Reworked parts for composite structures

Abstract

The invention is entitled to a repair part for a composite structure. A repair part (400) for a composite structure (403) is described. The repair part (400) includes an upper composite layer (404E) including an upper perimeter (408) extending beyond a damaged region (402) of the composite structure (403), and a bottom composite layer (404A) between the composite structure (403) and the upper composite layer (404E), the bottom composite layer (404A) including a bottom perimeter (410) extending beyond the upper perimeter (408) of the upper composite layer (404E). The repair part (400) further includes a bottom adhesive layer (406A) adhering the bottom composite layer (404A) to the composite structure (403), and a repair part adhesive layer (406E) adhering the upper composite layer (404E) to the bottom composite layer (404A) or an intermediate composite layer (404D).

Description

TECHNICAL FIELD

[0001] The present application relates to composite structures, and more particularly to rework parts for damaged composite structures. BACKGROUND

[0002] Structures and materials formed from resin-impregnated polymer composites (referred to herein as "composites," "composite layers," or "composite structures") are used in various industries and products, including but not limited to aircraft and aerospace vehicles, land-based vehicle bodies, watercraft, shipping containers, refrigeration panels, structural bulkheads and panels, and interior structures of assemblies. For example, aircraft can use composite structures in parts such as wings, fuselages, stabilizers, engine casings, control surfaces, thrust deflector parts, and the like. Other applications of composite structures within an aircraft can include overhead stowage bins, passenger stowage bins, floor panels, and bulkhead panels.

[0003] Composite structures can sustain damage in various situations. For example, during operation of an aircraft, the exterior and / or interior of the aircraft can sustain damage. Collisions between the aircraft and other objects, such as other vehicles moving in the vicinity of the aircraft, debris, or bird strikes, and lightning strikes are potential causes of exterior and / or interior damage. In some instances, exterior damage can be sustained in a skin that forms an exterior surface of the aircraft, and can propagate to structures beneath the skin, such as parts of the fuselage. Aircraft structures can also incur damage at times other than operation of the aircraft, such as during handling or installation of the structure.

[0004] Various methods of reworking damaged aircraft structures have been developed, some of which are based on the material composition of the aircraft structure involved. For example, adhesive rework such as scarf rework can be used to rework composite structures composed of composite materials. In this method, the damaged portion of the composite structure is removed, and a rework material patch is adhered to the surface exposed by the removal of the damaged portion. However, adhesive rework can be time-consuming, and thereby creates a significant time delay between the occurrence of damage and repair. In addition, removal of material from the damaged composite structure increases the risk of further damage to the structure, and the adhesive of the rework material can require multiple thermal cycles, which can also cause damage if applied improperly.

[0005] Various configurations of rework material have been developed for damaged composite structures. According to one configuration, a rework material patch includes two or more layers of composite material bonded together via an adhesive. Each layer includes two layers of composite material, such as resin-impregnated carbon composite material. A first layer having a minimum surface area is adhered to a surface of the damaged composite structure. Additional layers of increasing area are then stacked one on top of the other and overlapping each other to form a multi-layer rework material patch having a desired thickness. In this configuration, the first layer adhered to the structure has a minimum area, and each subsequent layer in the stack has a larger area covering all of the underlying layers, with the uppermost layer covering all of the underlying layers.

[0006] The geometric nature of this configuration causes each layer except the lowest layer to cover all of the underlying layers to form a seal over and around these layers. As a result, volatiles, air, and / or other substances in the composite layers of the underlying layers are instead trapped within the fully formed patch, and it is desirable to release the volatiles, air, and / or other substances from the reworked part. This trapped material can have a negative impact on the functionality, durability, and useful life of the patch. In some cases, one or more breather holes are drilled in the patch to release these trapped substances. However, such holes can reduce the structural integrity of the patch and increase the likelihood of degradation of the reworked part.

[0007] Accordingly, and in view of the foregoing, challenges exist in reworking damaged composite structures. SUMMARY

[0008] To address the above concerns, according to one aspect of the present disclosure, a rework part for a composite structure is provided. In this aspect, the rework part includes an upper composite layer including an upper perimeter extending beyond a damaged region of the composite structure, and a bottom composite layer between the composite structure and the upper composite layer, wherein the bottom composite layer includes a bottom perimeter extending beyond the upper perimeter of the upper composite layer. The rework part further includes a bottom adhesive layer adhering the bottom composite layer to the composite structure, and a rework part adhesive layer adhering the upper composite layer to the bottom composite layer or an intermediate composite layer.

[0009] Another aspect of the present disclosure relates to a method of providing a rework part for a composite structure. In this aspect, the method includes arranging an upper composite layer such that an upper perimeter of the upper composite layer extends beyond a damaged region of the composite structure, and arranging a bottom composite layer between the composite structure and the upper composite layer, the bottom composite layer including a bottom perimeter extending beyond the upper perimeter of the upper composite layer. The method further includes adhering the bottom composite layer to the composite structure, and adhering the upper composite layer to the bottom composite layer directly or indirectly through a rework part adhesive layer and one or more intermediate composite layers.

[0010] Another aspect of the present disclosure relates to a repair part for a composite structure. In this aspect, the repair part includes an upper composite layer including an upper perimeter extending beyond a damaged region of the composite structure, and a bottom composite layer between the damaged composite structure and the upper composite layer, wherein the bottom composite layer is adhered to the composite structure and includes a bottom perimeter extending beyond the upper perimeter of the upper composite layer. The repair part further includes an intermediate composite layer between the upper composite layer and the bottom composite layer, wherein the intermediate composite layer has an intermediate perimeter extending beyond the upper perimeter of the upper composite layer and not extending beyond the bottom perimeter of the bottom composite layer.

