Method for manufacturing lay-up of composite honeycomb core sandwich structure, and composite honeycomb core sandwich structure

Abstract

To provide a method for manufacturing a lay-up (600) of a composite honeycomb core sandwich structure.SOLUTION: Laying up a first group of unidirectional tows (602) on a tool (100) for layup of the composite honeycomb core sandwich structure using an automated fiber placement process to form a stack of under-core composite plies (604) secured to a rough surface (102) adhered to the tool (100), placing a honeycomb core (606) on the stack of under-core composite plies (604) in the rough surface (102), and laying up a second group of unidirectional tows (608) on the honeycomb core (606) using the automated fiber placement process to form a stack of over-core composite plies (610) securing the honeycomb core (606) to the rough surface (102).SELECTED DRAWING: Figure 6A

Description

[Technical Field]

[0001] The present disclosure relates generally to the fabrication of layups for composite honeycomb core sandwich structures, and more particularly to the layup of unidirectional tows to form a stack of composite plies below a honeycomb core and another stack above the honeycomb core. The unidirectional tows are laid up using an automated fiber placement process. The unidirectional tows can secure the honeycomb core to prevent movement or collapse during autoclave curing. [Background technology]

[0002] Composite sandwich structures manufactured using honeycomb cores pose significant processing challenges. One of these challenges occurs when pressure from the autoclave (e.g., typically between 30 psig and 45 psig) presses the structure against the tool during curing. The chamfered core edges along the core's periphery are particularly susceptible to movement when lateral pressure is applied. In the worst case scenario, the core can collapse completely. Both core movement and collapse result in significant rework and scrap of the composite sandwich structure. An existing method for preventing core movement and collapse is applicable to structures manufactured with woven materials. This method, known as the tie-down method, requires some plies of the composite structure to extend beyond the structure's typical manufacturing excess and contact a roughened surface known as a grit strip. This roughened surface secures the woven plies in place and prevents them from moving. The honeycomb core typically "beds in" the uncured fabric, which, if fixed and held in place, can prevent movement of the honeycomb core. These fabrics are typically bidirectional materials, with warp fibers oriented along the major axis of the material and fill fibers oriented perpendicular to the warp fibers. To ensure core movement is prevented, only the plies laid up immediately before and after the core need to be in contact with the grit strip. Typically, the ply placed in front of the core covers half of the grit strip, and the ply placed above the core covers the entire grit strip. However, this method is not suitable for unidirectional tapes, where the fibers in each ply are oriented in only one direction.

[0003] Therefore, those skilled in the art are engaged in ongoing research and development efforts to introduce new techniques for laying up composite sandwich structures using unidirectional tapes. Summary of the Invention

[0004] Disclosed herein are methods for fabricating composite honeycomb core sandwich structure layups and exemplary composite honeycomb core sandwich structures. The following are non-limiting examples of the subject matter of this disclosure, including some claimed and some unclaimed examples.

[0005] In one example, a method of the present disclosure for manufacturing a layup of a composite honeycomb core sandwich structure includes: (1) using an automated fiber placement process to lay up a first set of unidirectional tows on a tool for laying up the composite honeycomb core sandwich structure to form a stack of under-core composite plies secured to a rough surface bonded to the tool; (2) placing a honeycomb core on the stack of under-core composite plies within the rough surface; and (3) using the automated fiber placement process to lay up a second set of unidirectional tows on the honeycomb core to thereby form a stack of over-core composite plies securing the honeycomb core to the rough surface.

[0006] In one example, a composite honeycomb core sandwich structure of the present disclosure includes an under-core composite ply stack, a honeycomb core, and an over-core composite ply stack, wherein the under-core composite ply stack is laid up on a tool by laying up a first set of unidirectional tows using an automated fiber placement process, the honeycomb core is placed on the under-core composite ply stack, and the over-core composite ply stack is laid up on the honeycomb core by laying up a second set of unidirectional tows using the automated fiber placement process.

[0007] In another example, a method of the present disclosure for manufacturing a layup of a composite honeycomb core sandwich structure includes: (1) using an automated fiber placement process to lay up a first set of unidirectional tows on a tool for laying up the composite honeycomb core sandwich structure to form a stack of under-core composite plies secured to a rough surface bonded to the tool; (2) placing an under-core film adhesive on the stack of under-core composite plies within a trim line of the composite honeycomb core sandwich structure; (3) placing a honeycomb core on the under-core film adhesive within the trim line; (4) placing an over-core film adhesive on the honeycomb core within the trim line; and (5) laying up a second set of unidirectional tows on the over-core film adhesive and the rough surface using the automated fiber placement process, thereby forming a stack of over-core composite plies that secures the honeycomb core to the rough surface.

[0008] Other embodiments of the disclosed method of manufacturing a layup of a composite honeycomb core sandwich structure, and the composite honeycomb core sandwich structure, will become apparent from the detailed description set forth below, the accompanying drawings, and the appended claims. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a top view of an example tool for laying up a composite honeycomb core sandwich structure. [Figure 2] FIG. 1 is a schematic diagram illustrating an example layup of a composite honeycomb core sandwich structure in a 0 degree ply orientation. [Figure 3] FIG. 10 is a schematic diagram illustrating another example of a layup of a composite honeycomb core sandwich structure in a 90 degree ply orientation. [Figure 4] FIG. 2 is a top view of an example under-core composite ply stack layup positioned on the tool of FIG. 1. [Figure 5] FIG. 1 is a flow diagram illustrating an example method for manufacturing a composite honeycomb core sandwich structure layup. [Figure 6A-B] FIG. 2 is an exploded view illustrating an example composite honeycomb core sandwich structure layup placed on the tool of FIG. 1. [Figure 7] FIG. 6 is a flow diagram illustrating an example of the placement of the composite fabric sheet of FIG. 5. [Figure 8] FIG. 6 is a flow diagram showing an example of the placement of the under-core film adhesive in FIG. 5. [Figure 9] FIG. 6 is a flow diagram showing an example of the arrangement of the honeycomb cores in FIG. 5. [Figure 10] FIG. 6 is a flow diagram showing an example of the placement of the film adhesive on the core in FIG. 5. [Figure 11] 6 is a flow diagram illustrating another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure in combination with FIG. 5. [Figure 12] FIG. 6 is a flow diagram illustrating an example of laying up the first group of unidirectional tows of FIG. 5. [Figure 13] 13 is a flow diagram illustrating another example of laying up the first group of unidirectional tows of FIG. 5 in combination with FIG. 12. FIG. [Figure 14] 14 is a flow diagram illustrating, in combination with FIGS. 12 and 13, yet another example of laying up the first group of unidirectional tows of FIG. 5. FIG. [Figure 15] FIG. 6 is a flow diagram illustrating an example of laying up the second group of unidirectional tows of FIG. 5. [Figure 16] 16 is a flow diagram illustrating another example of laying up the second group of unidirectional tows of FIG. 5 in combination with FIG. 15. FIG. [Figure 17] 17 is a flow diagram illustrating yet another example of laying up the second group of unidirectional tows of FIG. 5 in combination with FIGS. 15 and 16. FIG. [Figure 18] 5 is a flow diagram illustrating yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 19] 5 is a flow diagram illustrating yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 20]5 is a flow diagram illustrating yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 21] FIG. 1 is a top view of an example composite honeycomb core sandwich structure. [Figure 22] FIG. 22 is a side view of the composite honeycomb core sandwich structure of FIG. 21. [Figure 23] FIG. 23 is an exploded view of the composite honeycomb core sandwich structure of FIG. 22. [Figure 24] FIG. 10 is a flow diagram illustrating another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 25] 25 is a flow diagram illustrating, in combination with FIG. 24, yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 26] FIG. 25 is a flow diagram illustrating an example of laying up the first group of unidirectional tows of FIG. 24. [Figure 27] 26 is a flow diagram illustrating another example of laying up the first group of unidirectional tows of FIG. 24. FIG. [Figure 28] 26 and 27, is a flow diagram illustrating yet another example of laying up the first group of unidirectional tows of FIG. 24. [Figure 29A-B] FIG. 25 is a flow diagram illustrating an example of laying up the second group of unidirectional tows of FIG. 24. [Figure 30] FIG. 25 is a flow diagram illustrating, in combination with FIG. 24, yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 31] 5 is a flow diagram illustrating yet another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure. [Figure 32] FIG. 6 is a flow diagram illustrating an example of laying up the first group of unidirectional tows of FIG. 5. [Figure 33] FIG. 6 is a flow diagram illustrating yet another example of laying up the second group of unidirectional tows of FIG. 5. [Figure 34]6 is a flow diagram illustrating another example of a method for manufacturing a layup of a composite honeycomb core sandwich structure in combination with FIG. 5. [Figure 35] FIG. 1 is a block diagram illustrating an aircraft manufacturing and service method embodying one or more example methods for manufacturing a composite honeycomb core sandwich structure layup of the present disclosure. [Figure 36] FIG. 1 is a schematic diagram illustrating an aircraft incorporating one or more of the composite honeycomb core sandwich structures of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Disclosed herein are methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, 3400 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100, and various examples of the composite honeycomb core sandwich structure 2100. The disclosed methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, 3400 illustrate design concepts that allow for the use of tie downs in processing the composite honeycomb core sandwich structure 2100 using automated fiber placement equipment. Methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, and 3400 describe the placement and orientation of plies of composite unidirectional tape 402 to secure a honeycomb core 606 to prevent movement and collapse using grit strips 110. The grit strips are roughened surfaces 102 that are applied to layup mandrels (e.g., tools 100) to provide high friction to the material. This allows for the fabrication of complex honeycomb core sandwich structures 2100, such as nacelle components, via automated fiber placement equipment. That is, the methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, 3400 of the present disclosure allow for the use of composite unidirectional tape 402 in complex honeycomb core sandwich structures 2100 while preventing the honeycomb core 606 from shifting or collapsing during autoclave curing.

[0011] The verification methodology, described in the next few paragraphs, was developed and subsequently tested on a verification test specimen fabricated in late October 2023. The verification test specimen was based on a 737 MAX nose landing gear door, a complex honeycomb core structure typically fabricated using a tie-down technique with woven carbon fiber materials during a manual layup process. The verification methodology was developed to prevent core movement during fabrication of the verification test specimen, in which the honeycomb core was secured using composite unidirectional tape 402. Because composite unidirectional tape 402 has fibers oriented in only one direction, the solution required the creation of a dual-ply system in which the orientation of the two plies is perpendicular to one another. The ply below the core is referred to as the tool-side or under-core composite ply 604, and the ply above the core is referred to as the bag-side or over-core composite ply 610.

[0012] An analysis was performed to determine which of the two tie-down ply orientations would be the primary tie-down and which would be the secondary tie-down. For the demonstration specimen, the honeycomb core 606 was rectangular with a 30-degree chamfer on its long side and a 20-degree chamfer on its short side. Because a steeper chamfer angle (i.e., 30 degrees) increases the risk of core movement, the plies perpendicular to the chamfer were laid up immediately before and after the honeycomb core 606. The secondary tie-down plies were positioned farther away from the honeycomb core 606 in either direction. The other tool-side plies terminated at the beginning of the grit strip 110, and the bag-side plies terminated at the outer edge of the grit strip 110.

