Method and system for manufacturing a cured composite structure

Abstract

The title of this invention is a method and system for manufacturing a cured composite structure. A method of manufacturing a cured composite structure from first stringers, second stringers, and a panel including a first side and a second side, the method including, for each first stringer, supporting the first stringer on the first side of the panel using a substantially rigid mandrel positioned in a first cavity defined between the first stringer and the first side of the panel, for each second stringer, supporting the second stringer on the second side of the panel using a flexible mandrel positioned in a second cavity defined between the second stringer and the second side of the panel, and co-curing the first stringers, the panel, and the second stringers while each of the one or more first stringers is supported by the respective substantially rigid mandrel and each of the one or more second stringers is supported by the respective flexible mandrel.

Description

Technical Field

[0001] The present disclosure relates generally to composite structures and, more particularly, to reinforced structures comprising composite materials. Still more particularly, the present disclosure relates to systems and methods for fabricating cured composite structures. Background Art

[0002] Composite materials can be used to construct composite structures for aircraft and other vehicles and components. Composite structures used to construct aircraft or other vehicles or other components can include reinforced composite panels.

[0003] Sometimes it is desirable to form a composite structure with multiple sides, each side having one or more stringers or stiffeners thereon to strengthen the panels. In some manufacturing processes, the composite structure is manufactured, cured, and otherwise processed into discrete parts that are then fastened together. Some of these manufacturing processes include fastening stiffeners to the structure, which can increase cost and weight, and thermoplastic welding, which can be difficult at the intersection of stiffeners and can increase cost. An alternative to each of these latter manufacturing processes is co-curing the structure. However, an example problem with prior attempts to co-cure structures having stiffeners on both sides of the structure is that prior attempts result in defects in the center structure. In some cases, these defects are due to pressure imbalances at the intersection of stiffeners. These pressure imbalances cause the laminate to warp or wrinkle.

[0004] There continues to be interest in developing and improving cured composite structures and methods of making such cured composite structures.It would be desirable to have methods and apparatus that produce more uniform pressure at the intersections of reinforcements, thereby reducing or eliminating distortion in the central structure. Summary of the Invention

[0005] A method is disclosed for fabricating a cured composite structure from one or more first stringers, one or more second stringers, and a face sheet including a first side and a second side opposite the first side.

[0006] In one embodiment, the disclosed method includes the following steps: (1) for each of one or more first longitudinal beams, supporting the first longitudinal beam on a first side of a panel using a substantially rigid mandrel such that the substantially rigid mandrel is positioned within a first cavity defined between the first longitudinal beam and the first side of the panel; (2) for each of one or more second longitudinal beams, supporting the second longitudinal beam on a second side of the panel using a flexible mandrel such that the flexible mandrel is positioned within a second cavity defined between the second longitudinal beam and the second side of the panel; and (3) co-curing the one or more first longitudinal beams, the panel, and the one or more second longitudinal beams, with each of the one or more first longitudinal beams supported by its respective substantially rigid mandrel and each of the one or more second longitudinal beams supported by its respective flexible mandrel.

[0007] In another example, a method is disclosed that employs a rigid tool having one or more slots defined therein and includes the following steps: (1) for each of one or more first longitudinal beams, (i) positioning the first longitudinal beam on the rigid tool such that the first longitudinal beam is at least partially within the slot of the one or more slots, and (ii) positioning a substantially rigid mandrel on the first longitudinal beam such that the substantially rigid mandrel is at least partially within the slot; (2) positioning a panel over the one or more first longitudinal beams and over the substantially rigid mandrel such that a first side of the panel faces the one or more first longitudinal beams and the substantially rigid mandrel, and a second side of the panel faces away from the one or more first longitudinal beams and the substantially rigid mandrel; and (3) for each of the one or more second longitudinal beams, (i) positioning a flexible mandrel over the second side of the panel, and (ii) positioning the second longitudinal beam over the flexible mandrel.

[0008] In still another example, the disclosed method employs a rigid tool having one or more slots defined therein and includes the following steps: (1) for each of one or more first longitudinal beams, (i) positioning the first longitudinal beam on the rigid tool such that the first longitudinal beam is at least partially within the slot of the one or more slots, and (ii) positioning a flexible mandrel on the first longitudinal beam such that the flexible mandrel is at least partially within the slot; (2) positioning a panel over the one or more first longitudinal beams and over the flexible mandrel such that a first side of the panel faces the one or more first longitudinal beams and the flexible mandrel, and a second side of the panel faces away from the one or more first longitudinal beams and the flexible mandrel; and (3) for each of the one or more second longitudinal beams, (i) positioning the substantially rigid mandrel over the second side of the panel, and (ii) positioning the second longitudinal beam over the substantially rigid mandrel.

[0009] Also disclosed is a system for fabricating a cured composite structure from one or more first stringers, one or more second stringers, and a face sheet including a first side and a second side opposite the first side.

[0010] In one example, a system is disclosed that includes one or more substantially rigid mandrels, each substantially rigid mandrel positioned within a first cavity defined between a first stringer of one or more first stringers and a first side of a panel; one or more flexible mandrels, each flexible mandrel positioned within a second cavity defined between a second stringer of one or more second stringers and a second side of the panel; and a curing oven configured to receive the panel, the one or more first stringers, the one or more second stringers, the one or more substantially rigid mandrels, and the one or more flexible mandrels therein.

[0011] Also disclosed are cured composite structures made using the disclosed systems and methods.

[0012] Other examples of the disclosed methods and systems for making cured composite structures, and cured composite structures made using the disclosed systems and methods, will become apparent from the following detailed description, the accompanying drawings, and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a perspective view of an instance of a composite structure.

[0014] Figure 2 is a perspective view of a close-up portion of the composite structure.

[0015] Figure 3 is a perspective view of an example of a partially assembled composite structure.

[0016] Figure 4 is a perspective view of a close-up portion of the composite structure.

[0017] Figure 5A is a perspective view of an example of a partially assembled composite structure.

[0018] Figure 5B is a perspective view of an example of a partially assembled composite structure.

[0019] Figure 6A is a perspective view of an example of a partially assembled composite structure.

[0020] Figure 6B is a perspective view of an example of a partially assembled composite structure.

[0021] Figure 7A is a perspective view of an example of a partially assembled composite structure.

[0022] Figure 7B is a perspective view of an example of a partially assembled composite structure.

[0023] Figure 8 is a perspective view of an example of a composite hat stringer and mandrel subassembly.

[0024] Figure 9 is a close-up partial view of an example of a tooling trough and mandrel subassembly.

[0025] Figure 10 is a perspective view of an example of a mandrel including an elastic material.

[0026] Figure 11 is a perspective view of an example of a bladestringer with angle caul tooling thereon.

[0027] Figure 12A is a cross-sectional view of an example of a mandrel in a cavity defined between a stringer and a panel.

[0028] Figure 12B is a cross-sectional view of an example of a mandrel between a stringer and a panel.

[0029] Figure 13 is a cross-sectional view of an example of a mandrel in a cavity defined between a stringer and a panel.

[0030] Figure 14 is a plan view of an example of a set of stringers on one side of an opaque panel.

[0031] Figure 15 is a plan view of an example of a set of stringers on one side of an opaque panel.

[0032] Figure 16 is a plan view of an example of a transparent panel having a first side and a second side opposite the first side, a first set of stringers on the first side and a second set of stringers on the second side.

[0033] Figure 17 is a plan view of an example of a set of stringers including both hat stringers and blade stringers on one side of an opaque panel.

[0034] Figure 18 is a block diagram showing a number of different materials.

[0035] Figure 19 is a block diagram showing a system for fabricating a cured composite structure.

[0036] Figure 20A is a block diagram showing the mandrel and the first volume.

[0037] Figure 20B is a block diagram showing the cavity and the second volume.

[0038] Figure 20C is a block diagram showing the mandrel and the first volume.

[0039] Figure 20D is a block diagram showing the cavity and the second volume.

[0040] Figure 21A It is a cross-sectional view of an I-beam.

[0041] Figure 21B is a cross-sectional view of a J-shaped longitudinal beam.

[0042] Figure 22 is a flow chart depicting one example of the disclosed method of making a cured composite structure.

[0043] Figure 23 is a flow chart depicting another example of the disclosed method of making a cured composite structure.

[0044] Figure 24 is a flow chart depicting yet another example of the disclosed method of making a cured composite structure.

[0045] Figure 25 It is a flowchart of the methods of aircraft manufacturing and use.

[0046] Figure 26 It is a block diagram of an aircraft. DETAILED DESCRIPTION

[0047] The following detailed description is with reference to the accompanying drawings, which illustrate specific non-limiting examples of the present disclosure. Other examples with different structures and operations do not depart from the scope of the present disclosure. In different drawings, like reference numerals may refer to the same elements or parts.

[0048] Non-limiting examples of methods and systems for making cured composite structures are disclosed. Figure 1 As shown, non-limiting aspects of a first example of a cured composite structure 100 include one or more first stringers 120, one or more second stringers 140, and a faceplate 160. In this first example, the faceplate 160 includes a first side 162 and a second side 166 opposite the first side 162.

