Bidirectional sewing composite material longitudinal and transverse stiffened wall plate and preparation method thereof

Abstract

The invention discloses a bi-directionally sewed composite longitudinal and transverse stiffened wallboard and a preparation method thereof, the longitudinal and transverse stiffened wallboard comprises a bulkhead, a stringer, a stringer R area filling core material, a stringer crack arrest belt, a bulkhead crack arrest belt and a skin, and the bulkhead is connected with the stringer in an inserted manner; a stringer and a stringer crack arrest belt are arranged at the top of the skin in the Y direction, and a bulkhead and a bulkhead crack arrest belt are arranged at the top of the skin in the X direction; the bulkhead and the wrapping layer on the outer side of the stringer are connected with the skin in a sewing mode through a bulkhead crack arresting belt and a stringer crack arresting belt respectively, and the bulkhead is connected with the bottom of the wrapping layer on the outer side of the stringer in a sewing mode. The transverse ribs keep good continuity, the two-way continuous rib structure enables the stiffened wall plate to have a more efficient stress conduction path, the suture line plays a role in Z-direction reinforcement, interlayer strength and toughness are improved, damage tolerance is improved, the comprehensive performance of the stiffened wall plate is improved, and good practicability is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material manufacturing, and particularly relates to a bidirectionally stitched composite material longitudinally and transversely reinforced wallboard and a preparation method thereof. Background Art

[0002] Reinforced wall panels are one of the most common composite material structures in the aviation field and are widely used in areas such as aircraft wings, fuselages, doors and fuel tanks. As a typical main load-bearing component in aviation, its basic structure consists of skin and ribs, among which the ribs reinforce the skin and ensure the overall stiffness and strength of the reinforced wall panels. Common forms of ribs in reinforced wall panels include cap-type, L-type, T-type and J-type. The existing manufacturing method of reinforced wall panels is to lay up the skin and ribs separately, and then combine the two into one by co-bonding, secondary bonding or RTM molding technology. In conventional reinforced wall panels, where the longitudinal and transverse ribs intersect, only the ribs in one direction are continuous, and the ribs in the other direction must be interrupted, which reduces the continuity of stress conduction. For example, the existing CN214190067U discloses a co-cured longitudinally and transversely reinforced composite integral wall panel, which includes a co-cured component and an L-shaped ordinary frame inner edge. The co-cured component is co-cured and formed by co-curing a skin, a T-shaped long stringer and a T-shaped ordinary frame outer edge. The T-shaped long stringer and the T-shaped ordinary frame outer edge are crisscrossed on the skin surface; the L-shaped ordinary frame inner edge is fixed to the T-shaped ordinary frame outer edge.

[0003] The need for prepreg and autoclaves leads to high manufacturing costs. Furthermore, conventional reinforced panel structures lack fiber reinforcement in the out-of-plane direction (i.e., along the panel thickness, commonly referred to as the Z-direction), resulting in low interlaminar strength, poor toughness, and susceptibility to cracking. Furthermore, each of the aforementioned reinforced panel forming processes has its own drawbacks. In the co-bonding process, the ribs used are "wet"—uncured—when assembled with the skin. Because wet ribs lack rigidity, complex molds must be used to maintain their shape during the curing process, further increasing the complexity of the forming process and manufacturing costs. In the secondary bonding process, adhesive film is used to bond the cured ribs to the skin. While this forming method eliminates the need for a mold to secure the ribs, the presence of an interface between the ribs and the skin makes debonding between the ribs and the skin a risk over long-term use. In the process of using the RTM process to form reinforced wall panels, since the prefabricated body is not self-supporting and the injection process requires the use of a complex block assembly mold to fix the prefabricated body and ensure the molding quality, there are problems such as high mold cost and complex mold assembly process.

[0004] As composite materials become increasingly common in aircraft and aircraft speeds increase, the aviation industry is placing higher demands on composite material performance and manufacturing costs. High-performance, low-cost composite materials are a key future development trend. As one of the most composite-intensive components in aviation, reinforced panels urgently require a manufacturing method that balances low cost and high performance. However, current conventional reinforced panel forming methods struggle to meet this demand. Summary of the Invention

[0005] The object of the present invention is to provide a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel and a preparation method thereof, in order to solve the above-mentioned problems.

