A method for connecting composite material and metal skeleton based on unequal thickness mold cavity

Abstract

The application provides a connecting method of a composite material and a metal framework based on an unequal-thickness mold cavity, comprising the following steps: manufacturing a mold according to a line type of a composite material shell plate; manufacturing a connecting area laminated plate preform; manufacturing a connecting area preform; filling a polyurethane core mold in a metal framework; laying a lower panel fiber material on the metal framework and the polyurethane core mold, and laying an upper panel fiber material on the mold; laying a flexible fabric on the lower panel fiber material and the upper panel fiber material, wherein the mold, the upper panel fiber material and the flexible fabric form a first structure, and the metal framework, the polyurethane core mold, the lower panel fiber material and the flexible fabric form a pre-structure; forming a second structure after installing the connecting area preform and a first core material on the pre-structure; and integrating and forming the second structure on the first structure. The connecting method can avoid uneven resin flow rate during vacuum infusion, and can improve forming quality and structural strength.

Description

Technical Field

[0001] This invention relates to the field of composite material molding, and more specifically, to a method for connecting a composite material and a metal skeleton based on a mold cavity of unequal thickness. Background Technology

[0002] Fiber-reinforced resin matrix composites are high-performance materials with excellent stiffness, mechanical properties, vibration damping, and weight reduction effects, and are widely used in the manufacture of yachts, luxury cruise ships, and other shipbuilding industries. In the molding process of thick composite materials, the connection between the composite material and the metal frame structure is often involved, and the connection structure and molding quality directly affect the safety and stability of the overall structure.

[0003] Currently, most thick composite materials with metal frames are formed using vacuum-assisted processes. The connection area between the composite material and the metal frame is mainly formed by pre-forming a preform, followed by integrated molding. Patent application CN202210668419.9 discloses a method for connecting an integrated composite material skin to a skeleton, including the following steps: (1) processing a mold according to the skeleton structure; (2) laying reinforcing material on the mold surface, sealing the mold, and curing a U-shaped connector according to process requirements; (3) demolding the U-shaped connector; (4) bonding the inner cavity of the U-shaped connector to the skeleton; (5) integrally molding the outer side of the U-shaped connector with the composite material skin. The method for connecting the composite material skin to the skeleton mentioned in this patent involves pre-forming a composite material preform and then integrally molding the composite material skin. The molding accuracy of this method is mainly controlled by mold-closing technology. During resin injection, the composite material is located between the metal skeleton and the mold. The composite material below the metal frame is subjected to pressure from the vacuum and the weight of the metal frame itself. Although the gap between the composite material and the mold can be precisely controlled during the initial mold closing, slight differences in the mold closing gap will cause uneven stress on the composite material under the metal frame. The gaps between the composite material layers with high stress are smaller, while the gaps between the composite material layers with low stress are larger. The unevenness of the gaps results in unequal thickness of the mold cavity between the metal frame and the mold. This causes different resin flow rates during vacuum injection. The resin cannot fully penetrate the areas with smaller gaps, which are under greater pressure from the metal frame, and greatly affects the molding quality and structural strength of the connection area between the composite material and the metal frame.

[0004] How to design a molding method for composite material connection areas based on unequal thickness mold cavities to improve the molding quality of composite material and metal structure connection structures with large thickness unequal thickness mold cavities is a key problem that urgently needs to be solved in this field.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to propose a method for connecting composite materials and metal skeletons based on unequal thickness mold cavities, in order to solve the problem in the prior art where the mold cavity between the metal skeleton and the mold has unequal thickness. This causes different resin flow rates during vacuum injection, and the resin cannot fully penetrate the areas under greater pressure from the metal frame, which greatly affects the molding quality and structural strength of the connection area between the composite material and the metal frame.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for connecting a composite material and a metal skeleton based on a mold cavity of unequal thickness, the method comprising the following steps:

[0009] S1. Make corresponding molds according to the profile of the composite material shell plate;

[0010] S2. Fabricate the prefabricated laminated slab structure for the connection area;

[0011] S3. Bond the core material of the transition area to the laminated precast body to make the connection area precast body, and reduce the thickness of the connection area precast body.

[0012] S4. Fill the metal frame with polyurethane core mold;

[0013] S5. Lay the lower panel fiber material on the metal frame and polyurethane core mold, and lay the upper panel fiber material on the mold.

[0014] S6. Flexible fabric is laid on both the bottom panel fiber material and the top panel fiber material. The mold, the top panel fiber material and the flexible fabric form a first structure. The metal skeleton, the polyurethane core mold, the bottom panel fiber material and the flexible fabric form a prestructure.

[0015] S7. After installing the prefabricated connecting area body and the first core material on the pre-structure, a second structure is formed;

[0016] S8. The second structure is attached to the first structure and integrally formed.

[0017] The warp and weft weaving density of the flexible fabric is reduced by 50% to 80% compared with the fiber materials of the upper and lower panels, and the weight of the flexible fabric is increased by 20% to 50% compared with the fiber materials of the upper and lower panels.