[0013] The demonstration specimen was designed with a quasi-isotropic, balanced, and symmetric layup. The schematic diagram in Figure 2 shows the layup of 0-degree plies (i.e., P2, P6, P10, P15, P19, and P23). The same diagram also shows the layup of +45-degree plies (i.e., P1, P5, P9, P16, P20, and P24) and -45-degree plies (i.e., P3, P7, P11, P14, P18, and P22). Figure 2 also shows the 0-degree plies extending over the grid strips 110. Figure 3 is a similar schematic diagram showing the plies oriented 90 degrees perpendicular to the other tie-down plies. Figure 4 shows the under-core composite plies 604 in the demonstration specimen before the honeycomb core 606 is installed. The 0-degree plies 404 are oriented vertically, and the 90-degree plies 406 are oriented horizontally. As shown in Figures 2 and 3, the ply extends over half of the grit strip 110. The demonstration method was found to be successful: no movement or collapse of the honeycomb core was observed in the construction of the demonstration specimens.

[0014] 1, 4-21, and 31 generally, for example, the present disclosure relates to methods 500, 1100, 1800, 1900, 2000, 3100, and 3400 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100. FIG. 1 is a top view of an example tool 100 for the layup 600 of a composite honeycomb core sandwich structure 2100. FIG. 4 illustrates an example layup 600 of a stack of under-core composite plies 604 positioned on the tool 100 of FIG. 1. FIG. 5 illustrates an example method 500 for manufacturing a layup of a composite honeycomb core sandwich structure. FIG. 6 is an exploded view of an example layup 600 of a composite honeycomb core sandwich structure 2100 positioned on the tool 100 of FIG. 1. FIG. 7 illustrates an example arrangement 508 of a composite fabric sheet 616 of FIG. 5. Figure 8 shows an example of the arrangement 510 of the under-core film adhesive 618 of Figure 5. Figure 9 shows an example of the arrangement 504 of the honeycomb core 606 of Figure 5. Figure 10 shows an example of the arrangement 512 of the over-core film adhesive 628 of Figure 5. Figure 11, in combination with Figure 5, shows an example of a method 1100 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100. Figure 12 shows an example of laying up 502 the first group of unidirectional tows 602 of Figure 5. Figure 13, in combination with Figure 12, shows another example of laying up 502 the first group of unidirectional tows 602 of Figure 5.

[0015] Figure 14, in combination with Figures 12 and 13, illustrates yet another example of laying up 502 the first group of unidirectional tows 602 of Figure 5. Figure 15 illustrates an example of laying up 506 the second group of unidirectional tows 608 of Figure 5. Figure 16, in combination with Figure 15, illustrates another example of laying up 506 the second group of unidirectional tows 608 of Figure 5. Figure 17, in combination with Figures 15 and 16, illustrates yet another example of laying up 506 the second group of unidirectional tows 608 of Figure 5. Figure 18, in combination with Figure 5, illustrates an example of a method 1800 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100. Figure 19, in combination with Figure 5, illustrates an example of a method 1900 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100. Figure 20, in combination with Figure 5, illustrates an example of a method 2000 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100. Figure 21 illustrates an example of a composite honeycomb core sandwich structure 2100. Figure 31, in combination with Figure 5, illustrates an example of a method 3100 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100.

[0016] 1, 4-10, and 21, in one or more examples, a method 500 (see FIG. 5) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes laying up 502 a first set of unidirectional tows 602 on a tool 100 for the layup 600 of the composite honeycomb core sandwich structure 2100 using an automated fiber placement process to form a stack of under-core composite plies 604 secured to a rough surface 102 bonded to the tool 100. At 504, a honeycomb core 606 is placed on the stack of under-core composite plies 604 within the rough surface 102. At 506, a second set of unidirectional tows 608 is laid up on the honeycomb core 606 using the automated fiber placement process, thereby forming a stack of over-core composite plies 610 that secure the honeycomb core 606 to the rough surface 102.

[0017] In another example of the method 500, the first set of unidirectional tows 602 extend beyond the trim line 612 of the composite honeycomb core sandwich structure 2100. In another example of the method 500, each unidirectional tow 614 includes unidirectional reinforcing fibers impregnated with a polymer resin to form the composite unidirectional tape 402. In another example, the unidirectional reinforcing fibers include carbon fibers, glass fibers, polyaramid fibers, acrylic fibers, viscose rayon fibers, or other suitable reinforcing fibers in any suitable combination. In yet another example of the method 500, the laminate orientation of the under-core composite ply 604 is quasi-isotropic.

[0018] In yet another example of the method 500, the roughened surface 102 is disposed on the tool 100 and surrounds the trim line 612 of the composite honeycomb core sandwich structure 2100. In another example of the method 500, the roughened surface 102 includes grit strips 110 or other suitable roughened surfaces in any suitable combination. In yet another example of the method 500, the honeycomb core 606 is disposed within the trim line 612 of the composite honeycomb core sandwich structure 2100. In yet another example of the method 500, the second set of unidirectional tows 608 extends beyond the trim line 612 of the composite honeycomb core sandwich structure 2100. In yet another example of the method 500, the stack orientation of the core-over-composite plies 610 is quasi-isotropic. In another example of method 500 , the lamination orientation of over-core composite ply 610 is symmetrical relative to the lamination orientation of under-core composite ply 604 relative to honeycomb core 606 .

[0019] In yet another example, the method 500 further includes disposing 508 a composite fabric sheet 616 on the roughened surface 102. In a further example, the composite fabric sheet 616 is impregnated with a polymer resin and includes fiberglass sheets, carbon fiber sheets, polyaramid sheets, or other suitable composite fabric sheets in any suitable combination. In yet another example, the composite fabric sheet 616 is sized to cover the roughened surface 102 and surround the trim line 612 of the composite honeycomb core sandwich structure 2100. In yet another example, the composite fabric sheet 616 is sized to cover the roughened surface 102 and cover the portion 104 of the top surface 106 of the tool 100 surrounded by the roughened surface 102. In yet another example, the composite fabric sheet 616 is sized to cover the roughened surface 102, as well as a first portion 104 of the top surface 106 of the tool 100 that is surrounded by the roughened surface 102, and a second portion 108 of the top surface 106 of the tool 100 that is outside the roughened surface 102. In yet another example, positioning 508 of the composite fabric sheet 616 includes sealing 702 the composite fabric sheet 616 to the tool 100 with a compression bag 112 (see FIG. 7 ). At 704, a vacuum is applied to the tool 100 for a predetermined time to press the composite fabric sheet 616 onto the roughened surface 102. At 706, the vacuum is released. At 708, the compression bag 112 is unsealed. At 710, the compression bag 112 is removed from the composite fabric sheet 616.

[0020] In yet another example, the method 500 further includes placing 510 an under-core film adhesive 618 on the under-core composite ply 604 stack within the trim line 612 of the composite honeycomb core sandwich structure 2100. In a further example, the under-core film adhesive 618 includes an epoxy film adhesive, a polyurethane film adhesive, a polyimide film adhesive, or any other suitable adhesive in any suitable combination. In yet another example, the under-core film adhesive 618 is sized to cover the bottom surface 620 of the honeycomb core 606. In yet another example, placing 510 the under-core film adhesive 618 includes sealing 802 (see FIG. 8 ) the under-core film adhesive 618 and the under-core composite ply 604 stack to the tool 100 with a compression bag 112. At 804, a vacuum is applied to the tool 100 for a predetermined time to press the under-core film adhesive 618 against the under-core composite ply 604 stack. At 806, the vacuum is released. At 808, the compression bag 112 is unsealed. At 810, the compression bag 112 is removed from the under-core film adhesive 618 and under-core composite ply 604 stack.

[0021] In yet another example of method 500, honeycomb core 606 includes a three-dimensional body 622 having a top surface 624, a bottom surface 620, and at least three sides 626 that are chamfered from top surface 624 to bottom surface 620.

[0022] In another example of the method 500, positioning 504 of the honeycomb core 606 includes positioning 902 (see FIG. 9 ) the honeycomb core 606 within the trim line 612 of the composite honeycomb core sandwich structure 2100. At 904, the honeycomb core 606 and the stack of under-core composite plies 604 are sealed to the tool 100 with a compression bag 112. At 906, a vacuum is applied to the tool 100 for a predetermined time, pressing the honeycomb core 606 against the stack of under-core composite plies 604. At 908, the vacuum is released. At 910, the compression bag 112 is unsealed. At 912, the compression bag 112 is removed from the stack of honeycomb core 606 and under-core composite plies 604.

[0023] In a further example, the honeycomb core 606 includes a plurality of segments 2102. In a further example, the plurality of segments 2102 of the honeycomb core 606 includes a front segment 2104, a center segment 2106, and a rear segment 2108. In a further example, the honeycomb core 606 includes a non-metallic material, a flame-retardant meta-aramid material, an aramid paper material, a fiberglass material, a metal material, an aluminum material, or any other suitable material in any suitable combination. In a further example, the honeycomb core 606 is positioned using at least two tool pins. Note that the honeycomb core 606 can also be positioned using other techniques, such as overhead laser templating.

[0024] In another example, the method 500 also includes placing 512 an over-core film adhesive 628 on the honeycomb core 606 within the trim line 612 of the composite honeycomb core sandwich structure 2100. In a further example, the over-core film adhesive 628 includes an epoxy film adhesive, a polyurethane film adhesive, a polyimide film adhesive, or any other suitable adhesive in any suitable combination. In another further example, the over-core film adhesive 628 is sized to cover the top surface 624 and the sides 626 of the honeycomb core 606. In yet another example, placing 512 the over-core film adhesive 628 includes sealing 1002 (see FIG. 10 ) the over-core film adhesive 628, honeycomb core 606, and under-core composite ply 604 stack up against the tool 100 using a compression bag 112. At 1004, a vacuum is applied to the tool 100 for a predetermined time to press the over-core film adhesive 628 against the under-core composite ply 604 stack up. The vacuum is released at 1006. The compression bag 112 is unsealed at 1008. At 1010, the compression bag 112 is removed from the stack of over-core film adhesive 628, honeycomb core 606, and under-core composite ply 604.

[0025] 1, 5, 6, 11-17, and 21, in one or more examples, a method 1100 (see FIG. 11) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. In the method 1100, a honeycomb core 606 includes a three-dimensional body 622 having a top surface 624, a bottom surface 620, and at least three sides 626 that are chamfered from the top surface 624 to the bottom surface 620. The method 1100 includes analyzing 1102 the honeycomb core 606 to determine a risk of collapse of the at least three sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 1104, a primary side 630 of the at least three sides 626 that has the highest risk of collapse is selected. The method 1100 continues from 1104 to 502 shown in FIG.

[0026] In another example of method 1100, primary side 630 is selected based at least in part on primary side 630 having the steepest chamfer of at least three sides 626. In yet another example of method 1100, primary side 630 is selected based at least in part on primary side 630 being the longest side of at least three sides 626. In yet another example of method 1100, the last composite ply 632 in the stack of under-core composite plies 604 is closest to honeycomb core 606 and is oriented orthogonal to primary side 630. In a further example, the under-core composite plies 639 of each set of four 634 in the stack of under-core composite plies 604 are oriented to be quasi-isotropic based on the orientation of the last composite ply 632 being orthogonal to primary side 630. In another further example, the under-core composite plies 639 of each pair 670 in the stack of under-core composite plies 604 are oriented to have quasi-isotropy based on the orientation of the last composite ply 632 being orthogonal to the primary side 630.

[0027] In yet another example of the method 1100, the first composite ply 636 in the stack of over-core composite plies 610 is closest to the honeycomb core 606 and is oriented orthogonal to the primary side 630. In a further example, the over-core composite plies 640 of each four-ply 638 in the stack of over-core composite plies 610 are oriented quasi-isotropically based on the orientation of the first composite ply 636 being orthogonal to the primary side 630. In a further example, the over-core composite plies 640 of each two-ply 671 in the stack of over-core composite plies 610 are oriented quasi-isotropically based on the orientation of the first composite ply 636 being orthogonal to the primary side 630.