[0049] As a way of introduction, Figure 1-4 Details of certain aspects of the cured composite structure 100 are shown. Figure 1 The cured composite structure 100 is shown wherein the panel 160 includes a set of first stringers 120 (eg, hat stringers) on a first side 162 and a set of second stringers 140 (eg, hat stringers) on a second side 166 . Figure 2 Shown Figure 1 A close-up of the longitudinal beams 120 , 140 is shown, showing how the longitudinal beams 120 , 140 are arranged and the reinforcement member 110 intersects. Figure 3The completed cured composite structure 100 is shown with the panel 160 including a set of first stringers (not shown in this view) on a first side 162 comprising hat stringers, and a set of second stringers 140 on a second side 166 comprising hat stringers and blade stringers 34 . Figure 4 Shown Figure 2 , showing how the stringers 120, 140 are arranged and the stiffeners intersect 110. Some methods of producing these aspects of the cured composite structure 100 are detailed below.

[0050] Figure 5A 、 6A and 7A illustrate the formation of Figure 1 Example steps that may be used in some methods of curing the composite structure 100. Figure 5A 、 6A 7A, a plurality of first longitudinal beams 120 and a plurality of second longitudinal beams 140 are shown. However, in other examples, more or fewer first longitudinal beams 120 and / or more or fewer second longitudinal beams 140 are possible. Figure 5A 、 6A The example steps of 7A and 7A are further described below. Figure 5B 、 6B 7B illustrate alternative examples that may be used in some methods of forming cured composite structures. Figure 5B 、 6B The example steps of 7A and 7B are further described below.

[0051] refer to Figure 1 、 5A 6A, a first non-limiting example of a first method of manufacturing a cured composite structure 100 includes, for each of the one or more first stringers 120, using a substantially rigid mandrel 130 to form the first stringer 120 (see also FIG. Figure 12A ) is supported on the first side 162 of the panel 160. The mandrel can be considered to be substantially rigid if the loads experienced by the mandrel during use do not cause the mandrel to deform beyond the tolerances for which the mandrel was manufactured. Thus, the substantially rigid mandrel 130 is positioned within the first cavity 192 defined between the first stringer 120 and the first side 162 of the panel 160 (see Figure 12A ).

[0052] Now refer to Figure 1 、 6A7A, the first non-limiting example of the first method of manufacturing the cured composite structure 100 further includes, for each of the one or more second stringers 140, supporting the second stringer 140 on the second side 166 of the panel 160 using the flexible mandrel 150. Thus, the flexible mandrel 150 is positioned within a second cavity 194 defined between the second stringer 140 and the second side 166 of the panel 160 (see Figure 13 ).

[0053] like Figure 19 As shown, for example, the first non-limiting example of the first method of manufacturing the cured composite structure 100 further includes co-curing (e.g., in the oven 106 ) the one or more first stringers 120 , the facesheet 160 , and the one or more second stringers 140 , while each of the one or more first stringers 120 is supported by a respective substantially rigid mandrel 130 , and each of the one or more second stringers 140 is supported by a respective flexible mandrel 150 .

[0054] refer to Figure 1 、 2 and 6A, in some aspects of the first method, the first side 162 of the panel 160 is substantially flat. For these purposes, a side may be considered substantially flat if it meets relevant manufacturing and engineering acceptance criteria for being flat. Without limitation and with particular reference to Figure 14 and 15 In the latter first approach, the second side 166 of the panel 160 is contoured. The contoured side optionally includes a smoothly curved surface, a discontinuous surface, a stepped or terraced surface, or a combination thereof.

[0055] refer to Figure 1 、 5A , 6A and 7A, in some aspects of the first method, supporting the one or more first stringers 120 on the first side 162 further includes supporting the one or more first stringers 120 on the first side 162 of the panel 160 using a rigid tool 170 having one or more slots 174 defined therein. The latter supporting the one or more first stringers 120 on the first side 162 of the panel 160 using the rigid tool 170 optionally includes the one or more first stringers 120 and the substantially rigid mandrel 130 being at least partially received in the one or more slots 174 (see Figure 5A and 6A ).

[0056] It should be understood that the present disclosure contemplates the first longeron 120 and the substantially rigid mandrel 130 being fully received in the slot 174 of the rigid tool 170, wherein the slot 174 fully supports all components of the first longeron 120 and the substantially rigid mandrel 130. It should be understood that the present disclosure also contemplates the first longeron 120 and the substantially rigid mandrel 130 being partially received in the slot 174, wherein the substantially rigid mandrel 130 or one or more components of the first longeron 120 protrude from the slot 174, extend from the slot 174, or are otherwise not fully supported by the slot 174.

[0057] Now refer to Figure 7A and 13 The first method further includes supporting one or more second stringers 140 on the second side 166 of the panel 160 using the flexible mandrel 150. Thus, the flexible mandrel 150 is positioned within a second cavity 194 defined between the second stringer 140 and the second side 166 of the panel 160.

[0058] In certain non-limiting aspects, such as Figure 1 , the rigid tool 170 includes a flat surface 172. In certain other non-limiting aspects, the rigid tool 170 includes a smoothly curved surface, a discontinuous surface, a stepped or stepped surface, or some combination thereof. In certain non-limiting aspects, the rigid tool 170 includes a negative surface, i.e., a surface adapted to mate with and conform to the first side 162 of the panel 160. For example, but not limitation, in those instances where the first side 162 of the panel 160 is a flat surface, the rigid tool 170 includes such a surface, which is a mating flat surface.

[0059] As described above, and with reference to Figure 5A 、 6A , 7A and 19, the example first method includes co-curing one or more first stringers 120, a panel 160 and one or more second stringers 140, while each of the one or more first stringers 120 is supported by a respective substantially rigid mandrel 130 and each of the one or more second stringers 140 is supported by a respective flexible mandrel 150. Some aspects of the first example further include removing the substantially rigid mandrel 130 and the flexible mandrel 150 from the cured composite structure 100 (see Figure 22 , box 240).

[0060] Now refer to Figure 12A 、 20Aand 20B, in some aspects of the first method, during co-curing, the substantially rigid mandrel 130 expands the first volume 132, and the first cavity 192 expands the second volume 193. In some non-limiting aspects of the first method in which, during co-curing, the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193, the first volume 132 is substantially the same as the second volume 193. In some non-limiting aspects of the first method in which, during co-curing, the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193, the first volume 132 is between about 95% and about 105% of the second volume 193, or the first volume 132 is between about 90% and about 110% of the second volume 193, or the first volume 132 is between about 85% and about 115% of the second volume 193, or the first volume 132 is between about 80% and about 120% of the second volume 193, or the first volume 132 is between about 75% and about 125% of the second volume 193, or the first volume 132 is between about 70% and about 130% of the second volume 193.

[0061] Referring now to Figure 13 , 20C and 20D, in some aspects of the first method, during co-curing, the flexible mandrel 150 expands the first volume 152, and the second cavity 194 expands the second volume 191. In some non-limiting aspects of the first method in which, during co-curing, the flexible mandrel 150 expands the first volume 152 and the second cavity 142 expands the second volume 191, the first volume 152 is substantially the same as the second volume 191. In some non-limiting aspects of the first method in which, during co-curing, the flexible mandrel 150 expands the first volume 152 and the second cavity 194 expands the second volume 191, the first volume 152 is between about 95% and about 105% of the second volume 191, or in which the first volume 152 is between about 90% and about 110% of the second volume 191, or in which the first volume 152 is between about 85% and about 115% of the second volume 191, or in which the first volume 152 is between about 80% and about 120% of the second volume 191, or in which the first volume 152 is between about 75% and about 125% of the second volume 191, or in which the first volume 152 is between about 70% and about 130% of the second volume 191.

[0062] Referring now to Figure 1 , 5A, 6A and 7A, and as mentioned above, in the first method, one or more first stringers 120 are supported on the first side 162 of the panel 160 using a substantially rigid mandrel 130, and one or more second stringers 140 are supported on the second side 166 of the panel 160 using a flexible mandrel 150. In an example, a single first stringer 120 is supported on the first side 162 of the panel 160 using a substantially rigid mandrel 130, and / or a single second stringer 140 is supported on the second side 166 of the panel 160 using a flexible mandrel 150. However, in other examples, multiple stringers are supported on both sides. For example, with continued reference to Figure 1 、 5A and 7A, some aspects of the first method further include placing a first plurality of stringers 30 (see, Figure 5A ) is supported on a first side 162 of the panel 160, wherein the first plurality of stringers 30 includes one or more first stringers 120; and the second plurality of stringers 32 (see, Figure 7A ) is supported on a second side 166 of the panel 160 , wherein the second plurality of longitudinal beams 32 includes one or more second longitudinal beams 140 .

[0063] refer to Figure 3 、 4 , 11, 17, 21A and 21B, in some non-limiting aspects of the first method, at least one of the first plurality of stringers 30 and the second plurality of stringers 32 further comprises a blade stringer 34 (see, Figure 11 ), or I-beam 36 (see, Figure 21A ), or J-shaped longitudinal beam 37 (see, Figure 21B ), or some combination thereof. Figure 3 An example is illustrated where the second plurality of stringers 32 includes blade stringers 34 .

[0064] refer to Figure 22 The first method is further described. Figure 22 , an example of a disclosed method 200 for manufacturing a cured composite structure 100 is shown. The method 200 utilizes one or more first stringers 120, one or more second stringers 140, and a panel 160, wherein the panel 160 includes a first side 162 and a second side 166 opposite the first side 162.

