A method of manufacturing a double-needle stitched reinforced panel structure

Abstract

This application discloses a method for preparing a double-needle stitched reinforced wall panel structure, relating to the field of fiber composite material reinforcement technology. The method includes the following steps: designing and machining a digital model of a double-needle stitching mold based on the reinforced wall panel structure; creating oblique grooves along the stitching direction in the double-needle stitching mold, the depth and width of which are adapted to the movement trajectory of the double needles; cutting carbon fiber cloth as reinforcing layer and skin layer according to the reinforced wall panel structure; stacking the reinforcing layer and skin layer on the double-needle stitching mold in a predetermined order and fixing them; using a double-needle stitching device, simultaneously stitching the flanges of the reinforcing layer and skin layer along the stitching path to form a double-stitch preform; impregnating the double-stitch preform with resin using a vacuum-assisted liquid molding process, and curing it to obtain the reinforced wall panel structure. This application is the first to apply double-needle synchronous stitching technology to mainstream reinforced structures without foam cores, solving the problem of insufficient interlayer strength in traditional adhesive / co-curing processes, and can cover most reinforced wall panel structural forms in the aerospace field.

Description

Technical Field

[0001] This application relates to the field of fiber composite material reinforcement technology, and in particular to a method for preparing a double-needle stitch reinforced wall panel structure. Background Technology

[0002] Stiffened panels, as core components of the main load-bearing structures in aerospace, consist of skin and stiffeners and are widely used in areas such as aircraft wings, fuselages, doors, and fuel tanks. Traditional manufacturing methods primarily involve laying prepregs separately onto the skin and stiffeners, then combining them through co-curing, co-bonding, or secondary bonding. However, this method has significant drawbacks: weak interlaminar properties, lack of fiber reinforcement in the out-of-plane (Z-direction), resulting in low interlaminar strength, poor toughness, and susceptibility to delamination failure; and the risk of interface debonding, as the interface between the stiffeners and skin is prone to debonding under long-term loads, posing a structural safety hazard. To improve interlaminar properties, stitch reinforcement technology has been introduced into the field of fiber composite materials. This technology uses stitches to penetrate multiple layers of fabric, forming Z-direction reinforcement to improve interlaminar strength and damage tolerance. However, existing stitching techniques are mainly focused on flat panels or foam-core sandwich structures (such as cap-shaped stiffeners), while the foam-free sandwich reinforced panels (such as L-shaped, C-shaped, T-shaped, I-shaped and other reinforced panels) widely used in the aerospace field lack effective reinforcement methods; moreover, the stitching method mainly adopts single-needle stitching, which only forms a single stitch at a time, making it difficult to meet the high-efficiency production requirements of aerospace composite materials. Summary of the Invention

[0003] The main objective of this application is to provide a method for preparing a double-needle stitched reinforced wall panel structure, which aims to solve the technical problems that existing stitching techniques are not applicable to the reinforcement of foam-free sandwich reinforced wall panels and have low stitching efficiency.

[0004] To achieve the above objectives, this application proposes a method for preparing a double-needle stitched reinforced wall panel structure, comprising the following steps: Based on the reinforced wall panel structure, a digital model of a double-needle sewing mold is designed and processed. The double-needle sewing mold has an oblique groove along the sewing direction, and the depth and width of the oblique groove are adapted to the movement trajectory of the double needles. Based on the reinforced wall panel structure, carbon fiber cloth is cut into stiffener layup and skin layup respectively. The reinforcing bar layer and the skin layer are laid on the double-needle stitching mold in a preset order and then fixed. Using a double-needle suturing device, the suture thread is simultaneously sutured along the suturing path to the flange of the rib ply and the flange of the skin ply, forming a double-stitch prefabricated body; The double-line preform is impregnated with resin using a vacuum-assisted liquid molding process, and after curing, a reinforced and stiffened wall panel structure is obtained.