[0011] The features, functions, and advantages that have been discussed can be implemented independently in various embodiments or can be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 A diagram depicting an example aircraft including one or more composite structures is shown.

[0013] Figure 2 A diagram depicting a damaged portion of a wing of an aircraft is shown. Figure 1

[0014] Figure 3 A diagram depicting a planning example of a repair part configured to repair the damage illustrated in the diagram is shown. Figure 2

[0015] Figure 4 A diagram depicting a cross-sectional view of an example repair part configured to repair a damaged region of a damaged composite structure is shown.

[0016] Figure 5 A diagram depicting a repair part of Figure 4 having an adhesive ring is shown.

[0017] Figure 6 A diagram depicting another example repair part is shown.

[0018] Figure 7 A diagram depicting another example repair part is shown.

[0019] Figure 8 A diagram depicting another example repair part adhered to a stringer is shown.

[0020] Figure 9 A flow diagram illustrating a method of providing a repair part for a composite structure is shown. DETAILED DESCRIPTION

[0021] ​​In view of the considerations discussed above, components and methods related to rework of damaged composite structures are provided. Briefly, a rework component for a damaged composite structure includes a bottom composite layer and an upper composite layer. The bottom composite layer has a bottom perimeter that extends beyond an upper perimeter of the upper composite layer. The upper perimeter of the upper composite layer extends beyond a damaged region of the composite structure. A bottom adhesive layer adheres the bottom composite layer to the composite structure, and a rework component adhesive layer adheres the upper composite layer to the bottom composite layer or an intermediate composite layer. Additional intermediate composite layers can be provided to achieve a desired profile of the rework component. The layers of the rework component can then be adhered to form an assembly adhered to the damaged composite structure by, for example, applying heat and / or pressure.

[0022] In this arrangement, composite layers of decreasing area are stacked in sequence to form the rework component. The geometry of this arrangement is such that composite layers further from the damaged structure do not cover the underlying layers closer to the structure, and thus each layer has an exposed perimeter portion through which air, volatiles, and / or other substances in the rework component can be aspirated. Moreover, by this configuration, the rework component can be adhered to the damaged composite structure without the need to remove the damaged portion of the composite structure, and both approaches reduce the likelihood of further damage to the damaged composite structure when the rework component is applied, by using a low temperature adhesive.

[0023] Figure 1 An example aircraft 100 including one or more composite structures is illustrated. Any suitable structure of the aircraft 100 can be a composite structure, including but not limited to a skin 102 forming an outer surface of the aircraft 100, and / or a fuselage part below the skin 102 such as a wing, a spar, a sandwich panel, a stabilizer, and / or a tail. In the depicted example, the skin 102 is formed of a composite material and sustains damage 104 at a location where the skin 102 covers a right wing 106 of the aircraft 100. The damage 104 can be caused by a collision between the aircraft 100 and another object, a lightning strike, or other various circumstances.

[0024] Examples of repair components configured to repair damage 104 and restore the mechanical structure of the skin 102 in the damaged region are described below. In the present disclosure, an aircraft 100 is provided as one example of a device having a composite structure(s) that can be repaired using the repair components disclosed herein. Accordingly, the repair components and methods of the present disclosure can be used to repair any suitable composite structure in any suitable device. As further examples, the disclosed repair components can be used to repair composite parts of light aircraft, large aircraft, powered aircraft, unpowered aircraft, airplanes, airships, helicopters, spacecraft, seacraft, manned vehicles, unmanned vehicles, and / or any other suitable conveyance. The disclosed repair components can be used to repair composite parts of stationary devices including, but not limited to, buildings, dwellings, containers, and the like.

[0025] Figure 2 An enlarged view of the damage 104 in the right wing 106 is illustrated, including an outline 300 superimposed on the wing for planning repair components as described further below. The depicted example is illustrated with reference to an enlarged portion of the right wing 106, as can be seen by the rivets (e.g., rivets 200) spanning the enlarged portion. In some examples, the damage 104 is analyzed to determine the extent of the damage and an outline of the repair components is drawn.

[0026] The damage can be analyzed in any suitable form. For example, the analysis can include measuring the area of the damage 104 - e.g., the two-dimensional extent of the damage 104 across the outer surface of the aircraft 100. The analysis can further include measuring the depth of the damage 104 - e.g., the distance the damage extends in a direction substantially perpendicular to the outer surface of the aircraft 100. The extent of the damage 104 can be determined using any suitable technique, including but not limited to structural analysis techniques, X-rays, thermal and other imaging techniques, and tomographic techniques.

[0027] Based on the analysis of the damage 104 and the material properties of the skin 102 and repair components as disclosed herein, a configuration of repair components suitable for restoring the structural capabilities and functionality of the skin 102 can be determined. In different examples, such repair components can have a number N of pre-cured composite layers sufficient to repair the damage 104, where N is an integer greater than or equal to 2. As described in greater detail below, in some examples, each composite layer of the repair components is composed of two layers of composite material cured together. In other examples, each composite layer of the repair components is composed of three or more layers of composite material cured together.

[0028] As one example, where the skin 102 includes a composite laminate that includes a plurality of composite plies or lamina, the damage 104 can exist in 6 consecutive plies of the skin. In this example, and where each composite ply of the rework part contains two layers of composite material, analysis of the damage 104 is used to determine that a rework part including 3 composite plies (6 layers) is sufficient to restore the structural capability and functionality of the skin 102. In other examples, the total number of plies in the rework part can differ from the number of damaged plies in the damaged composite structure.