[0065] At block 210, the method 200 includes, for each of the one or more first stringers 120, supporting the first stringer 120 on the first side 162 of the panel 160 using the substantially rigid mandrel 130. Thus, the substantially rigid mandrel 130 is positioned within the first cavity 192 defined between the first stringer 120 and the first side 162 of the panel 160.

[0066] At block 220, the method 200 includes, for each of the one or more second stringers 140, supporting the second stringer 140 on a second side 161 of the panel 160 using the flexible mandrel 150. Thus, the flexible mandrel 150 is positioned within a second cavity 194 defined between the second stringer 140 and the second side 166 of the panel 160.

[0067] At block 230, the method 200 includes co-curing the one or more first stringers 120, the panel 160, and the one or more second stringers 140, while each of the one or more first stringers 120 is supported by the respective substantially rigid mandrel 130 and each of the one or more second stringers 140 is supported by the respective flexible mandrel 150.

[0068] At block 240, the method 200 includes removing the substantially rigid mandrels 130 and the flexible mandrels 150 from the cured composite structure 100.

[0069] While Figure 1 While the first side 162 of the panel 160 is shown as being substantially flat and the second side 166 is shown as being contoured, it should be appreciated that this is not the only aspect contemplated. As set forth in more detail below, in some non-limiting alternative aspects to those described above in the first example, the first side 162 of the panel 160 is contoured and the second side 166 of the panel 160 is substantially flat.

[0070] As described above, prior efforts to co-cure structures having reinforcements on both sides of the structure have resulted in defects in the central structure due to pressure imbalances at the reinforcement intersections 110, which in turn cause the laminate structure to warp or wrinkle. The first method described above helps reduce, minimize, or prevent pressure imbalances at the reinforcement intersections by providing dimensional constraints on both sides 162, 166 of the panels 160 of the structure 100 sufficient to support the structure 100 during co-cure and provide the desired geometry, while also providing flexibility on one side 166 sufficient to allow for slight degrees of freedom in dimensional and / or geometric variations and thereby reduce, minimize, or prevent the warping or wrinkling that would otherwise occur due to the aforementioned pressure imbalances. More specifically, the first method described above helps promote uniform pressure at the reinforcement intersections 110, which promotes a central structure with little or no warping. During curing, the substantially rigid mandrel 130 on the rigid tool 170 reacts to the varying forces of the autoclave and the thermal expansion growth of the flexible mandrel 150 to produce a part with a small, acceptable amount of lamination variation at the reinforcement intersections 110. It should also be appreciated that the substantially rigid mandrel 130 and rigid tool 170 facilitate creating the desired surface at the reinforcement intersection 110, while the flexible mandrel allows the second stringer 140 on the second side 166 to follow the contour of the second side 166. This combination allows for design flexibility (e.g., height, amount of plies, drop off plies, location of reinforcements, type of reinforcements) of the profiled side without having to change the rigid tool 170 for structures 100 having different profiles / designs.

[0071] Reference again Figure 1 、 5A 6A, a non-limiting example of a second method of manufacturing a cured composite structure 100 includes using a rigid tool 170 having one or more slots 174 defined therein, one or more first stringers 120, one or more second stringers 140, and a panel 160, the panel 160 including a first side 162 and a second side 166 opposite the first side 162. The second method includes, for each of the one or more first stringers 120: (i) positioning the first stringer 120 on the rigid tool 170 such that the first stringer 120 is at least partially within the slot 174 of the one or more slots and (ii) positioning a substantially rigid mandrel 130 on the first stringer 120 such that the substantially rigid mandrel 130 is at least partially within the slot 174 (see, Figure 5AThe second method further includes positioning a panel 160 over the one or more first stringers 120 and over the substantially rigid mandrel 130 such that a first side 162 of the panel 160 faces the one or more first stringers 120 and the substantially rigid mandrel 130, and a second side 166 of the panel 160 faces away from the one or more first stringers 120 and the substantially rigid mandrel 130 (see Figure 6A ). Thus, the substantially rigid mandrel 130 is positioned in the first cavity 192 defined between the first stringer 120 and the first side 162 of the panel 160 (see, Figure 12A )Inside.

[0072] Now refer to Figure 7A and 13 The second method further includes, for each of the one or more second stringers: (i) positioning a flexible mandrel 150 on the second side 166 of the panel 160 and (ii) positioning the second stringer 140 over the flexible mandrel 150. Thus, the flexible mandrel 150 is positioned within a second cavity 194 defined between the second stringer 140 and the second side 166 of the panel 160.

[0073] refer to Figure 1 、 14 and 15, without limitation, in some aspects of the second method, the second side 166 of the panel 160 is corrugated. Figure 6A An aspect of the second approach is depicted wherein the first side 162 of the panel 160 is substantially flat.

[0074] refer to Figure 1 、 6A , 14 and 15, some aspects of the second method include producing a panel 160 by laying up plies 163 over one or more first stringers 120. Figure 6A 、 14 and 15, and especially Figure 6A In some of the latter aspects, stacking the plies 163 over the one or more first stringers 120 includes applying the one or more plies 163 supported by a rigid tool 170 and at least one substantially rigid mandrel 130. Figure 6A As shown in , in some aspects of the second method, the plies 163 are stacked to form a substantially flat surface. Figure 14 and 15 As shown in, in some aspects of the second method, the plies 163 are stacked to form a wavy or stepped surface. Thus, the method is suitable for continuously forming a plurality of differently shaped panels 160 using the same rigid tool 170, which is a flat surface (see, Figure 6A ) or wavy (see, Figure 14 and 15) or other means.

[0075] refer to Figure 5A 、 7A and 12B, some aspects of the second method include bagging one or more first stringers 120, a substantially rigid mandrel 130, a face sheet 160, a flexible mandrel 150, and one or more second stringers 140 into a vacuum bag 104. Figure 5A and 7A , the vacuum bag 104 is illustrated as transparent. Without limitation, some subsequent aspects of the second method further include at least partially evacuating the vacuum bag 104. In some aspects, partially evacuating the vacuum bag 104 includes evacuating the vacuum bag 104 by pulling a vacuum on the vacuum bag 104 to a vacuum of 0.1 atmosphere below atmospheric pressure; 0.2 atmosphere below atmospheric pressure; 0.3 atmosphere below atmospheric pressure; 0.4 atmosphere below atmospheric pressure; 0.5 atmosphere below atmospheric pressure; 0.6 atmosphere below atmospheric pressure; 0.7 atmosphere below atmospheric pressure; 0.8 atmosphere below atmospheric pressure; 0.9 atmosphere below atmospheric pressure; or greater than 0.9 atmosphere below atmospheric pressure.

[0076] Unrestricted, and further reference Figure 19 Some aspects of the second method further include co-curing (e.g., in the oven 106) one or more first stringers 120, the panel 160, and the one or more second stringers 140. Without limitation, some aspects of the second method including the latter co-curing further include, for each first stringer, removing the substantially rigid mandrel 130; and for each second stringer, removing the flexible mandrel 150 (see, Figure 23 , box 390).

[0077] Now refer to Figure 12A 、 20Aand 20B, and without limitation, further including some aspects of the second method of co-curing described above further including that, during co-curing, the substantially rigid mandrel 130 expands the first volume 132, and the first cavity 192 expands the second volume 193. In some non-limiting aspects of the second method wherein, during co-curing, the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193, the first volume 132 and the second volume 193 are substantially the same. In some non-limiting aspects of the second method in which the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193 during co-curing, the first volume 132 is between approximately 95% and approximately 105% of the second volume 193, or the first volume 132 is between approximately 90% and approximately 110% of the second volume 193, or the first volume 132 is between approximately 85% and approximately 115% of the second volume 193, or the first volume 132 is between approximately 80% and approximately 120% of the second volume 193, or the first volume 132 is between approximately 75% and approximately 125% of the second volume 193, or the first volume 132 is between approximately 70% and approximately 130% of the second volume 193.

[0078] Now refer to Figure 13 、 20C and 20D, and without limitation, further including some aspects of the second method of co-curing described above further including that, during co-curing, the flexible mandrel 150 expands the first volume 152, and the second cavity 194 expands the second volume 191. In some non-limiting aspects of the second method wherein, during co-curing, the flexible mandrel 150 expands the first volume 152 and the second cavity 194 expands the second volume 191, the first volume 152 is substantially the same as the second volume 191. In some non-limiting aspects of the second method in which the flexible mandrel 150 expands the first volume 152 and the second cavity 194 expands the second volume 191 during co-curing, the first volume 152 is between about 95% and about 105% of the second volume 191, or wherein the first volume 152 is between about 90% and about 110% of the second volume 191, or wherein the first volume 152 is between about 85% and about 115% of the second volume 191, or wherein the first volume 152 is between about 80% and about 120% of the second volume 191, or wherein the first volume 152 is between about 75% and about 125% of the second volume 191, or wherein the first volume 152 is between about 70% and about 130% of the second volume 191.

[0079] Now refer to Figure 12A and 12BSome non-limiting aspects of the systems and methods provided herein include incorporating radius fillers 198 (also referred to as noodles). The radius fillers 198 comprise a composite material and fill the margin between parts of one or more composite components, such as in Figure 12A and 12B The fillet filler 198 provides additional local structural reinforcement for the margin it fills and helps distribute local loads and forces.

