of drop-off plies 218B are second closest to the first end 210A, the tips 220 of the third pair of drop-off plies 218B are third closest to the first end 210A, and the tips 220 of the fourth pair of drop-off plies 218B are furthest from the first end 210A.

[0047] Additionally, for example, for each pair of drop-off plies 218B, each one of the drop-off plies 218B of the first subset and each one of the drop-off plies 218B of the second subset are substantially equidistant from the central portion 224 in the dimension between the first exterior surface 214 and the second exterior surface 216. For example, as shown in FIG. 2, each of the first pair of drop-off plies 218B includes a single ply 218 i A second pair of drop-off plies 218B are each spaced apart from central portion 224 a distance equal to the ply thickness 226, a second pair of drop-off plies 218B are each spaced apart from central portion 224 a distance equal to three times the ply thickness 226, a third pair of drop-off plies 218B are each spaced apart from central portion 224 a distance equal to five times the ply thickness 226, and a fourth pair of drop-off plies 218B are each spaced apart from central portion 224 a distance equal to seven times the ply thickness 226. Arranging the drop-off plies 218B in pairs, (i) descending pair-by-pair from the first end 210A to the second end 210B, and / or (ii) equidistant to the central portion 224, can facilitate a more gradual and / or smoother transition from the first gauge 212A at the first end 210A to the second gauge 212B at the second end 210B, and / or can help achieve greater symmetry with respect to, for example, the arrangement of tips 120 in FIG. 1 (which are clustered near the first outer surface 114).

[0048] Within the scope of the embodiment, each drop-off ply 218B can have a ply angle that is between approximately -30 degrees and +30 degrees relative to the longitudinal axis of the composite structure 200 (e.g., longitudinal axis 348). This allows for a relatively small (or minimal) amount of ply 218B to be i This can help achieve a desired stiffness, and thus reduce (or minimize) the weight of the composite structure 200 and / or the cost of manufacturing the composite structure 200. In one example, for each pair, the ply angles are approximately the same for the drop-off plies 218B of the pair. This can help increase (or maximize) the symmetry of the composite structure 200.

[0049] According to additional or alternative aspects of the monotonically outward pattern shown in FIG. 2, the monotonically outward pattern may include tips 220 of the first subset of drop-off plies 218B alternating with tips 220 of the second subset of drop-off plies 218B along a direction from the first end 210A to the second end 210B. For example, in FIG. 2, the tips 220 of the drop-off plies 218B are in the following order from the first end 210A to the second end 210B: (i) tips 220 of the second subset of plies 218B from the first end 210A to the second end 210B. i=18 (ii) the tip 220 of the ply 218 from the first subset i=13 (iii) the tip 220 of the ply 218 from the second subset i=20 (iv) the tip 220 of the ply 218 from the first subset i=11 (v) the tip 220 of the ply 218 from the second subset i=22 (vi) the tip 220 of the ply 218 from the first subset i=9 (vii) the tip 220 of the ply 218 from the second subset i=24 and (viii) the tip 220 of the ply 218 from the first subset. i=7 The tips 220 of the drop-off plies 218B may alternate positions of each of the tips 220. Alternating the positions of each of the tips 220 of the drop-off plies 218B may additionally or alternatively facilitate a more gradual and / or smoother transition from the first gauge 212A at the first end 210A to the second gauge 212B at the second end 210B.

[0050] As discussed above, arranging the drop-off plies 218B such that their tips 220 are staggered from one another may additionally or alternatively help to reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength. By way of example, in FIG. 2, the locations of each of the tips 220 of the drop-off plies 218B may be staggered from the first end 210A to the second end 210B. By "staggered," it is meant that the tips 220 of the drop-off plies 218B are each at a respective distance from the second end 210B, and that the respective distances between the tips 220 and the second end 210B are quite different from one another (i.e., the tips of the two drop-off plies are not equidistant from the second end 210B). Staggering the tips 220 of the drop-off plies 218B may help alleviate some or all of the problems associated with clustering the drop-off plies described above.

[0051] Also, as noted above, spacing the tips 220 apart from one another by at least one threshold distance may additionally or alternatively help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength. For example, for each drop-off ply 218B, the distance 228 between the tip 220 of the drop-off ply 218B and the tip 220 of an adjacent ply of the drop-off ply 218B may be at least 10 times greater than the ply thickness 226 of the drop-off ply 218B. In this example, for each drop-off ply 218B, the adjacent ply of the drop-off ply 218B is adjacent to the drop-off ply 218B in a dimension extending between the first exterior surface 214 and the second exterior surface 216. That is, two of the drop-off plies 218B are adjacent to one another only if there is no other one of the drop-off plies 218B between the two of the drop-off plies 218B in the dimension extending between the first exterior surface 214 and the second exterior surface 216. Thus, for example, plies 218 i=18 Ply 218 i=16 and Ply 218 i=20 adjacent to another drop-off ply 218B (i.e., ply 218 i=7,9,11,13,22,24 ) is not adjacent to

[0052] A representative one of the distances 228 is the distance between adjacent plies 218 in FIG. i=18 Tip 220 and ply 218 i=16 As shown in FIG. i=18 Tip 220 and ply 218 i=16 The distance 228 between the tips of the plies 218 i=182, the tips 220 of other adjacent ones of the drop-off plies 218B are separated by respective distances 228 that are at least 10 times greater than the ply thickness 226. As noted above, positioning the drop-off plies 218B such that the tips 220 of adjacent ones of the drop-off plies 218B are separated by distances 228 that are at least 10 times greater than the ply thickness 226 can help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength.

[0053] Additionally or alternatively, for example, the distance 230 between non-adjacent ones of the drop-off plies 218B can be at least three times greater than the ply thickness 226 of each drop-off ply 218B. i=16 Ga ply 218 i=18 and Ply 218 i=13 between the ply 218 i=18 Tip 220 and ply 218 i=13 As shown in FIG. i=18 Tip 220 and ply 218 i=13 The distance 230 between the tips of the plies 218 i=18 The tips 220 of the other non-adjacent ones of the drop-off plies 218B are separated by respective distances 230 that are at least three times greater than the ply thickness 226. Similarly, the tips 220 of the other non-adjacent ones of the drop-off plies 218B are separated by respective distances 230 that are at least three times greater than the ply thickness 226. As noted above, arranging the drop-off plies 218B such that the tips 220 of the other non-adjacent ones of the drop-off plies 218B are separated by a distance 228 that is at least three times the ply thickness 226 can help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength.

[0054] In FIG. 2, ply thickness 226 is the thickness of ply 218 iHowever, in another example, ply 218 i One or more of the plies 218 i In some embodiments, ply 218 may have a different thickness than another one of plies 218. i Providing the laminate in different ply thicknesses can help provide greater flexibility in achieving manufacturing quality goals.

[0055] Additionally, in FIG. 2, all of the tips 220 of the drop-off plies 218B have a tapered shape. However, in another example, one or more of the tips 220 of the drop-off plies 218B can have the blunt shape shown in FIG. 1. Although a tapered shape can be beneficial for at least the reasons described above, a composite structure including a drop-off ply 218B having a blunt tip 120 in a pattern having one or more of the characteristics described above with respect to FIG. 2 may provide an improvement over the composite structure 100 shown in FIG. 1. Similarly, a composite structure including a drop-off ply 118B arranged in the pattern shown in FIG. 1, but with a tip 220 having a tapered shape, may provide an improvement over the composite structure 100 shown in FIG. 1. Thus, within the scope of the embodiment, the drop-off plies 118B, 218B can have a tapered leading edge 220 and / or a blunt tip 120, and the drop-off plies 118B, 218B can be arranged in a clustered pattern (as shown in FIG. 1) and / or in a pattern having one or more of the characteristics described above with respect to FIG. 2.

[0056] As described, arranging the tips 220 of the drop-off plies 218B in a pattern having one or more of the above characteristics may help achieve greater symmetry for the composite structure 200 (e.g., about the central portion 224) as compared to, for example, the arrangement of the tips 120 of FIG. 1. As used herein, the term "symmetry" is intended to be a relative term and does not imply exact symmetry. For example, as shown in FIG. 2, the composite structure 200 has 14 plies 218 between the central portion 224 and the first exterior surface 214. i 12 plies 218 between the central portion 224 and the second outer surface 216 i However, in the context of this disclosure, the composite structure 200 shown in FIG. 2 has greater symmetry than the composite structure 100 shown in FIG.

[0057] Within the scope of the embodiments, providing composite structure 200 with greater symmetry around central portion 224 may help increase (or maximize) interlaminar strength. Additionally or alternatively, providing composite structure 200 with greater symmetry around central portion 224 may help reduce (or minimize) recuring, tooling, material handling costs, and / or weight.

[0058] 2 illustrates composite structure 200 with drop-off plies 218B arranged in an exemplary pattern having one or more properties that may aid in improving performance, reducing rehardening, reducing tooling, reducing material handling costs, and / or reducing the weight of composite structure 200. Other exemplary patterns having one or more properties are possible.

[0059] For example, Figure 3 illustrates a composite structure 300 having a variable gauge according to another embodiment. As shown in Figure 3, the composite structure 300 includes a first end 310A having a first gauge 312A and a second end 310B having a second gauge 312B that is smaller than the first gauge 312A of the first end 310A. Additionally, as shown in Figure 3, 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.