[0029] In another example, the configuration of the rework part can be determined based at least in part on the aircraft structure that will be removed in order to access and rework the underlying damaged composite structure. In such examples, the underlying damaged composite structure can be subject to access limitations - for example, access to the damage can be limited to a single surface or single side only, and disassembly of the part to expose the damaged surface can pose an undesirable risk of further damaging the part. As one particular example, damage can occur in a stringer beneath an aircraft skin. In order to access and rework the stringer, the overlying skin can be removed, and a rework part can be adhered to the stringer. In some examples, the rework part is configured with a number of composite plies equal to the number of composite plies in the overlying skin.

[0030] As yet another example, a portion of the skin that has debonded from the underlying stringer can be removed and replaced with a rework part adhered to the stringer. In some of these examples, the number of plies in the rework part is equal to the number of plies in the skin. In these examples, by matching the number of rework part composite plies to the number of plies in the skin, the outer surface of the rework part can be substantially flush with the surrounding portion of the skin that was not removed, thereby providing a rework part with desirable aesthetic properties.

[0031] Figure 3 An example of planning a rework part configured to rework the damage 104 based on analysis of the damage is illustrated. In this example, various dimensional aspects of the rework part are determined to produce a profile 300 of the rework part and its individual composite plies. While in this example the dimensioning process is described as being performed on a workbench, the dimensioning can be performed in any suitable manner, including but not limited to on a computing device.

[0032] In this example, the dimensioning includes adjusting the size and shape of the rework part such that the periphery 302 of the upper composite ply of the rework part extends beyond the area of the damage 104 as shown. More specifically, the periphery 302 of the upper composite ply extends beyond the periphery 304 of the damage 104 around the entire extent of the periphery 304. In some examples, this extension beyond the periphery of the damage is greater than or equal to a predetermined distance, as described below.

[0033] As described above, any suitable inspection, structural analysis, and / or imaging technique can be used to analyze the damaged area and its perimeter. The size determination process illustrated in the depicted example also includes arranging the composite layers such that a given layer, other than the uppermost composite layer, has a perimeter that extends beyond the perimeter of the adjacent layer above the given layer. In some examples, this extension of each composite layer perimeter beyond the perimeter of its upper adjacent neighboring layer is greater than or equal to another predetermined distance, as described below. In some examples, the pre-cured composite layers can be manufactured in a preconfigured shape, such as 24” x 24” or 36” x 36”, and then trimmed to the desired perimeter shape. In other examples, the pre-cured composite layers can be manufactured (and possibly post-processed) to obtain any suitable shape and size.

[0034] Returning temporarily to Figure 2 The outline 300 is shown superimposed on an enlarged portion of the right wing 106 of the aircraft 100. In some examples, the outline 300 can be superimposed to provide a visual aid for accurately placing and adhering the repair part onto the right wing 106, and thus the repair damage 104. The outline 300 can be superimposed on the right wing 106 by any suitable mechanism, such as by printing the outline on the right wing 106, projecting the outline onto the right wing 106 via a projection display, or by a human operator drawing the outline on the right wing 106. Further, the outline 300 can be represented by data in a computer-readable format (e.g., a computer-aided design (CAD) file) that can be used to form, cure, bond, analyze, and / or perform any other suitable action with respect to the repair part.

[0035] After determining the size and composition of the repair part, the repair part can be formed and adhered to the aircraft 100, and thus the repair damage 104. Example processes for forming the repair part and adhering the repair part to the damaged composite structure are described below. Briefly, one example process includes nesting bonding layers between the composite layers of the repair part, bonding the bonding layers and the composite layers together, and adhering the repair part to the damaged composite structure. As described below, in some examples, the bonding and adhering stages can be implemented in separate steps, with an intermediate tool surface that can be used to bond the layers of the repair part. In other examples, the bonding and adhering stages can be implemented in a common step using the aircraft or other device that includes the damaged composite structure as a bonding and adhering surface.

[0036] Figure 4 A cross-sectional view of an example repair part 400 is illustrated, which is configured to repair a damaged area (indicated at 402) of a composite structure 403 according to the present disclosure. In one example, the repair part 400 is developed to repair the damage 104 on the right wing 106 and includes a plurality of composite layers 404, 406, 408, 410, 412, 414, 416, 418, 420, 422, 424, 426, 428, 430, 432, 434, 436, 438, 440, 442, 444, 446, 448, 450, 452, 454, 456, 458, 460, 462, 464, 466, 468, 470, 472, 474, 476, 478, 480, 482, 484, 486, 488, 490, 492, 494, 496, 498, 500, 502, 504, 506, 508, 510, 512, 514, 516, 518, 520, 522, 524, 526, 528, 530, 532, 534, 536, 538, 540, 542, 544, 546, 548, 550, 552, 554, 556, 558, 560, 562, 564, 566, 568, 570, 572, 574, 576, 578, 580, 582, 584, 586, 588, 590, 592, 594, 596, 598, 600, 602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, 640, 642, 644, 646, 648, 650, 652, 654, 656, 658, 660, 662, 664, 666, 668, 670, 672, 674, 676, 678, 680, 682, 684, 686, 688, 690, 692, 694, 696, 698, 700, 702, 704, 706, 708, 710, 712, 714, 716, 718, 720, 722, 724, 726, 728, 730, 732, 734, 736, 738, 740, 742, 744, 746, 748, 750, 752, 754, 756, 758, 760, 762, 764, 766, 768, 770, 772, 774, 776, 778, 780, 782, 784, 786, 788, 790, 792, 794, 796, 798, 800, 802, 804, 806, 808, 810, 812, 814, 816, 818, 820, 822, 824, 826, 828, 830, 832, 834, 836, 838, 840, 842, 844, 846, 848, 850, 852, 854, 856, 858, 860, 862, 864, 866, 868, 870, 872, 874, 876, 878, 880, 882, 884, 886, 888, 890, 892, 894, 896, 898, 900, 902, 904, 906, 908, 910, 912, 914, 916, 918, 920, 922, 924, 926, 928, 930, 932, 934, 936, 938, 940, 942, 944, 946, 948, 950, 952, 954, 956, 958, 960, 962, 964, 966, 968, 970, 972, 974, 976, 978, 980, 982, 984, 986, 988, 990, 992, 994, 996, 998, 1000, 1002, 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018, 1020, 1022, 1024, 1026, 1028, 1030, 1032, 1034, 1036, 1038, 1040, 1042, 1044, 1046, 1048, 1050, 1052, 1054, 1056, 1058, 1060, 1062, 1064, 1066, 1068, 1070, 1072, 1074, 1076, 1078, 1080, 1082, 1084, 1086, 1088, 1090, 1092, 1094, 1096, 1098, 1100, 1102, 1104, 1106, 1108, 1110, 1112, 1114, 1116, 1118, 1120, 1122, 1124, 1126, 1128, 1130, 1132, 1134, 1136, 1138, 1140, 1142, 1144, 1146, 1148, 1150, 1152, 1154, 1156, 1158, 1160, 1162, 1164, 1166, 1168, 1170, 1172, 1174, 1176, 1178, 1180, 1182, 1184, 1186, 1188, 1190, 1192, 1194, 1196, 1198, 1200, 1202, 1204, 1206, 1208, 1210, 1212, 1214, 1216, 1218, 1220, 1222, 1224, 1226, 1228, 1230, 1232, 1234, 1236, 1238, 1240, 1242, 1244, 124Figure 2 and 3 the perimeter of the profile 300 in FIG. 4B. In this example, the composite structure 403 represents a skin 102 and / or an underlying damaged composite structure, such as a stringer. As noted above, other examples of damage that can be repaired according to the disclosed methods include, but are not limited to, delamination (e.g., in a multi-layer aircraft skin), surface gouges, cracks, loss of adhesion between structures (e.g., between a skin and a stringer), etc.