[0080] refer to Figure 23 The second method is further described. Figure 23 , another example of a disclosed method 300 for manufacturing a cured composite structure 100 is shown. The method 300 utilizes a rigid tool 170 having one or more slots 174 defined therein, one or more first stringers 120, one or more second stringers 140, and a panel 160, wherein the panel 160 includes a first side 162 and a second side 166 opposite the first side 162.

[0081] At block 310 , the method 300 includes, for each of the one or more first longerons 120 , positioning the first longeron 120 on the rigid tool 170 such that the first longeron 120 is at least partially within the slot 174 of the one or more slots.

[0082] At block 320 , the method 300 includes, for each of the one or more first longerons 120 , positioning the substantially rigid mandrel 130 on the first longeron 120 such that the substantially rigid mandrel 130 is at least partially within the slot 174 .

[0083] At block 330 , the method 300 includes positioning the panel 160 over the one or more first longerons 120 and over the substantially rigid mandrel 130 such that the first side 162 of the panel 160 faces the one or more first longerons 120 and the substantially rigid mandrel 130 and the second side 166 of the panel 160 faces away from the one or more first longerons 120 and the substantially rigid mandrel 130 .

[0084] At block 340 , the method 300 includes, for each of the one or more second stringers, positioning the flexible mandrel 150 on the second side 166 of the panel 160 .

[0085] At block 350 , the method 300 includes, for each of the one or more second stringers, positioning the second stringer 140 over the flexible mandrel 150 .

[0086] At block 360, the method 300 includes bagging the one or more first stringers 120, the substantially rigid mandrel 130, the face sheet 160, the flexible mandrel 150, and the one or more second stringers 140 into the vacuum bag 104.

[0087] At block 370, the method 300 includes at least partially evacuating the vacuum bag 104.

[0088] At block 380, the method 300 includes co-curing the one or more first stringers 120, the face sheet 160, and the one or more second stringers 140.

[0089] At block 390, the method 300 includes removing the substantially rigid mandrel 130 and removing the flexible mandrel 150.

[0090] As described above, prior efforts to co-cure structures having stiffeners on both sides of the structure resulted in defects in the central structure due to pressure imbalances at the stiffener intersections, which in turn caused the laminate structure to twist or wrinkle. The second method described above helps to reduce, minimize, or prevent pressure imbalances at the stiffener intersections by providing sufficient dimensional constraints at both sides 162, 166 of the face sheet 160 of the structure 100 to support the structure 100 during co-curing and to provide the desired geometry, while at the same time providing flexibility on one side 166 sufficient to allow for slight degrees of freedom and / or geometric variations, and thereby reducing, minimizing, or preventing the twisting or wrinkling that would otherwise occur due to the pressure imbalances mentioned above. More specifically, the second method described above helps to promote uniform pressure at the stiffener intersections 110, which promotes a central structure with little or no twist. During curing, the substantially rigid mandrel 130 on the rigid tool 170 reacts to the varying forces of the autoclave and the thermal expansion growth of the flexible mandrel 150 to produce a part with an acceptable amount of laminate variation at the stiffener intersections 110. It should also be appreciated that the substantially rigid mandrel 130 and the rigid tool 170 help to produce the desired surface at the stiffener intersections 110, while the flexible mandrel allows the second stringers 140 on the second side 166 to follow the contours of the second side 166. This combination allows for design flexibility of the contoured side (e.g., height, ply amount, ply drop-off, location of stiffeners, type of stiffeners) without the need to change the rigid tool 170 for structures 100 having different contours / designs.

[0091] 3, 5B, 6B, and 7B, a non-limiting example of a third method of manufacturing a cured composite structure 100 is further provided using a rigid tool 170 having one or more slots 174 defined therein, one or more first stringers 120, one or more second stringers 140, and a panel 160, the panel 160 including a first side 162 and a second side 166 opposite the first side 162. The non-limiting example of the third method of manufacturing the cured composite structure 100 includes, for each of the one or more first stringers 120, (i) positioning the first stringer 120 on the rigid tool 170 such that the first stringer 120 is at least partially within a slot of the one or more slots 174 and (ii) positioning the flexible mandrel 150 on the first stringer 120 such that the flexible mandrel 150 is at least partially within the slot 174 (see, Figure 5B ). The third method further includes positioning a panel 160 over the one or more first stringers 120 and over the flexible mandrel 150 such that a first side 162 of the panel 160 faces the one or more first stringers 120 and the flexible mandrel 150, and a second side 166 of the panel 160 faces away from the one or more first stringers 120 and the flexible mandrel 150 (see, Figure 6B ). Now refer to Figure 7B The third method further includes, for each of the one or more second stringers: (i) positioning a substantially rigid mandrel 130 on the second side 166 of the panel 160 and (ii) positioning a second stringer 140 over the substantially rigid mandrel 130 .

[0092] Without limitation, in some aspects of the third method, first side 162 of panel 160 is corrugated and second side 166 of panel 160 is substantially flat. In certain non-limiting aspects of this example, wherein first side 162 of panel 160 is corrugated and second side 166 of panel 160 is substantially flat, rigid tool 170 is corrugated. For example, rigid tool 170 may include a smoothly curved surface, a discontinuous surface, a stepped or stepped surface, or some combination thereof.

[0093] refer to Figure 6B , and without limitation, some aspects of the third method further include producing the panel 160 by stacking plies 163 over the one or more first stringers 120 .

[0094] refer to Figure 5B 、 6B and 7B, and without limitation, some aspects of the third method further include bagging the one or more first stringers 120, the substantially rigid mandrel 130, the face sheet 160, the flexible mandrel 150, and the one or more second stringers 140 into the vacuum bag 104. Figure 5B and7B , the vacuum bag 104 is illustrated as transparent. Without limitation, some aspects, including the third example of bagging described later, further include at least partially evacuating the vacuum bag 104. In some aspects, partially evacuating the vacuum bag 104 includes evacuating the vacuum bag 104 by pulling a vacuum on the vacuum bag 104 to a vacuum of 0.1 atmosphere below atmospheric pressure; 0.2 atmosphere below atmospheric pressure; 0.3 atmosphere below atmospheric pressure; 0.4 atmosphere below atmospheric pressure; 0.5 atmosphere below atmospheric pressure; 0.6 atmosphere below atmospheric pressure; 0.7 atmosphere below atmospheric pressure; 0.8 atmosphere below atmospheric pressure; 0.9 atmosphere below atmospheric pressure; or greater than 0.9 atmosphere below atmospheric pressure.

[0095] Without limitation, some aspects of the third example of vacuuming further include co-curing one or more first stringers 120, panels 160, and one or more second stringers 140. Without limitation, some aspects of the third example of co-curing further include, for each first stringer, removing a flexible mandrel 150; and for each second stringer, removing a substantially rigid mandrel 130 (see, Figure 24 , box 490).

[0096] Now refer to Figure 20A and 20B , and without limitation, in some aspects including the third example of the latter co-curing, during co-curing, the substantially rigid mandrel 130 expands the first volume 132, and the first cavity 192 expands the second volume 193. In some non-limiting aspects of the latter method in which during co-curing, the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193, the first volume 132 is substantially the same as the second volume 193. In some non-limiting aspects of the following method in which during co-curing, the substantially rigid mandrel 130 expands the first volume 132 and the first cavity 192 expands the second volume 193, the first volume 132 is between about 95% and about 105% of the second volume 193, or the first volume 132 is between about 90% and about 110% of the second volume 193, or the first volume 132 is between about 85% and about 115% of the second volume 193, or the first volume 132 is between about 80% and about 120% of the second volume 193, or the first volume 132 is between about 75% and about 125% of the second volume 193, or the first volume 132 is between about 70% and about 130% of the second volume 193.

[0097] Now refer to Figure 20C and 20D, and without limitation, some aspects of the third method further include the above-described co-curing method further comprising, during co-curing, the flexible mandrel 150 expanding the first volume 152, and the second cavity 194 expanding the second volume 191. In some non-limiting aspects of the latter method wherein, during co-curing, the flexible mandrel 150 expanding the first volume 152 and the second cavity 194 expanding the second volume 191, the first volume 152 is substantially the same as the second volume 191. In some non-limiting aspects of the following method in which during co-curing, the flexible mandrel 150 expands the first volume 152 and the second cavity 194 expands the second volume 191, the first volume 152 is between about 95% and about 105% of the second volume 191, or wherein the first volume 152 is between about 90% and about 110% of the second volume 191, or wherein the first volume 152 is between about 85% and about 115% of the second volume 191, or wherein the first volume 152 is between about 80% and about 120% of the second volume 191, or wherein the first volume 152 is between about 75% and about 125% of the second volume 191, or wherein the first volume 152 is between about 70% and about 130% of the second volume 191.

[0098] refer to Figure 24 The third example is further described. Figure 24 , another example of a disclosed method 400 for manufacturing a cured composite structure 100 is shown. The method 400 utilizes a rigid tool 170 having one or more slots 174 defined therein, one or more first stringers 120, one or more second stringers 140, and a panel 160, wherein the panel 160 includes a first side 162 and a second side 166 opposite the first side 162.