[0060] As also shown in FIG. 3 , the composite structure 300 includes a plurality of plies 318 of composite material disposed in a stack between the second exterior surface 316 and the first exterior surface 314. i=1 ~318 i=n (Hereafter collectively referred to as "Ply318 i In FIG. 3, the composite structure 300 includes a total of 28 plies 318. i (i.e., n=28). However, in other examples, the composite structure 300 may include plies 318 i Fewer or more plies may be included.

[0061] In this configuration, the first gauge 312A at the first end 310A and the second gauge 312B at the second end 310B are the thickness between the second outer surface 316 and the first outer surface 314 at the first end 310A and the second end 310B, respectively. Additionally, the first gauge 312A is the thickness between the ply 318 at the first end 310A and the ply 318 at the second end 310B. i The second gauge 312B is related to the amount of ply 318 at the second end 310B. i For example, in FIG. 3, the amount of ply 318 at first end 310A is i The amount of ply 318 at the second end 310B is such that the first gauge 312A is greater than the second gauge 312B. i greater than the amount of

[0062] As described above, the variable gauge of the composite structure 300 is formed by stacking plies 318 of composite material including a plurality of continuous plies 318A and a plurality of drop-off plies 318B disposed between the second exterior surface 316 and the first exterior surface 314. i 3, each continuous ply 318A extends from a first end 310A to a second end 310B, while each drop-off ply 318B includes a tip 320, and each drop-off ply 318B extends from the first end 310A to a respective location of the tip 320 of the drop-off ply 318B between the first end 310A and the second end 310B.

[0063] For clarity of illustration, a representative subset of continuous plies 318A is labeled with reference numeral 318A and a representative subset of drop-off plies 318B is labeled with reference numeral 318B in FIG. i Each of the plies 318 is one of the continuous plies 318A and terminates between the first end 310A and the second end 310B. i Each of plies 318B is one of the drop-off plies 318B. i=1-4,6,8,,10,12,14,15,17,19,21,23,25-28 is continuous ply 318A, ply 318 i=5,7,9,11,13,16,18,20,22,24 is a drop-off ply 318B.

[0064] 3, the tip 320 of each drop-off ply 318B has a tapered shape as described above with respect to the tip 220 shown in FIG 2. Thus, the tapered tip 320 can reduce (or minimize) resin pockets at the tips 320 of the drop-off plies 318B and help improve (or maximize) the interlaminar strength of the composite structure 300. However, in other examples, one or more of the drop-off plies 318B can have the blunt shape shown in FIG 1.

[0065] As discussed above, the load-bearing capacity of the composite structure 300 may additionally or alternatively be improved by the ply 318. i3, the drop-off plies 318B may be separated from one another by at least one of the continuous plies 318A. For example, in FIG. 3, each drop-off ply 318B may be sandwiched between and abut two respective continuous plies 318A of the plurality of continuous plies 318A. By separating the drop-off plies 318B from one another and / or sandwiching the drop-off plies 318B between the continuous plies 318A, the drop-off plies 318B may be more evenly distributed between the second exterior surface 316 and the first exterior surface 314 (compared to the clustered arrangement of the drop-off plies 118B shown in FIG. 1). This may help (or may prevent) a reduction in ply kinking and / or wrinkling, a reduction in resin pockets, and / or a reduction in interlaminar strength of the composite structure 300.

[0066] Within the scope of the embodiment, the pattern of tips 320 of the drop-off plies 218B may additionally or alternatively include one or more of the following characteristics: (i) arranging the tips 320 of the front half of the composite structure 300 in a pattern that mirrors the pattern of the tips 320 of the back half of the composite structure 300, (ii) staggering the tips 320 relative to each other, and / or (iii) maintaining the tips 320 spaced apart from each other by at least one threshold distance. As discussed above, each of these characteristics, alone or in combination, may contribute to arranging the drop-off plies 318B in a pattern that may reduce (or prevent) ply kinking and / or wrinkling, may reduce (or prevent) resin pockets, and / or may increase (or maximize) interlaminar strength.

[0067] 3 illustrates tips 320 arranged in a mirror pattern relative to a central portion 324 of a composite structure 300, according to another example. The central portion 324 includes one or more plies 318B that provide a frame of reference for characterizing the pattern of tips 320 of the drop-off plies 318B on either side of the central portion 324. iAs described above, generally, central portion 324 (i) is between second outer surface 316 and first outer surface 314, and (ii) extends from first end 310A to second end 310B.

[0068] In FIG. 3 , the central portion 324 is i=14,15 3, the central portion 324 may include two continuous plies 318A. However, in another example, the central portion 324 may include two drop-off plies 318B and at least one continuous ply 318A. In yet another example, the central portion 324 may consist of only a single drop-off ply 318B. In another example, the central portion 324 may consist of at least one continuous ply 318A and omit the drop-off ply 318B. More specifically, the central portion 324 may include one or more of the continuous plies 318A and / or one or more of the drop-off plies 318B.

[0069] 3, the tips 320 of the drop-off plies 318B can be arranged in a substantially mirror or mirror pattern relative to the central portion 324. For example, a first subset of the drop-off plies 318B can be between the first exterior surface 314 and the central portion 324, and a second subset of the drop-off plies 318B can be between the central portion 324 and the second exterior surface 316. In this arrangement, the tips 320 of the first subset of the drop-off plies 318B are arranged in a pattern that substantially mirrors the pattern of the tips 320 of the second subset of the drop-off plies 318B. In essence, the respective positions of the tips 320 of the first subset of the drop-off plies 318B are arranged (i) oppositely and (ii) similarly (or equally) relative to the central portion 324 as compared to the respective positions of the tips 320 of the second subset of the drop-off plies 318B.

[0070] For example, in FIG. 3, central portion 324 is made of ply 318. i=14,15a first subset of drop-off plies 318B may include plies 318 i=5,7,9,11,13 and a second subset of drop-off plies 318B may include plies 318 i=16,18,20,22,24 3, the pattern of tips 320 of the first subset of drop-off plies 318B substantially mirrors the pattern of tips 320 of the second subset of drop-off plies 318B. For example, with respect to the central portion 324, the location of each of the tips 320 of the first subset is oppositely and similarly positioned compared to the location of each of the tips 320 of the second subset.

[0071] As noted above, FIG. 2 illustrates the pattern of tips 220 of the drop-off plies 218B as a monotonically outward pattern. FIG. 3 illustrates tips 320 of the drop-off plies 318B arranged in a monotonically inward pattern, according to an embodiment. In a first sequence of a first subset of drop-off plies 318B from the first exterior surface 314 toward the central portion 324, the relative distance between the tips 320 of the drop-off plies 318B and the second ends 310B decreases as each successive drop-off ply 318B is in the first sequence. Also, in a second sequence of a second subset of drop-off plies 318B from the second exterior surface 316 toward the central portion 324, the relative distance between the tips 320 of the drop-off plies 318B and the second ends 310B decreases as each successive drop-off ply 318B is in the second sequence.

[0072] Thus, in FIG. 3, (i) ply 218 i=5 (ii) the tip 320 of the ply 318 is a first distance from the second end 310B; i=7 (iii) the tip 320 of the ply 318 is at a second distance from the second end 310B that is less than the first distance; i=9 (iv) the tip 320 of the ply 318 is at a third distance from the second end 310B that is less than the second distance; i=11 (v) the tip 320 of the ply 318 is at a fourth distance from the second end 310B that is less than the third distance; i=13The tip 320 of the ply 318 is at a fifth distance from the second end 310B, which is smaller than the fourth distance. i=24 (vii) the tip 320 of the ply 318 is a sixth distance from the second end 310B; i=22 (viii) the tip 320 of the ply 318 is at a seventh distance from the second end 310B that is less than the sixth distance; i=20 (ix) the tip 320 of the ply 318 is at an eighth distance from the second end 310B that is less than the seventh distance; i=18 (x) ply 318 has a tip 320 at a ninth distance from second end 310B that is less than the eighth distance; i=16 The tip 320 is a tenth distance from the second end 310B, which is less than the ninth distance.

[0073] Thus, in the monotonically inward pattern of tips 320 shown in FIG. 3, the tips 320 of the drop-off ply 318B appear to generally converge inwardly from the first and second outer surfaces 314, 316 to the central portion 324 in a direction from the first end 310A to the second end 310B. The monotonically inward pattern of tips 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, the monotonically inward pattern of tips 320 can facilitate achieving greater symmetry with respect to, for example, the arrangement of tips 120 of FIG. 1 (clustered near the first outer surface 114).

[0074] 3, the drop-off plies 318B may be arranged in pairs of drop-off plies 318B that define an order in which the drop-off plies 318B descend in a direction from the first end 310A toward the second end 310B (i.e., an order of respective positions of the tips 320 in a direction from the first end 310A toward the second end 310B). In particular, each pair of drop-off plies 318B may include one respective drop-off ply 318B of the first subset and one respective drop-off ply 318B of the second subset.

[0075] For example, in FIG. 3, the first pair is ply 318 i=5,24 and the second pair includes ply 318 i=7,22 and the third pair includes ply 318 i=9,20 and the fourth pair includes ply 318 i=11,18 and the fifth pair includes ply 318 i=13,16 3, in a direction from the first end 310A to the second end 310B, the drop-off plies 318B descend in order from the first pair to the fifth pair. In short, the tip 320 of the first pair of drop-off plies 318B is closest to the first end 310A, the tip 320 of the second pair of drop-off plies 318B is second closest to the first end 310A, the tip 320 of the third pair of drop-off plies 318B is third closest to the first end 310A, the tip 320 of the fourth pair of drop-off plies 318B is second furthest from the first end 310A, and the tip 320 of the fifth pair of drop-off plies 318B is furthest from the first end 310A.

