Preparation method of double-needle suture reinforced stiffened wallboard structure

Abstract

The invention discloses a preparation method of a double-needle suture reinforced stiffened wallboard structure, and relates to the technical field of fiber composite material reinforcement. Comprising the following steps that a digital model of a double-needle suture mold is designed and processed according to the structure of the stiffened wall plate, an inclined groove is formed in the double-needle suture mold in the suture direction, and the depth and the width of the inclined groove are matched with the moving track of double needles; according to the structure of the stiffened wall plate, the carbon fiber cloth is cut off to serve as a rib laying layer and a skin laying layer; the rib laying layer and the skin laying layer are laid on a double-needle sewing mold according to a preset sequence and fixed; synchronously sewing the turned-over edge of the rib laying layer and the turned-over edge of the skin laying layer by using a sewing line along a sewing path by adopting double-needle sewing equipment to form a double-stitch prefabricated body; and impregnating the resin into the double-stitch prefabricated body through a vacuum auxiliary liquid forming process, and curing and forming to obtain the reinforced stiffened wallboard structure. The double-needle synchronous sewing technology is applied to the mainstream reinforced structure of the foam-free sandwich for the first time, the problem that the interlayer strength of a traditional gluing / co-curing process is insufficient is solved, and the structural form of most reinforced wall plates in the aviation field can be covered.

Description

Technical Field

[0001] The present application relates to the technical field of fiber composite material reinforcement, and in particular to a method for preparing a double-needle stitched reinforced stiffened wall panel structure. Background Art

[0002] As the core component of the main load-bearing structure of aviation, stiffened panels are composed of skins and ribs and are widely used in areas such as aircraft wings, fuselages, doors and fuel tanks. The traditional manufacturing method mainly uses prepreg to lay up the skins and ribs separately, and then form them through co-curing, co-bonding or secondary bonding. However, this method has significant defects: the interlayer performance is weak, there is no fiber reinforcement in the out-of-plane direction (Z direction), resulting in low interlayer strength and poor toughness, and easy delamination failure; there is a risk of interface debonding, and the interface between the ribs and the skin is prone to debonding under long-term loads, causing structural safety hazards. In order to improve the interlayer performance, stitching reinforcement technology has been introduced into the field of fiber composite materials. This technology uses stitching lines to penetrate multiple layers of fabric to form Z-direction reinforcement to improve interlayer strength and damage tolerance. However, existing stitching technologies are mainly focused on flat panels or foam-containing sandwich structures (such as hat-type ribs), while the foam-free sandwich reinforced wall panels widely used in the aviation field (such as L-type, C-type, T-type, I-type and other reinforced wall panels) lack effective reinforcement means; and the stitching method mainly adopts single-needle stitching, which only forms a single trace at a time, which is difficult to meet the efficient production needs of aviation composite materials. Summary of the Invention

[0003] The main purpose of this application is to provide a preparation method of a double-needle stitched reinforced stiffened wall panel structure, aiming to solve the technical problems that the existing stitching technology is not suitable for the reinforcement of foam-free sandwich stiffened wall panels and the stitching efficiency is low.

[0004] To achieve the above objectives, the present application proposes a method for preparing a double-needle stitched reinforced wall panel structure, comprising the following steps: According to the reinforced wall panel structure, a digital model of a double-needle sewing mold is designed and processed. The double-needle sewing mold is provided with 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. According to the structure of the reinforced wall panel, carbon fiber cloth is cut into reinforcement layer and skin layer respectively; Laying the rib ply and the skin ply on the double-needle stitching mold in a preset order and fixing them; Using a double-needle sewing device, the sewing thread is used to synchronously sew the flange of the rib layup and the flange of the skin layup along a sewing path to form a double-stitch preform; The double-stitch preform is impregnated with resin through a vacuum-assisted liquid molding process, and after curing and molding, a reinforced stiffened wall panel structure is obtained.