[0028] In another example of the method 1100, laying up 502 the first set of unidirectional tows 602 includes laying up 1202 (see FIG. 12 ) a first under-core composite ply 642 of a first set of four 644 under-core composite plies 639 on the tool 100 at an approximately 45 degree orientation relative to the primary side 630 of the honeycomb core 606 to minimize overlap with the roughened surface 102. At 1204, a second under-core composite ply 646 of the first set of four 644 under-core composite plies 639 is laid up on the first under-core composite ply 642 at an approximately 0 degree orientation relative to the primary side 630 of the honeycomb core 606 to generally align with the roughened surface 102. At 1206, a third under-core composite ply 648 of the first set of four 644 under-core composite plies 639 is laid up on the second under-core composite ply 646 at an approximately −45 degree orientation relative to the primary side 630 of the honeycomb core 606 to minimize overlap with the roughened surface 102. At 1208, a fourth under-core composite ply 650 of the first set of four 658 over-core composite plies 640 is laid up on the third under-core composite ply 648 at an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 to overlap with the roughened surface 102.

[0029] In a further example, laying up 502 the first group of unidirectional tows 602 further includes laying up 1302 (see FIG. 13 ) a second set of four 652 before laying up 1202, 1204, 1206, 1208 of the first set of four 644, such that the under-core composite ply 639 of the second set of four 652 is disposed below the first set of four 644. The second set of four 652 is laid up in a similar (e.g., the same) manner as the first set of four 644, except that the fourth under-core composite ply 650 in the second set of four 652 has less overlap with the rough surface 102 compared to the fourth under-core composite ply 650 in the first set of four 644.

[0030] In a further example, laying up 502 the first group of unidirectional tows 602 further includes laying up 1402 (see FIG. 14 ) a third set of four 654 before laying up 1302 the second set of four 652 such that the under-core composite ply 639 of the third set of four 654 is disposed below the second set of four 652. The third set of four 654 is laid up in a similar (e.g., the same) manner as the second set of four 652, except that the fourth under-core composite ply 650 in the third set of four 654 has less overlap with the rough surface 102 compared to the fourth under-core composite ply 650 in the second set of four 652.

[0031] In yet another example of the method 1100, laying up 502 the first group of unidirectional tows 602 includes laying up 3202 (see FIG. 32 ) a first under-core composite ply 672 of a first set of two under-core composite plies 639 on the tool 100 at an approximately 0 degree orientation relative to the primary side 630 of the honeycomb core 606 to minimize overlap with the rough surface 102. At 3204, a second under-core composite ply 676 of the first set of two under-core composite plies 639 is laid up on the first under-core composite ply 672 at an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 to overlap the rough surface 102.

[0032] In a further example, laying up 502 the first group of unidirectional tows 602 further includes laying up 3206 a second duplex 678 before laying up 3202 and 3204 of the first duplex 674, such that the under-core composite ply 639 of the second duplex 678 is disposed below the first duplex 674. The second duplex 678 is laid up in a similar (e.g., the same) manner as the first duplex 674, except that the second under-core composite ply 676 in the second duplex 678 has less overlap with the rough surface 102 compared to the second under-core composite ply 676 in the first duplex 674.

[0033] In a further example, laying up 502 the first group of unidirectional tows 602 further includes laying up 3208 a third duplex 680 prior to laying up 3206 of the second duplex 678 such that the under-core composite ply 639 of the third duplex 680 is disposed below the second duplex 678. The third duplex 680 is laid up in a similar (e.g., the same) manner as the second duplex 678, except that the second under-core composite ply 676 in the third duplex 680 has less overlap with the rough surface 102 compared to the second under-core composite ply 676 in the second duplex 678.

[0034] In yet another example of the method 1100, laying up 506 the second group of unidirectional tows 608 includes laying up 1502 (see FIG. 15 ) a first core-over-core composite ply 656 of the first set of four core-over-core composite plies 640 over the honeycomb core 606 and the first group of unidirectional tows 602 in an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap at least the first portion 114 of the rough surface 102. At 1504, a second core-over-core composite ply 660 of the first set of four 658 over-core composite plies 640 is laid up on the first core-over-core composite ply 656 at an orientation of approximately −45 degrees relative to the primary side 630 of the honeycomb core 606 so as to generally overlap at least a portion of the first core-over-core composite ply 656 and at least a second portion 116 of the roughened surface 102. At 1506, a third core-over-core composite ply 662 of the first set of four 658 over-core composite plies 640 is laid up on the second core-over-core composite ply 660 at an orientation of approximately 0 degrees relative to the primary side 630 of the honeycomb core 606 so as to generally overlap the first core-over-core composite ply 656 and at least a portion of the second core-over-core composite ply 660. At 1508, the fourth core-over-core composite ply 664 of the first set of four core-over-core composite plies 640 658 is laid up on the third core-over-core composite ply 662 at an approximately 45 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap the second core-over-core composite ply 660 and at least a portion of the third core-over-core composite ply 662.

[0035] In a further example, laying up 506 the second group of unidirectional tows 608 further includes laying up 1602 (see FIG. 16 ) a second set of four 666 over-the-core composite plies 640 on the first set of four 658. The second set of four 666 is laid up in a similar (e.g., the same) manner as the first set of four 658. In a further example, laying up 506 the second group of unidirectional tows 608 further includes laying up 1702 (see FIG. 17 ) a third set of four 668 over-the-core composite plies 640 on the second set of four 666. The third set of four 668 is laid up in a similar (e.g., the same) manner as the second set of four 666.

[0036] In yet another example of the method 1100, laying up 506 the second group of unidirectional tows 608 includes laying up 3302 (see FIG. 33 ) a first core-over-core composite ply 682 of the first pair of core-over-core composite plies 640 over the honeycomb core 606 and the first group of unidirectional tows 602 in an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap the honeycomb core 606 and at least the first portion 114 of the rough surface 102. At 3304, a second core-over-core composite ply 684 of the first duo 686 of over-core composite plies 640 is laid up on the first core-over-core composite ply 682 at an approximately 0 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap at least a portion of the first core-over-core composite ply 682 and at least the second portion 116 of the rough surface 102. In a further example, laying up 506 the second group of unidirectional tows 608 further includes laying up 3306 a second duo 688 of over-core composite plies 640 on the first duo 686 of over-core composite plies 640. The second duo 688 is laid up in a similar (e.g., the same) manner as the first duo 686. In a further example, laying up 506 the second group of unidirectional tows 608 further includes laying up 3308 a third set of two 690 over-the-core composite plies 640 on the second set of two 688 over-the-core composite plies 640. The third set of two 690 is laid up in a similar (e.g., the same) manner as the second set of two 688.

[0037] 1, 5, 6, 11, 18, and 21, in one or more examples, a method 1800 (see FIG. 18) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. In the method 1800, the three-dimensional volume 622 of the honeycomb core 606 includes at least four sides 626 that are chamfered from the top surface 624 to the bottom surface 620. The method 1800 includes analyzing 1802 the honeycomb core 606 to determine a risk of collapse of the at least four sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 1804, it is determined that the at least four sides 626 include two pairs of opposed sides 626, with the first pair having a steeper chamfer angle than the second pair. At 1806, a first pair of the at least four sides 626 is selected as the pair that is at higher risk of collapse than the second pair. At 1808, a primary side 630 is selected from the first pair as the side at highest risk of collapse of the at least four sides 626, with the opposite side not being selected. Method 1800 continues from 1808 to 502 shown in FIG. 5.

[0038] 1, 5, 6, 11, 19, and 21, in one or more examples, a method 1900 (see FIG. 19) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. In the method 1900, the three-dimensional volume 622 of the honeycomb core 606 includes at least six sides 626 that are chamfered from the top surface 624 to the bottom surface 620. The method 1900 includes analyzing 1902 the honeycomb core 606 to determine a risk of collapse of the at least six sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 1904, it is determined that the at least six sides 626 include three pairs of opposing sides 626, with a first pair being longer than the second and third pairs. At 1906, a first pair of the at least six sides 626 is selected as the pair that is at higher risk of collapse than the second and third pairs. At 1908, a primary side 630 is selected from the first pair as the side at highest risk of collapse of the at least six sides 626, with the opposite side not being selected. Method 1900 continues from 1908 to 502 shown in FIG. 5.

[0039] 1, 5, 6, 20, and 21, in one or more examples, a method 2000 (see FIG. 20) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. In the method 2000, the three-dimensional body 622 of the honeycomb core 606 includes at least eight sides 626 that are chamfered from the top surface 624 to the bottom surface 620. The method 2000 includes analyzing 2002 the honeycomb core 606 to determine a risk of collapse of the at least eight sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. At 2004, it is determined that the at least eight sides 626 include four pairs of opposing sides 626, where the first pair has a steeper chamfer angle than the second, third, and fourth pairs and the first pair is longer than the second, third, and fourth pairs. At 2006, a first pair of the at least eight sides 626 is selected as a pair that is at a higher risk of collapse than the second, third, and fourth pairs. At 2008, a primary side 630 is selected from the first pair as the side at the highest risk of collapse of the at least eight sides 626, and the opposite side is not selected. Method 2000 continues from 2008 to 502 shown in FIG. 5.

[0040] 1, 5, 6, 21, and 34, in one or more examples, a method 3400 (see FIG. 34) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. In method 3400, a honeycomb core 606 includes a three-dimensional body 622 having a top surface 624, a bottom surface 620, and one or more non-linear sides 626 that are chamfered from the top surface 624 to the bottom surface 620. Method 3400 includes analyzing 3402 the honeycomb core 606 to determine a risk of collapse of the one or more non-linear sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 3404, a primary reference point 692 is selected along the one or more non-linear sides 626 based on the highest collapse risk. The method 3400 continues from 3404 to 502 shown in FIG.

[0041] Referring again to steps 1, 5, 6, 21, and 31, in one or more examples, a method 3100 (see FIG. 31) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 500 shown in FIG. 5. The method 3100 continues from step 506 to step 3102 shown in FIG. 5, in which the stack of under-core composite plies 604, honeycomb core 606, and over-core composite plies 610 are sealed to the tool 100 with a compression bag 112. At step 3104, a vacuum is applied to the tool 100. At step 3106, the composite honeycomb core sandwich structure 2100 is cured in an autoclave. At step 3108, the vacuum is released. At step 3110, the compression bag 112 is unsealed. At step 3112, the compression bag 112 is removed from the composite honeycomb core sandwich structure 2100. At 3114, excess portions of the under-core composite ply 604 lamination and the above-core composite ply 610 lamination are cut along the trim line of the composite honeycomb core sandwich structure 2100. At 3116, the composite honeycomb core sandwich structure 2100 is removed from the tool 100. Alternatively, at 3118, the composite honeycomb core sandwich structure 2100 may be removed from the tool 100. Thereafter, at 3120, excess portions of the under-core composite ply 604 lamination and the above-core composite ply 610 lamination are cut along the trim line of the composite honeycomb core sandwich structure 2100.

[0042] 1, 4, 6, and 21, for example, the present disclosure relates to a composite honeycomb core sandwich structure 2100. FIG. 1 is a top view of an example tool 100 for laying up 600 of the composite honeycomb core sandwich structure 2100. FIG. 4 shows an example layup 600 of a stack of under-core composite plies 604 placed on the tool 100 of FIG. 1. FIG. 6 is an exploded view of an example layup 600 of the composite honeycomb core sandwich structure 2100 placed on the tool 100 of FIG. 1. FIG. 21 shows an example composite honeycomb core sandwich structure 2100.

[0043] 1, 4, 6, and 21, in one or more examples, a composite honeycomb core sandwich structure 2100 (see FIG. 21) includes a stack of under-core composite plies 604, a honeycomb core 606, and a stack of over-core composite plies 610. The stack of under-core composite plies 604 is laid up on the tool 100 by laying up a first set of unidirectional tows 602 using an automated fiber placement process. The honeycomb core 606 is placed on the stack of under-core composite plies 604. The stack of over-core composite plies 610 is laid up on the honeycomb core 606 by laying up a second set of unidirectional tows 608 using an automated fiber placement process.