[0076] Additionally, for example, for each pair of drop-off plies 318B, each one of the drop-off plies 318B of the first subset and each one of the drop-off plies 318B of the second subset are equidistant from the central portion 324 in the dimension between the first exterior surface 314 and the second exterior surface 316. For example, as shown in FIG. 3, each of the first pair of drop-off plies 318B includes a single ply 318 ia second pair of drop-off plies 318B are each spaced apart from central portion 324 a distance equal to eight times the ply thickness 326, a third pair of drop-off plies 318B are each spaced apart from central portion 324 a distance equal to six times the ply thickness 326, a fourth pair of drop-off plies 318B are each spaced apart from central portion 324 a distance equal to two times the ply thickness 326, and a fifth pair of drop-off plies 318B are each immediately adjacent to and abutting central portion 324. Arranging the drop-off plies 318B in pairs, (i) descending pair-by-pair from the first end 310A to the second end 310B, and / or (ii) equidistant to the central portion 324, can help provide a more gradual and / or smoother transition from the first gauge 312A at the first end 310A to the second gauge 312B at the second end 310B, and / or can help achieve greater symmetry with respect to, for example, the arrangement of tips 120 in FIG. 1 (which are clustered near the first outer surface 114).

[0077] According to additional or alternative aspects of the monotonically inward pattern shown in FIG. 3, the monotonically inward pattern may include tips 320 of a first subset of drop-off plies 318B alternating with tips 320 of a second subset of drop-off plies 318B along a direction from the first end 310A to the second end 310B. For example, in FIG. 3, the tips 320 of the drop-off plies 318B are in the following order from the first end 310A to the second end 310B: (i) tips 320 of the first subset of plies 318B alternate with tips 320 of the second subset of plies 318B along a direction from the first end 310A to the second end 310B. i=5 (ii) the tip 320 of the ply 318 from the second subset i=24 (iii) the tip 320 of the ply 318 from the first subset i=7 (iv) the tip 320 of the ply 318 from the second subset i=22 (v) the tip 320 of the ply 318 from the first subset i=9 (vi) the tip 320 of the ply 318 from the second subset i=20(vii) the tip 320 of the ply 318 from the first subset i=11 (viii) the tip 320 of the ply 318 from the second subset i=18 (ix) the tip 320 of the ply 318 from the first subset i=13 and (x) the tip 320 of the ply 318 from the second subset. i=16 Alternating the location of each of the tips 320 of the drop-off plies 318B can additionally or alternatively facilitate a more gradual and / or smoother transition from the first gauge 312A at the first end 310A to the second gauge 312B at the second end 310B.

[0078] As discussed above, arranging the drop-off plies 318B such that their tips 320 are staggered from one another may additionally or alternatively help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength. By way of example, in FIG. 3 , the locations of each of the tips 320 of the drop-off plies 318B may be staggered from the first end 310A to the second end 310B. By “staggered,” it is meant that the tips 320 of the drop-off plies 318B are each at a respective distance from the second end 310B, and that the respective distances between the tips 320 and the second end 310B are quite different from one another (i.e., the tips of the two drop-off plies are not equidistant from the second end 310B). Staggering the tips 320 of the drop-off plies 318B may help alleviate some or all of the problems associated with clustering the drop-off plies described above.

[0079] Also, as noted above, spacing the tips 320 apart from one another by at least one threshold distance may additionally or alternatively help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength. For example, for each drop-off ply 318B, the distance 328 between the tip 320 of the drop-off ply 318B and the tip 320 of an adjacent ply of the drop-off ply 318B may be at least ten times greater than the ply thickness 326 of the drop-off ply 318B. In this example, for each drop-off ply 318B, the adjacent ply of the drop-off ply 318B is adjacent to the drop-off ply 318B in a dimension extending between the first exterior surface 314 and the second exterior surface 316. For example, as described above, two of the drop-off plies 318B are adjacent to one another only if there is no other one of the drop-off plies 318B between the two of the drop-off plies 318B in the dimension extending between the first exterior surface 314 and the second exterior surface 316. Thus, for example, plies 318 i=7 Ply 318 i=5 and ply 318 i=9 adjacent to another drop-off ply 318B (i.e., ply 218 i=11,13,16,18,20,22,24 ) is not adjacent to

[0080] A representative one of the distances 328 is the distance between adjacent plies 318 in FIG. i=7 Tip 320 and ply 318 i=5 As shown in FIG. i=7 Tip 320 and ply 318 i=5 The distance 328 between the tips of the plies 318 i=73, the tips 320 of adjacent ones of the drop-off plies 318B are separated by respective distances 328 that are at least 10 times greater than the ply thickness 326. As noted above, positioning the drop-off plies 318B such that the tips 320 of adjacent ones of the drop-off plies 318B are separated by distances 328 that are at least 10 times greater than the ply thickness 326 can help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength.

[0081] Additionally or alternatively, for example, the distance 330 between non-adjacent ones of the drop-off plies 318B can be at least three times greater than the ply thickness 326 of each drop-off ply 318B. i=9,11,13,16,18,20 Ga ply 318 i=7 and Ply 318 i=22 between the ply 318 i=7 Tip 320 and ply 318 i=22 As shown in FIG. i=7 Tip 320 and ply 318 i=22 The distance 330 between the tips of the plies 318 i=7 The tips 320 of the other non-adjacent plies of drop-off ply 318B are separated by respective distances 330 that are at least three times greater than the ply thickness 326. Similarly, the tips 320 of other non-adjacent plies of drop-off ply 318B are separated by respective distances 330 that are at least three times greater than the ply thickness 326. As noted above, arranging drop-off ply 318B such that the tips 320 of non-adjacent plies of drop-off ply 318B are separated by distances 328 that are at least three times the ply thickness 326 can help reduce (or prevent) ply kinking and / or wrinkling, reduce (or prevent) resin pockets, and / or increase (or maximize) interlaminar strength.

[0082] In FIG. 3, ply thickness 326 is the thickness of ply 318 iHowever, in another example, ply 318 is the same for all of the plies. i One or more of the plies 318 i In some embodiments, ply 318 may have a different thickness than another one of plies 318. i Providing the laminate in different ply thicknesses can help provide greater flexibility in achieving manufacturing quality goals.

[0083] Additionally, in Figure 3, all of the tips 320 of the drop-off plies 318B have a tapered shape. However, in another example, one or more of the tips 320 of the drop-off plies 318B can have the blunt shape of the tips 120 shown in Figure 1. Although a tapered shape can be beneficial for at least the reasons described above, a composite structure including drop-off plies 318B having blunt tips 120 in a pattern having one or more of the characteristics described above with respect to Figure 3 may provide an improvement over the composite structure 100 shown in Figure 1.

[0084] 1-3, the composite structures 100, 200, 300 are shown having a curved shape between a first end 110A, 210A, 310A and a second end 110B, 210B, 310B. However, in other examples, the composite structures 100, 200, 300 can have different shapes, such as, for example, planar, scalloped, corrugated, uniform, non-uniform, polygonal, and / or non-polygonal shapes.

[0085] In some examples, the first end 110A, 210A, 310A and / or the second end 110B, 210B, 310B may form an exterior 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 a respective interface with another segment of a larger composite structure. For example, the composite structures 100, 200, 300 shown in FIGS. 1-3 may provide a transition segment of the composite structure for transitioning from one gauge to another within the composite structure.

[0086] Referring to Figure 4, a simplified block diagram of a composite structure 400 having a variable gauge according to another embodiment is shown. As shown in Figure 4, the composite structure 400 includes a first segment 440, a second segment 442, and a transition segment 444 between the first segment 440 and the second segment 442. The first segment 440 has a first gauge 412A, and the second segment 442 has a second gauge 412B that is smaller than the first gauge 412A. Although Figure 4 shows the composite structure 400 having three segments (i.e., the first segment 440, the transition segment 444, and the second segment 442), the composite structure 400 can have a lesser or greater amount of segments in other examples.

[0087] The transition segment 444 can have a variable gauge to transition from between the first gauge 412A and the second gauge 412B. For example, the transition segment 444 can include one or more continuous plies and one or more drop-off plies that are configured to transition between the first gauge 412A and the second gauge 412B, as described above for the composite structures 100, 200, 300 shown in FIGS. 1-3.

[0088] 4, the transition segment 444 includes a first end 410A of the first segment 440 having a first gauge 412A, a second end 410B of the second segment 442 having a second gauge 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 an interface between the first segment 440 and the transition segment 444, and the second end 410B can provide an interface between the second segment 442 and the transition segment 444.

[0089] The transition segment 444 also includes a plurality of plies 418 (i) extending between the first end 410A and the second end 410B, and (ii) arranged in a stack between the first exterior surface 414 and the second exterior surface 416. As shown in FIG. 4, the plies 418 include a plurality of continuous plies 418A and at least one drop-off ply 418B. As described above, each continuous ply 418A extends from the first end 410A to the second end 410B, and each drop-off ply 418B extends from the first end 410A to a respective location of a tip 420 of the drop-off ply 418B between the first end 410A and the second end 410B. Within the scope of the embodiment, the tip 420 of the drop-off ply 418B can have a tapered shape (e.g., as shown in FIGS. 2-3) and / or a blunt shape (e.g., as shown in FIG. 1).

[0090] In some examples, each drop-off ply 418B is sandwiched between and abuts two respective continuous plies 418A of the plurality of continuous plies 418A. Additionally or alternatively, the tips 420 of the drop-off plies 418B can be arranged in the monotonically outward pattern (e.g., as shown in FIG. 2), monotonically inward pattern (e.g., as shown in FIG. 3), staggered pattern (e.g., as shown in FIG. 2-3), and / or substantially mirrored pattern (e.g., as shown in FIG. 2-3) described above.