[0006] The present invention is mainly achieved through the following technical solutions: A bidirectionally stitched composite material longitudinally and transversely reinforced wall panel comprises a bulkhead, a stringer, a core material filled in the R zone of the stringer, a stringer crack arrest tape, a bulkhead crack arrest tape and a skin, wherein the bulkhead is spliced with the stringer; the top of the skin is provided with a stringer and a stringer crack arrest tape along the Y direction, and a bulkhead and a bulkhead crack arrest tape along the X direction; the outer wrapping layers of the bulkhead and the stringer are sewn to the skin via the bulkhead crack arrest tape and the stringer crack arrest tape respectively, and the bulkhead is sewn to the bottom of the outer wrapping layers of the stringer.

[0007] In order to better realize the present invention, further, the long girder includes a pultruded rod wrapping layer and a pultruded rod, the middle part of the pultruded rod wrapping layer is folded in half, and the top of the folded middle part is provided with a cylinder with open ends corresponding to the pultruded rod, and the two sides of the pultruded rod wrapping layer are flanged; the bottom of the cylinder and the bottom of the folded middle part are respectively provided with a first suture line and a second suture line; the pultruded rod is sleeved in the cylinder, and the two sides extend outward; the flange is sewn and connected to the crack-stop belt of the long girder.

[0008] In order to better implement the present invention, further, a plug-in slot is provided in the middle portion of the bulkhead corresponding to the long stringer, and the plug-in slot is a key-shaped hole.

[0009] In order to better realize the present invention, further, the bulkhead includes a foam core wrapping layer and a foam core, the middle part of the foam core wrapping layer is wrapped with a foam core, and foam core wrapping layer flanges are respectively provided on both sides, and the foam core wrapping layer flanges are sewn and connected to the bulkhead crack-stopping tape.

[0010] A method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel comprises the following steps: Step A1: preparing a long stringer; Step A11: Sewing the pultruded rod wrap: Cut a carbon fiber cloth according to the diameter of the pultruded rod to form the pultruded rod wrap; fold the middle portion of the pultruded rod wrap in half and sew the carbon fiber cloth twice: the first sew forms a cylinder with open ends above the folded carbon fiber cloth, tightly wrapping the pultruded rod; the second sew ensures that the distance h1 between the first sew line and the second sew line is the distance between the symmetry axis of the pultruded rod and the skin; Step A12: Assemble the long stringer: insert the pultruded rod into the cylinder of the pultruded rod wrapping layer; Step A2: Prepare the bulkhead; Step A21: Processing the foam core: A key-shaped slot is provided at the bottom of the foam core so that the long stringer passes through the foam core and the long stringer and the foam core fit tightly together; Step A22: Processing the foam core wrapping layer: Cutting carbon fiber cloth to prepare the foam core wrapping layer; then, processing corresponding openings on the foam core wrapping layer according to the size of the plug-in slots on the foam core; Step A23: Assemble the bulkhead: spray the foam core with a shaping spray adhesive and then cover the foam core with a foam core wrap layer; Step A3: Cutting carbon fiber cloth to prepare cutting stringer crack arrest strips and bulkhead crack arrest strips; Step A4: Cutting carbon fiber cloth to prepare skin; Step A5: Assemble the vertical and horizontal reinforced wall panels: Step A51: Assemble the bulkhead, stringer, stringer R-area filling core material, stringer crack arrest tape, bulkhead crack arrest tape, and skin from top to bottom; Step A52: Sewing the pultruded rod wrapping layer and the skin, and the foam core wrapping layer and the skin together to obtain a preform; Step A53: Place the stitched preform on a flat mold, then place auxiliary materials and a packaging vacuum bag in sequence, and then vacuum the bag to introduce liquid resin into the vacuum bag to impregnate the preform. Finally, cure the preform after resin impregnation according to the resin curing process.

[0011] In order to better realize the present invention, further, the carbon fiber cloth is any one of carbon fiber unidirectional fabric, carbon fiber plain fabric, carbon fiber twill fabric, carbon fiber satin fabric, carbon fiber woven fabric, and carbon fiber warp knitted fabric.