[0005] Optionally, the carbon fiber cloth is 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; the material of the suture thread is one of nylon, polyester, aramid, polyarylate and poly(p-phenylene benzobisoxazole).

[0006] Optionally, in the step of designing a digital model of a double-needle suture mold and processing it, the double-needle suture mold opens an oblique groove along the suture direction, and the depth and width of the oblique groove adapt to the moving trajectory of the double needle. The double-needle suture mold is processed by a five-axis machine tool or 3D printing, and the material of the double-needle suture 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 steps of separately cutting carbon fiber cloth as rib plies and skin plies, the ply angles of the rib plies include one or more combinations of 0°, ±45°, and 90°; the ply angles of the skin plies include one or more combinations of 0°, ±45°, and 90°.

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

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

[0010] Optionally, the step of using a double-needle sewing device to synchronously sew the flange of the rib layup and the flange of the skin layup along a sewing path to form a double-stitch preform includes: A double-needle sewing device is used to synchronously sew the flange of the rib ply and the flange of the skin ply along the single-side flanging direction, and two parallel stitches are formed in one stitch to obtain a double-stitch preform.

[0011] Optionally, the reinforced wall panel structure is a double-flange 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 sewing device to synchronously sew the flange of the rib layup and the flange of the skin layup along a sewing path to form a double-stitch preform includes: A double-needle sewing device is used to synchronously sew the flange of the rib ply and the flange of the skin ply along the direction of the flanging on one side with the suture thread, and then the rotary sewing head of the double-needle sewing device is rotated 180°, and the flanging of the rib ply and the flange of the skin ply are synchronously sewed along the direction of the flanging on the other side with the suture thread. During sewing, twist strips are filled at the junction of the flangings, and two parallel stitches are formed by one stitch to obtain a double-stitch preform.

[0013] Optionally, in the step of impregnating the double-trace preform with resin through a vacuum-assisted liquid molding process and obtaining a reinforced stiffened wall panel structure after curing and molding, the resin is one of epoxy resin, phenolic resin or bismaleimide resin; and the curing molding process is hot press curing or oven curing.

[0014] The beneficial effects of this application include at least: This application is the first to apply stitching reinforcement to mainstream reinforced structures (L-type / C-type / Z-type / T-type / I-type / J-type) without a foam core. The stitching runs through the skin and the rib flange to form a three-dimensional reinforcement network. The stitching can play a role in Z-direction reinforcement, thereby increasing the interlaminar shear strength and toughness, improving damage tolerance. The contact surface between the skin and the rib flange is no longer a weak point prone to delamination, improving the overall performance of the reinforced wall panel and solving the problem of insufficient interlaminar strength in traditional bonding / co-curing processes. This application uses double-needle synchronous suturing technology, which can form two suture traces at the same time, and the suturing efficiency is significantly improved compared with conventional single-needle suturing; This application designs a double-needle stitching mold based on the process characteristics of double-needle stitching, which has an oblique groove along the stitching direction. The depth and width of the oblique groove are adapted to the moving trajectory of the double needle, ensuring zero collision of the double needle during the stitching process. At the same time, it provides support for the skin layer and the rib layer, playing a fixing role. A single set of molds is adapted to single flange (L-type / C-type / Z-type) and double flange (T-type / I-type / J-type) structures, which can cover most of the structural forms of reinforced wall panels in the aviation field, replacing the traditional bonding between the skin and rib flanges. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0016] Figure 1 This is a flow chart of the method for preparing the double-needle stitched reinforced stiffened wall panel structure described in an embodiment of the present application; Figure 2 This is a schematic structural diagram of the double-needle suture mold described in an embodiment of the present application; Figure 3 This is a cross-sectional schematic diagram of the double-needle suturing mold described in an embodiment of the present application; Figure 4 This is a cross-sectional schematic diagram of the reinforcement layer and the skin layer stacked on a double-needle stitching mold according to an embodiment of the present application; Figure 5 Schematic diagram of the stitches of the double-stitch preform after double-needle stitching according to the embodiment of the present application; wherein (a) is a schematic diagram of the stitches on the front side; (b) is a schematic diagram of the stitches on the back side; Figure 6 This is a schematic structural diagram of a single-flange L-shaped reinforced wall panel according to an embodiment of the present application; Figure 7 This is a cross-sectional schematic diagram of the embodiment of the present application after the rib flanging junction is filled with twist strips; Figure 8 This is a schematic structural diagram of the double-flange T-shaped reinforced wall panel described in an embodiment of the present application; Figure 9 This is a schematic diagram of the double-needle suturing process described in an embodiment of the present application; Figure 10 This is a schematic diagram of the double-needle suturing process described in the comparative example of this application.