[0091] For example, in an implementation in which the plies are arranged in a monotonically inward pattern, (i) a first subset of the drop-off plies 418B are between the first outer surface 414 and a central portion of the stack and a second subset of the drop-off plies 418B are between the central portion and the second outer surface 416, (ii) in a first sequence of the first subset of the drop-off plies 418B from the first outer surface 414 toward the central portion, as each successive drop-off ply 418B is in the first sequence, the relative distance between the tip 420 and the second end 410B of the drop-off ply 418B decreases, and (iii) in a second sequence of the second subset of the drop-off plies 418B from the second outer surface 416 toward the central portion, as each successive drop-off ply 418B is in the second sequence, the relative distance between the tip 420 and the second end 410B of the drop-off ply 418B decreases.

[0092] Additionally, for example, in an implementation in which the tips 420 are arranged in a monotonically outward pattern, (i) a first subset of the drop-off plies 418B are between the first outer surface 414 and a central portion of the stack and a second subset of the drop-off plies 418B are between the central portion and the second outer surface 416, (ii) in a first sequence of the first subset of the drop-off plies 418B from the central portion toward the first outer surface 414, as each successive drop-off ply 418B is in the first sequence, the relative distance between the tips 420 and the second ends 410B of the drop-off plies 418B decreases, and (iii) in a second sequence of the second subset of the drop-off plies 418B from the central portion toward the second outer surface 416, as each successive drop-off ply 418B is in the second sequence, the relative distance between the tips 420 and the second ends 410B of the drop-off plies 418B decreases.

[0093] Additionally or alternatively, for each drop-off ply 418B, the distance between the tip 420 of the drop-off ply 418B and the tip 420 of an adjacent ply of the drop-off ply 418B can be at least 10 times greater than the thickness of the drop-off ply 418B. Additionally or alternatively, the distance between non-adjacent plies of the drop-off ply 418B can be at least 3 times greater than the thickness of each drop-off ply 418B.

[0094] Within the scope of the embodiments, the composite structures 100, 200, 300, 400 described above with respect to Figures 1-4 can be used to form a variety of structures. By way of example, aircraft, spacecraft, rotorcraft, ships, automobiles, trucks, and other types of vehicles (e.g., passenger capsules or cargo containers) can include the composite structures 100, 200, 300, 400 described above. In addition, for example, buildings, bridges, swimming pools, storage tanks, robot frame structures, energy structures (e.g., wind blades, turbine blades, propulsion blades, and / or solar panels), sporting goods (e.g., bicycle frames, skis, snowboards, surfboards, paddles, etc.), homes, office buildings, and / or medical board frames can include the composite structures 100, 200, 300, 400 described above.

[0095] As one example, Figures 5A-5B show composite stringers 550, which may include one or more of the composite structures 100, 200, 300, 400 described above with respect to Figures 1-4. Generally, the composite stringers 550 are each elongated members that may be coupled to one or more skin panels to help carry and / or transfer loads from the skin panels to another structure of the aircraft (e.g., the aircraft's frame, ribs, and / or spars). In this manner, the composite stringers 550 may help prevent buckling of the skin panels due to compression or shear loads and / or mitigate bending of the skin panels. For these and other reasons, aircraft typically include one or more composite stringers 550 in the aircraft's fuselage, wing assemblies, and / or empennage.

[0096] Generally, composite stringer 550 includes one or more flanges 552A-552C and one or more webs 554A-554B. More specifically, in Figures 5A-5B, composite stringer 550 includes a skin flange 552A configured to be coupled to a support structure 556 (e.g., a skin panel of an aircraft), a top flange 552B, and a web 554A extending between skin flange 552A and top flange 552B. In Figure 5, composite stringer 550 is in the form of a hat-shaped stringer. Thus, the web 554A can extend from a first side of the top flange 550B, and the composite stringer 550 can further include a second skin flange 552C configured to be coupled to the support structure 556 and to a second web 554B extending between the skin flange 552C and the second side of the top flange 552B.

[0097] Within the scope of the embodiments, the composite stringer 550 may include one or more corner portions, each of which provides a transition segment between two other segments of the composite stringer 550 (i.e., between two of the skin flange 552A, the web 554A, the top flange 552B, the second web 554B, and the second skin flange 552C). For example, in FIG. 5, 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 top 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 top flange 552B.

[0098] 5, the top flange 552B has a first gauge 512A. The skin flange 552A, the second skin flange 552C, the web 554A, and the second web 554B all have a second gauge 512B. In this example, the first gauge 512A is larger than the second gauge 512B.

[0099] In this arrangement, the second corner portion 558B and the fourth corner portion 558D can be composite structures having variable gauge. For example, the top flange 552B can be a first segment (e.g., first segment 440), the web 554A can be a second segment (e.g., second segment 442 in FIG. 4), and the second corner portion 558B can be a transition segment between the top flange 552B and the web 554A (e.g., transition segment 444 in FIG. 4). Similarly, for example, the top flange 552B can be a first segment (e.g., first segment 440), the second web 554B can be a second segment (e.g., second segment 442 in FIG. 4), and the fourth corner portion 558D can be a transition segment between the top flange 552B and the second web 554B (e.g., transition segment 444 in FIG. 4).

[0100] In particular, in Figure 5A, the second corner portion 558B and the fourth corner portion 558D each include the composite structure 100 shown in Figure 1. Meanwhile, in Figure 5B, the second corner portion 558B and the fourth corner portion 558D each include the composite structure 300 shown in Figure 3. As shown in Figures 5A-5B, the composite structure 300 of Figure 3, which includes drop-off plies 318B having tapered tips 320 arranged in a monotonically inward pattern, provides a smoother and relatively symmetrical transition from the first gauge 512A to the second gauge 512B than the composite structure 100 of Figure 1, which includes drop-off plies 118B having blunt tips 120 arranged in clusters at or near the first exterior surface 114.

[0101] As noted above, Figures 5A-5B show one example of a structure that may include the composite structures 100, 200, 300, 400 described herein. However, as noted above, the composite structures 100, 200, 300, 400 may be incorporated into structures other than the composite stringer 550 shown in Figures 5A-5B.

[0102]

[0031] Referring now to Figure 6, a flow chart of a process 600 for forming a composite structure having variable gauge is described according to an embodiment. As shown in Figure 6, at block 610, the process 600 includes forming a plurality of continuous plies. At block 612, the process 600 includes forming a plurality of drop-off plies. Forming the plurality of drop-off plies at block 612 may include forming, for each drop-off ply, a tip of the drop-off ply having a tapered shape at block 614.

[0103] At block 616, the process 600 includes positioning the plurality of continuous plies and the plurality of drop-off plies in a stack having a first end and a second end. The first end has a first gauge. The second end has a second gauge that is smaller than the first gauge. As shown in FIG. 6, positioning the plurality of continuous plies and the plurality of drop-off plies at block 616 may include positioning the plurality of continuous plies at block 618 such that each continuous ply extends from a first end to a second end. Positioning the plurality of continuous plies and the plurality of drop-off plies at block 616 may also include positioning the plurality of drop-off plies at block 620 such that (i) each drop-off ply extends from a first end to a respective location of a tip of the drop-off ply between the first end and the second end, and (ii) the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies.

[0104] 7-14 illustrate additional aspects of the process 600 according to further embodiments. As shown in FIG. 7, the process 600 may further include, after positioning the plurality of continuous plies and the plurality of drop-off plies in a stack at block 616, curing the plurality of continuous plies and the plurality of drop-off plies at block 622.

[0105] 8, positioning the plurality of continuous plies and the plurality of drop-off plies in a stack at block 616 may further include forming a first outer surface extending from a first end to a second end at block 624, and forming a second outer surface extending from the first end to the second end at 626. The first gauge and the second gauge may each be a thickness between the first outer surface and the second outer surface at the first end and the second end, respectively.

[0106] 9, positioning the plurality of continuous plies and the plurality of drop-off plies in a stack at block 616 may further include positioning a first subset of the plurality of drop-off plies between the first outer surface and a 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 in FIG. 9, positioning the plurality of continuous plies and the plurality of drop-off plies in a stack at block 616 may include positioning a second subset of the plurality of drop-off plies between the central portion and the second outer surface at block 630.

[0107] As shown in FIG. 10 , positioning a first subset of the plurality of drop-off plies in block 628 and positioning a second subset of the plurality of drop-off plies in block 630 may include positioning the plurality of drop-off plies in block 632 such that tips of the first subset of the plurality of drop-off plies are arranged in a pattern that substantially mirrors the pattern of tips of the second subset of the plurality of drop-off plies.

[0108] As shown in FIG. 11 , positioning the plurality of drop-off plies in block 620 may include positioning the plurality of drop-off plies such that the positions of the respective tips of the plurality of drop-off plies are staggered from the first end to the second end in block 634.

[0109] As shown in FIG. 12 , positioning the first subset of the plurality of drop-off plies in block 628 may include (i) positioning the first subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the first outer surface in block 636, and (ii) positioning the first subset of the plurality of drop-off plies in block 638 such that a tip pattern of the first subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply with each successive drop-off ply positioned in sequence.

[0110] Also, as shown in FIG. 12 , positioning the second subset of the plurality of drop-off plies in block 630 may include: (i) positioning the second subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the second outer surface in block 640; and (ii) positioning the second subset of the plurality of drop-off plies in block 642 such that a tip pattern of the second subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply with each successive drop-off ply positioned in sequence.