[0037] The repair part 400 includes five composite layers: a bottom composite layer 404A, a first intermediate composite layer 404B, a second intermediate composite layer 404C, a third intermediate composite layer 404D, and an upper composite layer 404E. An adhesive layer is disposed between each pair of adjacent composite layers / structures to bond the layers / structures: a bottom adhesive layer 406A is disposed between the composite structure 403 and the bottom composite layer 404A, a first repair part adhesive layer 406B is disposed between the bottom composite layer 404A and the first intermediate composite layer 404B, a second repair part adhesive layer 406C is disposed between the first intermediate composite layer 404B and the second intermediate composite layer 404C, a third repair part adhesive layer 406D is disposed between the second intermediate composite layer 404C and the third intermediate composite layer 404D, and an uppermost repair part adhesive layer 406E is disposed between the third intermediate composite layer 404D and the upper composite layer 404E. For ease of illustration, the repair part 400 is shown with spaces between adjacent layers.

[0038] The composite layers 404A-404E can be formed of any suitable composite material. As one example, each of the composite layers 404A-404E can be formed of a composite material, such as a resin-impregnated carbon composite material. In some examples, each of the composite layers 404A-404E can be formed of a pre-cured laminate, e.g., a laminate formed of two or more composite layers or plies. The plies can be bonded together by applying pressure and heat (e.g., by autoclave, vacuum bagging with a heat blanket, vacuum bagging with an oven) or in any other suitable manner.

[0039] As described above, in some examples, the selection of the number of composite layers for the rework part can be based at least in part on the number of plies in each composite layer of the rework part and / or the number of plies damaged in the composite structure to be reworked or other composite structures involved in the rework. For example, if the damaged composite structure to be reworked includes six plies, and each composite layer of the rework part includes two plies of composite material, in some examples, the rework part can be configured with three composite layers. Further, the material composition of the composite layers can be selected based on the material composition of the composite structure to be reworked. For example, the material composition of the composite layers 404A-404E can be selected to substantially match the material composition of the composite structure 403.

[0040] The adhesive layers 406 can be composed of any suitable material. In some examples, each adhesive layer 406 can be composed of an adhesive material that cures at a temperature of approximately 250°F. Such an adhesive material can be considered a low temperature adhesive, as it can be cured at such a relatively low temperature, which can reduce the likelihood of causing heat-related damage when curing the adhesive layers 406, particularly in the case where the composite structure 403 includes a laminate. In other examples, each adhesive layer 406 can be composed of an adhesive material that cures at a temperature of approximately 350°F. As different curing temperatures of adhesive materials can be used, the rework part described herein supports a variety of adhesive materials.

[0041] As described above, the design of the rework part 400 includes arranging the composite layers to achieve a desired degree of overlap between the layers and with respect to the damaged area. In the depicted example, the upper composite layer 404E is sized such that the upper perimeter 408 of the upper composite layer extends at least a distance di beyond the damaged area 402 around the entire perimeter of the upper perimeter. In one example, the distance di is approximately one inch or greater. In some examples, the distance di can be determined using test and analysis results of the composite structure 403 and / or the damaged area 402 to calculate a sufficient overlap that enables the restoration of the structural capabilities of the composite structure 403. In another description of such overlap, and again with reference to FIG. 3, Figure 3 , the perimeter 302 of the upper composite layer of the rework part extends beyond the perimeter 304 of the damage 104 around the entire outer perimeter of the perimeter 302.

[0042] Further, and as Figure 4As shown in the example, the dimensions of each of the bottom composite layer 404A, the first intermediate composite layer 404B, the second intermediate composite layer 404C, and the third intermediate composite layer 404D are determined such that the perimeter of the layer extends beyond the perimeter of the adjacent higher layer by at least a distance d2. For example, the dimensions of the bottom composite layer 404A are determined such that its perimeter 410 extends beyond the perimeter 412 of the first intermediate composite layer 404B directly above it by a distance d2. In one example, the distance d2 is approximately one-half inch or more.