[0099] At block 410 , the method 400 includes, for each of the one or more first longerons 120 , positioning the first longeron 120 on the rigid tool 170 such that the first longeron 120 is at least partially within the slot 174 of the one or more slots.

[0100] At block 420 , the method 400 includes, for each of the one or more first longerons 120 , positioning the flexible mandrel 150 on the first longeron 120 such that the flexible mandrel 150 is at least partially within the slot 174 .

[0101] At block 430 , the method 400 includes positioning the panel 160 over the one or more first stringers 120 and over the flexible mandrel 150 such that the first side 162 of the panel 160 faces the one or more first stringers 120 and the flexible mandrel 150 and the second side 166 of the panel 160 faces away from the one or more first stringers 120 and the flexible mandrel 150 .

[0102] At block 440 , the method 400 includes, for each of the one or more second stringers, positioning a substantially rigid mandrel 130 on the second side 166 of the panel 160 .

[0103] At block 450 , the method 400 includes, for each of the one or more second longerons, positioning the second longeron 140 over the substantially rigid mandrel 130 .

[0104] At block 460 , the method 400 includes bagging the one or more first stringers 120 , the flexible mandrel 150 , the facesheet 160 , the substantially rigid mandrel 130 , and the one or more second stringers 140 into the vacuum bag 104 .

[0105] At block 470 , the method 400 includes at least partially evacuating the vacuum bag 104 .

[0106] At block 480 , the method 400 includes co-curing the one or more first stringers 120 , the face sheet 160 , and the one or more second stringers 140 .

[0107] At block 490 , the method 400 includes removing the substantially rigid mandrel 130 and removing the flexible mandrel 150 .

[0108] The third method described above provides improved quality for the stringers 140 on the second side 166 of the panel 160 when the stringers 140 are cured on the straight, substantially rigid mandrel 130. Further, the third method helps reduce, minimize, or prevent stress imbalances at the intersection of the stiffeners by providing dimensional constraints on both sides 162, 166 of the panel 160 of the structure 100 sufficient to support the structure 100 during co-curing and to provide the desired geometry. Still further, the third method allows the first side 162 of the panel 160 to be contoured based on the design of the rigid tool 170 (e.g., a smooth curved surface, a discontinuous surface, a stepped or stepped surface, or some combination thereof). The flexible mandrel 150 can be placed in the rigid tool 170 to accommodate the rigid tool design.

[0109] refer to Figure 1 、 3And 19, further providing a first non-limiting example of a system for manufacturing a cured composite structure 100, the composite structure 100 including a panel 160 having a first side 162 and a second side 166 opposite the first side 162, one or more first stringers 120 connected to the first side 162, and one or more second stringers 140 connected to the second side 166. The first non-limiting example of the system includes one or more substantially rigid mandrels 130, wherein each substantially rigid mandrel 130 is positioned within a first cavity 192 defined between a first stringer 120 of the one or more first stringers 120 and the first side 162 of the panel 160. The first non-limiting example of the system includes one or more flexible mandrels 150, wherein each flexible mandrel 150 is positioned within a second cavity 194 defined between a second stringer 140 of the one or more second stringers 140 and the second side 166 of the panel 160. The first non-limiting example of the system includes a curing oven 106 configured to receive therein the panel 160, the one or more first stringers 120, the one or more second stringers 140, the one or more substantially rigid mandrels 130, and the one or more flexible mandrels 150.

[0110] Without limitation, in some aspects of the first example of the system, the first side 162 of the panel 160 is substantially flat. Without limitation, in some aspects of the first example of the system, the first side 162 of the panel 160 is substantially flat and the second side 166 of the panel 160 is contoured.

[0111] Reference is made to Figure 16In some aspects of the above methods and systems, the one or more first longitudinal beams 120 are elongated and define a first elongated path 122. In these latter aspects of the above methods and systems, optionally, the one or more second longitudinal beams 140 are also elongated and define a second elongated path 142. In some non-limiting aspects of the above methods and systems in which the one or more first longitudinal beams 120 are elongated and define the first elongated path 122 and the one or more second longitudinal beams 140 are elongated and define the second elongated path 142, the first elongated path 122 intersects the second elongated path 142. In some non-limiting aspects of the above methods and systems in which the first elongated path 122 intersects the second elongated path 142, the first elongated path 122 is at an angle 20 relative to the second elongated path 142. In some non-limiting aspects of the above methods and systems wherein the first elongated path 122 is angled 20 relative to the second elongated path 142, the angle 20 is between about 10 degrees and about 170 degrees, or between about 20 degrees and about 160 degrees, or between about 30 degrees and about 150 degrees, or between about 40 degrees and about 140 degrees, or between about 50 degrees and about 130 degrees, or between about 60 degrees and about 120 degrees, or between about 70 degrees and about 110 degrees, or between about 80 degrees and about 100 degrees. In some non-limiting aspects of the above methods and systems wherein the first elongated path 122 is angled 20 relative to the second elongated path 142, the angle 20 is approximately 90 degrees. For example, in Figure 16 In the example of FIG. 1 , the angle 20 of the first elongated path 122 relative to the second elongated path 142 is 90 degrees. In some non-limiting aspects of the above methods and systems in which one or more first longitudinal beams 120 are elongated and define the first elongated path 122 and one or more second longitudinal beams 140 are elongated and define the second elongated path 142, a projection of the first elongated path 122 onto the imaginary viewing plane 40 intersects a projection of the second elongated path 142 onto the imaginary viewing plane 40 at an angle 20. In some aspects, the angle 20 is between about 10 degrees and about 170 degrees, or between about 20 degrees and about 160 degrees, or between about 30 degrees and about 150 degrees, or between about 40 degrees and about 140 degrees, or between about 50 degrees and about 130 degrees, or between about 60 degrees and about 120 degrees, or between about 70 degrees and about 110 degrees, or between about 80 degrees and about 100 degrees, or approximately 90 degrees.

[0112] refer to Figure 1-4 , and with particular reference to Figure 2In some aspects of the above methods and systems, one or more first stringers 120 include a first composite material 124, the panel 160 includes a second composite material 144, and one or more second stringers 140 include a third composite material 164. In certain non-limiting aspects of this latter aspect of the above methods and systems, the first composite material 124 is the same as the second composite material 144, or the first composite material 124 is the same as the third composite material 164, or the second composite material 144 is the same as the third composite material 164, or some combination thereof. As used herein, materials are substantially the same for a given purpose if the differences between the materials are small enough that they can be interchanged for the given purpose.

[0113] In some aspects of the above methods and systems, the substantially rigid mandrel 130 has a thermal expansion coefficient between about 86 μm / (m·K) and about 160 μm / (m·K), or a thermal expansion coefficient between about 50 μm / (m·K) and about 190 μm / (m·K), or a thermal expansion coefficient between about 60 μm / (m·K) and about 180 μm / (m·K), or a thermal expansion coefficient between about 70 μm / (m·K) and about 170 μm / (m·K). number, or a thermal expansion coefficient between about 80 μm / (m·K) and about 160 μm / (m·K), or a thermal expansion coefficient between about 90 μm / (m·K) and about 150 μm / (m·K), or a thermal expansion coefficient between about 100 μm / (m·K) and about 140 μm / (m·K), or a thermal expansion coefficient between about 110 μm / (m·K) and about 130 μm / (m·K), or a thermal expansion coefficient of about 120 μm / (m·K). Now referring to Figure 13 In some non-limiting aspects, the coefficient of thermal expansion of the flexible mandrel 150 is different than the coefficient of thermal expansion of the second stringer 140 , such that after curing, a gap exists between the flexible mandrel 150 and the second stringer 140 .

[0114] In some aspects of the above methods and systems, the substantially rigid mandrel 130 has a tensile modulus of at least about 35 MPa, or at least about 50 MPa, or at least about 100 MPa, or at least about 500 MPa, or at least about 1000 MPa, or at least about 5000 MPa, or at least about 10,000 MPa, or at least about 50,000 MPa, or at least about 10,000 MPa, or at least about 50,000 MPa, or at least about 100,000 MPa. These above examples of tensile moduli for the substantially rigid mandrel 130 are not limiting: the tensile modulus of the substantially rigid mandrel 130 should be selected using good engineering judgment.

[0115] In examples of the above methods and systems, the substantially rigid mandrel 130 can be formed from a variety of one or more materials. For example, in some aspects of the above methods and systems, the substantially rigid mandrel 130 comprises foam 195, polymethacrylimide 11, or polymethacrylimide 11 foam 195. In some aspects of the above methods and systems, the substantially rigid mandrel 130 comprises at least one of polytetrafluoroethylene 12, solid fluorinated ethylene propylene 13, silicone with glass, nylon 16, and combinations thereof. In some aspects of the above methods and systems, the substantially rigid mandrel 130 comprises aluminum, iron, steel, bronze, brass, copper, titanium, or some combination thereof. In some aspects where it is used as part of the substantially rigid mandrel 130, silicone with glass refers to silicone 17 having greater than 35% glass.