[0044] In another example of the composite honeycomb core sandwich structure 2100, each unidirectional tow 614 includes unidirectional reinforcing fibers impregnated with a polymer resin to form the composite unidirectional tape 402. In another example, the unidirectional reinforcing fibers include carbon fiber, glass fiber, polyaramid fiber, acrylic fiber, viscose rayon fiber, or other suitable reinforcing fibers in any suitable combination. In yet another example of the composite honeycomb core sandwich structure 2100, the lamination orientation of the under-core composite ply 604 is quasi-isotropic. In yet another example of the composite honeycomb core sandwich structure 2100, the lamination orientation of the over-core composite ply 610 is quasi-isotropic. In another example of the composite honeycomb core sandwich structure 2100, the lamination orientation of the over-core composite ply 610 is symmetrical relative to the lamination orientation of the under-core composite ply 604 relative to the honeycomb core 606.

[0045] In yet another example, the composite honeycomb core sandwich structure 2100 further includes a composite fabric sheet 616 below the stack of under-core composite plies 604. In a further example, the composite fabric sheet 616 is impregnated with a polymer resin and includes fiberglass sheets, carbon fiber sheets, polyaramid sheets, or other suitable composite fabric sheets in any suitable combination. In yet another example, the composite honeycomb core sandwich structure 2100 further includes an under-core film adhesive 618 between the stack of under-core composite plies 604 and the honeycomb core 606. In a further example, the under-core film adhesive 618 includes an epoxy film adhesive, a polyurethane film adhesive, a polyimide film adhesive, or other suitable adhesives in any suitable combination.

[0046] In yet another example of the composite honeycomb core sandwich structure 2100, the honeycomb core 606 includes a plurality of segments 2102. In a further example, the plurality of segments 2102 of the honeycomb core 606 includes a forward segment 2104, a center segment 2106, and an aft segment 2108. In a further example of the composite honeycomb core sandwich structure 2100, the honeycomb core 606 includes a non-metallic material, a flame-retardant meta-aramid material, an aramid paper material, a fiberglass material, a metal material, an aluminum material, or other suitable material in any suitable combination. In yet another example, the composite honeycomb core sandwich structure 2100 further includes an over-core film adhesive 628 between the honeycomb core 606 and the stack of over-core composite plies 610. In a further example, the over-core film adhesive 628 includes an epoxy film adhesive, a polyurethane film adhesive, a polyimide film adhesive, or other suitable adhesive in any suitable combination.

[0047] In yet another example of the composite honeycomb core sandwich structure 2100, the honeycomb core 606 includes a three-dimensional body 622 having a top surface 624, a bottom surface 620, and at least three sides 626 that are chamfered from the top surface 624 to the bottom surface 620. In this example, during manufacturing of the composite honeycomb core sandwich structure 2100, a primary side 630 of the at least three sides 626 is deemed to be at greatest risk of collapse during autoclave curing. In a further example, the primary side 630 is selected based at least in part on the primary side 630 having the steepest chamfer of the at least three sides 626. In yet another example, the primary side 630 is selected based at least in part on the primary side 630 being the longest side of the at least three sides 626.

[0048] In yet another example, the last composite ply 632 in the stack of under-core composite plies 604 is closest to the honeycomb core 606 and is oriented orthogonal to the primary side 630. In a further example, the under-core composite ply 639 of each set of four 634 in the stack of under-core composite plies 604 is oriented quasi-isotropically based on the orientation of the last composite ply 632 being orthogonal to the primary side 630. In yet another example, the first composite ply 636 in the stack of over-core composite plies 610 is closest to the honeycomb core 606 and is oriented orthogonal to the primary side 630. In a further example, the over-core composite ply 640 of each set of four 638 in the stack of over-core composite plies 610 is oriented quasi-isotropically based on the orientation of the first composite ply 636 being orthogonal to the primary side 630.

[0049] With reference to Figures 1, 6, 21, and 24-30, for example, the present disclosure relates to methods 2400, 2500, 3000 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100. Figure 1 is a top view of an example of a tool 100 for the layup 600 of the composite honeycomb core sandwich structure 2100. Figure 6 is an exploded view of an example of the layup 600 of the composite honeycomb core sandwich structure 2100 positioned on the tool 100 of Figure 1. Figure 21 illustrates an example of the composite honeycomb core sandwich structure 2100. Figure 24 illustrates an example of a method 2400 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100. Figure 25, in combination with Figure 24, illustrates an example of a method 2500 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100. Figure 26 shows an example of laying up 2402 the first group of unidirectional tows 602 of Figure 24. Figure 27, in combination with Figure 26, shows another example of laying up 2402 the first group of unidirectional tows 602 of Figure 24. Figure 28, in combination with Figures 26 and 27, shows yet another example of laying up 2402 the first group of unidirectional tows 602 of Figure 24. Figures 29A-29B show an example of laying up 2410 the second group of unidirectional tows 608 of Figure 24. Figure 30, in combination with Figure 24, shows an example of a method 3000 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100.

[0050] 1, 6, 21, and 24, in one or more examples, a method 2400 (see FIG. 24) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes laying up 2402 a first set of unidirectional tows 602 on a tool 100 for the layup 600 of the composite honeycomb core sandwich structure 2100 using an automated fiber placement process to form a stack of under-core composite plies 604 secured to rough surfaces 102 bonded to the tool 100. At 2404, an under-core film adhesive 618 is placed on the stack of under-core composite plies 604 within a trim line 612 of the composite honeycomb core sandwich structure 2100. At 2406, a honeycomb core 606 is placed on the under-core film adhesive 618 within the trim line 612. At 2408, an over-core film adhesive 628 is placed on the honeycomb core 606 within the trim line 612. At 2410, an automated fiber placement process is used to lay up the second set of unidirectional tows 608 on the over-core film adhesive 628 and the roughened surface 102, thereby forming a stack of over-core composite plies 610 that secures the honeycomb core 606 to the roughened surface 102. In another example, the method 2400 further includes placing 2412 a composite fabric sheet 616 on the roughened surface 102.

[0051] 1, 6, 21, and 24-29, in one or more examples, a method 2500 (see FIG. 25) for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 includes the method 2400 shown in FIG. 24. In method 2500, a honeycomb core 606 includes a three-dimensional body 622 having a top surface 624, a bottom surface 620, and at least three sides 626 that are chamfered from the top surface 624 to the bottom surface 620. Method 2500 includes analyzing 2502 the honeycomb core 606 to determine a risk of collapse of the at least three sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 2504, a primary side 630 of the at least three sides 626 that has the highest risk of collapse is selected.

[0052] In another example of the method 2500, laying up 2402 the first set of unidirectional tows 602 includes laying up 2602 (see FIG. 26 ) a first under-core composite ply 642 of a first set of four 644 under-core composite plies 639 on the tool 100 at an orientation of approximately 45 degrees relative to the primary side 630 of the honeycomb core 606 to minimize overlap with the rough surface 102. At 2604, a second under-core composite ply 646 of the first set of four 644 under-core composite plies 639 is laid up on the first under-core composite ply 642 at an orientation of approximately 0 degrees relative to the primary side 630 of the honeycomb core 606 to generally align with the rough surface 102. At 2606, a third under-core composite ply 648 of the first set of four 644 under-core composite plies 639 is laid up on the second under-core composite ply 646 at an approximately −45 degree orientation relative to the primary side 630 of the honeycomb core 606 to minimize overlap with the roughened surface 102. At 2608, a fourth under-core composite ply 650 of the first set of four 644 over-core composite plies 640 is laid up on the third under-core composite ply 648 at an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 to overlap with the roughened surface 102.

[0053] In a further example, laying up 2402 the first group of unidirectional tows 602 further includes laying up 2702 (see FIG. 27 ) a second set of four 652 before laying up 2602, 2604, 2606, 2608 of the first set of four 644, such that the under-core composite ply 639 of the second set of four 652 is disposed below the first set of four 644. The second set of four 652 is laid up in a similar (e.g., the same) manner as the first set of four 644, except that the fourth under-core composite ply 650 in the second set of four 652 has less overlap with the rough surface 102 compared to the fourth under-core composite ply 650 in the first set of four 644.

[0054] In a further example, laying up 2402 the first group of unidirectional tows 602 further includes laying up 2802 (see FIG. 28 ) the under-core composite plies 639 of the third set of four 654 before laying up 2702 the second set of four 652, such that the under-core composite plies 639 of the third set of four 654 are disposed below the second set of four 652. The third set of four 654 is laid up in a similar (e.g., the same) manner as the second set of four 652, except that the fourth under-core composite ply 650 in the third set of four 654 has less overlap with the rough surface 102 compared to the fourth under-core composite ply 650 in the second set of four 652.

[0055] In yet another example of method 2500, laying up 2410 the second group of unidirectional tows 608 includes laying up 2902 (see Figures 29A-29B) a first core-over-core composite ply 656 of the first set of four core-over-core composite plies 640 over the core-over-film adhesive 628 and the first group of unidirectional tows 602 in an approximately 90 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap at least a first portion of the honeycomb core 606 and the rough surface 102. At 2904, a second core-over-core composite ply 660 of the first set of four 658 over-core composite plies 640 is laid up on the first core-over-core composite ply 656 at an approximately -45 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap at least a portion of the first core-over-core composite ply 656 and at least a second portion 116 of the rough surface 102. At 2906, a third core-over-core composite ply 662 of the first set of four 658 over-core composite plies 640 is laid up on the second core-over-core composite ply 660 at an approximately 0 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap the first core-over-core composite ply 656 and at least a portion of the second core-over-core composite ply 660. At 2908, a fourth core-over-core composite ply 664 of a first set of four 658 over-core composite plies 640 is laid up on the third core-over-core composite ply 662 at an approximately 45 degree orientation relative to the primary side 630 of the honeycomb core 606 so as to generally overlap the second core-over-core composite ply 660 and at least a portion of the third core-over-core composite ply 662. At 2910, a second set of four 666 over-core composite plies 640 are laid up on the first set of four 658 over-core composite plies 640. The second set of four 666 is laid up in a similar (e.g., the same) manner as the first set of four 658. At 2912, a third set of four 668 over-core composite plies 640 are laid up on the second set of four 666 over-core composite plies 640. The third set of four 668 is laid up in a similar (eg, the same) manner as the second set of four 666 .

[0056] 1, 6, 21, 24, and 30, in one or more examples, a method 3000 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 (see FIG. 30) includes the method 2400 shown in FIG. 24. In method 3000, a three-dimensional volume 622 of a honeycomb core 606 includes at least four sides 626 that are chamfered from a top surface 624 to a bottom surface 620. Method 3000 includes analyzing 3002 the honeycomb core 606 to determine a risk of collapse of the at least four sides 626 during autoclave curing of the composite honeycomb core sandwich structure 2100. In 3004, it is determined that the at least four sides 626 include two pairs of opposed sides 626, the first pair having a steeper chamfer angle than the second pair. At 3006, a first pair of the at least four sides 626 is selected as the pair that is at higher risk of collapse than the second pair. At 3008, a primary side 630 is selected from the first pair as the side at highest risk of collapse of the at least four sides 626, with the opposite side not being selected.

[0057] The methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, and 3400 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100 and the composite honeycomb core sandwich structure 2100 may be related to or used in the field of aircraft design and manufacturing. Also, while examples are described in terms of aircraft applications, the examples and principles of the present disclosure may be applied to other products in the aerospace industry and in other industries, such as the automotive, space, construction, and design and manufacturing industries. Thus, the examples and principles of the present disclosure may be applied to methods for designing and manufacturing various vehicles and the design and construction of various transportation structures, in addition to aircraft.