[0043] As described above, by arranging the plurality of composite layers in this stepped, overlapping configuration, the edges of the composite layers below a given composite layer are not pinched off by the given composite layer, advantageously enabling air, volatiles, and / or other substances to freely escape from the composite layers. In different examples, the composite layers 404A-404E of the rework part 400 can be configured to have any suitable degree of overlap with the damaged region 402, and any suitable degree of overlap between adjacent composite layers. In some examples, the amount of overlap between adjacent composite layers is substantially the same. In other examples, the amount of overlap between adjacent composite layers can vary throughout the rework part 400.

[0044] Referring now to Figure 5 In some examples, an adhesive ring is provided around the perimeter of each composite layer in the rework part. Figure 5 A cross-section of another configuration of the rework part 400 is illustrated, including an adhesive ring around the perimeter of each composite layer: a bottom adhesive ring 500A arranged around the perimeter 410 of the bottom composite layer 404A, a first intermediate adhesive ring 500B arranged around the perimeter 412 of the first intermediate composite layer 404B, a second intermediate adhesive ring 500C arranged around the perimeter 416 of the second intermediate composite layer 404C, a third intermediate adhesive ring 500D arranged around the perimeter 420 of the third intermediate composite layer 404D, and an uppermost adhesive ring 500E arranged around the perimeter 408 of the upper composite layer 404E.

[0045] In Figure 5In the depicted example, the adhesive rings 500A-500D have substantially equal thicknesses that are greater than the thickness of the uppermost adhesive ring 500E. In other examples, all of the adhesive rings 500 can be configured to have substantially equal thicknesses, or the thicknesses of one or more of the adhesive rings can be different. The depicted example also shows that the upper surfaces of the adhesive rings 500B, 500C, and 500D are approximately aligned / flush with the tops of the adjacent adhesive layers 406B, 406C, and 406D, respectively, and that the lower surfaces of the adhesive rings 500B, 500C, and 500D are approximately aligned / flush with the bottoms of the adjacent first, second, and third intermediate composite layers 404B, 404C, and 404D, respectively. In other examples, other arrangements of the adhesive rings 500 relative to the adjacent adhesive layers and composite layers are possible.

[0046] In some examples and as described above, the rework part 400 can be adhered to an exterior surface of a device. For example, the rework part 400 can be adhered to an exterior surface of an aircraft, in which case the composite structure 403 can be a skin forming an exterior surface of the aircraft. In such examples, the rework part 400 can be visible from the exterior of the aircraft, and the rework part 400 can be visible from the exterior of the aircraft. Figure 4 In contrast to the stepped edges depicted in FIG. 1, the use of adhesive rings 500 provides a smoother and more continuous perimeter surface for the rework part 400. In these examples, the adhesive rings 500 can cure to cause the adhesive material to flow and form a smoother profile around the perimeter of the rework part 400. Advantageously, this smoother profile perimeter can make the presence of the rework part 400 less conspicuous. Thus, the adhesive rings 500 can provide the rework part 400 with an additional desirable aesthetic property.

[0047] In other example uses, the adhesive rings 500 can not be used with the rework part 400. For example, in cases where the rework part 400 is adhered to an interior surface of a device or where the presence of the rework part is not visible or is less likely to be seen from an exterior view of the device or surface, the adhesive rings 500 can not be used.

[0048] Other variations of the configuration of the rework part 400 are possible. As one example, a filler material and a glass fiber overlay can be disposed over the upper composite layer 404E to conceal the underlying layers and make the appearance of the rework part 400 inconspicuous or substantially unnoticeable. As yet another example, the rework part 400 can include a lightning protection layer. For example, the lightning protection layer can include an aluminum foil sandwiched between two layers of glass fiber and adhered to the upper composite layer 404E.

[0049] In the depicted example, the rework part 400 includes a first intermediate composite layer 404B, a second intermediate composite layer 404C, and a third intermediate composite layer 404D. In other examples, the rework part 400 can include more or fewer intermediate composite layers. Figure 4 and Figure 5 In the depicted example, each of the adhesive layers 406, except for the bottom adhesive layer 406A, extends beyond the perimeter of the adjacent and higher composite layer 404. In other examples, the relative overlap between the adhesive layers and the adjacent composite layers can be different.Figure 6 An example of this variation is illustrated, depicting a reworked part 600 comprising five composite layers 604A, 604B, 604C, 604D, and 604E and five adhesive layers 606A, 606B, 606C, 606D, and 606E. Each adhesive layer 606 has a perimeter substantially flush with the perimeter of the adjacent composite layer 602 on the upper side of the adhesive layer 604. For example, the bottom adhesive layer 606A has a perimeter 610 substantially flush with the perimeter 614 of the bottom composite layer 602.

[0050] As mentioned above, the number of composite layers in a reworked component can vary based on factors such as damage inspection, structural analysis of the damaged area, and the characteristics of the composite structure. As an example, Figure 7 A reworked component 700 is shown, comprising two composite layers: a bottom composite layer 702 and an upper composite layer 704. The bottom composite layer 702 is directly adhered to the damaged composite structure 706 via a bottom adhesive layer 708, and the upper composite layer 704 is directly adhered to the bottom composite layer 702 via a reworked component adhesive layer 710. In this example, the reworked component adhesive layer 710 has a perimeter 712 that is substantially flush with the perimeter 714 of the upper composite layer 704. However, the relative arrangement and dimensions between the composite layers and the adhesive layer can vary as described above.