[0005] Optionally, the carbon fiber cloth is one of carbon fiber unidirectional fabric, carbon fiber plain weave fabric, carbon fiber twill weave fabric, carbon fiber satin weave fabric, carbon fiber woven fabric, and carbon fiber warp knitted fabric; the material of the stitching thread is one of nylon, polyester, aramid, polyarylate, and poly(p-phenylenebenzodioxazole).

[0006] Optionally, in the step of designing and machining the digital model of the double-needle sewing mold, wherein the double-needle sewing mold has an oblique groove along the sewing direction, and the depth and width of the oblique groove are adapted to the movement trajectory of the double needles, the double-needle sewing mold is manufactured by a five-axis machine tool or 3D printing, and the material of the double-needle sewing mold is one of steel, aluminum alloy or hard plastic; the depth of the oblique groove is 50mm-80mm, and the width of the oblique groove is 20mm-30mm.

[0007] Optionally, in the step of separately cutting carbon fiber cloth as a reinforcing layer and a skin layer, the layup angle of the reinforcing layer includes one or more combinations of 0°, ±45° and 90°; the layup angle of the skin layer includes one or more combinations of 0°, ±45° and 90°.

[0008] Optionally, the double-needle sewing device is a three-dimensional sewing machine controlled by a six-axis robot. The double-needle sewing device includes a rotating sewing head, and the double-needle sewing device performs multi-angle sewing through the rotating sewing head. The sewing path of the double-needle sewing device includes straight lines, curves, or complex three-dimensional curved surfaces, and two parallel stitches are formed in one sewing.

[0009] Optionally, the reinforced wall panel structure is a single-flanged structure, including one of L-shaped reinforced wall panels, C-shaped reinforced wall panels, or Z-shaped reinforced wall panels.

[0010] Optionally, the step of using a double-needle suturing device to simultaneously sew the flanges of the reinforcing rib ply and the skin ply along the suturing path to form a double-stitch prefabricated body includes: Using a double-needle sewing device, along the direction of one-sided flange, the suture thread is simultaneously sewn to the flange of the rib ply and the flange of the skin ply, and two parallel stitches are formed in one sewing to obtain a double-stitch preform.

[0011] Optionally, the reinforced wall panel structure is a double-flanged structure, including one of a T-shaped reinforced wall panel, an I-shaped reinforced wall panel, or a J-shaped reinforced wall panel.

[0012] Optionally, the step of using a double-needle suturing device to simultaneously sew the flanges of the reinforcing rib ply and the skin ply along the suturing path to form a double-stitch prefabricated body includes: Using a double-needle sewing device, along one side of the flange direction, the suture thread is simultaneously sewn together with the flange of the rib ply and the flange of the skin ply. Then, the rotating sewing head of the double-needle sewing device is rotated 180°, and along the other side of the flange direction, the suture thread is simultaneously sewn together with the flange of the rib ply and the flange of the skin ply. During sewing, twist strips are filled at the flange joint, and two parallel stitches are formed in one sewing to obtain a double-stitch preform.

[0013] Optionally, in the step of impregnating the double-line preform with resin through a vacuum-assisted liquid molding process and curing it to obtain a reinforced wall panel structure, the resin is one of epoxy resin, phenolic resin or bismaleimide resin; the curing process is hot pressing curing or oven curing.