[0058] The above detailed description refers to the accompanying drawings, which illustrate specific examples described in the present disclosure. It should be noted that other examples having different structures or operations do not depart from the scope of the present disclosure. The same reference numerals in different drawings indicate the same feature, element, or component. Throughout this disclosure, any one of multiple elements may be individually referred to as "the element," or multiple elements may be collectively referred to as "the elements," and may be designated by the same reference numeral. Furthermore, in this specification, the term "a" or "an" preceding a feature, element, component, or step does not exclude multiple features, elements, components, or steps, unless otherwise specified.

[0059] Illustrative, non-exhaustive examples of the subject matter disclosed herein have been provided above, and these examples may include those that are or are not recited in the claims. As used herein, the term "example" means that one or more features, structures, elements, components, or characteristics described in connection with that example are included in at least one aspect, embodiment, and / or implementation of the subject matter disclosed herein. Thus, in this disclosure, terms such as "one example," "another example," "one or more examples," and similar terms may, but do not necessarily, refer to the same example. Furthermore, features characterizing one example may, but do not necessarily, include features characterizing other examples. Furthermore, features characterizing one example may, but do not necessarily, be combined with features characterizing other examples.

[0060] As used herein, a system, apparatus, control system, device, computing unit, processor, structure, article, element, component, or hardware that is "configured" to perform a particular function refers to one that can perform that particular function without any modification, and not one that could perform that particular function if modified in some way. In other words, a system, apparatus, device, control system, computing unit, processor, structure, article, element, component, or hardware that is "configured" to perform a particular function refers to one that is specifically selected, made, implemented, utilized, programmed, and / or designed to perform that particular function. As used herein, "configured" refers to properties that a system, apparatus, control system, device, computing unit, processor, structure, article, element, component, or hardware already possesses that enable the system, apparatus, control system, device, computing unit, processor, structure, article, element, component, or hardware to perform that particular function without any modification. In this disclosure, a system, apparatus, device, control system, device, computing unit, processor, structure, article, element, component, or hardware described as being "configured" to perform a particular function may additionally or instead be described as being "adapted" and / or "operable" to perform that function.

[0061] Unless otherwise specified, the terms "first," "second," "third," etc. are used merely as labels and do not impose any order, position, or hierarchy requirements on the elements to which these terms refer. Furthermore, a reference to, for example, a "second" element does not require or exclude the presence of, for example, a "first" element or a lower ordinal element, and / or a "third" or higher ordinal element.

[0062] As used herein, when the phrase "at least one" is used in connection with a list of elements, it means that one or more of the listed elements may be used in various combinations, or that only one of the listed elements may be required. For example, "at least one of element A, element B, and element C" may include, but is not limited to, element A, or element A and element B. Also in this example, it may include elements A, element B, and element C, or element B and element C. In other examples, "at least one" may mean, but is not limited to, two elements A, one element B, and ten elements C, or four elements B and seven elements C, or any other suitable combination. As used herein, the phrase "and / or" and the symbol " / " include any and all combinations of one or more of the associated listed elements.

[0063] As used herein, the terms "coupled," "coupled," and similar terms refer to two or more elements being joined, coupled, fixed, attached, connected, in communication with, or otherwise associated with one another (e.g., mechanically, electrically, fluidly, optically, electromagnetically). In various examples, multiple elements may be directly or indirectly associated. For example, element A may be directly associated with element B. Element A may also be indirectly associated with element B, for example, via another element C. Note that not all associations between various disclosed elements are necessarily shown. Thus, other couplings than those shown may exist.

[0064] As used herein, the term "about" refers to a condition that is not exactly the same as the described condition, but is close to the described condition and is capable of performing a desired function or achieving a desired result. For example, the term "about" refers to a condition that is within an acceptable range of a predetermined tolerance or precision, for example, a condition that is within 10% of the described condition. However, the term "about" does not exclude a condition that is exactly the same as the described condition. As used herein, the term "substantially" refers to a condition that is essentially the same as the described condition and is capable of performing a desired function or achieving a desired result.

[0065] In Figures 5, 7-20, 24-28, 29A-B, 30, and 31 referenced in the above description, blocks may represent processes, steps, and / or portions thereof, and lines connecting various blocks do not imply a particular order or dependency relationship of the processes or portions thereof. It should be noted that not all dependencies between the various processes disclosed are necessarily shown. Figures 5, 7-20, 24-28, 29A-B, 30, and 31, and the accompanying disclosure describing the processes in the methods described herein, do not necessarily dictate the order in which those processes are performed. Rather, an exemplary order is shown, but the order of those processes can be changed as appropriate. Therefore, modifications, additions, and / or omissions can be made to the illustrated processes, and some processes can be performed in a different order or simultaneously. Additionally, one skilled in the art will recognize that not all of the steps described need to be performed.

[0066] The figures referenced in the foregoing description depict functional elements, features, or components and do not necessarily imply a particular, specific structure. Accordingly, modifications, additions, and / or omissions may be made to the depicted structures. Additionally, those skilled in the art will recognize that not all elements, features, and / or components shown and described in figures 1-4, 6, and 21-23 need be included in every example, and not all described elements, features, and / or components may be shown in each illustrated example. Accordingly, some of the elements, features, and / or components shown and described in figures 1-4, 6, and 21-23 may be combined in various ways without including other features shown in figures 1-4, 6, and 21-23, other figures, and / or the accompanying disclosure, without such combinations necessarily being expressly stated in this disclosure. Similarly, additional features not limited to the described examples may be combined with some or all of the features shown and described herein. Unless otherwise noted, the schematic diagrams of the above-described embodiments shown in Figures 1-4, 6, and 21-23 are not intended to imply any architectural limitations on the example embodiments. Rather, they illustrate one example structure, which may be varied as appropriate. Accordingly, modifications, additions, and / or omissions may be made to the illustrated structure. Furthermore, elements, features, and / or components serving similar, or at least substantially similar, purposes in Figures 1-4, 6, and 21-23 are labeled with the same reference numerals, and such elements, features, and / or components may not be described in detail with reference to Figures 1-4, 6, and 21-23. Similarly, not all elements, features, and / or components are labeled with reference numerals in Figures 1-4, 6, and 21-23, although the reference numerals associated with these elements may be used in the description for consistency.

[0067] Furthermore, the use of features, advantages, or similar expressions in this specification does not imply that all features and advantages that can be realized in embodiments of the present disclosure should or are included in a single example. Rather, the description of features and advantages means that a particular feature, advantage, or characteristic described in connection with an example is included in at least one example. Thus, features, advantages, and similar expressions described in this disclosure may or may not refer to the same example.

[0068] Embodiments of the disclosed subject matter may be described in relation to an aircraft manufacturing and service method 3500 shown in FIG. 35 and an aircraft 3600 shown in FIG. 36. In one or more examples, the disclosed methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, 3400 for manufacturing a layup 600 of a composite honeycomb core sandwich structure 2100 and the composite honeycomb core sandwich structure 2100 may be used in the manufacture of an aircraft. During pre-production, the service method 3500 may include specification and design of the aircraft 3600 (block 3502) and material procurement (block 3504). During production, components and subassemblies of the aircraft 3600 are manufactured (block 3506), and systems integration (block 3508) occurs. The aircraft 3600 then undergoes certification and delivery (block 3210) and enters service (block 3212). While in service with the customer, the aircraft 3600 undergoes routine maintenance and maintenance (block 3214). Routine maintenance and maintenance may include upgrading, reconfiguring, modifying, etc., one or more systems of the aircraft 3600.

[0069] Each step of maintenance method 3500 may be performed or implemented by a system integrator, a third party, and / or an operator (e.g., a customer). Note that a system integrator may include, but is not limited to, an aircraft manufacturer and any number of major system subcontractors. A third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers. An operator may be an airline, a leasing company, a military entity, a service organization, etc.

[0070] As shown in FIG. 36 , aircraft 3600 produced by maintenance method 3500 may include an airframe 3602 with multiple high-level systems 3604 and an interior 3606. Examples of high-level systems 3604 include one or more of a propulsion system 3608, an electrical system 3510, a hydraulic system 3512, and an environmental system 3514. The aircraft may also include any number of other systems. Additionally, while described with reference to the aerospace industry, the principles of the present disclosure may be applied to other industries, such as the automotive industry. Thus, in addition to aircraft 3600, the principles of the present disclosure may be applied to other vehicles, such as land vehicles, sea vehicles, and spacecraft.

[0071] The disclosed methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, 3400 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100, and the composite honeycomb core sandwich structure 2100, may be employed at any one or more stages in the manufacturing and service method 3500. For example, the components or subassemblies corresponding to component and subassembly manufacturing (block 3506) may be manufactured or produced similarly to the components or subassemblies produced while the aircraft 3600 is in service (block 3212). Additionally, one or more embodiments of the above-described toolset, system, method, or combination thereof may be utilized, for example, in the manufacturing process (blocks 3506 and 3508), to substantially increase the speed or reduce the cost of assembly of the aircraft 3600. Similarly, one or more embodiments implementing the above-described toolsets, systems, or methods, or combinations thereof, may be used, for example, but not limited to, during the in-service (block 3212) and maintenance and maintenance (block 3214) processes of the aircraft 3600.

[0072] The features, advantages, and characteristics of any described embodiment may be combined in any suitable manner in one or more other embodiments. Those skilled in the art will appreciate that the embodiments described herein may be practiced without one or more of the specific features or advantages of a particular embodiment. In some cases, additional features and advantages may be recognized in certain embodiments, but these may not be present in all embodiments. Furthermore, while various embodiments of the disclosed methods 500, 1100, 1800, 1900, 2000, 2400, 2500, 3000, 3100, and 3400 for manufacturing the layup 600 of the composite honeycomb core sandwich structure 2100 and the composite honeycomb core sandwich structure 2100 have been shown and described, modifications will occur to those skilled in the art upon reading this specification. The present application encompasses all such modifications and is limited only by the scope of the claims.

[0073] The present disclosure further includes the following notes:

[0074] Appendix 1. A method (500) for manufacturing a layup (600) of a composite honeycomb core sandwich structure (2100), comprising: laying up (502) a first set of unidirectional tows (602) on a tool (100) for laying up (600) the composite honeycomb core sandwich structure (2100) using an automated fiber placement process to form a stack of under-core composite plies (604) secured to the roughened surface (102) bonded to the tool (100); placing (504) a honeycomb core (606) on the stack of under-core composite plies (604) within the roughened surface (102); laying up a second set of unidirectional tows (608) on the honeycomb core (606) using the automated fiber placement process, thereby forming a stack of composite plies over the core (610) that secures the honeycomb core (606) to the roughened surface (102).

[0075] Appendix 2. The method of Appendix 1, wherein the first set of unidirectional tows (602) extends beyond a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0076] Clause 3. The method of clause 1, wherein each unidirectional tow (614) comprises unidirectional reinforcing fibers impregnated with a polymer resin to form a composite unidirectional tape (402).

[0077] Appendix 4. The method of Appendix 3, wherein the unidirectional reinforcing fibers include at least one of carbon fibers, glass fibers, polyaramid fibers, acrylic fibers, and viscose rayon fibers.

[0078] Appendix 5. The method of Appendix 1, wherein the orientation of the under-core composite ply (604) stack is quasi-isotropic.

[0079] Appendix 6. The method of Appendix 1, wherein the roughened surface (102) is disposed on the tool (100) and surrounds a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0080] Clause 7. The method of clause 1, wherein the roughened surface (102) comprises grit strips (110).