[0051] As described above, the reworked parts according to the method described herein can be applied to any suitable composite structure. As another example of a composite structure to which reworked parts can be applied, Figure 8 The diagram illustrates a rework component 800 bonded to a damaged composite longitudinal beam 802. In the area where the rework component 800 is applied, the longitudinal beam 802 exhibits a non-planar U-shaped geometry. Therefore, the rework component 800 is configured to have a non-planar U-shaped geometry to match the shape of the longitudinal beam 802 and achieve the desired adhesion between the rework component and the longitudinal beam, thereby providing the desired rework for the damage experienced by the longitudinal beam.

[0052] Figure 8 Examples of implementations are shown, in which, in addition to having, for example... Figures 1-7 Beyond the planar geometry of composite structures illustrated in the diagram, reworkable components can also be applied to composite structures with non-planar (e.g., curved, irregular) geometries. In these embodiments, the composite layer of the reworkable component can be pre-cured into a geometry that is based on, or in some instances substantially matches, the composite structure to be reworked, or mates with or complements the composite structure to be reworked. Thus, in various instances, the composite layers can be pre-cured during their formation into planar geometries for planar composite structures and non-planar geometries for non-planar composite structures. As another example, the composite layer can be pre-cured into an L-shaped geometry for an L-shaped composite structure.

[0053] Referring now to Figure 9 A flowchart illustrating a method 900 of providing a rework part for a composite structure is presented. For example, the method 900 can be performed to provide one or more of the rework parts 400, 600, 700, and 800.

[0054] At 902, the method 900 includes arranging an upper composite layer such that an upper perimeter of the upper composite layer extends beyond a damaged region of the composite structure. The upper composite layer can be arranged such that the upper perimeter extends 904 about 1 inch or more beyond the damaged region. At 906, the method 900 includes arranging a bottom composite layer between the composite structure and the upper composite layer, the bottom composite layer including a bottom perimeter that extends beyond the upper perimeter of the upper composite layer. In some examples, each composite layer can include two layers of resin-impregnated carbon composite material that can be bonded together by the application of heat and pressure. At 908, the method 900 includes affixing the bottom composite layer to the composite structure. In some examples, one or more of a heat source, a pressure source, and a vacuum source can be used to affix the bottom composite layer to the composite structure via a bottom bonding layer. In some examples, the bonding layer of the rework part can be cured at about 250 °F. In other examples, the bonding layer of the rework part can be cured at about 350 °F. Further, in some examples, the bottom composite layer can be affixed to the composite structure via fastener(s) in addition to or instead of being affixed to the composite structure via the bottom bonding layer.

[0055] At 910, the method 900 includes bonding the upper composite layer to the bottom composite layer directly through the rework part bonding layer or indirectly through the rework part bonding layer and one or more intermediate composite layers. At 912, the method 900 includes arranging an intermediate composite layer between the upper composite layer and the bottom composite layer, where the intermediate composite layer has an intermediate perimeter that extends beyond the upper perimeter of the upper composite layer and does not extend beyond the bottom perimeter of the bottom composite layer. At 914, the method 900 includes bonding the upper composite layer directly to the intermediate composite layer via the rework part bonding layer. At 916, the method 900 includes arranging a rework part bonding layer perimeter of the rework part bonding layer to be substantially flush with the intermediate perimeter of the intermediate composite layer.

[0056] At 918, the method 900 includes disposing an additional intermediate composite layer between the intermediate composite layer and the bottom composite layer, where the additional intermediate composite layer has an additional intermediate composite layer perimeter that extends beyond the intermediate perimeter of the intermediate composite layer and does not extend beyond the bottom perimeter of the bottom composite layer. At 920, the method 900 includes bonding the additional intermediate composite layer to the intermediate composite layer, where the additional intermediate composite layer perimeter extends beyond the intermediate perimeter of the intermediate composite layer by about one-half inch or more. At 922, the method 900 includes bonding an upper bonding ring around the upper perimeter of the upper composite layer. At 924, the method 900 includes bonding a bottom bonding ring around the bottom perimeter of the bottom composite layer. In some examples, other layers can be incorporated into the rework part, including but not limited to a lightning protection layer or a cover layer.

[0057] In some examples, the bonding layers in the rework part can be cured, and thus the adjacent bonding and composite layers are bonded, separately from or in combination with adhering the rework part to the composite structure. Where the bonding and adhering are performed separately, a tool surface separate from the composite structure or a device including the composite structure can be used to cure the bonding layers and achieve the intra-layer bonding. The tool surface can be configured based on (e.g., substantially matching, mating, or complementary to) the geometry of the surface of the composite structure to which the rework part will be applied. After curing, the cured rework part can then be adhered to the composite structure. In other examples where the bonding and adhering are performed in the same process, the composite structure can be used to cure the bonding layers and achieve the intra-layer bonding, as well as to adhere the rework part to the surface of the composite structure. In yet other examples, the rework part can be affixed to the composite structure via bolt(s) and / or any other suitable fastener, in addition to or instead of adhering the rework part to the composite structure via the bonding layers. As one example of fastening, Figure 8 Four bolts (e.g., bolts 804) are depicted affixing the bottom layer of the rework part 800 to the composite stringer 802. As used herein, “affix” refers to bonding the rework part to the composite structure via the bonding layers and / or fastening the rework part to the composite structure via fastener(s).

[0058] The methods described herein can enable damage to a composite structure to be repaired in the field, potentially using the composite structure itself to bond the layers of the repaired part. Advantageously, the geometry of the disclosed repaired part is such that the edges of the layers beneath a given layer are not pinched off by the given layer, due to the continuously decreasing layer area as the repaired part traverses upward. Thus, air, volatiles, and other substances can be drawn out of the disclosed repaired part without the need to drill vent holes. The described methods can enable the repair of composite structure damage using cryogenic adhesives without the need to remove the damage, which can reduce the likelihood of further damage or failure of the repair, and reduce the lead time between the occurrence of the damage and its repair. Using the adhesive ring, a smooth edge of the repaired part can be produced to provide an unobtrusive or unnoticeable appearance of the repaired part, thereby preserving the desired aesthetic features of the composite structure or device. In some examples, the repaired part can be implemented such that the upper composite layer is substantially flush with the surface of the composite structure adjacent to the damaged region.