[0012] In order to better realize the present invention, further, the pultruded rod is prepared by pultrusion molding of unidirectional carbon fiber reinforced resin, and the resin matrix is any one or more of epoxy resin, bismaleimide resin, cyanate resin, polyimide resin, polyetherimide resin, polyaryletherketone resin, and polyarylene sulfide resin.

[0013] In order to better implement the present invention, further, the foam core is a closed-cell foam board, and the material is any one or more of polymethacrylimide, polyurethane, polystyrene, polyvinyl chloride, polyethylene terephthalate, styrene-acrylonitrile copolymer, and polyetherimide.

[0014] In order to better implement the present invention, further, the foam core is a closed-cell foam board, and the material is any one or more of polymethacrylimide, polyurethane, polystyrene, polyvinyl chloride, polyethylene terephthalate, styrene-acrylonitrile copolymer or polyetherimide.

[0015] In order to better implement the present invention, the carbon fiber cloth is further subjected to lock stitching or chain stitching; the stitching thread used for stitching is a twisted or untwisted fiber thread, and the material is any one or more of nylon, polyester, aramid, polyarylate, and poly(p-phenylene benzobisoxazole).

[0016] The beneficial effects of the present invention are as follows: (1) The present invention innovatively uses a pultruded rod and a pultruded rod wrapping layer made of dry carbon fiber cloth as a long stringer (longitudinal rib), a foam core and a foam core wrapping layer made of dry carbon fiber cloth as a bulkhead (transverse rib), and a dry carbon fiber cloth as a skin. The present invention combines the skin and the wrapping layer into one body through single-sided double-needle stitching to obtain a self-supporting reinforced wall panel preform, which does not require the use of complex tooling during molding. At the same time, the dry fiber cloth combined with the VARI liquid molding process avoids the use of prepreg and autoclave, making its manufacturing cost significantly lower than that of conventional reinforced wall panels; and the stitching line plays a role in Z-direction reinforcement, increases the interlayer strength and toughness, improves the damage tolerance, and improves the comprehensive performance of the reinforced wall panel.

[0017] (2) In the reinforced wall panel, the key-shaped openings in the transverse ribs, which are of the same cross-sectional dimensions as the longitudinal ribs, allow the longitudinal ribs to pass through the transverse ribs while ensuring a close fit between the longitudinal and transverse ribs. This ensures good continuity between the longitudinal and transverse ribs. The bidirectionally continuous rib structure provides the reinforced wall panel with a more efficient stress conduction path.

[0018] (3) The present invention can realize the one-time integral manufacturing of bidirectional continuous reinforced wall panels. Through numerical simulation and ground tests, it is verified that the basic mechanical properties of the tension and compression of the low-cost three-dimensional stitched-liquid-molded planar longitudinal and transverse reinforced wall panel elements based on domestic composite materials are comparable to those of traditional wall panel elements, with a load-bearing efficiency of more than 30% lower cost. The present invention can realize the automated manufacturing of bidirectional continuous reinforced wall panel prefabricated bodies and achieve a high degree of integration of the prefabricated structure. The wall panel manufacturing efficiency is improved by more than 50% compared with the traditional process of separately manufacturing ribs and skins and performing secondary bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the dimensions of the pultruded rod wrapping layer; Figure 2 Schematic diagram of the structure of the pultruded rod wrapping layer; Figure 3 This is a schematic diagram of the structure for assembling the long stringer; Figure 4 Schematic diagram of the structure of the foam core; Figure 5 is the main view of the foam core; Figure 6 Schematic diagram of the structure of the foam core wrapping layer; Figure 7 Schematic diagram of the connection structure between the foam core wrapping layer and the foam core; Figure 8 It is a schematic diagram of the assembly structure of the present invention; Figure 9 It is a schematic diagram of the structure after suturing of the present invention.