[0116] In examples of the above methods and systems, the flexible mandrel 150 can be formed from one or more different materials. For example, in some aspects of the above methods and systems, the flexible mandrel 150 comprises an elastic material 196. In some aspects of the above methods and systems, the flexible mandrel 150 has an elastic modulus of less than 30 MPa, or less than 25 MPa, or less than 20 MPa, or less than 15 MPa, or less than 10 MPa, or less than 5 MPa. These examples of the tensile modulus of the flexible mandrel 150 are not limiting: the tensile modulus of the flexible mandrel 150 should be selected using good engineering judgment. In some aspects of the above methods and systems, the flexible mandrel 150 is solid. In some aspects of the above methods and systems, the flexible mandrel 150 is foam. In some aspects of the above methods and systems, the flexible mandrel 150 comprises ethylene propylene diene monomer 14, or silicone with glass, or fluoropolymer elastomer 18, or some combination thereof. In some aspects where it is used as part of the flexible mandrel 150 , silicone with glass refers to silicone 15 having less than 35% glass.

[0117] You can Figure 25 Aircraft manufacturing and service method 1000 and the like are shown Figure 26 Examples of the present disclosure are described in the context of an aircraft 1002 as shown. During pre-production, aircraft manufacturing and service method 1000 may include specification and design 1004 of aircraft 1002 and material procurement 1006. During production, part / subassembly manufacturing 1008 and system integration 1010 of aircraft 1002 occur. Thereafter, aircraft 1002 may be certified and delivered 1012 for entry into service 1014. While in customer service, aircraft 1002 may be scheduled for routine maintenance and service 1016, which may also include modification, reconfiguration, refurbishment, etc.

[0118] Each process of method 1000 may be performed or executed by a system integrator, a third party, and / or an operator (e.g., a customer). For purposes of this description, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors; a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers; and an operator may include, for example, an airline, a leasing company, a service organization, or the like.

[0119] like Figure 26 As shown, aircraft 1002 produced by example method 1000 may include airframe 1018 and interior 1022 having plurality of systems 1020. Examples of plurality of systems 1020 may include one or more of propulsion system 1024, electrical system 1026, hydraulic system 1028, and environmental system 1030. Any number of other systems may be included.

[0120] The disclosed cured composite structure can be a composite structure used in aircraft structures. For example, in one example, the disclosed cured composite structure is a composite structure used in bulkheads, such as structural bulkheads, pivot bulkheads, wheel well bulkheads, or cargo bulkheads. Other examples are possible. The disclosed method and system for manufacturing a cured composite structure, and the resulting cured composite structure, can be employed during any one or more stages of aircraft manufacturing and service method 1000. As an example, the disclosed method and system for manufacturing a cured composite structure, and the resulting cured composite structure, can be employed during material procurement 1006. As another example, the disclosed method and system for manufacturing a cured composite structure, and the resulting cured composite structure, can be used to manufacture or fabricate parts or subassemblies corresponding to part / subassembly manufacturing 1008, system integration 1010, and / or maintenance and service 1016. As another example, the disclosed method and system for manufacturing a cured composite structure, and the resulting cured composite structure, can be used to construct fuselage 1018 and interior 1022. Furthermore, one or more apparatus instances, method instances, or a combination thereof may be utilized, for example, during parts / subassembly manufacturing 1008 and / or system integration 1010, for example, by substantially accelerating assembly of the aircraft 1002 or reducing the cost of the aircraft 1002. Similarly, one or more system instances, method instances, or a combination thereof may be utilized while the aircraft 1002 is in service, such as, but not limited to, during maintenance and service 1016.

[0121] Without wishing to be bound by any particular theory, it is contemplated that some aspects of the systems and methods provided herein provide time savings, improved structural integrity, design engineering flexibility, or some combination thereof. Some aspects of the systems and methods provided herein improve certain quality attributes, such as thickness uniformity of the panel laminate, or finer control over part placement and orientation, such as, but not limited to, placing planar fibers or other parts over desired areas of the entire panel, over the area of ​​the first stringer, over the area of ​​the second stringer, over the area where the first stringer and the second stringer intersect, or a combination thereof.

[0122] The disclosed methods and systems for manufacturing a cured composite structure, and the resulting cured composite structure, are described in the context of an aircraft; however, one of ordinary skill in the art will readily recognize that the disclosed methods and systems for manufacturing a cured composite structure, and the resulting cured composite structure, can be used in a variety of applications. For example, the disclosed methods and systems for manufacturing a cured composite structure, and the resulting cured composite structure, can be implemented in various types of vehicles, including, for example, helicopters, passenger ships, automobiles, and the like.

[0123] Furthermore, the present disclosure includes embodiments according to the following clauses:

[0124] Clause 1. A method (200) of manufacturing a cured composite structure (100) from one or more first stringers (120), one or more second stringers (140), and a face sheet (160), the face sheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising:

[0125] (210) for each of the one or more first stringers (120), supporting the first stringer (120) on the first side (162) of the panel (160) using a substantially rigid mandrel (130) such that the substantially rigid mandrel (130) is positioned within a first cavity (192) defined between the first stringer (120) and the first side (162) of the panel (160);

[0126] (220) for each of the one or more second stringers (140), supporting the second stringer (140) on the second side (166) of the panel (160) using a flexible mandrel (150) such that the flexible mandrel (150) is positioned within a second cavity (194) defined between the second stringer (140) and the second side (166) of the panel (160); and

[0127] (230) co-curing the one or more first stringers (120), the face sheet (160), and the one or more second stringers (140) while the one or more first stringers (120) are supported by the substantially rigid mandrel (130) and the one or more second stringers (140) are supported by the flexible mandrel (150).

[0128] Clause 2. The method (200) according to Clause 1, wherein the first side (162) of the face sheet (160) is substantially flat.

[0129] Clause 3. The method (200) according to Clause 1 or Clause 2, wherein the second side (166) of the face sheet (160) is contoured.

[0130] Clause 4. The method (200) according to any one of Clauses 1-3, wherein supporting the one or more first stringers (120) on the first side (162) further comprises supporting the one or more first stringers (120) on the first side (162) of the face sheet (160) using a rigid tool (170) defining one or more slots (174) therein, wherein the one or more first stringers (120) and the substantially rigid mandrel (130) are at least partially received within the one or more slots (174).

[0131] Clause 5. The method (200) according to any one of Clauses 1-4, wherein the one or more first stringers (120) are elongate and define a first elongate path (122), and wherein the one or more second stringers (140) are elongate and define a second elongate path (142).

[0132] Clause 6. The method (200) according to Clause 5, wherein the first elongate path (122) intersects the second elongate path (142).

[0133] Clause 7. The method (200) according to Clause 6, wherein the first elongate path (122) is angled (20) relative to the second elongate path (142), and wherein the angle (20) is between about 80 degrees and about 100 degrees.

[0134] Clause 8. The method (200) according to Clause 5, wherein a projection of the first elongate path (122) on an imaginary view plane (40) and a projection of the second elongate path (142) on the imaginary view plane (40) intersect at an angle (20), wherein the angle (20) is between about 80 degrees and about 100 degrees.

[0135] Clause 9. The method (200) according to any one of Clauses 4-8, wherein the rigid tool (170) comprises a flat surface (172).

[0136] Clause 10. The method (200) according to any one of Clauses 1-9, further comprising (240) removing the substantially rigid mandrel (130) and the flexible mandrel (150) from the cured composite structure (100).

[0137] Clause 11. The method (200) according to any one of Clauses 1-10, wherein the one or more first stringers (120) comprise a first composite material (124), the face sheet (160) comprises a second composite material (144), and the one or more second stringers (140) comprise a third composite material (164).

[0138] Clause 12. The method (200) according to Clause 11, wherein the first composite material (124) is the same as the second composite material (144), and wherein the first composite material (124) is the same as the third composite material (164).

[0139] Clause 13. The method (200) according to any one of Clauses 1-12, wherein the substantially rigid mandrel (130) has a coefficient of thermal expansion between about 86 pm / (m-K) and about 160 pm / (m-K).

[0140] Clause 14. The method (200) according to any one of Clauses 1-13, wherein the substantially rigid mandrel (130) has a tensile modulus of at least about 35 MPa.

[0141] Clause 15. The method (200) according to any one of Clauses 1-14, wherein the substantially rigid mandrel (130) comprises a foam (195).

[0142] Clause 16. The method (200) according to any one of Clauses 1-15, wherein the substantially rigid mandrel (130) comprises a polymethacrylimide (11).

[0143] Clause 17. The method (200) according to any one of Clauses 1-16, wherein the substantially rigid mandrel (130) comprises a polymethacrylimide (11) foam (195).

[0144] Clause 18. The method (200) according to any one of Clauses 1-14, wherein the substantially rigid mandrel (130) comprises at least one of a polytetrafluoroethylene (12), a solid fluorinated ethylene propylene (13), a siloxane with glass (15), and a nylon (16).

[0145] Clause 19. The method (200) according to any one of Clauses 1-18, wherein the flexible mandrel (150) comprises an elastomeric material (196).

[0146] Clause 20. The method (200) of any one of clauses 1 to 19, wherein the flexible mandrel (150) comprises an elastic modulus of less than 20 MPa.

[0147] Clause 21. The method (200) of any one of clauses 1 to 20, wherein the flexible mandrel (150) is solid.

[0148] Clause 22. The method (200) of any one of Clauses 1 to 21, wherein the flexible mandrel (150) comprises ethylene propylene diene monomer (14).