[0111] 13, positioning the plurality of drop-off plies in block 620 may include positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply in block 644. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface.

[0112] As shown in FIG. 14 , positioning the plurality of drop-off plies in block 620 may include positioning the plurality of drop-off plies in block 646 such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply.

[0113] 15, a flow chart of a process 1500 for forming a composite structure having variable gauge is described according to an embodiment. As shown in FIG. 15, at block 1510, the process 1500 includes forming a plurality of continuous plies. At block 1512, the process 1500 includes forming a plurality of drop-off plies. At block 1512, forming the plurality of drop-off plies may include, for each drop-off ply, forming a tip of the drop-off ply having a tapered shape at block 1514.

[0114] At block 1516, the process 1500 may include positioning the plurality of continuous plies and the plurality of drop-off plies 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 gauge. The second end has a second gauge that is smaller than the first gauge.

[0115] 15, positioning the plurality of continuous plies and the plurality of drop-off plies in block 1516 may include positioning the plurality of continuous plies such that each continuous ply extends from a first end to a second end in block 1518. Additionally, positioning the plurality of continuous plies and the plurality of drop-off plies in block 1516 may also include positioning the plurality of drop-off plies such that each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end in block 1520. A first subset of the plurality of drop-off plies is between the first outer surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second outer surface.

[0116] 16-21 depict additional aspects of process 1500 according to further embodiments. As shown in FIG. 16, stacking and positioning the plurality of successive plies and the plurality of drop-off plies in block 1516 may further include arranging the plurality of drop-off plies in a monotonically inward pattern in block 1522, including (i) a first sequence of a first subset of the plurality of drop-off plies from the first outer surface toward the central portion, where the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the first sequence, and (ii) a second sequence of a second subset of the plurality of drop-off plies from the second outer surface toward the central portion, where the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the second sequence.

[0117] As shown in FIG. 17, after stacking and positioning the plurality of continuous plies and the plurality of drop-off plies in block 1516, process 1500 may further include curing the plurality of continuous plies and the plurality of drop-off plies in block 1524.

[0118] As shown in FIG. 18 , positioning the multiple continuous plies and the multiple drop-off plies in block 1516 may include positioning the multiple continuous plies and the multiple drop-off plies in block 1526 such that the multiple drop-off plies are separated from one another by at least one of the multiple continuous plies.

[0119] As shown in FIG. 19 , positioning the plurality of drop-off plies in block 1520 may include positioning the plurality of drop-off plies in block 1528 such that the positions of the respective tips of the plurality of drop-off plies are staggered from the first end to the second end.

[0120] 20 , positioning the plurality of drop-off plies in block 1520 may include positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface.

[0121] As shown in FIG. 21 , positioning the plurality of drop-off plies in block 1520 may include positioning the plurality of drop-off plies in block 1532 such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply.

[0122] One or more of the blocks illustrated in FIG. 6-21 may represent a module, segment, or portion of a program code, including one or more instructions executable by a processor to implement a particular logical function or step in a process. The program code may be stored in any type of computer-readable medium or data storage device, such as a storage device including a disk drive or hard drive. Furthermore, the program code may be encoded in a machine-readable form in a computer-readable storage medium or other non-transitory medium or product. The computer-readable medium may include a non-transitory computer-readable medium or memory (e.g., a computer-readable medium that stores data for a short period of time, such as a register memory, a processor cache, and a random access memory (RAM)). The computer-readable medium may also include a non-transitory medium (e.g., a secondary or permanent long-term storage device, such as a read-only memory (ROM), an optical or magnetic disk, a compact disk read-only memory (CD-ROM), etc.). The computer-readable medium may be any other volatile or non-volatile storage system. The computer readable medium may be considered, for example, a tangible computer readable storage medium.

[0123] In some examples, the components of the devices and / or systems described herein may be configured to perform a function, whereby the components are actually configured and constructed (with hardware and / or software) to enable such performance. The example configurations then include one or more processors that execute instructions that cause the system to perform those functions. Similarly, the components of the devices and / or systems may be configured, for example, such that they are adapted, capable of, or suitable for performing that function when operated in a particular manner.