[0020] Among them: 1-cylinder, 2-first suture line, 3-second suture line, 4-flange, 5-pultruded rod, 6-foam core wrapping layer, 7-foam core wrapping layer flange, 8-foam core, 9-long stringer crack arrest strip, 10-frame crack arrest strip, 11-skin. DETAILED DESCRIPTION

[0021] Example 1: A method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel comprises the following steps: Step S101: preparing dry raw materials: preparing carbon fiber cloth, pultruded rods 5, foam core 8 and sutures that meet the performance requirements of the reinforced wall panel; Step S102: Sewing the Pultruded Rod Wrap: Cut a carbon fiber cloth according to the diameter of the pultruded rod 5 to form the pultruded rod wrap. Fold the pultruded rod wrap in half and stitch the carbon fiber cloth twice at appropriate locations using single-needle double-sided stitching. The first stitching forms a cylinder 1 with open ends above the carbon fiber cloth. The diameter of the cylinder 1 allows the pultruded rod 5 to pass through it while being tightly wrapped by the cylinder 1. The second stitching ensures that the distance between the two lines of stitching is the distance between the axis of symmetry of the pultruded rod 5 and the skin 11. Flanged edges 4 are provided on both sides of the pultruded rod wrap.

[0022] Step S103: Assembling the long stringer: inserting the pultruded rod 5 into the cylinder 1 of the pultruded rod wrapping layer; Step S104: Processing the foam core 8: Cut the foam core 8 into a rectangular parallelepiped of the desired size and then process the foam core 8 into the desired shape. The finished foam core 8 has a key-shaped hole at the bottom, which allows the long stringer to pass through the foam core 8 while ensuring a tight fit between the long stringer and the foam core 8. Step S105: Processing the Foam Core Wrap 6: Cut the carbon fiber cloth according to the size of the foam core 8 to form the foam core wrap 6. Then, cut the foam core wrap 6 according to the size of the key-shaped hole in the foam core 8, and machine a hole in the foam core wrap 6 that is the same size as the key-shaped hole in the foam core 8. Pultruded rod 5 wrap flanges 7 are provided on both sides of the foam core wrap 6. Step S106 : Assembling the partition frame: spraying shaping glue on the surface of the foam core 8 , and then covering the foam core 8 with the foam core wrapping layer 6 .

[0023] Step S107: Cutting the long stringer crack arresting strip 9: Cutting the carbon fiber cloth according to the length and width of the long stringer to form the long stringer crack arresting strip 9; Step S108: Cutting the bulkhead crack arrest tape 10: Cutting the carbon fiber cloth according to the length and width of the bulkhead to form the bulkhead crack arrest tape 10; Step S109: Cutting the skin 11: Cutting the carbon fiber cloth according to the length and width of the stiffened wall panel to form the skin 11.

[0024] Step S110: Assemble dry raw materials: Assemble the dry raw materials in order. From top to bottom, they are: bulkhead (wrapped with foam core 8), stringer (wrapped with pultruded rod 5), stringer R zone filling core material, stringer crack arrest tape 9, bulkhead crack arrest tape 10, and skin 11. Step S111: Sewing the dry raw materials: using a single-sided double-needle sewing device to sew the pultruded rod wrapping layer and the skin 11, and the foam core wrapping layer 6 and the skin 11 together to obtain a preform; Step S112: Encapsulation and curing: Place the stitched preform on a flat mold, then place auxiliary materials and a packaging vacuum bag in sequence, and then vacuum the bag to introduce liquid resin into the vacuum bag to impregnate the preform. Finally, cure the preform after resin impregnation according to the resin curing process.

[0025] Preferably, the carbon fiber cloth in step S101 can be a unidirectional carbon fiber fabric, a plain carbon fiber fabric, a twill carbon fiber fabric, a satin carbon fiber fabric, a woven carbon fiber fabric, or a warp-knitted carbon fiber fabric. The pultruded rod 5 is a circular cross-section rod obtained by pultrusion of a unidirectional carbon fiber reinforced resin. The resin matrix can be epoxy resin, bismaleimide resin, cyanate ester resin, polyimide resin, polyetherimide resin, polyaryletherketone resin, or polyarylethersulfide resin. The foam core 8 is a closed-cell foam board made of polymethacrylimide (PMI), polyurethane (PU), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), styrene-acrylonitrile copolymer (SAN), or polyetherimide (PEI). The suture is a twisted or untwisted fiber made of nylon, polyester, aramid, polyarylate, or poly(p-phenylene benzobisoxazole).