[0149] Clause 23. The method (200) of any one of clauses 1 to 22, wherein the flexible mandrel (150) comprises at least one of a silicone with glass (17); and a fluoropolymer elastomer (18).

[0150] Clause 24. The method (200) of any one of clauses 1 to 23, wherein during co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) is substantially the same as the second volume (193).

[0151] Clause 25. The method (200) of any one of clauses 1 to 23, wherein during co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) is between about 95% and about 105% of the second volume (193).

[0152] Clause 26. The method (200) according to any one of clauses 1 to 25, further comprising:

[0153] supporting a first plurality of stringers (30) on a first side (162) of the panel (160), wherein the first plurality of stringers (30) includes one or more first stringers (120); and

[0154] A second plurality of stringers (32) is supported on a second side (166) of the panel (160), wherein the second plurality of stringers (32) includes one or more second stringers (140).

[0155] Clause 27. The method (200) of clause 26, wherein at least one of the first plurality of stringers (30) and the second plurality of stringers (32) further comprises blade stringers (34), or I-stringers (36), or J-stringers (37), or some combination thereof.

[0156] Clause 28. A cured composite structure (100) manufactured according to the method (200) of any one of Clauses 1 to 27.

[0157] Clause 29. A method (300) of manufacturing a cured composite structure (100) using a rigid tool (170) defining one or more slots (174) therein, one or more first stringers (120), one or more second stringers (140), and a facesheet (160), the facesheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising:

[0158] For each of the one or more first stringers (120), (i) (310) positioning the first stringer (120) on the rigid tool (170) such that the first stringer (120) is at least partially within the slot (174) of the one or more slots, and (ii) (320) positioning the substantially rigid mandrel (130) on the first stringer (120) such that the substantially rigid mandrel (130) is at least partially within the slot (174);

[0159] (330) positioning the panel (160) over the one or more first stringers (120) and over the substantially rigid mandrel (130) such that a first side (162) of the panel (160) faces toward the one or more first stringers (120) and the substantially rigid mandrel (130), and a second side (166) of the panel (160) faces away from the one or more first stringers (120) and the substantially rigid mandrel (130); and

[0160] For each of the one or more second stringers, (i) (340) positioning the flexible mandrel (150) on the second side (166) of the panel (160), and (ii) (350) positioning the second stringer (140) over the flexible mandrel (150).

[0161] Clause 30. The method (300) of Clause 29, wherein the first side (162) of the panel (160) is substantially flat and wherein the second side (166) of the panel (160) is corrugated.

[0162] Clause 31. The method (300) of Clause 29 or Clause 30, further comprising producing the panel (160) by stacking plies (163) over one or more first stringers (120).

[0163] Clause 32. The method (300) of any one of clauses 29 to 31, further comprising (360) bagging the one or more first stringers (120), the substantially rigid mandrel (130), the face sheet (160), the flexible mandrel (150), and the one or more second stringers (140) into a vacuum bag (104).

[0164] Clause 33. The method (300) of Clause 32, further comprising (370) at least partially evacuating the vacuum bag (104).

[0165] Clause 34. The method (300) of Clause 33, further comprising (380) co-curing the one or more first stringers (120), the face sheet (160), and the one or more second stringers (140).

[0166] Clause 35. The method (300) of clause 34, further comprising:

[0167] For each first stringer, (390) removing the substantially rigid mandrel (130); and

[0168] For each second stringer, (390) the flexible mandrel (150) is removed.

[0169] Clause 36. The method (300) of clause 34 or clause 35, wherein the first cavity (192) is defined between one or more first longitudinal beams (120) and the first side (162) of the panel (160); and during co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193) and wherein the first volume (132) is between about 95% and about 105% of the second volume (193).

[0170] Clause 37. A method (400) of manufacturing a cured composite structure (100) using a rigid tool (170) defining one or more slots (174) therein, one or more first stringers (120), one or more second stringers (140), and a facesheet (160), the facesheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising:

[0171] For each of the one or more first stringers (120), (i) (410) positioning the first stringer (120) on the rigid tool (170) such that the first stringer (120) is at least partially within a slot of the one or more slots (174), and (ii) (420) positioning the flexible mandrel (150) on the first stringer (120) such that the flexible mandrel (150) is at least partially within the slot (174);

[0172] (430) positioning the panel (160) over the one or more first stringers (120) and over the flexible mandrel (150) such that a first side (162) of the panel (160) faces the one or more first stringers (120) and the flexible mandrel (150), and a second side (166) of the panel (160) faces away from the one or more first stringers (120) and the flexible mandrel (150); and

[0173] For each of the one or more second stringers, (i) (440) positioning a substantially rigid mandrel (130) on the second side (166) of the panel (160), and (ii) (450) positioning the second stringer (140) over the substantially rigid mandrel (130).

[0174] Clause 38. The method (400) of Clause 37, wherein the first side (162) of the panel (160) is corrugated and wherein the second side (166) of the panel (160) is substantially flat.

[0175] Clause 39. The method (400) of Clause 37 or Clause 38, further comprising producing the panel (160) by stacking plies (163) over one or more first stringers (120).

[0176] Clause 40. The method (400) of any one of clauses 37 to 39, further comprising (460) bagging the one or more first stringers (120), the substantially rigid mandrel (130), the face sheet (160), the flexible mandrel (150), and the one or more second stringers (140) into a vacuum bag (104).

[0177] Clause 41. The method (400) of Clause 40, further comprising (470) at least partially evacuating the vacuum bag (104).

[0178] Clause 42. The method (400) of Clause 41, further comprising (480) co-curing the one or more first stringers (120), the face sheet (160), and the one or more second stringers (140).

[0179] Clause 43. The method (400) of clause 42, further comprising:

[0180] For each first stringer, (490) removing the flexible mandrel (150); and

[0181] For each second longitudinal beam, (490) a substantially rigid mandrel (150) is removed.

[0182] Clause 44. The method (400) of clause 42 or clause 43, wherein the first cavity (192) is defined between one or more first longitudinal beams (120) and the first side (162) of the panel (160); and during co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) is between about 95% and about 105% of the second volume (193).

[0183] Clause 45. A system for making a cured composite structure (100), the composite structure comprising a panel (160) having a first side (162) and a second side (166) opposite the first side (162), one or more first stringers (120) connected to the first side (162), and one or more second stringers (140) connected to the second side (166), the system comprising:

[0184] one or more substantially rigid mandrels (130), each substantially rigid mandrel (130) positioned within a first cavity (192) defined between a first stringer (120) of the one or more first stringers (120) and a first side (162) of the panel (160);

[0185] one or more flexible mandrels (150), each flexible mandrel (150) positioned within a second cavity (194) defined between a second stringer (140) of the one or more second stringers (140) and a second side (166) of the panel (160); and

[0186] A curing oven (106) is configured to receive therein a panel (160), one or more first stringers (120), one or more second stringers (140), one or more substantially rigid mandrels (130), and one or more flexible mandrels (150).

[0187] Clause 46. The system of clause 45, wherein the first side (162) of the panel (160) is substantially flat.

[0188] Clause 47. The system of clause 46, wherein the second side (166) of the panel (160) is corrugated.

[0189] Clause 48. The system of any of clauses 45 to 47, wherein the one or more first longitudinal beams (120) are elongated and define a first elongated path (122), and wherein the one or more second longitudinal beams (140) are elongated and define a second elongated path (142).

[0190] Clause 49. The system of clause 48, wherein the first elongated path (122) intersects the second elongated path (142).

[0191] Clause 50. A system according to clause 48, wherein a projection of the first elongated path (122) on the imaginary viewing plane (40) and a projection of the second elongated path (142) on the imaginary viewing plane (40) intersect at an angle (20), wherein the angle (20) is between about 80 degrees and about 100 degrees.

[0192] While various examples of the disclosed method and system for making a cured composite structure and the resulting cured composite structure have been shown and described, modifications may occur to one skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.

Claims

1. A method of manufacturing a cured composite structure (100) from one or more first stringers (120), one or more second stringers (140), and a face sheet (160), the face sheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising: For each of the one or more first stringers (120), supporting the first stringer (120) on a first side (162) of the panel (160) using a substantially rigid mandrel (130) such that the substantially rigid mandrel (130) is positioned within a first cavity (192) defined between the first stringer (120) and the first side (162) of the panel (160); For each of the one or more second stringers (140), supporting the second stringer (140) on the second side (166) of the panel (160) using a flexible mandrel (150) such that the flexible mandrel (150) is positioned within a second cavity (194) defined between the second stringer (140) and the second side (166) of the panel (160); and The one or more first stringers (120), the face sheet (160), and the one or more second stringers (140) are co-cured while the one or more first stringers (120) are supported by the substantially rigid mandrel (130) and the one or more second stringers (140) are supported by the flexible mandrel (150).

2. The method of claim 1, wherein the first side (162) of the panel (160) is substantially flat.

3. The method of claim 1, wherein the second side (166) of the panel (160) is corrugated.

4. The method of claim 1 , wherein supporting the one or more first longitudinal beams (120) on the first side (162) further comprises supporting the one or more first longitudinal beams (120) on the first side (162) of the panel (160) using a rigid tool (170) defining one or more slots (174) therein, wherein the one or more first longitudinal beams (120) and the substantially rigid mandrel (130) are at least partially received within the one or more slots (174).