[0014] The beneficial effects of this application include at least the following: This application is the first to apply stitch reinforcement to mainstream reinforced structures (L-type / C-type / Z-type / T-type / I-type / J-type) without foam cores. The stitches run through the skin and the rib flanges to form a three-dimensional reinforcement network. The stitches can play a role in Z-axis reinforcement, thereby increasing interlaminar shear strength and toughness, improving damage tolerance, and the contact surface between the skin and the rib flanges is no longer a weak point that is prone to delamination. This improves the overall performance of the reinforced wall panel and solves the problem of insufficient interlaminar strength in traditional adhesive / co-curing processes. This application uses a double-needle synchronous suturing technique, which can form two sutures at the same time, significantly improving suturing efficiency compared to conventional single-needle suturing. Based on the technological characteristics of double-needle stitching, this application designs a double-needle stitching mold with oblique grooves along the stitching direction. The depth and width of the oblique grooves are adapted to the movement trajectory of the double needles, ensuring zero collision during the stitching process. At the same time, it provides support for the skin layup and stiffener layup, playing a fixing role. Furthermore, a single mold is compatible with single-flanged (L-type / C-type / Z-type) and double-flanged (T-type / I-type / J-type) structures, covering most of the structural forms of stiffened panels in the aerospace field, replacing the traditional adhesive bonding between the skin and stiffener flanging. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating the preparation method of the double-needle stitching reinforced wall panel structure described in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of the double-needle stitching mold described in the embodiments of this application; Figure 3 This is a cross-sectional schematic diagram of the double-needle stitching mold described in the embodiments of this application; Figure 4 This is a cross-sectional schematic diagram of the rib layup and skin layup described in the embodiments of this application, stacked on a double-needle stitching mold; Figure 5 The diagram shows the stitch pattern of the double-stitched preform described in this application after double-needle stitching; wherein, (a) is a front stitch pattern diagram; and (b) is a back stitch pattern diagram. Figure 6 This is a structural schematic diagram of the single-flanged L-shaped stiffened wall panel described in the embodiments of this application; Figure 7 This is a schematic cross-sectional view of the joint between the reinforcing bars and the flange, as described in an embodiment of this application. Figure 8 This is a structural schematic diagram of the double-flanged T-shaped stiffened wall panel described in the embodiments of this application; Figure 9 This is a schematic diagram of the double-needle suturing process described in the embodiments of this application; Figure 10 This is a schematic diagram of the double-needle suturing process described in the comparative example of this application.

[0017] Figure label: 1-Hook needle; 2-Guide needle; 3-Sewing preform; 4-Sewing support; 5-Suture thread.

[0018] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] To address the technical problems existing in the prior art, embodiments of this application provide a method for preparing a double-needle stitched reinforced wall panel structure, such as... Figure 1 As shown, it includes the following steps: S1. Based on the reinforced wall panel structure, design and process the digital model of the double-needle sewing mold. The double-needle sewing mold has an oblique groove along the sewing direction. The depth and width of the oblique groove are adapted to the movement trajectory of the double needles.

[0021] In the specific implementation process, the double-needle stitching mold is processed by a five-axis machine tool or 3D printing. The material of the double-needle stitching mold is one of steel, aluminum alloy or hard plastic. The depth of the inclined groove is 50mm-80mm and the width of the inclined groove is 20mm-30mm.

[0022] Specifically, the top of the double-needle stitching mold has a 2mm-3mm recessed area. The design of the recessed area can accurately fix the position of the rib layup and the skin layup, avoiding displacement of the two during the stitching process and affecting the stitching reinforcement effect.

[0023] S2. Based on the reinforced wall panel structure, cut carbon fiber cloth as stiffener layup and skin layup respectively.

[0024] Specifically, the carbon fiber cloth is one of the following: carbon fiber unidirectional fabric, carbon fiber plain weave fabric, carbon fiber twill weave fabric, carbon fiber satin weave fabric, carbon fiber woven fabric, and carbon fiber warp knitted fabric.

[0025] In specific implementation, the ply angle of the reinforcing bar layer includes one or more combinations of 0°, ±45° and 90°; the ply angle of the skin layer includes one or more combinations of 0°, ±45° and 90°.

[0026] Specifically, the layup angle refers to the angle between the fiber direction of a single layer of carbon fiber and the reference axis (usually the principal axis of the material), which determines the mechanical properties of the material. The layup angle of the stiffener layup and the layup angle of the skin layup in this application may include one or more combinations of 0°, ±45° and 90°. 0° means that the fiber is along the principal load direction, mainly providing axial strength and stiffness; ±45° mainly provides resistance to shear load and prevents delamination failure; 90° mainly provides lateral support and balances in-plane performance.