[0026] Preferably, the single-needle double-sided suturing in step S102 is lock suturing, improved lock suturing or chain suturing, which can be achieved by a handheld sewing machine, a household sewing machine, a two-dimensional suturing device, etc.; Preferably, the single-sided double-needle suturing device in step S111 is a three-dimensional suturing machine controlled by a six-axis robot arm, which can suturing along a plane or curved path; Preferably, the package curing in step S112 is a prior art and is not an improvement point of the present invention, so it will not be described in detail.

[0027] The stitched preform of the reinforced siding panel of the present invention is self-supporting. When placed on a flat surface, the longitudinal and transverse ribs maintain their shape without the need for rib forming and fixing molds. Consequently, the subsequent molding tooling for the preform during glue injection and curing is extremely simple, requiring only a flat mold. This significantly reduces the manufacturing cost of the reinforced siding panel.

[0028] The carbon fiber raw material used in this invention is dry fiber cloth, eliminating the need for carbon fiber prepregs used in conventional reinforced siding. The raw material cost of dry fiber cloth is significantly lower than that of prepreg. Furthermore, dry fiber cloth can be stored indefinitely at room temperature, whereas prepregs require low-temperature refrigeration and have a shelf life. Therefore, the cost of using dry fiber cloth is further reduced compared to prepregs.

[0029] The curing of the present invention adopts vacuum assisted resin infusion molding technology (VARI), which can be carried out in an ordinary oven. There is no need to use expensive special equipment such as autoclaves used in manufacturing conventional reinforced wall panels. The main equipment is relatively cheap and the investment cost is low.

[0030] The ribs and skin 11 of the present invention are tightly connected by stitching. The stitching significantly enhances the connection between the ribs and skin 11, improving the integrity of the stiffened panel. The stitching also provides Z-direction reinforcement, increasing interlaminar strength and toughness, enhancing damage tolerance, and improving the overall performance of the stiffened panel.

[0031] Example 2: A method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel, such as Figures 1-9 As shown, the following steps are included: Step S101: Prepare dry raw materials: carbon fiber cloth, pultruded rods 5, foam core 8, and sutures. The carbon fiber cloth is a warp-knitted carbon fiber cloth consisting of seven layers of unidirectional carbon cloth, with a total thickness of 1.3 mm and a total surface density of 1450 gsm. The layup angles are +45° / -45° / 0° / 90° / 0° / -45° / +45°. The pultruded rods 5 are 0° carbon fiber reinforced epoxy resin, 60 cm long, and 9 mm in diameter. The foam core 8 is a closed-cell polymethacrylimide (PMI) foam board with a density of 110 kg / cm³. The sutures are 400D / 3 aramid 1414 ply-twisted yarn.

[0032] Step S102: Suture the pultruded rod wrapping layer: Figure 1 and Figure 2 As shown, a carbon fiber warp-knitted fabric was cut into a 600 mm long and 180 mm wide rectangle to serve as the pultruded rod wrap. The pultruded rod wrap was folded in half and stitched twice at appropriate locations using single-needle, double-sided stitching. The first stitching formed a cylinder 1 with open ends above the carbon fiber fabric, with a diameter D1 of 9.5 mm. The second stitching established a distance h1 of 30 mm between the first stitching line 2 and the second stitching line 3. The length L1 of the pultruded rod wrap was 600 mm, the width w1 of the flange 4 was 45 mm, and the thickness t1 was 1.3 mm.

[0033] Step S103: Assemble the long stringer: Figure 3 As shown, the pultruded rod 5 is passed through the cylinder 1 of the pultruded rod wrapping layer. The diameter D2 of the pultruded rod 5 is 9 mm.

[0034] Step S104: Processing the foam core 8: Figure 4 and Figure 5 As shown, a cuboid with a length of 300 mm, a width of 12.7 mm, and a height of 150 mm is processed into the desired shape of a foam core 8. The finished foam core 8 has a semicircular top and a key-shaped hole at the bottom. The foam core 8 has a length L2 of 300 mm, a width t2 of 12.7 mm, a height h2 of 150 mm, a diameter D3 of the semicircular top of 12.7 mm, a diameter D4 of the key-shaped hole of 12 mm, a height h3 of 27.4 mm, a width w2 of 2.7 mm, a w3 of 100 mm, and a h4 of 2.6 mm.