[0124] Additionally, the disclosure includes examples according to the following clauses: Clause 1. A composite structure including a first end having a first gauge and a second end having a second gauge less than the first gauge. The composite structure also includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a tapered shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. The plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 2. The composite structure of clause 1, further comprising a first exterior surface extending from the first end to the second end and a second exterior surface extending from the first end to the second end. The plurality of continuous plies and the plurality of drop-off plies are stacked and disposed between the first exterior surface and the second exterior surface. The first gauge and the second gauge are thicknesses between the first exterior surface and the second exterior surface at the first end and the second end, respectively. Clause 3. The composite structure of clause 2, wherein a first subset of the plurality of drop-off plies is between the first exterior surface and a central portion. The central portion (i) is between the first exterior surface and the second exterior surface and (ii) extends from a first end to a second end. The second subset of the plurality of drop-off plies is between the central portion and the second exterior surface. Tips of the first subset of the plurality of drop-off plies are arranged in a pattern that substantially mirrors a pattern of tips of the second subset of the plurality of drop-off plies. Clause 4. The composite structure of clause 3, wherein the central portion includes a single drop-off ply of the plurality of drop-off plies. Clause 5. The composite structure of clause 3, wherein the central portion includes two drop-off plies of the plurality of drop-off plies and at least one continuous ply of the plurality of continuous plies between the two drop-off plies. Clause 6. The composite structure of any one of clauses 1 to 5, wherein the locations of each of the tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 7. The composite structure of clause 6, wherein the first subset of the plurality of drop-off plies are arranged in order from a drop-off ply closest to the central portion to a drop-off ply closest to the first exterior surface. The tip pattern of the first subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply with each successive drop-off ply arranged in the sequence. The second subset of the plurality of drop-off plies are arranged in order from a drop-off ply closest to the central portion to a drop-off ply closest to the second exterior surface. The tip pattern of the second subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply with each successive drop-off ply arranged in the sequence. Clause 8. The composite structure of any one of clauses 2 to 7, wherein, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first exterior surface and the second exterior surface. Clause 9. The composite structure of any one of clauses 1 to 8, wherein a distance between non-adjacent ones of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 10. A method of forming a composite structure having variable gauge includes forming a plurality of continuous plies and forming a plurality of drop-off plies. Forming the plurality of drop-off plies includes forming, for each drop-off ply, a tip of the drop-off ply having a tapered shape. The method also includes positioning the plurality of continuous plies and the plurality of drop-off plies in a stack having a first end and a second end. The first end has a first gauge. The second end has a second gauge that is smaller than the first gauge. Positioning the plurality of continuous plies and the plurality of drop-off plies includes (a) positioning the plurality of continuous plies such that each continuous ply extends from the first end to the second end, and (b) positioning the plurality of drop-off plies such that (i) each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end, and (ii) the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 11. The method of clause 10, further comprising curing the plurality of continuous plies and the plurality of drop-off plies after positioning the plurality of continuous plies and the plurality of drop-off plies in a stack. Clause 12. The method of clause 10 or 11, wherein stacking and positioning the plurality of continuous plies and the plurality of drop-off plies further includes 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 gauge and second gauge are thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively. Clause 13. The method of clause 12, wherein positioning the plurality of continuous plies and the plurality of drop-off plies in a stack includes positioning a first subset of the plurality of drop-off plies between a first outer surface and a central portion, the central portion (i) being between the first outer surface and the second outer surface and (ii) extending from the first end to the second end. Positioning the plurality of continuous plies and the plurality of drop-off plies in a stack also includes positioning a second subset of the plurality of drop-off plies between the central portion and the second outer surface. Positioning the first subset of the plurality of drop-off plies and positioning the second subset of the plurality of drop-off plies include positioning the plurality of drop-off plies such that tips of the first subset of the plurality of drop-off plies are arranged in a pattern that substantially mirrors a pattern of tips of the second subset of the plurality of drop-off plies. Clause 14. The method of clause 13, wherein the central portion includes a single drop-off ply of the plurality of drop-off plies. Clause 15. The method of clause 13, wherein the central portion includes two drop-off plies of the plurality of drop-off plies and at least one continuous ply of the plurality of continuous plies between the two drop-off plies. Clause 16. The method of any one of clauses 10 to 15, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that respective positions of tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 17. The method of clause 16, wherein positioning the first subset of the plurality of drop-off plies includes: (i) positioning the first subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the first exterior surface; and (ii) positioning the first subset of the plurality of drop-off plies such that a pattern of tips of the first subset of the plurality of drop-off plies includes a decreasing relative distance between the tips and the second ends of the drop-off plies with each successive drop-off ply positioned in sequence. Positioning the second subset of the plurality of drop-off plies includes (a) positioning the second subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the second outer surface; and (b) positioning the second subset of the plurality of drop-off plies such that a pattern of tips of the second subset of the plurality of drop-off plies includes a decreasing relative distance between the tips of the drop-off plies and the second end with each successive drop-off ply positioned in sequence. Clause 18. The method of any one of clauses 10 to 17, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface. Clause 19. The method of any one of clauses 10 to 18, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 20. Composite structure having variable gauge. The composite structure includes a first segment having a first gauge and a second segment having a second gauge less than the first gauge. The composite structure also includes a transition segment between the first segment and the second segment. The transition segment includes a first end of the first segment having the first gauge, a second end of the second segment having a 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 plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes (a) a plurality of continuous plies, each extending from a first end to a second end, and (b) at least one drop-off ply, each including a tip having a tapered shape and each extending from the first end to a respective location of the tip of the drop-off ply between the first end and the second end, Each drop-off ply is sandwiched between and abuts two respective continuous plies of the plurality of continuous plies. Clause 21. A composite structure including a first end having a first gauge and a second end having a second gauge less than the first gauge. The composite structure also includes 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 plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a tapered shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first exterior surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second exterior surface, and tips of the plurality of drop-off plies are arranged in a monotonically inward pattern including: (i) in a first sequence of the first subset of the plurality of drop-off plies from the first exterior surface toward the central portion, a relative distance between the tips and second ends of the drop-off plies decreases with each successive drop-off ply in the first sequence, and (ii) in a second sequence of the second subset of the plurality of drop-off plies from the second exterior surface toward the central portion, a relative distance between the tips and second ends of the drop-off plies decreases with each successive drop-off ply in the second sequence. Clause 22. The composite structure of clause 21, wherein the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 23. The composite structure of clause 21 or 22, wherein the first gauge and the second gauge are respectively thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively. Clause 24. The composite structure of any one of clauses 21 to 23, wherein the central portion comprises at least one continuous ply of the plurality of continuous plies. Clause 25. The composite structure of any one of clauses 21 to 24, wherein the locations of each of the tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 26. The composite structure of any one of clauses 21 to 25, wherein the monotonically inward pattern further comprises tips of a first subset of the plurality of drop-off plies alternating with tips of a second subset of the plurality of drop-off plies along a direction from the first end to the second end. Clause 27. The composite structure of any one of clauses 21 to 26, wherein the plurality of drop-off plies are arranged in a plurality of pairs of drop-off plies, each pair of drop-off plies including a respective one of the first subset and a respective one of the second subset, and for each pair of drop-off plies, the respective one of the drop-off plies of the first subset and the respective one of the drop-off plies of the second subset are substantially equidistant from the central portion in a dimension between the first outer surface and the second outer surface. Clause 28. The composite structure of any one of clauses 21 to 27, wherein each drop-off ply has a ply angle that is between approximately -30 degrees and +30 degrees relative to a longitudinal axis of the composite structure. Clause 29. The composite structure of clause 28, wherein for each pair, the ply angle is approximately the same for the drop-off plies of that pair. Clause 30. The composite structure of any one of clauses 21 to 29, wherein, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first exterior surface and the second exterior surface. Clause 31. The composite structure of any one of clauses 21 to 30, wherein a distance between non-adjacent ones of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 32. A method of forming a composite structure having a variable gauge includes forming a plurality of continuous plies and forming a plurality of drop-off plies. Forming the plurality of drop-off plies includes forming, for each drop-off ply, a tip of the drop-off ply having a tapered shape. The method also includes positioning the plurality of continuous plies and the plurality of drop-off plies 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 gauge and the second end has a second gauge less than the first gauge. Positioning the plurality of continuous plies and the plurality of drop-off plies includes positioning the plurality of continuous plies such that each continuous ply extends from a first end to a second end, and positioning the plurality of drop-off plies such that each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first outer surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second outer surface. Positioning the plurality of continuous plies and the plurality of drop-off plies in a stack further includes arranging the plurality of drop-off plies in a monotonically inward pattern that includes: (a) in a first sequence of a first subset of the plurality of drop-off plies from the first outer surface toward the central portion, the relative distance between the tip and the second end of the drop-off ply decreases as each successive drop-off ply is in the first sequence; and (b) in a second sequence of a second subset of the plurality of drop-off plies from the second outer surface toward the central portion, the relative distance between the tip and the second end of the drop-off ply decreases as each successive drop-off ply is in the second sequence. Clause 33. The method of clause 32, further comprising curing the plurality of continuous plies and the plurality of drop-off plies after positioning the plurality of continuous plies and the plurality of drop-off plies in a stack. Clause 34. The method of clause 32 or 33, wherein positioning the plurality of continuous plies and the plurality of drop-off plies includes positioning the plurality of continuous plies and the plurality of drop-off plies such that the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 35. The method of any one of clauses 32 to 34, wherein the central portion comprises at least one continuous ply of the plurality of continuous plies. Clause 36. The method of any one of clauses 32 to 35, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that respective positions of tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 37. The method of any one of clauses 32-36, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface. Clause 38. The method of any one of clauses 32 to 37, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 39. Composite structure having variable gauge. The composite structure includes a first segment having a first gauge and a second segment having a second gauge less than the first gauge. The composite structure also includes a transition segment between the first segment and the second segment. The transition segment includes a first end of the first segment having a first gauge, a second end of the second segment having a second gauge, a first outer surface extending from the first end to a second end, a second outer surface extending from the first end to the second end, and a plurality of plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a tapered shape. Each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first outer surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second outer surface. The tips of the plurality of drop-off plies are arranged in a monotonically inward pattern including: (a) a first sequence of the first subset of the plurality of drop-off plies from the first outer surface to the central portion, in which the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the first sequence; and (b) a second sequence of the second subset of the plurality of drop-off plies from the second outer surface to the central portion, in which the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the second sequence. Clause 40. The composite structure of clause 39, wherein the first segment is a flange of the composite stringer and the second segment is a web of the composite stringer. Clause 41. A composite structure including a first end having a first gauge and a second end having a second gauge less than the first gauge. The composite structure also includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a blunt end shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. The plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 42. The composite structure of clause 41, further comprising a first exterior surface extending from the first end to the second end and a second exterior surface extending from the first end to the second end. The plurality of continuous plies and the plurality of drop-off plies are stacked and disposed between the first exterior surface and the second exterior surface. The