[0027] S3. Lay the reinforcing bar layer and the skin layer on the double-needle stitching mold in a preset order and fix them.

[0028] Specifically, the layup methods include symmetrical layup and asymmetrical layup. Symmetrical layup involves mirroring the 0° layer as the axis of symmetry, while asymmetrical layup involves no mirroring rule. When laying up the rib layup and skin layup, the rib layup is first laid on the double-needle sewing mold. Then, as needed, twist strips are filled at the joint of the rib flanges (R area). The twist strips can eliminate gaps and improve interface strength. Next, the skin layup is placed on top of the rib layup and twist strips. Finally, the positions of the rib layup and skin layup are fixed through the recessed area at the top of the double-needle sewing mold, and then sewed.

[0029] S4. Using a double-needle suturing device, the suture thread is simultaneously sutured along the suturing path to the flange of the rib ply and the flange of the skin ply, forming a double-stitch prefabricated body.

[0030] Specifically, the suture is a high-strength fiber twisted or untwisted thread, and the material is one of nylon, polyester, aramid, polyarylate, and poly(p-phenylenebenzodioxazole).

[0031] In the specific implementation process, the double-needle sewing device is a three-dimensional sewing machine controlled by a six-axis robot. The double-needle sewing device includes a rotating sewing head, and the double-needle sewing device performs multi-angle sewing through the rotating sewing head. The sewing path of the double-needle sewing device includes straight lines, curves or complex three-dimensional curved surfaces, and two parallel stitches are formed in one sewing.

[0032] The reinforced wall panel structure is a single-flanged structure, including one of L-shaped, C-shaped, or Z-shaped reinforced wall panels. During the specific stitching process, a double-needle stitching device is used to simultaneously stitch the flanges of the reinforcing rib layer and the skin layer along the direction of the single-sided flange, forming two parallel stitches in one stitch to obtain a double-stitch prefabricated body.

[0033] The reinforced wall panel structure is a double-flanged structure, including one of a T-shaped reinforced wall panel, an I-shaped reinforced wall panel, or a J-shaped reinforced wall panel. In the specific sewing process, a double-needle sewing device is used. Along one side of the flanging direction, the suture thread is simultaneously sewn together with the flanging of the reinforcing layer and the flanging of the skin layer. Then, the rotating sewing head of the double-needle sewing device is rotated 180°, and along the other side of the flanging direction, the suture thread is simultaneously sewn together with the flanging of the reinforcing layer and the flanging of the skin layer. During sewing, twisted strips are filled at the flanging joint, and two parallel stitches are formed in one stitch to obtain a double-stitch prefabricated body.

[0034] This application uses a six-axis robot to control a three-dimensional sewing device for sewing, which can support sewing of planar or curved paths, including irregular curved surfaces with rib flanges, thereby adapting to complex reinforced wall panel structures. When sewing double flanges, the rotating sewing head can directly rotate 180° to sew the flanges on both sides in steps, thus solving the problem of spatial interference.

[0035] S5. The double-line preform is impregnated with resin using a vacuum-assisted liquid molding process, and after curing, a reinforced and stiffened wall panel structure is obtained.

[0036] In the specific implementation process, the resin used is one of epoxy resin, phenolic resin or bismaleimide resin; the curing process is hot pressing curing or oven curing.

[0037] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0038] Example 1 The preparation of a single-flanged L-shaped stiffened wall panel includes the following steps: Step 1: Prepare raw materials Carbon fiber cloth: Unidirectional carbon fiber cord fabric (thickness 0.1 mm, areal density 100 gsm). Suture material: 400D / 3 aramid 1414 twisted yarn; Mold material: 410 polyurethane wood substitute (density 0.58 g / cm³) 3 ); Resin: Epoxy resin LY1564SP; Step 2: Process the double-needle sewing mold Double-needle sewing molds are manufactured using digital models, such as... Figure 2 and Figure 3 As shown, the parameters are as follows: Length L1 = 600mm, width W1 = 150mm, height H1 = 100mm; The top depression height H2 = 2.2 mm; The depth of the inclined groove is H3=57mm on one side and H4=72mm on the other side; The top width of the sloping groove is W3=29mm, and the bottom width is W4=25mm.