[0035] Step S105: Processing the foam core wrapping layer 6: Cut the carbon fiber warp knitted fabric into a rectangle with a length of 397.3 mm and a width of 300 mm as the foam core wrapping layer 6. Figure 6 As shown, the foam core wrapping layer 6 is cut, and an opening having the same size as the key-shaped hole on the foam core 8 is processed on the foam core wrapping layer 6. The width w4 of the foam core wrapping layer flange 7 is 45 mm.

[0036] Step S106: Assemble the bulkhead: Figure 7 As shown, shaping glue is sprayed on the surface of the foam core 8, and then the foam core wrapping layer 6 is used to cover the foam core 8.

[0037] Step S107 : Cutting the long string crack arresting strip 9 : Cutting the carbon fiber warp knitted fabric into a rectangle with a length of 600 mm and a width of 90 mm to serve as the long string crack arresting strip 9 .

[0038] Step S108: Cutting the bulkhead crack arresting strip 10: Cutting the carbon fiber warp knitted fabric into a rectangle with a length of 300 mm and a width of 102.7 mm to serve as the bulkhead crack arresting strip 10.

[0039] Step S109 : Cutting the skin 11 : Cutting the carbon fiber warp knitted fabric into a rectangle with a length of 600 mm and a width of 300 mm as the skin 11 .

[0040] Step S110: Assemble dry raw materials: Figure 8 As shown, the dry raw materials are assembled together in order, from top to bottom: the bulkhead (with the foam core 8 wrapped therein), the long stringer (with the pultruded rod 5 wrapped therein), the long stringer crack arrest tape 9, the bulkhead crack arrest tape 10 and the skin 11.

[0041] Step S111: Suture the dry raw materials: Figure 9 As shown, a single-sided double-needle sewing device is used to sew the pultruded rod wrapping layer and the skin 11, and the foam core wrapping layer 6 and the skin 11 together to obtain a preform.

[0042] Step S112: Encapsulation and curing: Place the stitched preform on a flat mold, then place auxiliary materials and a packaging vacuum bag in sequence, and then vacuum the bag to introduce liquid resin into the vacuum bag to impregnate the preform. Finally, cure the preform after resin impregnation according to the resin curing process.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A bidirectionally stitched composite material longitudinal and transverse reinforced wall panel, characterized in that: The invention comprises a bulkhead, a long stringer, a filling core material in the R zone of the long stringer, a long stringer crack-stopping strip (9), a bulkhead crack-stopping strip (10) and a skin (11), wherein the bulkhead is spliced with the long stringer; the top of the skin (11) is provided with a long stringer and a long stringer crack-stopping strip (9) along the Y direction, and a bulkhead and a bulkhead crack-stopping strip (10) along the X direction; the outer wrapping layers of the bulkhead and the long stringer are sewn together with the skin (11) through the bulkhead crack-stopping strip (10) and the long stringer crack-stopping strip (9) respectively, and the bulkhead is sewn together with the bottom of the outer wrapping layers of the long stringer.

2. The bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 1, characterized in that: The long girder comprises a pultruded rod wrapping layer and a pultruded rod (5); the middle portion of the pultruded rod wrapping layer is folded in half, and the top of the folded middle portion is provided with a cylinder (1) with two open ends corresponding to the pultruded rod (5); both sides of the pultruded rod wrapping layer are flanges (4); the bottom of the cylinder (1) and the bottom of the folded middle portion are provided with a first suture line (2) and a second suture line (3), respectively; the pultruded rod (5) is sleeved in the cylinder (1), and both sides extend outward; the flanges (4) are sutured and connected to the long girder crack arresting strip (9).

3. The bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 2, characterized in that: A plug-in slot is provided in the middle of the partition frame corresponding to the long stringer, and the plug-in slot is a key-shaped hole.