first gauge and the second gauge are thicknesses between the first exterior surface and the second exterior surface at the first end and the second end, respectively. Clause 43. The composite structure of clause 42, wherein a first subset of the plurality of drop-off plies is between the first exterior surface and a central portion. The central portion (i) is between the first exterior surface and the second exterior surface, and (ii) extends from a first end to a second end. The second subset of the plurality of drop-off plies is between the central portion and the second exterior surface. Tips of the first subset of the plurality of drop-off plies are arranged in a pattern that substantially mirrors a pattern of tips of the second subset of the plurality of drop-off plies. Clause 44. The composite structure of clause 43, wherein the central portion includes a single drop-off ply of the plurality of drop-off plies. Clause 45. The composite structure of clause 43, wherein the central portion includes two drop-off plies of the plurality of drop-off plies and at least one continuous ply of the plurality of continuous plies between the two drop-off plies. Clause 46. The composite structure of any one of clauses 41 to 45, wherein the locations of each of the tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 47. The composite structure of clause 46, wherein the first subset of the plurality of drop-off plies is arranged in order from a drop-off ply closest to the central portion to a drop-off ply closest to the first exterior surface. The tip pattern of the first subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply for each successive drop-off ply in the sequence. The second subset of the plurality of drop-off plies is arranged in order from a drop-off ply closest to the central portion to a drop-off ply closest to the second exterior surface. The tip pattern of the second subset of the plurality of drop-off plies includes a decreasing relative distance between the tip and the second end of the drop-off ply for each successive drop-off ply in the sequence. Clause 48. The composite structure of any one of clauses 42-47, wherein, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first exterior surface and the second exterior surface. Clause 49. The composite structure of any one of clauses 41 to 48, wherein a distance between non-adjacent ones of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 50. A method of forming a composite structure having variable gauge includes forming a plurality of continuous plies and forming a plurality of drop-off plies. Forming the plurality of drop-off plies includes forming, for each drop-off ply, a tip of the drop-off ply having a blunt end shape. The method also includes positioning the plurality of continuous plies and the plurality of drop-off plies in a stack having a first end and a second end. The first end has a first gauge. The second end has a second gauge smaller than the first gauge. Positioning the plurality of continuous plies and the plurality of drop-off plies includes (a) positioning the plurality of continuous plies such that each continuous ply extends from the first end to the second end, and (b) positioning the plurality of drop-off plies such that (i) each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end, and (ii) the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 51. The method of clause 50, further comprising curing the plurality of continuous plies and the plurality of drop-off plies after positioning the plurality of continuous plies and the plurality of drop-off plies in a stack. Clause 52. The method of clause 50 or 51, wherein stacking and positioning the plurality of continuous plies and the plurality of drop-off plies further includes 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 gauge and second gauge are thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively. Clause 53. The method of clause 52, wherein stacking and positioning the plurality of continuous plies and the plurality of drop-off plies includes positioning a first subset of the plurality of drop-off plies between a first outer surface and a central portion, the central portion (i) being between the first outer surface and the second outer surface and (ii) extending from the first end to the second end. Stacking and positioning the plurality of continuous plies and the plurality of drop-off plies also includes positioning a second subset of the plurality of drop-off plies between the central portion and the second outer surface. Positioning the first subset of the plurality of drop-off plies and positioning the second subset of the plurality of drop-off plies includes positioning the plurality of drop-off plies such that tips of the first subset of the plurality of drop-off plies are arranged in a pattern that substantially mirrors a pattern of tips of the second subset of the plurality of drop-off plies. Clause 54. The method of clause 53, wherein the central portion includes a single drop-off ply of the plurality of drop-off plies. Clause 55. The method of clause 53, wherein the central portion includes two drop plies of the plurality of drop-off plies and at least one continuous ply of the plurality of continuous plies between the two drop plies. Clause 56. The method of any one of clauses 50 to 55, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that respective positions of tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 57. The method of clause 56, wherein positioning the first subset of the plurality of drop-off plies includes: (i) positioning the first subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the first exterior surface; and (ii) positioning the first subset of the plurality of drop-off plies such that a pattern of tips of the first subset of the plurality of drop-off plies includes a decreasing relative distance between the tips and the second ends of the drop-off plies with each successive drop-off ply positioned in sequence. Positioning the second subset of the plurality of drop-off plies includes (a) positioning the second subset of the plurality of drop-off plies in order from a drop-off ply closest to the central portion to a drop-off ply closest to the second outer surface; and (b) positioning the second subset of the plurality of drop-off plies such that a pattern of tips of the second subset of the plurality of drop-off plies includes a decreasing relative distance between the tips of the drop-off plies and the second end with each successive drop-off ply positioned in sequence. Clause 58. The method of any one of clauses 50 to 57, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface. Clause 59. The method of any one of clauses 50 to 58, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 60. Composite structure having variable gauge. The composite structure includes a first segment having a first gauge and a second segment having a second gauge less than the first gauge. The composite structure also includes a transition segment between the first segment and the second segment. The transition segment includes a first end of the first segment having the first gauge, a second end of the second segment having a 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 plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes (a) a plurality of continuous plies, each extending from a first end to a second end, and (b) at least one drop-off ply, each including a tip having a blunt tip configuration and each extending from the first end to a respective location of the tip of the drop-off ply between the first end and the second end, Each drop-off ply is sandwiched between and abuts two respective continuous plies of the plurality of continuous plies. Clause 61. A composite structure including a first end having a first gauge and a second end having a second gauge less than the first gauge. The composite structure also includes 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 plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a blunt tip shape. Each drop-off ply extends from the first end to a respective location of the tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first exterior surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second exterior surface, and tips of the plurality of drop-off plies are arranged in a monotonically inward pattern including: (i) in a first sequence of the first subset of the plurality of drop-off plies from the first exterior surface toward the central portion, a relative distance between the tips and second ends of the drop-off plies decreases with each successive drop-off ply in the first sequence, and (ii) in a second sequence of the second subset of the plurality of drop-off plies from the second exterior surface toward the central portion, a relative distance between the tips and second ends of the drop-off plies decreases with each successive drop-off ply in the second sequence. Clause 62. The composite structure of clause 61, wherein the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 63. The composite structure of clause 61 or 62, wherein the first gauge and the second gauge are respectively thicknesses between the first outer surface and the second outer surface at the first end and the second end, respectively. Clause 64. The composite structure of any one of clauses 61 to 63, wherein the central portion comprises at least one continuous ply of the plurality of continuous plies. Clause 65. The composite structure of any one of clauses 61 to 64, wherein the locations of each of the tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 66. The composite structure of any one of clauses 61 to 65, wherein the monotonically inward pattern further comprises tips of a first subset of the plurality of drop-off plies alternating with tips of a second subset of the plurality of drop-off plies along a direction from the first end to the second end. Clause 67. The composite structure of any one of clauses 61 to 66, wherein the plurality of drop-off plies are arranged in a plurality of pairs of drop-off plies, each pair of drop-off plies including a respective one of the first subset and a respective one of the second subset, and for each pair of drop-off plies, the respective one of the drop-off plies of the first subset and the respective one of the drop-off plies of the second subset are substantially equidistant from the central portion in a dimension between the first outer surface and the second outer surface. Clause 68. The composite structure of any one of clauses 61 to 67, wherein each drop-off ply has a ply angle that is between approximately -30 degrees and +30 degrees relative to a longitudinal axis of the composite structure. Clause 69. The composite structure of clause 68, wherein for each pair, the ply angle is approximately the same for the drop-off plies of that pair. Clause 70. The composite structure of any one of clauses 61 to 69, wherein, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first exterior surface and the second exterior surface. Clause 71. The composite structure of any one of clauses 61 to 70, wherein a distance between non-adjacent ones of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 72. A method of forming a composite structure having a variable gauge includes forming a plurality of continuous plies and forming a plurality of drop-off plies. Forming the plurality of drop-off plies includes forming, for each drop-off ply, a tip of the drop-off ply having a blunt end shape. The method also includes positioning the plurality of continuous plies and the plurality of drop-off plies 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 gauge and the second end has a second gauge less than the first gauge. Positioning the plurality of continuous plies and the plurality of drop-off plies includes positioning the plurality of continuous plies such that each continuous ply extends from a first end to a second end, and positioning the plurality of drop-off plies such that each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first outer surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second outer surface. Positioning the plurality of continuous plies and the plurality of drop-off plies in a stack further includes arranging the plurality of drop-off plies in a monotonically inward pattern that includes: (a) in a first sequence of a first subset of the plurality of drop-off plies from the first outer surface toward the central portion, the relative distance between the tip and the second end of the drop-off ply decreases as each successive drop-off ply is in the first sequence; and (b) in a second sequence of a second subset of the plurality of drop-off plies from the second outer surface toward the central portion, the relative distance between the tip and the second end of the drop-off ply decreases as each successive drop-off ply is in the second sequence. Clause 73. The method of clause 72, further comprising curing the plurality of continuous plies and the plurality of drop-off plies after positioning the plurality of continuous plies and the plurality of drop-off plies in a stack. Clause 74. The method of clause 72 or 73, wherein positioning the plurality of continuous plies and the plurality of drop-off plies includes positioning the plurality of continuous plies and the plurality of drop-off plies such that the plurality of drop-off plies are separated from one another by at least one of the plurality of continuous plies. Clause 75. The method of any one of clauses 72 to 74, wherein the central portion comprises at least one continuous ply of the plurality of continuous plies. Clause 76. The method of any one of clauses 72 to 75, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that respective positions of tips of the plurality of drop-off plies are staggered from the first end to the second end. Clause 77. The method of any one of clauses 72-76, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that, for each drop-off ply, a distance between a tip of the drop-off ply and a tip of an adjacent ply of the plurality of drop-off plies is at least 10 times greater than a thickness of the drop-off ply. For each drop-off ply, an adjacent ply of the plurality of drop-off plies is adjacent to the drop-off ply in a dimension extending between the first outer surface and the second outer surface. Clause 78. The method of any one of clauses 72 to 77, wherein positioning the plurality of drop-off plies includes positioning the plurality of drop-off plies such that a distance between non-adjacent plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply. Clause 79. Composite structure having variable gauge. The composite structure includes a first segment having a first gauge and a second segment having a second gauge less than the first gauge. The composite structure also includes a transition segment between the first segment and the second segment. The transition segment includes a first end of the first segment having a first gauge, a second end of the second segment having a second gauge, a first outer surface extending from the first end to a second end, a second outer surface extending from the first end to the second end, and a plurality of plies (i) extending between the first end and the second end and (ii) arranged in a stack between the first outer surface and the second outer surface. The plurality of plies includes a plurality of continuous plies and a plurality of drop-off plies. Each continuous ply extends from the first end to the second end. Each drop-off ply includes a tip having a blunt tip shape. Each drop-off ply extends from the first end to a respective location of a tip of the drop-off ply between the first end and the second end. A first subset of the plurality of drop-off plies is between the first outer surface and a central portion of the stack, and a second subset of the plurality of drop-off plies is between the central portion and the second outer surface. The tips of the plurality of drop-off plies are arranged in a monotonically inward pattern including: (a) a first sequence of the first subset of the plurality of drop-off plies from the first outer surface toward the central portion, where the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the first sequence; and (b) a second sequence of the second subset of the plurality of drop-off plies from the second outer surface toward the central portion, where the relative distance between the tip and the second end of the drop-off ply decreases with each successive drop-off ply in the second sequence. Clause 80. The composite structure of clause 79, wherein the first segment is a flange of the composite stringer and the second segment is a web of the composite stringer.