[0081] Appendix 8. The method of Appendix 1, wherein the honeycomb core (606) is positioned within a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0082] Appendix 9. The method of Appendix 1, wherein the second set of unidirectional tows (608) extends beyond a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0083] Clause 10. The method of clause 1, wherein the orientation of the laminate of the core-over-composite plies (610) is quasi-isotropic.

[0084] Appendix 11. The method of Appendix 1, wherein the stack orientation of the above-core composite ply (610) is symmetrical relative to the stack orientation of the below-core composite ply (604) relative to the honeycomb core (606).

[0085] Clause 12. The method of clause 1, further comprising disposing (508) a composite woven fabric sheet (616) on the roughened surface (102).

[0086] Clause 13. The method of clause 12, wherein the composite woven sheet (616) is impregnated with a polymer resin and comprises at least one of a glass fiber sheet, a carbon fiber sheet, and a polyaramid sheet.

[0087] Appendix 14. The method of Appendix 12, wherein the composite fabric sheet (616) is sized to cover the roughened surface (102) and surround the trim line (612) of the composite honeycomb core sandwich structure (2100).

[0088] Appendix 15. The method of Appendix 12, wherein the composite fabric sheet (616) is sized to cover the roughened surface (102) and to cover a portion (104) of the top surface (106) of the tool (100) surrounded by the roughened surface (102).

[0089] Appendix 16. The method of Appendix 12, wherein the composite fabric sheet (616) is sized to cover the roughened surface (102) and to cover a first portion (104) of the top surface (106) of the tool (100) that is surrounded by the roughened surface (102) and a second portion (108) of the top surface (106) of the tool (100) that is located outside the roughened surface (102).

[0090] Appendix 17. The composite fabric sheet (616) arrangement (508) is sealing (702) the composite fabric sheet (616) to the tool (100) using a compression bag (112); applying (704) a vacuum to the tool (100) for a predetermined time to press the composite fabric sheet (616) onto the roughened surface (102); releasing the vacuum (706); Unsealing (708) the compression bag (112); and removing (710) the compression bag (112) from the composite fabric sheet (616).

[0091] Appendix 18. The method of Appendix 1, further comprising placing (510) an under-core film adhesive (618) on the stack of under-core composite plies (604) within a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0092] Clause 19. The method of clause 18, wherein the under-core film adhesive (618) comprises at least one of an epoxy film adhesive, a polyurethane film adhesive, and a polyimide film adhesive.

[0093] Clause 20. The method of clause 18, wherein the under-core film adhesive (618) is sized to cover the bottom surface (620) of the honeycomb core (606).

[0094] Appendix 21. The arrangement (510) of the under-core film adhesive (618) is sealing (802) the under-core film adhesive (618) and the under-core composite ply (604) stack to the tool (100) using a compression bag (112); applying (804) a vacuum to the tool (100) for a predetermined time to press the under-core film adhesive (618) against the stack of under-core composite plies (604); releasing the vacuum (806); Unsealing (808) the compression bag (112); and removing (810) the compression bag (112) from the under-core film adhesive (618) and the stack of under-core composite plies (604).

[0095] Appendix 22. The method of Appendix 1, wherein the honeycomb core (606) comprises a three-dimensional body (622), the three-dimensional body comprising a top surface (624), a bottom surface (620), and at least three sides (626) chamfered from the top surface (624) to the bottom surface (620).

[0096] Supplementary Note 23: The honeycomb core (606) arrangement (504) is placing (902) the honeycomb core (606) within a trim line (612) of the composite honeycomb core sandwich structure (2100); sealing (904) the honeycomb core (606) and under-core composite ply (604) stack to the tool (100) using a compression bag (112); applying (906) a vacuum to the tool (100) for a predetermined time to press the honeycomb core (606) against the stack of under-core composite plies (604); releasing the vacuum (908); Unsealing (910) the compression bag (112); and removing (912) the compression bag (112) from the honeycomb core (606) and the stack of under-core composite plies (604).

[0097] Clause 24. The method of clause 23, wherein the honeycomb core (606) comprises a plurality of segments (2102).

[0098] Appendix 25. The method of Appendix 24, wherein the plurality of segments (2102) of the honeycomb core (606) include a front segment (2104), a center segment (2106), and a rear segment (2108).

[0099] Clause 26. The method of clause 23, wherein the honeycomb core (606) comprises at least one of a non-metallic material, a flame-retardant meta-aramid material, an aramid paper material, a fiberglass material, a metal material, and an aluminum material.

[0100] Clause 27. The method of clause 23, wherein the honeycomb core (606) is positioned using at least two tool pins.

[0101] Clause 28. The method of clause 1, further comprising placing (512) an on-core film adhesive (628) on the honeycomb core (606) within a trim line (612) of the composite honeycomb core sandwich structure (2100).

[0102] Clause 29. The method of clause 28, wherein the film adhesive on the core (628) comprises at least one of an epoxy film adhesive, a polyurethane film adhesive, and a polyimide film adhesive.

[0103] Clause 30. The method of clause 28, wherein the core-on-film adhesive (628) is sized to cover the top surface (624) and sides (626) of the honeycomb core (606).

[0104] Appendix 31. The arrangement (512) of the film adhesive (628) on the core is sealing (1002) the stack of over-core film adhesive (628), the honeycomb core (606), and the under-core composite ply (604) to the tool (100) using a compression bag (112); applying (1004) a vacuum to the tool (100) for a predetermined time to press the over-core film adhesive (628) against the under-core composite ply (604) stack; releasing the vacuum (1006); Unsealing (1008) the compression bag (112); and removing (1010) the compression bag (112) from the stack of the over-core film adhesive (628), the honeycomb core (606), and the under-core composite ply (604).

[0105] Appendix 32. The honeycomb core (606) includes a three-dimensional body (622), the three-dimensional body including a top surface (624), a bottom surface (620), and at least three sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (1102) the honeycomb core (606) to determine the risk of collapse of at least three sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); 11. The method (1100) of claim 1, further comprising: selecting (1102) a primary side (630) from the at least three sides (626) that is at greatest risk of collapsing.

[0106] Clause 33. The method of clause 32, wherein the primary side (630) is selected based at least in part on the primary side (630) having the steepest chamfer of the at least three sides (626).

[0107] Clause 34. The method of clause 32, wherein the primary side (630) is selected based at least in part on the primary side (630) being the longest side of the at least three sides (626).

[0108] Item 35. The method of item 32, wherein the last composite ply (632) in the stack of under-core composite plies (604) is closest to the honeycomb core (606) and is oriented perpendicular to the primary side (630).

[0109] Item 36. The method of item 35, wherein the under-core composite plies (639) of each set of four (634) in the stack of under-core composite plies (604) are oriented to be quasi-isotropic based on the orientation of the last composite ply (632) being orthogonal to the primary side (630).

[0110] Item 37. The method of item 35, wherein the under-core composite plies (639) of each pair (670) in the stack of under-core composite plies (604) are oriented to have quasi-isotropy based on the orientation of the last composite ply (632) being orthogonal to the primary side (630).

[0111] Item 38. The method of item 32, wherein a first composite ply (636) in the stack of over-core composite plies (610) is closest to the honeycomb core (606) and is oriented perpendicular to the primary side (630).

[0112] Item 39. The method of item 38, wherein each four-ply (638) of composite plies (640) over the core in the stack of composite plies (610) over the core is oriented quasi-isotropically based on the orientation of the first composite ply (636) being orthogonal to the primary side (630).

[0113] Item 40. The method of item 38, wherein the core-over-composite plies (640) of each pair (671) in the stack of core-over-composite plies (610) are oriented quasi-isotropically based on the orientation of the first composite ply (636) being orthogonal to the primary side (630).

[0114] Note 41. Laying up (502) the first group of unidirectional tows (602) comprises: laying up (1202) a first under-core composite ply (642) of a first set of four (644) under-core composite plies (639) on the tool (100) at an approximately 45 degree orientation relative to the primary side (630) of the honeycomb core (606) to minimize overlap with the roughened surface (102); laying up (1204) a second under-core composite ply (646) of the first set of four under-core composite plies (639) on the first under-core composite ply (642) at an orientation of approximately 0 degrees relative to the primary side (630) of the honeycomb core (606) so as to be generally aligned with the roughened surface (102); laying up (1206) a third under-core composite ply (648) of the first set of four under-core composite plies (639) on the second under-core composite ply (646) at an orientation of approximately -45 degrees relative to the primary side (630) of the honeycomb core (606) to minimize overlap with the roughened surface (102); and laying up (1208) a fourth under-core composite ply (650) of the first set of four under-core composite plies (639) on the third under-core composite ply (648) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to overlap the roughened surface (102).

[0115] Note 42. Laying up (502) the first group of unidirectional tows (602) comprises: 42. The method of claim 41, further comprising laying up (1302) a second set of four (652) prior to laying up (1202, 1204, 1206, 1208) the first set of four (644) such that a second set of four (652) of under-core composite plies (639) is positioned below the first set of four (644), the second set of four (652) being laid up in a manner similar to the first set of four (644), except that the fourth under-core composite ply (650) in the second set of four (652) has less overlap with the rough surface (102) compared to the fourth under-core composite ply (650) in the first set of four (644).

[0116] Addendum 43. Laying up (502) the first group of unidirectional tows (602) comprises: 43. The method of claim 42, further comprising laying up (1402) a third set of four (654) prior to laying up (1302) the second set of four (652) such that an under-core composite ply (639) of the third set of four (654) is positioned below the second set of four (652), the third set of four (654) being laid up in a manner similar to the second set of four (652), except that the fourth under-core composite ply (650) in the third set of four (654) has less overlap with the rough surface (102) than the fourth under-core composite ply (650) in the second set of four (652).

[0117] Note 44. Laying up (502) the first group of unidirectional tows (602) comprises: laying up (3202) a first under-core composite ply (672) of a first pair of under-core composite plies (639) on the tool (100) at an approximately 0 degree orientation relative to the primary side (630) of the honeycomb core (606) to minimize overlap with the roughened surface (102); and laying up (3204) a second under-core composite ply (676) of the first pair of under-core composite plies (639) on the first under-core composite ply (672) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to overlap the roughened surface (102).

[0118] Addendum 45. Laying up (502) the first group of unidirectional tows (602) comprises: 45. The method of claim 44, further comprising laying up (3206) a second duo (678) prior to laying up (3202, 3204) the first duo (674) such that an under-core composite ply (639) of the second duo (678) is positioned below the first duo (674), the second duo (678) being laid up in a manner similar to the first duo (674), except that the second under-core composite ply (676) in the second duo (678) has a smaller overlap with the rough surface (102) compared to the second under-core composite ply (676) in the first duo (674).

[0119] Addendum 46. Laying up (502) the first group of unidirectional tows (602) comprises: 46. ​​The method of claim 45, further comprising laying up (3208) a third set of two (680) prior to laying up (3206) the second set of two (678) such that an under-core composite ply (639) of the third set of two (680) is positioned below the second set of two (678), the third set of two (680) being laid up in a manner similar to the second set of two (678), except that the second under-core composite ply (676) in the third set of two (680) has less overlap with the rough surface (102) compared to the second under-core composite ply (676) in the second set of two (678).

[0120] Addendum 47. Laying up (506) the second group of unidirectional tows (608) comprises: laying up (1502) a first composite ply (656) of a first set of four composite plies (640) over the honeycomb core (606) and the first set of unidirectional tows (602) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the honeycomb core (606) and at least a first portion (114) of the roughened surface (102); laying up (1504) a second over-core composite ply (660) of the first set of four over-core composite plies (640) on the first over-core composite ply (656) at an orientation of approximately -45 degrees relative to the primary side (630) of the honeycomb core (606) so as to generally overlap at least a portion of the first over-core composite ply (656) and at least a second portion (116) of the roughened surface (102); laying up (1506) a third over-core composite ply (662) of the first set of four over-core composite plies (640) on the second over-core composite ply (660) at an orientation of approximately 0 degrees relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the first over-core composite ply (656) and at least a portion of the second over-core composite ply (660); and laying up (1508) a fourth core-over-core composite ply (664) of the first set of four core-over-core composite plies (640) on the third core-over-core composite ply (662) at an approximately 45-degree orientation relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the second core-over-core composite ply (660) and at least a portion of the third core-over-core composite ply (662).