[0017] Reference numerals: 1-hook needle; 2-lead needle; 3-suture preform; 4-suture support platform; 5-suture thread.

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

[0019] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0020] In view of the technical problems existing in the prior art, the embodiment of the present application provides a method for preparing a double-needle stitched reinforced wall panel structure, such as Figure 1 As shown, the following steps are included: S1. According to 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. The depth and width of the oblique groove are adapted to the movement trajectory of the double needle.

[0021] During the specific implementation process, the double-needle suture mold is processed by a five-axis machine tool or 3D printing, and the material of the double-needle suture 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.

[0022] Specifically, a 2mm-3mm sunken area is provided on the top of the double-needle stitching mold. The design of the sunken area can accurately fix the positions of the rib layup and the skin layup to avoid displacement of the two during the stitching process, which would affect the stitching reinforcement effect.

[0023] S2. According to the structure of the reinforced wall panel, cut the carbon fiber cloth as the reinforcement layer and the skin layer respectively.

[0024] Specifically, the carbon fiber cloth is 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.

[0025] In a specific implementation process, the laying angle of the rib layup includes one or more combinations of 0°, ±45° and 90°; the laying angle of the skin layup 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 main axis of the material), which determines the mechanical properties of the material. The layup angles of the rib layup and the skin layup of this application may include one or more combinations of 0°, ±45° and 90°. 0° means that the fiber is along the main load direction, mainly providing axial strength and stiffness; ±45° mainly provides shear load resistance to prevent delamination failure; 90° mainly provides lateral support to balance in-plane performance.

[0027] S3. Lay the rib ply and the skin ply on the double-needle sewing mold in a preset order and fix them.

[0028] Specifically, layup methods include symmetrical and asymmetrical layup. Symmetrical layup involves mirroring the 0° layer with the symmetry axis, while asymmetrical layup involves no mirroring rule. When laying up the reinforcement and skin layers, the reinforcement layer is first placed on a double-needle stitching die. Then, as needed, twist strips are added to the rib flange junction (R zone). The twist strips eliminate gaps and enhance interface strength. The skin layer is then overlaid on the reinforcement layer and twist strips. Finally, the recessed area at the top of the double-needle stitching die is used to secure the reinforcement and skin layers in place before stitching.

[0029] S4. Use a double-needle sewing device to synchronously sew the flange of the rib ply and the flange of the skin ply along a sewing path to form a double-stitch preform.

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

[0031] During the specific implementation process, 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. The double-needle suturing device performs multi-angle suturing through the rotating sewing head. The suturing path of the double-needle suturing device includes a straight line, a curve or a complex three-dimensional surface, and two parallel lines are formed in one suturing.

[0032] The reinforced panel structure is a single-flange structure, including one of an L-shaped, C-shaped, or Z-shaped reinforced panel. During the stitching process, a double-needle stitching device is used to simultaneously stitch the flange of the rib layup and the flange of the skin layup along the single-sided flanging direction, forming two parallel seams in one stitch, resulting in a double-stitch preform.