4. A bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to any one of claims 1 to 3, characterized in that: The bulkhead comprises a foam core wrapping layer (6) and a foam core (8), wherein the middle portion of the foam core wrapping layer (6) is wrapped with the foam core (8), and foam core wrapping layer flanges (7) are respectively provided on both sides, and the foam core wrapping layer flanges (7) are sewn together with the bulkhead crack arresting strips (10).

5. A method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel, characterized in that: The following steps are involved: Step A1: preparing a long stringer; Step A11: Stitching the pultruded rod wrapping layer: cutting carbon fiber cloth according to the diameter of the pultruded rod (5) to serve as the pultruded rod wrapping layer; folding the middle portion of the pultruded rod wrapping layer in half, and stitching the carbon fiber cloth twice: the first stitching forms a cylinder (1) with two open ends above the folded carbon fiber cloth in half, and the cylinder (1) tightly wraps the pultruded rod (5); the second stitching makes the distance h1 between the first stitching line (2) and the second stitching line (3) equal to the distance between the symmetry axis of the pultruded rod (5) and the skin (11); Step A12: Assembling the long stringer: inserting the pultruded rod (5) into the cylinder (1) of the pultruded rod wrapping layer; Step A2: Prepare the bulkhead; Step A21: Processing the foam core (8): a key-shaped hole slot is provided at the bottom of the foam core (8) so that the long stringer passes through the foam core (8) and the long stringer and the foam core (8) fit tightly together; Step A22: Processing the foam core wrapping layer (6): Cutting carbon fiber cloth to prepare the foam core wrapping layer (6); and then processing corresponding openings on the foam core wrapping layer (6) according to the size of the plug-in slot on the foam core (8); Step A23: Assembling the partition frame: spraying the shaping glue on the surface of the foam core (8), and then covering the foam core (8) with the foam core wrapping layer (6); Step A3: Cutting carbon fiber cloth to prepare cutting long stringer crack arrest strips (9) and bulkhead crack arrest strips (10); Step A4: Cutting carbon fiber cloth to prepare skin (11); Step A5: Assemble the vertical and horizontal reinforced wall panels: Step A51: Assemble the bulkhead, the long stringer, the filling core material in the R area of the long stringer, the long stringer crack arresting strip (9), the bulkhead crack arresting strip (10) and the skin (11) in sequence from top to bottom; Step A52: Sewing the pultruded rod wrapping layer and the skin (11), and the foam core wrapping layer (6) and the skin (11) together to obtain a preform; Step A53: Place the stitched preform on a flat mold, then place auxiliary materials and a packaging vacuum bag in sequence, and then vacuum the bag to introduce liquid resin into the vacuum bag to impregnate the preform. Finally, cure the preform after resin impregnation according to the resin curing process.

6. The method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 5, characterized in that: The carbon fiber cloth is any one of carbon fiber unidirectional fabric, carbon fiber plain fabric, carbon fiber twill fabric, carbon fiber satin fabric, carbon fiber woven fabric, and carbon fiber warp knitted fabric.

7. The method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 5, characterized in that: The pultruded rod (5) is prepared by pultrusion molding of unidirectional carbon fiber reinforced resin, and the resin matrix is any one or more of epoxy resin, bismaleimide resin, cyanate resin, polyimide resin, polyetherimide resin, polyaryletherketone resin, and polyarylethersulfide resin.

8. The method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 5, characterized in that: The foam core (8) is a closed-cell foam board, and the material is any one or more of polymethacrylimide, polyurethane, polystyrene, polyvinyl chloride, polyethylene terephthalate, styrene-acrylonitrile copolymer, and polyetherimide.

9. The method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 5, characterized in that: The foam core (8) is a closed-cell foam board, and the material is any one or more of polymethacrylimide, polyurethane, polystyrene, polyvinyl chloride, polyethylene terephthalate, styrene-acrylonitrile copolymer or polyetherimide.

10. The method for preparing a bidirectionally stitched composite material longitudinally and transversely reinforced wall panel according to claim 5, characterized in that: The carbon fiber cloth is subjected to lock stitching or chain stitching; the stitching thread is a twisted or untwisted fiber thread, and the material is any one or more of nylon, polyester, aramid, polyarylate, and poly(p-phenylene benzobisoxazole).

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