[0121] 48. The method of claim 47, wherein laying up (506) the second group of unidirectional tows (608) further comprises laying up (1602) a second set of four (666) over-core composite plies (640) on the first set of four (658) over-core composite plies (640), wherein the second set of four (666) is laid up in a manner similar to the first set of four (658).

[0122] Clause 49. The method of clause 48, wherein laying up (506) the second group of unidirectional tows (608) further comprises laying up (1702) a third set of four (668) on top of the core composite plies (640) of the second set of four (666), wherein the third set of four (668) is laid up in a manner similar to the second set of four (666).

[0123] Note 50. Laying up (506) the second group of unidirectional tows (608) comprises: laying up (3302) a first composite ply (682) of a first pair of composite plies (640) over the honeycomb core (606) and the first set of unidirectional tows (602) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the honeycomb core (606) and at least a first portion (114) of the roughened surface (102); and laying up (3304) a second core-over-core composite ply (684) of the first pair of core-over-core composite plies (640) on the first core-over-core composite ply (682) at an orientation of approximately 0 degrees relative to the primary side (630) of the honeycomb core (606) so as to generally overlap at least a portion of the first core-over-core composite ply (682) and the second portion (116) of the roughened surface (102).

[0124] Addendum 51. The method of Addendum 50, wherein laying up (506) the second group of unidirectional tows (608) further comprises laying up (3306) a second set of two (688) of over-core composite plies (640) on the first set of two (686) of over-core composite plies (640), wherein the second set of two (688) is laid up in a manner similar to the first set of two (686).

[0125] Item 52. The method of item 51, wherein laying up (506) the second group of unidirectional tows (608) further comprises laying up (3308) a third set of two (690) of over-core composite plies (640) on the second set of two (688) of over-core composite plies (640), wherein the third set of two (690) is laid up in a manner similar to the second set of two (688).

[0126] Clause 53. The three-dimensional body (622) of the honeycomb core (606) includes at least four sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (1802) the honeycomb core (606) to determine the risk of collapse of at least four sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); determining (1804) that the at least four sides (626) include two pairs of opposed sides (626), a first pair having a steeper chamfer angle than a second pair; selecting (1806) the first pair of the at least four sides (626) as being at greater risk of collapse than the second pair; 33. The method (1800) of claim 32, further comprising: selecting (1808) the primary side (630) from the first pair as the side of the at least four sides (626) that is at greatest risk of collapse, and not selecting the side opposite it.

[0127] Clause 54. The three-dimensional body (622) of the honeycomb core (606) includes at least six sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (1902) the honeycomb core (606) to determine the risk of collapse of at least six sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); determining (1904) that the at least six sides (626) include three pairs of opposing sides (626), a first pair being longer than a second pair and a third pair; selecting (1906) the first pair of the at least six sides (626) as a pair that is at a higher risk of collapse than the second pair and the third pair; 33. The method (1900) of claim 32, further comprising: selecting (1908) the primary side (630) from a first pair as the side of the at least six sides (626) that is at greatest risk of collapse, and not selecting the side opposite it.

[0128] Clause 55. The three-dimensional body (622) of the honeycomb core (606) includes at least eight chamfered sides (626) from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (2002) the honeycomb core (606) to determine the risk of collapse of at least eight sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); determining (2004) that the at least eight sides (626) include four pairs of opposing sides (626), a first pair having a steeper chamfer angle than a second pair, a third pair, and a fourth pair, and the first pair being longer than the second pair, the third pair, and the fourth pair; selecting (2006) the first pair of the at least eight sides (626) as a pair that is at a higher risk of collapse than the second pair, the third pair, and the fourth pair; 33. The method (2000) of claim 32, further comprising: selecting (2008) the primary side (630) from the first pair as the side of the at least eight sides (626) that is at greatest risk of collapse, and not selecting the side opposite it.

[0129] Clause 56. The honeycomb core (606) includes a three-dimensional body (622), the three-dimensional body including a top surface (624), a bottom surface (620), and one or more non-linear sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (3402) the honeycomb core (606) to determine the risk of one or more non-linear sides (626) collapsing during autoclave curing of the composite honeycomb core sandwich structure (2100); 2. The method (3400) of claim 1, further comprising: selecting (3404) a primary reference point (692) along the one or more non-linear sides (626) based on the highest risk of collapse.

[0130] Clause 57. Using a compression bag (112), sealing (3102) the stack of the under-core composite ply (604), the honeycomb core (606), and the over-core composite ply (610) to the tool (100); applying (3104) a vacuum to the tool (100); curing (3106) the composite honeycomb core sandwich structure (2100) in an autoclave; releasing the vacuum (3108); Unsealing (3110) the compression bag (112); removing (3112) the compression bag (112) from the composite honeycomb core sandwich structure (2100); cutting (3114) excess portions of the under-core composite ply (604) stack and the over-core composite ply (610) stack along a trim line of the composite honeycomb core sandwich structure (2100); 2. The method (3100) of claim 1, further comprising: removing (3116) the composite honeycomb core sandwich structure (2100) from the tool (100).

[0131] Clause 58. A stack of under-core composite plies (604) laid up on a tool (100) by laying up a first set of unidirectional tows (602) using an automated fiber placement process; a honeycomb core (606) disposed on the stack of under-core composite plies (604); A composite honeycomb core sandwich structure (2100) comprising: a stack of core-on-core composite plies (610) laid up on the honeycomb core (606) by laying up a second set of unidirectional tows (608) using the automated fiber placement process.

[0132] Clause 59. The composite honeycomb core sandwich structure of clause 58, wherein each unidirectional tow (614) comprises unidirectional reinforcing fibers impregnated with a polymer resin to form a composite unidirectional tape (402).

[0133] Clause 60. The composite honeycomb core sandwich structure of clause 59, wherein the unidirectional reinforcing fibers include at least one of carbon fibers, glass fibers, polyaramid fibers, acrylic fibers, and viscose rayon fibers.

[0134] Clause 61. The composite honeycomb core sandwich structure of clause 58, wherein the orientation of the under-core composite plies (604) is quasi-isotropic.

[0135] Clause 62. The composite honeycomb core sandwich structure of clause 58, wherein the orientation of the stack of core-over-core composite plies (610) is quasi-isotropic.

[0136] Item 63. The composite honeycomb core sandwich structure of item 58, wherein the stacking orientation of the above-core composite plies (610) is symmetrical relative to the stacking orientation of the below-core composite plies (604) relative to the honeycomb core (606).

[0137] Clause 64. The composite honeycomb core sandwich structure of clause 58, further comprising a composite fabric sheet (616) disposed beneath the stack of under-core composite plies (604).

[0138] Item 65. The composite honeycomb core sandwich structure of Item 64, wherein the composite woven sheets (616) are impregnated with a polymer resin and include at least one of glass fiber sheets, carbon fiber sheets, and polyaramid sheets.

[0139] Clause 66. The composite honeycomb core sandwich structure of clause 58, further comprising an under-core film adhesive (618) disposed between the stack of under-core composite plies (604) and the honeycomb core (606).

[0140] Clause 67. The composite honeycomb core sandwich structure of Clause 66, wherein the under-core film adhesive (618) comprises at least one of an epoxy film adhesive, a polyurethane film adhesive, and a polyimide film adhesive.

[0141] Clause 68. The composite honeycomb core sandwich structure of clause 58, wherein the honeycomb core (606) comprises a plurality of segments (2102).

[0142] Appendix 69. The composite honeycomb core sandwich structure of Appendix 68, wherein the plurality of segments (2102) of the honeycomb core (606) include a front segment (2104), a center segment (2106), and a rear segment (2108).

[0143] Clause 70. The composite honeycomb core sandwich structure of Clause 58, wherein the honeycomb core (606) comprises at least one of a non-metallic material, a flame-retardant meta-aramid material, an aramid paper material, a fiberglass material, a metal material, and an aluminum material.

[0144] Clause 71. The composite honeycomb core sandwich structure of Clause 58, further comprising an over-core film adhesive (628) disposed between the honeycomb core (606) and the stack of over-core composite plies (610).

[0145] Clause 72. The composite honeycomb core sandwich structure of Clause 71, wherein the on-core film adhesive (628) comprises at least one of an epoxy film adhesive, a polyurethane film adhesive, and a polyimide film adhesive.

[0146] Addendum 73. The honeycomb core (606) includes a three-dimensional body (622), the three-dimensional body including a top surface (624), a bottom surface (620), and at least three sides (626) that are chamfered from the top surface (624) toward the bottom surface (620); 59. The composite honeycomb core sandwich structure of claim 58, wherein during manufacturing of the composite honeycomb core sandwich structure (2100), a primary side (630) of the at least three sides (626) is identified as being at highest risk of collapse during autoclave curing.

[0147] Clause 74. The composite honeycomb core sandwich structure of Clause 73, wherein the primary side (630) is selected based at least in part on the primary side (630) having the steepest chamfer of the at least three sides (626).

[0148] Clause 75. The composite honeycomb core sandwich structure of clause 73, wherein the primary side (630) is selected based at least in part on the primary side (630) being the longest side of the at least three sides (626).

[0149] Item 76. The composite honeycomb core sandwich structure of item 73, wherein the last composite ply (632) in the stack of under-core composite plies (604) is closest to the honeycomb core (606) and oriented perpendicular to the primary side (630).

[0150] Item 77. The composite honeycomb core sandwich structure of Item 76, wherein the under-core composite plies (639) of each set of four (634) in the stack of under-core composite plies (604) are oriented quasi-isotropically based on the orientation of the last composite ply (632) being orthogonal to the primary side (630).

[0151] Item 78. The composite honeycomb core sandwich structure of Item 73, wherein a first composite ply (636) in the stack of core-over-core composite plies (610) is closest to the honeycomb core (606) and oriented perpendicular to the primary side (630).

[0152] Item 79. The composite honeycomb core sandwich structure of Item 78, wherein each four-ply (638) of composite plies (640) over the core in the stack of composite plies (610) over the core is oriented quasi-isotropically based on the orientation of the first composite ply (636) being orthogonal to the primary side (630).

[0153] Appendix 80. A method (2400) for manufacturing a layup (600) of a composite honeycomb core sandwich structure (2100), comprising: laying up (2402) a first set of unidirectional tows (602) on a tool (100) for laying up (600) the composite honeycomb core sandwich structure (2100) using an automated fiber placement process to form a stack of under-core composite plies (604) secured to a roughened surface (102) bonded to the tool (100); placing (2404) an under-core film adhesive (618) on the stack of under-core composite plies (604) within the trim line (612) of the composite honeycomb core sandwich structure (2100); placing (2406) a honeycomb core (606) within the trim line (612) and on the under-core film adhesive (618); placing (2408) an on-core film adhesive (628) on the honeycomb core (606) within the trim line (612); laying up (2410) a second set of unidirectional tows (608) onto the over-core film adhesive (628) and the roughened surface (102) using the automated fiber placement process, thereby forming a stack of over-core composite plies (610) that secures the honeycomb core (606) to the roughened surface (102).

[0154] Clause 81. The method of clause 80, further comprising disposing (2412) a composite woven sheet (616) on the roughened surface (102).