[0033] The reinforced wall panel structure is a double-flange structure, including one of a T-type reinforced wall panel, an I-type reinforced wall panel, or a J-type reinforced wall panel. During the specific sewing process, a double-needle sewing device is used to simultaneously sew the flange of the reinforcement layer and the flange of the skin layer along one side of the flange. The rotary sewing head of the double-needle sewing device is then rotated 180 degrees, and the sewing thread is simultaneously sewn along the other side of the flange. During sewing, a twist strip is filled at the flange junction, and two parallel stitches are formed in one stitch, resulting in a double-stitch preform.

[0034] This application uses a six-axis robot to control a three-dimensional sewing device for sewing, which can support stitching of plane or curved paths, including special-shaped curved surfaces of rib flanges, so as to adapt to complex reinforced wall panel structures. When sewing double flanges, the rotating sewing head directly rotates 180° to sew the flanges on both sides in steps, thereby solving the problem of spatial interference.

[0035] S5. Impregnating the double-stitch preform with resin through a vacuum-assisted liquid molding process, and obtaining a reinforced stiffened wall panel structure after curing and molding.

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

[0037] The above technical solutions of the present application are described in detail below with reference to specific embodiments.

[0038] Example 1 The preparation of the single-flange L-shaped reinforced wall panel includes the following steps: Step 1. Prepare raw materials Carbon fiber cloth: unidirectional carbon fiber cord cloth (thickness 0.1 mm, surface density 100 gsm); Suture thread: 400D / 3 aramid 1414 ply twisted thread; Mold material: 410 polyurethane wood substitute (density 0.58 g / cm 3 ); Resin: Epoxy resin LY1564SP; Step 2: Processing the double-needle suture mold According to the digital model processing double needle sewing mold, such as Figure 2 and Figure 3 As shown, the parameters are as follows: Length L1 = 600mm, width W1 = 150mm, height H1 = 100mm; Top depression height H2 = 2.2mm; The depth of the oblique groove on one side is H3 = 57 mm, and the depth on the other side is H4 = 72 mm; The top width of the oblique groove is W3 = 29 mm, and the bottom width is W4 = 25 mm.

[0039] Step 3: Cut the rib layup and skin layup The unidirectional carbon fiber cord fabric is cut into 22 layers of 600mm×100mm rectangles as reinforcement layers. The laying angle of the reinforcement layers is: (45° / -45° / 0° / -45° / 0° / 45° / 90° / 45° / 0° / -45° / 0°)s, the sequence is repeated twice, “ / ” indicates the separation of different plies, 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 layers of 600mm×300mm rectangles as the skin layer. The laying angle of the skin layer is: (45° / -45° / 0° / -45° / 90° / 45° / 0°)s, the sequence is repeated twice, arranged from bottom to top (or from the mold surface to the outside).

[0040] Step 4: Lay and fix like Figure 4 As shown, the reinforcement layer is laid on a double-needle stitching mold; The skin layer is laid over the rib layer and fixed in place by double-needling the sunken area at the top of the mold.

[0041] Step 5: Double needle suturing A three-dimensional stitching machine controlled by a six-axis robot (KSL, Germany) was used to stitch the flange of the rib layer and the flange of the skin layer synchronously along the single-side flanging path (needle distance 3mm, stitch spacing 2mm), forming two parallel stitches in one stitch to obtain a double-stitch preform, such as Figure 5 As shown; The principle process of double needle suture is as follows Figure 9 As shown, (a) shows that the suture preform 3 is placed flat on the suture support table 4, and the positions of each mechanism are in the initial state; (b) shows that the mechanism is running, the hook needle 1 and the guide needle 2 move at the same time, and the suture thread 5 reaches the lower limit first; (c) shows that the guide needle 2 is retracted, and due to the friction between the suture thread 5 and the suture preform 3, a thread loop is formed at the top of the guide needle 2; (d) shows that the hook needle runs downward and passes through the middle of the thread loop; (e) shows that the guide needle 2 is pulled out from the preform, and the hook needle starts to retract; (f) shows that during the retraction of the hook needle, the suture falls into the tip groove and is hooked out by the hook needle, thereby completing a suture cycle.