[0059] The present disclosure includes all novel and nonobvious combinations and subcombinations of the various features and techniques disclosed herein. The various features and techniques disclosed herein are not necessarily all required to be present in all examples of the present disclosure. Furthermore, the various features and techniques disclosed herein can define patentable subject matter apart from the disclosed examples and can find utility in other implementations not explicitly disclosed herein.

[0060] While the scope of protection is determined by the appended claims, the disclosure can be embodied in various ways, including, but not limited to, those in accordance with the following clauses:

[0061] Clause 1. A repaired part for a composite structure, the repaired part comprising an upper composite layer comprising an upper perimeter extending beyond a damaged region of the composite structure; a bottom composite layer between the composite structure and the upper composite layer, the bottom composite layer comprising a bottom perimeter extending beyond the upper perimeter of the upper composite layer; a bottom adhesive layer adhering the bottom composite layer to the composite structure; and a repaired part adhesive layer bonding the upper composite layer to the bottom composite layer or an intermediate composite layer.

[0062] Clause 2. The repaired part of clause 1, further comprising an upper adhesive ring around the upper perimeter of the upper composite layer, and a bottom adhesive ring around the bottom perimeter of the bottom composite layer.

[0063] Clause 3. The repaired part of any of clauses 1 or 2, wherein the repaired part adhesive layer bonds the upper composite layer to the intermediate composite layer, and wherein the intermediate composite layer has an intermediate perimeter extending beyond the upper perimeter of the upper composite layer and not extending beyond the bottom perimeter of the bottom composite layer.

[0064] Clause 4. The rework part of Clause 3, wherein the rework part adhesive layer has a rework part adhesive layer perimeter that is substantially flush with an intermediate perimeter of the intermediate composite layer.

[0065] Clause 5. The rework part of any of Clauses 1-4, wherein the rework part adhesive layer has a rework part adhesive layer perimeter that is substantially flush with an upper perimeter of the upper composite layer.

[0066] Clause 6. The rework part of Clauses 3-5, further comprising an additional intermediate composite layer between the intermediate composite layer and the bottom composite layer, wherein the additional intermediate composite layer has an additional intermediate composite layer perimeter that extends beyond the intermediate perimeter of the intermediate composite layer and does not extend beyond the bottom perimeter of the bottom composite layer.

[0067] Clause 7. The rework part of Clause 6, wherein the additional intermediate composite layer is adhered to the intermediate composite layer and the additional intermediate composite layer perimeter extends beyond the intermediate perimeter of the intermediate composite layer by about one-half inch or more.

[0068] Clause 8. The rework part of any of Clauses 1-7, wherein the upper composite layer is an uppermost composite layer of the rework part and the upper perimeter of the uppermost composite layer extends beyond the damaged area by about 1 inch or more.

[0069] Clause 9. The rework part of any of Clauses 1-8, wherein each of the upper composite layer and the bottom composite layer comprises two layers of resin-impregnated carbon composite material.

[0070] Clause 10. A method of providing a rework part for a composite structure, the method comprising arranging an upper composite layer such that an upper perimeter of the upper composite layer extends beyond a damaged area of the composite structure, arranging a bottom composite layer between the composite structure and the upper composite layer, the bottom composite layer comprising a bottom perimeter that extends beyond the upper perimeter of the upper composite layer, affixing the bottom composite layer to the composite structure, and adhering the upper composite layer to the bottom composite layer directly or indirectly through a rework part adhesive layer and one or more intermediate composite layers.

[0071] Clause 11. The method of Clause 10, further comprising adhering an upper adhesive ring around the upper perimeter of the upper composite layer and adhering a bottom adhesive ring around the bottom perimeter of the bottom composite layer.

[0072] Clause 12. The method of any of clauses 10 or 11, further comprising disposing an intermediate composite layer between the upper composite layer and the bottom composite layer, wherein the intermediate composite layer has an intermediate perimeter that extends beyond the upper perimeter of the upper composite layer and does not extend beyond the bottom perimeter of the bottom composite layer.

[0073] Clause 13. The method of clause 12, further comprising directly bonding the upper composite layer to the intermediate composite layer via the rework part bonding layer.

[0074] Clause 14. The method of clause 12 or 13, wherein the rework part bonding layer has a rework part bonding layer perimeter, the method further comprising disposing the rework part bonding layer perimeter to be substantially flush with the intermediate perimeter of the intermediate composite layer.

[0075] Clause 15. The method of clause 13, wherein the rework part bonding layer has a rework part bonding layer perimeter, the method further comprising disposing the rework part bonding layer perimeter to be substantially flush with the upper perimeter of the upper composite layer.

[0076] Clause 16. The method of clause 12, further comprising disposing an additional intermediate composite layer between the intermediate composite layer and the bottom composite layer, wherein the additional intermediate composite layer has an additional intermediate composite layer perimeter that extends beyond the intermediate perimeter of the intermediate composite layer and does not extend beyond the bottom perimeter of the bottom composite layer.

[0077] Clause 17. The method of clause 16, further comprising bonding the additional intermediate composite layer to the intermediate composite layer, wherein the additional intermediate composite layer perimeter extends beyond the intermediate perimeter of the intermediate composite layer by about one-half inch or more.

[0078] Clause 18. The method of any of clauses 10-17, wherein the upper composite layer is an uppermost composite layer of the rework part, and the upper perimeter of the uppermost composite layer extends beyond the damaged area by about 1 inch or more.