[0039] Step 3: Trim the reinforcing bar layers and the skin layers The unidirectional carbon fiber cord fabric is cut into 22 rectangles of 600mm × 100mm each as reinforcement layers. The layup angle of the reinforcement layers is as follows: (45° / -45° / 0° / -45° / 0° / 45° / 90° / 45° / 0° / -45° / 0°)s, the sequence is repeated twice, " / " indicates that different plies are separated, and "s" indicates symmetrical plies, arranged in order from bottom to top (or from the mold surface to the outside); The unidirectional carbon fiber cord fabric is cut into 14 rectangles of 600mm × 300mm as the skin layup. The layup angle of the skin layup is: (45° / -45° / 0° / -45° / 90° / 45° / 0°)s, the sequence is repeated twice, arranged in order from bottom to top (or from the mold surface to the outside).

[0040] Step 4: Laying and fixing like Figure 4 As shown, the reinforcing strips are layered and stacked on a double-needle sewing mold; The skin layer is placed over the rib layer and the position is fixed by double-needle stitching the recessed area at the top of the mold.

[0041] Step 5: Double-needle suture A three-dimensional stitching machine (KSL GmbH, Germany) controlled by a six-axis robot simultaneously stitches the flanges of the rib ply and the skin ply along a single-sided flange path (stitch spacing 3mm, suture spacing 2mm), forming two parallel stitches in one stitch to obtain a double-stitch preform, such as... Figure 5 As shown; The principle and process of this double-needle suture are as follows: Figure 9 As shown, (a) the suture prefabricated body 3 is placed flat on the suture support table 4, and the positions of each mechanism are in the initial state; (b) the mechanism is in operation, with the hook needle 1 and the guide needle 2 moving simultaneously, and the suture 5 reaching the lower limit first; (c) the guide needle 2 is pulled back, and due to the friction between the suture 5 and the suture prefabricated body 3, a loop is formed at the top of the guide needle 2; (d) the hook needle moves downward and passes through the middle of the loop; (e) the guide needle 2 is pulled out of the prefabricated body, and the hook needle begins to pull back; (f) the suture falls into the tip groove during the pullback of the hook needle and is hooked out by the hook needle, thus completing one suture cycle.

[0042] Step 6: Encapsulation and Curing Place the double-stitch preform into the molding mold, and then lay the release cloth, flow guide net, and vacuum bag in sequence; Evacuate to -0.1 MPa and inject preheated epoxy resin at 80℃; After curing at 120℃ for 2 hours, the temperature is raised to 180℃ and held for 4 hours to obtain a single-flanged L-shaped stiffened wall panel, such as... Figure 6 As shown.

[0043] Example 2 The preparation of double-flanged T-shaped stiffened wall panels includes the following steps: Step 1: Prepare raw materials Carbon fiber cloth: Unidirectional carbon fiber cord fabric (thickness 0.1 mm, areal density 100 gsm). Suture material: 400D / 3 aramid 1414 twisted yarn; Mold material: 410 polyurethane wood substitute (density 0.58 g / cm³) 3 ); Resin: Epoxy resin LY1564SP; Step 2: Process the double-needle sewing mold Double-needle sewing molds are manufactured using digital models, such as... Figure 2 and Figure 3 As shown, the parameters are as follows: Length L1 = 600mm, width W1 = 150mm, height H1 = 100mm; The top depression height H2 = 2.2 mm; The depth of the inclined groove is H3=57mm on one side and H4=72mm on the other side; The top width of the sloping groove is W3=29mm, and the bottom width is W4=25mm.