[0155] Clause 82. The honeycomb core (606) includes a three-dimensional body (622), the three-dimensional body including a top surface (624), a bottom surface (620), and at least three sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (2502) the honeycomb core (606) to determine the risk of collapse of at least three sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); 81. The method (2500) of claim 80, comprising selecting a primary side (630) from the at least three sides (626) that is at greatest risk of collapsing.

[0156] Addendum 83. Laying up (2402) the first group of unidirectional tows (602) comprises: laying up (2602) a first under-core composite ply (642) of a first set of four (644) under-core composite plies (639) on the tool (100) at an approximately 45 degree orientation relative to the primary side (630) of the honeycomb core (606) to minimize overlap with the roughened surface (102); laying up (2604) a second under-core composite ply (646) of the first set of four under-core composite plies (639) on the first under-core composite ply (642) at an orientation of approximately 0 degrees relative to the primary side (630) of the honeycomb core (606) so as to be generally aligned with the roughened surface (102); laying up (2606) a third under-core composite ply (648) of the first set of four under-core composite plies (639) on the second under-core composite ply (646) at an orientation of approximately -45 degrees relative to the primary side (630) of the honeycomb core (606) to minimize overlap with the roughened surface (102); and laying up (2608) a fourth under-core composite ply (650) of the first set of four over-core composite plies (640) on the third under-core composite ply (648) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to overlap the roughened surface (102).

[0157] Addendum 84. Laying up (2402) the first group of unidirectional tows (602) comprises: 84. The method of claim 83, further comprising laying up (2702) the under-core composite plies (639) of the second set of four (652) prior to laying up (2602, 2604, 2606, 2608) of the first set of four (644) such that the under-core composite plies (639) of the second set of four are positioned below the first set of four (644), the second set of four (652) being laid up in a manner similar to the first set of four (644), except that the fourth under-core composite ply (650) in the second set of four (652) has less overlap with the rough surface (102) compared to the fourth under-core composite ply (650) in the first set of four (644).

[0158] Addendum 85. Laying up (2402) the first group of unidirectional tows (602) comprises: 85. The method of claim 84, further comprising laying up (2802) a third set of four (654) prior to laying up (2702) the second set of four (652) such that an under-core composite ply (639) of the third set of four (654) is positioned below the second set of four (652), the third set of four (654) being laid up in a manner similar to the second set of four (652), except that the fourth under-core composite ply (650) in the third set of four (654) has less overlap with the rough surface (102) than the fourth under-core composite ply (650) in the second set of four (652).

[0159] Addendum 86. Laying up (2410) the second group of unidirectional tows (608) comprises: laying up (2902) a first over-core composite ply (656) of a first set of four over-core composite plies (640) on the over-core film adhesive (628) and the first set of unidirectional tows (602) at an approximately 90 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to generally overlap at least a first portion of the honeycomb core (606) and the roughened surface (102); laying up (2904) a second over-core composite ply (660) of the first set of four over-core composite plies (640) on the first over-core composite ply (656) at an orientation of approximately -45 degrees relative to the primary side (630) of the honeycomb core (606) so as to generally overlap at least a portion of the first over-core composite ply (656) and at least a second portion (116) of the roughened surface (102); laying up (2906) a third core-over-core composite ply (662) of the first set of four core-over-core composite plies (640) on the second core-over-core composite ply (660) at an orientation of approximately 0 degrees relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the first core-over-core composite ply (656) and at least a portion of the second core-over-core composite ply (660); laying up (2908) a fourth core-over-core composite ply (664) of the first set of four core-over-core composite plies (640) on the third core-over-core composite ply (662) at an approximately 45 degree orientation relative to the primary side (630) of the honeycomb core (606) so as to generally overlap the second core-over-core composite ply (660) and at least a portion of the third core-over-core composite ply (662); laying up (2910) a second set of four (666) over-the-core composite plies (640) on the first set of four (658) over-the-core composite plies (640), wherein the second set of four (666) is laid up in a manner similar to the first set of four (658); 83. The method of claim 82, comprising laying up (2912) a third set of four (668) over-core composite plies (640) on the second set of four (666) over-core composite plies (640), wherein the third set of four (668) is laid up in a manner similar to the second set of four (666).

[0160] Clause 87. The three-dimensional body (622) of the honeycomb core (606) includes at least four sides (626) that are chamfered from the top surface (624) to the bottom surface (620), and the method further comprises: analyzing (3002) the honeycomb core (606) to determine the risk of collapse of at least four sides (626) during autoclave curing of the composite honeycomb core sandwich structure (2100); determining (3004) that the at least four sides (626) include two pairs of opposed sides (626), a first pair having a steeper chamfer angle than a second pair; selecting (3006) the first pair of the at least four sides (626) as being at greater risk of collapse than the second pair; The method (3000) of claim 82, further comprising selecting (3008) the primary side (630) from the first pair as the side of the at least four sides (626) that is at greatest risk of collapse, and not selecting the side opposite it.

Claims

1. 1. A method for manufacturing a composite honeycomb core sandwich structure layup, comprising: laying up a first set of unidirectional tows on a layup tool for the composite honeycomb core sandwich structure using an automated fiber placement process to form a stack of under-core composite plies secured to a rough surface bonded to the tool; placing a honeycomb core over the stack of under-core composite plies within the roughened surface; and laying up a second set of unidirectional tows on the honeycomb core using the automated fiber placement process, thereby forming a stack of composite plies on the core that secures the honeycomb core to the roughened surface.

2. The method of claim 1 , wherein the first set of unidirectional tows extends beyond a trim line of the composite honeycomb core sandwich structure.

3. The method of claim 1 , wherein the under-core composite ply stack orientation is quasi-isotropic.

4. The method of claim 1 , wherein the roughened surface is disposed on the tool and surrounds a trim line of the composite honeycomb core sandwich structure.

5. The method of claim 1 , wherein the honeycomb core is positioned within a trim line of the composite honeycomb core sandwich structure.

6. The method of claim 1 further comprising placing a composite woven sheet on the roughened surface.

7. disposing the composite fabric sheet; sealing the composite fabric sheet to the tool with a compression bag; applying a vacuum to the tool for a predetermined time to press the composite fabric sheet onto the roughened surface; releasing the vacuum; Unsealing the compression bag; and removing the compression bag from the composite fabric sheet.

8. The method of claim 1 further comprising placing an under-core film adhesive on a stack of under-core composite plies within a trim line of the composite honeycomb core sandwich structure.

9. disposing the film adhesive under the core sealing the under-core film adhesive and under-core composite ply stack to the tool with a compression bag; applying a vacuum to the tool for a predetermined time to press the under-core film adhesive against the under-core composite ply stack; releasing the vacuum; Unsealing the compression bag; and removing the compression bag from the under-core film adhesive and the under-core composite ply stack.

10. disposing the honeycomb core; placing the honeycomb core within a trim line of the composite honeycomb core sandwich structure; sealing the honeycomb core and under-core composite ply stack to the tool with a compression bag; applying a vacuum to the tool for a predetermined time to press the honeycomb core against the stack of under-core composite plies; releasing the vacuum; Unsealing the compression bag; and removing the compression bag from the honeycomb core and the stack of under-core composite plies.

11. The method of claim 1 further comprising placing an on-core film adhesive on the honeycomb core within a trim line of the composite honeycomb core sandwich structure.

12. The honeycomb core includes a three-dimensional body having a top surface, a bottom surface, and at least three sides chamfered from the top surface to the bottom surface, and the method includes: analyzing the honeycomb core to determine a risk of at least three side collapse during autoclave curing of the composite honeycomb core sandwich structure; The method of claim 1 , further comprising: selecting a primary side of the at least three sides that is at greatest risk of collapsing.

13. Laying up the first set of unidirectional tows comprises: laying up a first under-core composite ply of a first set of four under-core composite plies on the tool at an approximately 45 degree orientation relative to the primary side of the honeycomb core to minimize overlap with the roughened surface; laying up a second under-core composite ply of the first set of four under-core composite plies on the first under-core composite ply at an orientation of about 0 degrees relative to the primary side of the honeycomb core so as to be generally aligned with the roughened surface; laying up a third under-core composite ply of the first set of four under-core composite plies on the second under-core composite ply at an orientation of about −45 degrees relative to the primary side of the honeycomb core to minimize overlap with the roughened surface; and laying up a fourth under-core composite ply of the first set of four under-core composite plies on the third under-core composite ply at an orientation of about 90 degrees relative to the primary side of the honeycomb core so as to overlap the roughened surface.

14. Laying up the first set of unidirectional tows comprises:

14. The method of claim 13, further comprising laying up a second set of four prior to laying up the first set of four such that a second set of four under-core composite ply is disposed below the first set of four, the second set of four being laid up in a manner similar to the first set of four except that the fourth under-core composite ply in the second set of four has less overlap with the rough surface compared to the fourth under-core composite ply in the first set of four.

15. Laying up the first set of unidirectional tows comprises: laying up a first under-core composite ply of a first pair of under-core composite plies on the tool at an approximately 0 degree orientation relative to the primary side of the honeycomb core to minimize overlap with the roughened surface; and laying up a second under-core composite ply of the first pair of under-core composite plies on the first under-core composite ply at an approximately 90 degree orientation relative to the primary side of the honeycomb core so as to overlap the roughened surface.

16. Laying up the first set of unidirectional tows comprises:

16. The method of claim 15, further comprising laying up a second duo prior to laying up the first duo such that a second duo of under-core composite plies is disposed below the first duo, the second duo being laid up in a manner similar to the first duo except that the second under-core composite ply in the second duo has less overlap with the rough surface compared to the second under-core composite ply in the first duo.

17. Laying up the second group of unidirectional tows comprises: laying up a first composite ply-over-core of a first set of four composite plies over the honeycomb core and the first set of unidirectional tows in an approximately 90 degree orientation relative to the primary side of the honeycomb core so as to generally overlap at least a first portion of the honeycomb core and the roughened surface; laying up a second one of the first set of four composite plies on the first composite ply at an orientation of approximately −45 degrees relative to the primary side of the honeycomb core so as to generally overlap at least a portion of the first composite ply and at least a second portion of the roughened surface; laying up a third composite ply of the first set of four composite plies on top of the second composite ply at an orientation of about 0 degrees relative to the primary side of the honeycomb core so as to generally overlap the first composite ply and at least a portion of the second composite ply; and laying up a fourth composite ply of the first set of four composite plies over the third composite ply at an orientation of about 45 degrees relative to the primary side of the honeycomb core so as to generally overlap the second composite ply and at least a portion of the third composite ply.

18. Laying up the second group of unidirectional tows comprises:

18. The method of claim 17, further comprising laying up a second set of four over-the-core composite plies over the first set of four over-the-core composite plies, wherein the second set of four is laid up in a manner similar to the first set of four.

19. a stack of under-core composite plies laid up on the tool by laying up a first set of unidirectional tows using an automated fiber placement process; a honeycomb core disposed on the stack of under-core composite plies; a stack of composite plies on the honeycomb core laid up by laying up a second set of unidirectional tows using the automated fiber placement process.

20. 1. A method for manufacturing a composite honeycomb core sandwich structure layup, comprising: laying up a first set of unidirectional tows on a layup tool for the composite honeycomb core sandwich structure using an automated fiber placement process to form a stack of under-core composite plies secured to a rough surface bonded to the tool; placing an under-core film adhesive on the under-core composite ply stack within a trim line of the composite honeycomb core sandwich structure; placing a honeycomb core within the trim line and on the under-core film adhesive; placing an on-core film adhesive on the honeycomb core within the trim line; and laying up a second set of unidirectional tows on the over-core film adhesive and the roughened surface using the automated fiber placement process, thereby forming a stack of over-core composite plies that secures the honeycomb core to the roughened surface.

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