[0079] Clause 19. A rework part for a composite structure, the rework part comprising an upper composite layer comprising an upper perimeter that extends beyond a damaged area of the composite structure; a bottom composite layer between the damaged composite structure and the upper composite layer, the bottom composite layer adhering to the composite structure and comprising a bottom perimeter that extends beyond the upper perimeter of the upper composite layer; and an intermediate composite layer between the upper composite layer and the bottom composite layer, wherein the intermediate composite layer has an intermediate perimeter that extends beyond the upper perimeter of the upper composite layer and does not extend beyond the bottom perimeter of the bottom composite layer.

[0080] Clause 20. The rework part of Clause 19, further comprising an upper adhesive ring around an upper perimeter of the upper composite layer, and a lower adhesive ring around a lower perimeter of the lower composite layer.

Claims

1. A rework component (400) for a composite structure (403), the rework component (400) comprising: The upper composite layer (404E) includes an upper perimeter (408) extending beyond the damaged area (402) of the composite structure (403); A bottom composite layer (404A) is located between the composite structure (403) and the upper composite layer (404E), the bottom composite layer (404A) including a bottom perimeter (410) extending beyond the upper perimeter (408) of the upper composite layer (404E); A bottom adhesive layer (406A) adheres the bottom composite layer (404A) to the composite structure (403); A rework component adhesive layer (406E) is provided, which bonds the upper composite layer (404E) to the bottom composite layer (404A) or the third intermediate composite layer (404D). An upper adhesive ring (500E) surrounding the upper perimeter (408) of the upper composite layer (404E); and Bottom adhesive ring (500A) surrounding the bottom perimeter (410) of the bottom composite layer (404A).

2. The rework component (400) according to claim 1, wherein the rework component adhesive layer (406E) bonds the upper composite layer (404E) to the third intermediate composite layer (404D), and wherein the third intermediate composite layer (404D) has an intermediate perimeter (420) extending beyond the upper perimeter (408) of the upper composite layer (404E) and not extending beyond the bottom perimeter (410) of the bottom composite layer (404A).

3. The reworked component (400) according to claim 1, further comprising a second intermediate composite layer (404C) between the third intermediate composite layer (404D) and the bottom composite layer (404A), wherein the second intermediate composite layer (404C) has an additional intermediate composite layer perimeter (416) extending beyond the intermediate perimeter of the third intermediate composite layer (404D) and not extending beyond the bottom perimeter (410) of the bottom composite layer (404A).

4. The reworked component (400) according to claim 3, wherein the second intermediate composite layer (404C) is bonded to the third intermediate composite layer (404D), and the perimeter (416) of the additional intermediate composite layer extends beyond the intermediate perimeter of the third intermediate composite layer (404D) by half an inch or more.

5. The reworked component (400) according to claim 1, wherein the upper composite layer (404E) is the uppermost composite layer of the reworked component (400), and the upper perimeter (408) of the uppermost composite layer extends beyond the damaged area (402) by 1 inch or more.

6. The reworked component (400) according to claim 1, wherein each of the upper composite layer (404E) and the bottom composite layer (404A) comprises two layers of resin-impregnated carbon composite material.

7. A method (900) for providing a reworked component (400) for a composite structure (403), the method (900) comprising: (902) An upper composite layer (404E) is arranged such that the upper perimeter (408) of the upper composite layer (404E) extends beyond the damaged area (402) of the composite structure (403). (906) A bottom composite layer (404A) is disposed between the composite structure (403) and the upper composite layer (404E), the bottom composite layer (404A) including a bottom perimeter (410) extending beyond the upper perimeter (408) of the upper composite layer (404E); (908) Attach the bottom composite layer (404A) to the composite structure (403); (910) The upper composite layer (404E) is bonded to the bottom composite layer (404A) directly or indirectly through the rework component adhesive layer (406E) and one or more intermediate composite layers; (922) An upper adhesive ring (500E) is bonded around the upper perimeter (408) of the upper composite layer (404E); and (924) Adhere a bottom adhesive ring (500A) around the bottom perimeter (410) of the bottom composite layer (404A).

8. The method (900) according to claim 7, further comprising: (912) A third intermediate composite layer (404D) is disposed between the upper composite layer (404E) and the bottom composite layer (404A), wherein the third intermediate composite layer (404D) has an intermediate perimeter (420) that extends beyond the upper perimeter (408) of the upper composite layer (404E) and does not extend beyond the bottom perimeter (410) of the bottom composite layer (404A).

9. The method (900) according to claim 8, further comprising (914) directly bonding the upper composite layer (404E) to the third intermediate composite layer (404D) via the rework component adhesive layer (406E).

10. The method (900) of claim 8, wherein the rework component adhesive layer (406E) has a rework component adhesive layer perimeter, the method further comprising (916) arranging the rework component adhesive layer perimeter flush with the intermediate perimeter (420) of the third intermediate composite layer (404D).

11. The method (900) of claim 9, wherein the rework component adhesive layer (406E) has a rework component adhesive layer perimeter, the method further comprising arranging the rework component adhesive layer perimeter to be flush with the upper perimeter (408) of the upper composite layer (404E).

12. The method (900) according to claim 8, further comprising: (918) A second intermediate composite layer (404C) is disposed between the third intermediate composite layer (404D) and the bottom composite layer (404A), wherein the second intermediate composite layer (404C) has an additional intermediate composite layer perimeter (416) extending beyond the intermediate perimeter of the third intermediate composite layer (404D) and not extending beyond the bottom perimeter (410) of the bottom composite layer (404A).

13. The method (900) of claim 7, wherein the upper composite layer (404E) is the uppermost composite layer of the reworked part (400), and the upper perimeter (408) of the uppermost composite layer extends beyond the damaged area (402) by 1 inch or more.

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