[0044] Step 3: Trim the reinforcing bar layers and the skin layers The unidirectional carbon fiber cord fabric is cut into 44 rectangles of 600mm × 100mm each as reinforcement layers. The layup angle of the reinforcement layers is as follows: (45° / -45° / 0° / -45° / 0° / 45° / 90° / 45° / 0° / -45° / 0°)2s, the sequence is repeated four times, arranged in order from bottom to top (or from the mold surface to the outside); The unidirectional carbon fiber cord fabric is cut into 14 rectangles of 600mm × 300mm as the skin layup. The layup angle of the skin layup is: (45° / -45° / 0° / -45° / 90° / 45° / 0°)s, the sequence is repeated twice, arranged in order from bottom to top (or from the mold surface to the outside).

[0045] Step 4: Laying and fixing The reinforcing strips are symmetrically layered on both sides of the double-needle sewing mold; Fill the joint of the reinforcing ribs (R zone) with polyurethane tack strips (5 mm in diameter), such as... Figure 7 As shown; The skin layup is placed over the rib layup and twist strips, and the position is fixed by double-needle stitching in the recessed area at the top of the mold.

[0046] Step 5: Double-needle suture A three-dimensional stitching machine (KSL, Germany) controlled by a six-axis robot is used to simultaneously stitch the rib ply and skin ply along one side of the flange direction. Then, the rotating sewing head of the double-needle stitching device is rotated 180° and stitched along the other side of the flange direction, forming two parallel stitches in one stitch, thus obtaining a double-stitch preform.

[0047] Step 6: Encapsulation and Curing Place the double-stitch preform into the molding mold, and then lay the release cloth, flow guide net, and vacuum bag in sequence; Evacuate to -0.1 MPa and inject preheated epoxy resin at 80℃; Curing at 120℃ for 2 hours, then raising the temperature to 180℃ and holding for 4 hours, yields a double-flanged T-shaped stiffened wall panel, such as... Figure 8 As shown.

[0048] Comparative Example Compared to Example 1, the double-needle stitching mold was not used, but all other steps were the same. The process for stitching the flanges of the rib ply and the skin ply was as follows: Figure 10As shown, (a) shows the rib ply's flange being pre-shaped below the skin ply's flange by spraying adhesive, and (b) and (c) show the suture needle pushing out the rib ply's flange during the sewing process, preventing the sewing process from running normally. This indicates that without the double-needle sewing mold of this application, the rib ply cannot be sewn to the skin ply.

[0049] In summary, this application is the first to apply stitch reinforcement to mainstream reinforced structures (L-type / C-type / Z-type / T-type / I-type / J-type) without foam cores. The stitches penetrate the skin and the stiffener flanges, forming a three-dimensional reinforcement network. The stitches provide Z-axis reinforcement, thereby increasing interlaminar shear strength and toughness, improving damage tolerance, and eliminating the weak points prone to delamination at the contact surfaces between the skin and stiffener flanges. This improves the overall performance of the reinforced panel and solves the problem of insufficient interlaminar strength in traditional adhesive / co-curing processes. This application employs a double-needle synchronous stitching technique, which can simultaneously form two stitches, significantly improving stitching efficiency compared to conventional single-needle stitching. Based on the characteristics of double-needle stitching, this application designs a double-needle stitching mold with oblique grooves along the stitching direction. The depth and width of these grooves are adapted to the movement trajectory of the double needles, ensuring zero collision during stitching while providing support and fixation for the skin and stiffener layups. Furthermore, a single mold is compatible with single flanges (L-type / C-type / Z-type). With double-flanged (T-type / I-type / J-type) structures, it can cover most of the structural forms of stiffened panels in the aerospace field, replacing the traditional adhesive bonding between the skin and the stiffening flange.