[0042] Step 6: Package curing Place the double-stitch preform into the forming mold, and lay the release cloth, guide net, and vacuum bag in sequence; The vacuum was evacuated to -0.1 MPa and epoxy resin preheated at 80°C was injected; After curing at 120℃ for 2h, the temperature was raised to 180℃ and kept at this temperature for 4h to obtain a single-flange L-shaped reinforced wall panel. Figure 6 shown.

[0043] Example 2 The preparation of double-flange T-shaped reinforced wall panels includes the following steps: Step 1. Prepare raw materials Carbon fiber cloth: unidirectional carbon fiber cord cloth (thickness 0.1 mm, surface density 100 gsm); Suture thread: 400D / 3 aramid 1414 ply twisted thread; Mold material: 410 polyurethane wood substitute (density 0.58 g / cm 3 ); Resin: Epoxy resin LY1564SP; Step 2: Processing the double-needle suture mold According to the digital model processing double needle sewing mold, such as Figure 2 and Figure 3 As shown, the parameters are as follows: Length L1 = 600mm, width W1 = 150mm, height H1 = 100mm; Top depression height H2 = 2.2mm; The depth of the oblique groove on one side is H3 = 57 mm, and the depth on the other side is H4 = 72 mm; The top width of the oblique groove is W3 = 29 mm, and the bottom width is W4 = 25 mm.

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

[0045] Step 4: Lay and fix Lay the ribs symmetrically on both sides of the double-needle stitching mold; Fill the rib flange joint (R area) with polyurethane twist strips (5 mm in diameter), such as Figure 7 As shown; The skin layer is covered on the rib layer and the twist strip, and fixed in position by sewing the sunken area on the top of the mold with a double needle.

[0046] Step 5: Double needle suturing A three-dimensional stitching machine (KSL, Germany) controlled by a six-axis robot is used to synchronously stitch the flange of the rib layer and the flange of the skin layer along the direction of the flange on one side. The rotary sewing head of the double-needle stitching device is then rotated 180° to stitch along the direction of the other side of the flange, and two parallel stitches are formed in one stitch to obtain a double-stitch preform.

[0047] Step 6: Package curing Place the double-stitch preform into the forming mold, and lay the release cloth, guide net, and vacuum bag in sequence; The vacuum was evacuated to -0.1 MPa and epoxy resin preheated at 80°C was injected; After curing at 120℃ for 2h, the temperature was raised to 180℃ and kept at this temperature for 4h to obtain a double-flange T-shaped reinforced wall panel. Figure 8 shown.

[0048] Comparative Example Compared with Example 1, the double needle sewing mold is not used, and the other steps are the same. When the flange of the rib layer and the flange of the skin layer are sewn together, the process is as follows: Figure 10As shown, wherein (a) is that the rib layer is preformed under the skin layer by glue spraying, (b) and (c) are that the rib layer is pushed out by the thread needle during the stitching process, and the stitching process cannot be normally operated, which illustrates that the rib layer cannot be stitched with the skin layer without using the double-needle stitching mold of the present application.

[0049] In summary, the present application first applies stitching reinforcement to the mainstream ribbed structure (L type / C type / Z type / T type / I type / J type) without foam sandwich, and the stitching line is penetrated through the skin and the rib flange to form a three-dimensional reinforcement network. The stitching line can play a role in Z-direction reinforcement, thereby increasing the interlaminar shear strength and toughness, improving the damage tolerance, and improving the comprehensive performance of the ribbed wall panel. The contact surface between the skin and the rib flange is no longer a weak point prone to delamination, and the problem of insufficient interlaminar strength in the traditional bonding / curing process is solved. The present application uses double-needle synchronous stitching technology, which can form two stitching lines at a time, and the stitching efficiency is significantly improved compared with the conventional single-needle stitching. According to the process characteristics of double-needle stitching, the present application designs a double-needle stitching mold, which is provided with a diagonal groove along the stitching direction. The depth and width of the diagonal groove are adapted to the movement trajectory of the double needle to ensure that the double needle moves without collision during the stitching process, and at the same time, the diagonal groove provides support for the skin layer and the rib layer, and plays a fixing role. In addition, a single set of mold is suitable for single flange (L type / C type / Z type) and double flange (T type / I type / J type) structure, which can cover most of the structure forms of the ribbed wall panel in the aviation field, and replace the traditional bonding between the skin and the rib flange.