[0125] The description of the various advantageous configurations has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the examples to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Moreover, the various advantageous examples may demonstrate different advantages over other advantageous embodiments. The selected embodiment or embodiments have been selected and described to explain the principles and practical applications of such embodiments and to enable others skilled in the art to appreciate the disclosure of the various embodiments with various modifications suitable for the particular applications envisioned.

Claims

1. A composite structure (200, 300, 400) having a variable gauge, a first end (210A, 310A, 410A) having a first gauge (212A, 312A, 412A); a second end (210B, 310B, 410B) having a second gauge (212B, 312B, 412B) smaller than the first gauge (212A, 312A, 412A); a plurality of continuous plies (218A, 318A, 418A) each extending from said first end (210A, 310A, 410A) to said second end (210B, 310B, 410B); a plurality of drop-off plies (218B, 318B, 418B), each including a tip (220, 320, 420) having at least one of a tapered and a blunt shape, each extending from the first end (210A, 310A, 410A) to a respective location of the tip (220, 320, 420) of the drop-off ply (218B, 318B, 418B) between the first end (210A, 310A, 410A) and the second end (210B, 310B, 410B); a first outer surface (214, 314, 414) extending from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); a second outer surface (216, 316, 416) extending from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); Including, the plurality of drop-off plies (218B, 318B, 418B) are separated from one another by at least one of the plurality of continuous plies (218A, 318A, 418A); the plurality of continuous plies (218A, 318A, 418A) and the plurality of drop-off plies (218B, 318B, 418B) are stacked and disposed between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416); the first gauge (212A, 312A, 412A) and the second gauge (212B, 312B, 412B) are thicknesses between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416) at the first end (210A, 310A, 410A) and the second end (210B, 310B, 410B), respectively; a first subset of the plurality of drop-off plies (218B, 318B, 418B) is between the first outer surface (214, 314, 414) and a central portion (224, 324), the central portion (224, 324) (i) is between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416) and (ii) extends from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); a second subset of the plurality of drop-off plies (218B, 318B, 418B) is between the central portion (224, 324) and the second outer surface (216, 316, 416); the tips (220, 320, 420) of the first subset of the plurality of drop-off plies (218B, 318B, 418B) are arranged in a pattern that substantially mirrors the pattern of the tips (220, 320, 420) of the second subset of the plurality of drop-off plies (218B, 318B, 418B); The positions of the tips (220, 320, 420) of the plurality of drop-off plies (218B, 318B, 418B) are shifted from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B). the first subset of the plurality of drop-off plies (218B, 318B, 418B) being arranged in order from a drop-off ply (218B, 318B, 418B) closest to the central portion (224, 324) to a drop-off ply (218B, 318B, 418B) closest to the first outer surface (214, 314, 414); the pattern of the tips (220, 320, 420) of the first subset of the plurality of drop-off plies (218B, 318B, 418B) includes a decreasing relative distance between the tips (220, 320, 420) of the drop-off plies (218B, 318B, 418B) and the second ends (210B, 310B, 410B) with each successive drop-off ply (218B, 318B, 418B) arranged in the order; the second subset of the plurality of drop-off plies (218B, 318B, 418B) being arranged in order from a drop-off ply (218B, 318B, 418B) closest to the central portion (224, 324) to a drop-off ply (218B, 318B, 418B) closest to the second outer surface (216, 316, 416); the pattern of the tips (220, 320, 420) of the second subset of the plurality of drop-off plies (218B, 318B, 418B) includes a decreasing relative distance between the tips (220, 320, 420) of the drop-off plies (218B, 318B, 418B) and the second ends (210B, 310B, 410B) with each successive drop-off ply (218B, 318B, 418B) arranged in the order; The composite structure (200, 300, 400), wherein the central portion (224, 324) includes a single drop-off ply (218B, 318B, 418B) of the plurality of drop-off plies (218B, 318B, 418B).

2. for each drop-off ply (218B, 318B, 418B), a distance (228, 328) between the tip (220, 320, 420) of the drop-off ply (218B, 318B, 418B) of the plurality of drop-off plies (218B, 318B, 418B) and the tip (220, 320, 420) of an adjacent drop-off ply is at least ten times greater than a thickness (226, 326) of the drop-off ply (218B, 318B, 418B); 2. The composite structure (200, 300, 400) of claim 1, wherein the drop-off plies are adjacent to one another when two of the plurality of drop-off plies (218B, 318B, 418B) are not adjacent to other drop-off plies of the plurality of drop-off plies in a dimension extending between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416).

3. 3. The composite structure of claim 1, wherein a distance between non-adjacent drop-off plies of the plurality of drop-off plies is at least three times greater than a thickness of each drop-off ply.

4. An aircraft comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

5. A spacecraft comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

6. A rotorcraft comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

7. A marine vessel comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

8. A motor vehicle comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

9. A vehicle comprising a composite structure (200, 300, 400) according to any one of claims 1 to 3.

10. A composite stringer comprising at least one composite structure (200, 300, 400) described in any one of claims 1 to 3.

11. 1. An aircraft, 11. An aircraft comprising at least one composite stringer according to claim 10 coupled to one or more skin panels of the aircraft.

12. A method of forming a composite structure (200, 300, 400) having variable gauge, comprising: forming a plurality of continuous plies (218A, 318A, 418A); forming a plurality of drop-off plies (218B, 318B, 418B), including forming a tip (220, 320, 420) of the drop-off ply (218B, 318B, 418B) having a tapered shape for each drop-off ply (218B, 318B, 418B); positioning the plurality of continuous plies (218A, 318A, 418A) and the plurality of drop-off plies (218B, 318B, 418B) in a stack having a first end (210A, 310A, 410A) and a second end (210B, 310B, 410B); Including, the first end (210A, 310A, 410A) has a first gauge (212A, 312A, 412A); the second end (210B, 310B, 410B) has a second gauge (212B, 312B, 412B) that is smaller than the first gauge (212A, 312A, 412A); Positioning the plurality of continuous plies (218A, 318A, 418A) and the plurality of drop-off plies (218B, 318B, 418B) positioning the plurality of continuous plies (218A, 318A, 418A) such that each continuous ply extends from the first end (210A, 310A, 410A) to a second end (210B, 310B, 410B); (i) each drop-off ply (218B, 318B, 418B) extends from the first end (210A, 310A, 410A) to a respective location of the tip (220, 320, 420) of the drop-off ply (218B, 318B, 418B) between the first end (210A, 310A, 410A) and the second end (210B, 310B, 410B); and (ii) the plurality of drop-off plies (218B, 318B, 418B) are spaced apart from the plurality of continuous plies (218B, 318B, 418B). positioning the plurality of drop-off plies (218B, 318B, 418B) so that they are separated from one another by at least one of the lies (218A, 318A, 418A), and (iii) such that the respective positions of the tips (220, 320, 420) of the plurality of drop-off plies (218B, 318B, 418B) are offset from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); forming a first outer surface (214, 314, 414) extending from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); forming a second outer surface (216, 316, 416) extending from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); positioning a first subset of the plurality of drop-off plies (218B, 318B, 418B) between the first outer surface (214, 314, 414) and a central portion (224, 324), the central portion (224, 324) (i) being between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416) and (ii) extending from the first end (210A, 310A, 410A) to the second end (210B, 310B, 410B); positioning a second subset of said plurality of drop-off plies (218B, 318B, 418B) between said central portion (224, 324) and said second outer surface (216, 316, 416); Including, the first gauge (212A, 312A, 412A) and the second gauge (212B, 312B, 412B) are thicknesses between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416) at the first end (210A, 310A, 410A) and the second end (210B, 310B, 410B), respectively; positioning the first subset of the plurality of drop-off plies (218B, 318B, 418B) and positioning the second subset of the plurality of drop-off plies (218B, 318B, 418B) comprises positioning the plurality of drop-off plies (218B, 318B, 418B) such that the tips (220, 320, 420) of the first subset of the plurality of drop-off plies (218B, 318B, 418B) are arranged in a pattern that substantially mirrors a pattern of the tips (220, 320, 420) of the second subset of the plurality of drop-off plies (218B, 318B, 418B); Positioning the first subset of the plurality of drop-off plies (218B, 318B, 418B) positioning the first subset of the plurality of drop-off plies (218B, 318B, 418B) in order from a drop-off ply (218B, 318B, 418B) closest to the central portion (224, 324) to a drop-off ply (218B, 318B, 418B) closest to the first outer surface (214, 314, 414); positioning the first subset of the plurality of drop-off plies (218B, 318B, 418B) such that the pattern of the tips (220, 320, 420) of the first subset of the plurality of drop-off plies (218B, 318B, 418B) includes a decreasing relative distance between the tips (220, 320, 420) of the drop-off plies (218B, 318B, 418B) and the second ends (210B, 310B, 410B) with each successive drop-off ply (218B, 318B, 418B) arranged in the order; Further comprising: Positioning the second subset of the plurality of drop-off plies (218B, 318B, 418B) positioning the second subset of the plurality of drop-off plies (218B, 318B, 418B) in order from a drop-off ply (218B, 318B, 418B) closest to the central portion (224, 324) to a drop-off ply (218B, 318B, 418B) closest to the second outer surface (216, 316, 416); positioning the second subset of the plurality of drop-off plies (218B, 318B, 418B) such that the pattern of the tips (220, 320, 420) of the second subset of the plurality of drop-off plies (218B, 318B, 418B) includes a decreasing relative distance between the tips (220, 320, 420) of the drop-off plies (218B, 318B, 418B) and the second ends (210B, 310B, 410B) with each successive drop-off ply (218B, 318B, 418B) arranged in the order; Including, the central portion (224, 324) includes a single drop-off ply (218B, 318B, 418B) of the plurality of drop-off plies (218B, 318B, 418B); method.

13. 13. The method of claim 12, further comprising curing the plurality of continuous plies (218A, 318A, 418A) and the plurality of drop-off plies (218B, 318B, 418B) after positioning the plurality of continuous plies (218A, 318A, 418A) and the plurality of drop-off plies (218B, 318B, 418B) in the stack.

14. positioning the plurality of drop-off plies (218B, 318B, 418B) includes positioning the plurality of drop-off plies (218B, 318B, 418B) such that, for each drop-off ply (218B, 318B, 418B), a distance (228, 328) between the tip (220, 320, 420) of one of the plurality of drop-off plies (218B, 318B, 418B) and the tip (220, 320, 420) of an adjacent drop-off ply is at least ten times greater than a thickness (226, 326) of the drop-off ply (218B, 318B, 418B); 14. The method of claim 12 or 13, wherein the drop-off plies are adjacent to each other when two of the plurality of drop-off plies (218B, 318B, 418B) are not adjacent to other drop-off plies of the plurality of drop-off plies in a dimension extending between the first outer surface (214, 314, 414) and the second outer surface (216, 316, 416).

15. 15. The method of claim 12, wherein positioning the plurality of drop-off plies (218B, 318B, 418B) comprises positioning the plurality of drop-off plies (218B, 318B, 418B) such that a distance (230, 330) between non-adjacent drop-off plies of the plurality of drop-off plies (218B, 318B, 418B) is at least three times greater than a thickness (226, 326) of each drop-off ply (218B, 318B, 418B).

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