[0050] The above description is merely an optional embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for preparing a double-needle stitched reinforced wall panel structure, characterized in that, Includes the following steps: Based on the reinforced wall panel structure, a digital model of a double-needle sewing mold is designed and processed. The double-needle sewing mold has an oblique groove along the sewing direction, and the depth and width of the oblique groove are adapted to the movement trajectory of the double needles. Based on the reinforced wall panel structure, carbon fiber cloth is cut into stiffener layup and skin layup respectively. The reinforcing bar layer and the skin layer are laid on the double-needle stitching mold in a preset order and then fixed. Using a double-needle suturing device, the suture thread is simultaneously sutured along the suturing path to the flange of the rib ply and the flange of the skin ply, forming a double-stitch prefabricated body; The double-line preform is impregnated with resin using a vacuum-assisted liquid molding process, and after curing, a reinforced and stiffened wall panel structure is obtained.

2. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, The carbon fiber fabric is one of the following: carbon fiber unidirectional fabric, carbon fiber plain weave fabric, carbon fiber twill weave fabric, carbon fiber satin weave fabric, carbon fiber woven fabric, and carbon fiber warp knitted fabric; the sewing thread is made of one of the following: nylon, polyester, aramid, polyarylate, and poly(p-phenylenebenzodioxazole).

3. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, In the step of designing and machining the digital model of the double-needle sewing mold, wherein the double-needle sewing mold has an oblique groove along the sewing direction, and the depth and width of the oblique groove are adapted to the movement trajectory of the double needles, the double-needle sewing mold is manufactured by a five-axis machine tool or 3D printing, and the material of the double-needle sewing mold is one of steel, aluminum alloy or hard plastic; the depth of the oblique groove is 50mm-80mm, and the width of the oblique groove is 20mm-30mm.

4. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, In the steps of separately cutting carbon fiber cloth as reinforcement layup and skin layup, the layup angle of the reinforcement layup includes one or more combinations of 0°, ±45° and 90°; the layup angle of the skin layup includes one or more combinations of 0°, ±45° and 90°.

5. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, The double-needle suturing device is a three-dimensional suturing machine controlled by a six-axis robot. The double-needle suturing device includes a rotating sewing head, and performs multi-angle suturing through the rotating sewing head. The suturing path of the double-needle suturing device includes straight lines, curves, or complex three-dimensional curved surfaces, and forms two parallel stitches in one suturing operation.

6. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, The reinforced wall panel structure is a single-flanged structure, including one of L-shaped reinforced wall panels, C-shaped reinforced wall panels, or Z-shaped reinforced wall panels.

7. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 6, characterized in that, The step of using a double-needle suturing device to simultaneously sew the flanges of the rib ply and the skin ply along the suturing path to form a double-stitch prefabricated body includes: Using a double-needle sewing device, along the direction of one-sided flange, the suture thread is simultaneously sewn to the flange of the rib ply and the flange of the skin ply, and two parallel stitches are formed in one sewing to obtain a double-stitch preform.

8. The method for preparing the double-needle stitched reinforced wall panel structure according to claim 5, characterized in that, The reinforced wall panel structure is a double-flanged structure, including one of T-type reinforced wall panels, I-type reinforced wall panels, or J-type reinforced wall panels.

9. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 8, characterized in that, The step of using a double-needle suturing device to simultaneously sew the flanges of the rib ply and the skin ply along the suturing path to form a double-stitch prefabricated body includes: Using a double-needle sewing device, along one side of the flange direction, the suture thread is simultaneously sewn together with the flange of the rib ply and the flange of the skin ply. Then, the rotating sewing head of the double-needle sewing device is rotated 180°, and along the other side of the flange direction, the suture thread is simultaneously sewn together with the flange of the rib ply and the flange of the skin ply. During sewing, twist strips are filled at the flange joint, and two parallel stitches are formed in one sewing to obtain a double-stitch preform.

10. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 1, characterized in that, In the step of impregnating the double-line preform with resin through a vacuum-assisted liquid molding process and curing it to obtain a reinforced and stiffened wall panel structure, the resin is one of epoxy resin, phenolic resin or bismaleimide resin; the curing process is hot pressing curing or oven curing.

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