[0050] The above only describes the optional embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation based on the inventive concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for preparing a double-needle sewing reinforced wall panel structure, characterized in that: The following steps are involved: According to the reinforced wall panel structure, a digital model of a double-needle sewing mold is designed and processed. The double-needle sewing mold is provided with 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. According to the structure of the reinforced wall panel, carbon fiber cloth is cut into reinforcement layer and skin layer respectively; Laying the rib ply and the skin ply on the double-needle stitching mold in a preset order and fixing them; Using a double-needle sewing device, the sewing thread is used to synchronously sew the flange of the rib layup and the flange of the skin layup along a sewing path to form a double-stitch preform; The double-stitch preform is impregnated with resin through a vacuum-assisted liquid molding process, and after curing and molding, a reinforced stiffened wall panel structure is obtained.

2. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 1, characterized in that: The carbon fiber cloth is 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; the material of the suture thread is one of nylon, polyester, aramid, polyarylate and poly(p-phenylene benzobisoxazole).

3. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 1, characterized in that: In the step of designing a digital model of a double-needle suture mold and processing it, the double-needle suture mold opens an oblique groove along the suture direction, and the depth and width of the oblique groove adapt to the movement trajectory of the double needle. The double-needle suture mold is processed by a five-axis machine tool or 3D printing, and the material of the double-needle suture 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 a double-needle stitched reinforced wall panel structure according to claim 1, characterized in that: In the steps of separately cutting carbon fiber cloth as rib plies and skin plies, the ply angles of the rib plies include one or more combinations of 0°, ±45°, and 90°; the ply angles of the skin plies include one or more combinations of 0°, ±45°, and 90°.

5. The method for preparing a 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. The double-needle suturing device performs multi-angle suturing through the rotating sewing head. The suturing path of the double-needle suturing device includes a straight line, a curve or a complex three-dimensional surface, and two parallel lines are formed in one suturing.

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-flange structure, including one of an L-shaped reinforced wall panel, a C-shaped reinforced wall panel or a Z-shaped reinforced wall panel.

7. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 6, characterized in that: The step of using a double-needle sewing device to synchronously sew the flange of the rib ply and the flange of the skin ply along a sewing path to form a double-stitch preform includes: A double-needle sewing device is used to synchronously sew the flange of the rib ply and the flange of the skin ply along the single-side flanging direction, and two parallel stitches are formed in one stitch to obtain a double-stitch preform.

8. The method for preparing a double-needle stitched reinforced wall panel structure according to claim 5, characterized in that: The reinforced wall panel structure is a double-flange structure, including one of a T-shaped reinforced wall panel, an I-shaped reinforced wall panel or a J-shaped reinforced wall panel.

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 sewing device to synchronously sew the flange of the rib ply and the flange of the skin ply along a sewing path to form a double-stitch preform includes: A double-needle sewing device is used to synchronously sew the flange of the rib ply and the flange of the skin ply along the direction of the flanging on one side with the suture thread, and then the rotary sewing head of the double-needle sewing device is rotated 180°, and the flanging of the rib ply and the flange of the skin ply are synchronously sewed along the direction of the flanging on the other side with the suture thread. During sewing, twist strips are filled at the junction of the flangings, and two parallel stitches are formed by one stitch 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-trace preform with resin through a vacuum-assisted liquid molding process and obtaining a reinforced stiffened wall panel structure after curing and molding, the resin is one of epoxy resin, phenolic resin or bismaleimide resin; the curing molding process is hot pressing curing or oven curing.

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