5. The method of any one of claims 1 to 4, wherein the one or more first longitudinal beams (120) are elongated and define a first elongated path (122), and wherein the one or more second longitudinal beams (140) are elongated and define a second elongated path (142).

6. The method of claim 5, wherein the first elongated path (122) intersects the second elongated path (142).

7. The method of claim 6, wherein the first elongated path (122) is angled (20) relative to the second elongated path (142), and wherein the angle (20) is between 80 degrees and 100 degrees.

8. The method of claim 5, wherein a projection of the first elongated path (122) on an imaginary viewing plane (40) and a projection of the second elongated path (142) on the imaginary viewing plane (40) intersect at an angle (20), wherein the angle (20) is between 80 degrees and 100 degrees.

9. The method of claim 4, wherein the rigid tool (170) includes a flat surface (172).

10. The method of any one of claims 1 to 4, further comprising removing the substantially rigid mandrel (130) and the flexible mandrel (150) from the cured composite structure (100).

11. The method of claim 1 , wherein the one or more first stringers (120) comprise a first composite material (124), the panel (160) comprises a second composite material (144), and the one or more second stringers (140) comprise a third composite material (164).

12. The method of claim 11, wherein the first composite material (124) is the same as the second composite material (144), and wherein the first composite material (124) is the same as the third composite material (164).

13. The method according to any one of claims 1 to 4, wherein the substantially rigid mandrel (130) has a coefficient of thermal expansion between 86 µm / (m⋅K) and 160 µm / (m⋅K).

14. The method of claim 1, wherein the substantially rigid mandrel (130) has a tensile modulus of at least 35 MPa.

15. The method of claim 1, wherein the substantially rigid mandrel (130) comprises foam.

16. The method of claim 1, wherein the substantially rigid mandrel (130) comprises polymethacrylimide.

17. The method of claim 1, wherein the substantially rigid mandrel (130) comprises polymethacrylimide foam.

18. The method of claim 1, wherein the substantially rigid mandrel (130) comprises at least one of polytetrafluoroethylene, solid fluorinated ethylene propylene, silicone with glass, and nylon.

19. The method of claim 1, wherein the flexible mandrel (150) comprises an elastic material.

20. The method of claim 1, wherein the flexible mandrel (150) comprises an elastic modulus of less than 20 MPa.

21. The method of claim 1, wherein the flexible mandrel (150) is solid.

22. The method of claim 1, wherein the flexible mandrel (150) comprises ethylene propylene diene monomer.

23. The method of claim 1, wherein the flexible mandrel (150) comprises at least one of: Silicone with glass; and Fluoropolymer elastomer.

24. The method of claim 1, wherein during the co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) and the second volume (193) are substantially the same.

25. The method of claim 1 , wherein during the co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) is between 95% and 105% of the second volume (193).

26. The method of claim 1, further comprising: supporting a first plurality of stringers (30) on a first side (162) of the panel (160), wherein the first plurality of stringers (30) includes the one or more first stringers (120); and A second plurality of stringers (32) is supported on a second side (166) of the panel (160), wherein the second plurality of stringers (32) includes the one or more second stringers (140).

27. The method of claim 26, wherein at least one of the first plurality of stringers (30) and the second plurality of stringers (32) further comprises a blade stringer (34).

28. The method of claim 26, wherein at least one of the first plurality of stringers (30) and the second plurality of stringers (32) further comprises an I-shaped stringer (36) or a J-shaped stringer (37).

29. A cured composite structure (100) manufactured according to the method of any one of claims 1 to 28.

30. A method of manufacturing a cured composite structure (100) using a rigid tool (170) defining one or more slots (174) therein, one or more first stringers (120), one or more second stringers (140), and a face sheet (160), the face sheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising: For each of the one or more first stringers (120), positioning the first stringer (120) on the rigid tool (170) such that the first stringer (120) is at least partially within a slot (174) of the one or more slots, and positioning a substantially rigid mandrel (130) on the first stringer (120) such that the substantially rigid mandrel (130) is at least partially within the slot (174); positioning the panel (160) above the one or more first stringers (120) and above the substantially rigid mandrel (130) such that a first side (162) of the panel (160) faces toward the one or more first stringers (120) and the substantially rigid mandrel (130), and a second side (166) of the panel (160) faces away from the one or more first stringers (120) and the substantially rigid mandrel (130); and For each of the one or more second stringers, a flexible mandrel (150) is positioned on a second side (166) of the panel (160), and the second stringer (140) is positioned over the flexible mandrel (150).

31. The method of claim 30, wherein the first side (162) of the panel (160) is substantially flat and wherein the second side (166) of the panel (160) is corrugated.

32. The method of claim 30, further comprising creating the panel (160) by stacking plies (163) over the one or more first stringers (120).

33. The method of claim 30, further comprising bagging the one or more first stringers (120), the substantially rigid mandrel (130), the face sheet (160), the flexible mandrel (150), and the one or more second stringers (140) into a vacuum bag (104).

34. The method of claim 33, further comprising at least partially evacuating the vacuum bag (104).

35. The method of claim 34, further comprising co-curing the one or more first stringers (120), the face sheet (160), and the one or more second stringers (140).

36. The method of claim 35, further comprising: For each first stringer, removing the substantially rigid mandrel (130); and For each second stringer, the flexible mandrel (150) is removed.

37. A method according to claim 35, wherein a first cavity (192) is defined between the one or more first longitudinal beams (120) and the first side (162) of the panel (160); and during the co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193) and wherein the first volume (132) is between 95% and 105% of the second volume (193).

38. A method of manufacturing a cured composite structure (100) using a rigid tool (170) defining one or more slots (174) therein, one or more first stringers (120), one or more second stringers (140), and a face sheet (160), the face sheet (160) including a first side (162) and a second side (166) opposite the first side (162), the method comprising: For each of the one or more first stringers (120), positioning the first stringer (120) on the rigid tool (170) such that the first stringer (120) is at least partially within a slot of the one or more slots (174), and positioning a flexible mandrel (150) on the first stringer (120) such that the flexible mandrel (150) is at least partially within the slot (174); Positioning the panel (160) above the one or more first stringers (120) and above the flexible mandrel (150) such that a first side (162) of the panel (160) faces toward the one or more first stringers (120) and the flexible mandrel (150), and a second side (166) of the panel (160) faces away from the one or more first stringers (120) and the flexible mandrel (150); and For each of the one or more second stringers, a substantially rigid mandrel (130) is positioned on a second side (166) of the panel (160), and the second stringer (140) is positioned above the substantially rigid mandrel (130).

39. The method of claim 38, wherein the first side (162) of the panel (160) is corrugated and wherein the second side (166) of the panel (160) is substantially flat.

40. The method of claim 38, further comprising creating the panel (160) by stacking plies (163) over the one or more first stringers (120).

41. The method of claim 38, further comprising bagging the one or more first stringers (120), the substantially rigid mandrel (130), the face sheet (160), the flexible mandrel (150), and the one or more second stringers (140) into a vacuum bag (104).

42. The method of claim 41, further comprising at least partially evacuating the vacuum bag (104).

43. The method of claim 42, further comprising co-curing the one or more first stringers (120), the face sheet (160), and the one or more second stringers (140).

44. The method of claim 43, further comprising: For each first stringer, removing the flexible mandrel (150); and For each second stringer, the substantially rigid mandrel (130) is removed.

45. A method according to claim 43, wherein a first cavity (192) is defined between the one or more first longitudinal beams (120) and the first side (162) of the panel (160); and during the co-curing, the substantially rigid mandrel (130) expands a first volume (132), the first cavity (192) expands a second volume (193), and wherein the first volume (132) is between 95% and 105% of the second volume (193).

46. ​​A system for manufacturing a cured composite structure (100), the cured composite structure (100) comprising a panel (160) having a first side (162) and a second side (166) opposite the first side (162), one or more first stringers (120) connected to the first side (162), and one or more second stringers (140) connected to the second side (166), the system comprising: one or more substantially rigid mandrels (130), each substantially rigid mandrel (130) positioned within a first cavity (192) defined between a first stringer (120) of the one or more first stringers (120) and a first side (162) of the panel (160); one or more flexible mandrels (150), each flexible mandrel (150) positioned within a second cavity (194) defined between a second stringer (140) of the one or more second stringers (140) and a second side (166) of the panel (160); and A curing oven (106) is configured to receive the panel (160), the one or more first stringers (120), the one or more second stringers (140), the one or more substantially rigid mandrels (130), and the one or more flexible mandrels (150) therein.

47. The system of claim 46, wherein the first side (162) of the panel (160) is substantially flat, and wherein the second side (166) of the panel (160) is corrugated.

48. The system of claim 46, wherein the one or more first longitudinal beams (120) are elongated and define a first elongated path (122), and wherein the one or more second longitudinal beams (140) are elongated and define a second elongated path (142).

49. The system of claim 48, wherein the first elongated path (122) intersects the second elongated path (142).

50. The system of claim 48, wherein a projection of the first elongated path (122) on an imaginary viewing plane (40) and a projection of the second elongated path (142) on the imaginary viewing plane (40) intersect at an angle (20), wherein the angle (20) is between 80 degrees and 100 degrees.

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