[0018] Furthermore, the thickness of the flexible fabric is 1 to 5 mm.

[0019] Furthermore, the flexible fabric, the upper panel fiber material, and the lower panel fiber material are of the same material system.

[0020] Furthermore, the flexible fabric includes a first fabric and a second fabric, wherein the first fabric is laid on the top plate fiber material and the second fabric is laid on the bottom plate fiber material.

[0021] Furthermore, the core material of the transition region and the first core material are made of at least one of polyurethane foam, polymethacrylamide foam, polyetherimide foam, polystyrene foam, polyvinyl chloride foam, polyethylene foam, and acrylonitrile-styrene foam.

[0022] Furthermore, the flexible fabric, the upper panel fiber material, and the lower panel fiber material are at least one of glass fiber, carbon fiber, and aramid fiber material systems.

[0023] Furthermore, the metal frame is made of at least one of steel, aluminum alloy, magnesium alloy, copper alloy, and titanium alloy.

[0024] Furthermore, the mold material is at least one of metal, wood, and composite materials.

[0025] Furthermore, the matrix resin of the composite material or laminate preform is at least one of unsaturated polyester resin, vinyl resin, phenolic resin, epoxy resin, and bismaleimide resin.

[0026] Furthermore, the molding process of the composite material and laminate preform is one of liquid molding, prepreg molding, or hand lay-up molding.

[0027] This invention proposes a method for connecting a composite material and a metal skeleton based on a mold cavity of unequal thickness. Compared with the prior art, the method for connecting a composite material and a metal skeleton based on a mold cavity of unequal thickness described in this invention has the following advantages:

[0028] (1) The present invention provides a method for connecting composite materials and metal skeletons based on unequal thickness mold cavities. By reducing the thickness of the preform in the connection area, on the one hand, it avoids the resin from being difficult to penetrate the underlying fabric due to the large thickness of the preform in the connection area, thus avoiding molding defects; on the other hand, it provides a laying space for laying flexible fabrics.

[0029] (2) The present invention describes a method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness. Flexible fabric is laid on both the bottom plate fiber material and the top plate fiber material. The flexible fabric is easy to extend and can effectively avoid the unevenness of the gap between the preform in the connection area and the bottom plate fiber material and the top plate fiber material, thereby avoiding the uneven resin flow rate during vacuum injection.

[0030] (3) The present invention provides a method for connecting composite materials and metal skeletons based on unequal thickness mold cavities. The method is simple and the materials are readily available. It can effectively improve the molding quality of composite materials and metal structures connected by large thickness unequal thickness mold cavities. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of the laying of a composite material and metal skeleton connection method based on unequal thickness mold cavity according to an embodiment of the present invention on a mold.

[0032] Figure 2 This is a schematic cross-sectional view of the laying of a composite material and a metal skeleton based on an unequal thickness mold cavity, as described in an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of an inverted cross-section of a molding method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness, as described in an embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Mold; 2. Upper panel fiber material; 3. Flexible fabric; 31. First fabric; 32. Second fabric; 4. Transition area core material; 5. Laminated preform; 6. Lower panel fiber material; 7. Polyurethane core mold; 8. Metal skeleton; 9. First core material. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. The descriptions of "first," "second," etc., mentioned in the embodiments of the present invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] In the prior art, when the connection area between the composite material and the metal skeleton 8 is molded, the cavity between the metal skeleton 8 and the mold 1 has different thicknesses. This causes the resin flow rate to be different during vacuum injection. The resin cannot fully penetrate the area under greater pressure from the metal skeleton 8, which greatly affects the molding quality and structural strength of the connection area between the composite material and the metal skeleton 8.

[0039] To address the aforementioned technical problems, this invention proposes a method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness, such as... Figures 1-3 As shown, the thickness of the preform in the connection area is reduced, and flexible fabric 3 is laid on both the lower panel fiber material 6 and the upper panel fiber material 2. The good flexibility and extensibility of the flexible fabric 3 can adjust the gap between the preform in the connection area and the lower panel fiber material 6 and the upper panel fiber material 2, which can effectively improve the molding quality of the composite material and metal structure connection structure with large thickness cavities.

[0040] Specifically, the method for connecting the composite material and the metal skeleton based on the unequal thickness mold cavity includes the following steps:

[0041] S1. Make the corresponding mold 1 according to the shape of the composite material shell plate;

[0042] S2. Fabricate the prefabricated laminate 5 for the connection area as the connection part between the composite material and the metal skeleton 8, which can improve the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0043] S3. Bond the transition area core material 4 onto the laminated preform 5 to create the connecting area preform. Reduce the thickness of the connecting area preform by 1-5mm. On the one hand, this avoids the resin from being unable to penetrate the underlying fabric due to the large thickness of the connecting area preform, thus avoiding molding defects. On the other hand, it provides space for laying the flexible fabric 3.

[0044] S4. Polyurethane core mold 7 is filled into the metal skeleton 8 frame to prepare for the forming of the connection structure between the composite material and the metal skeleton 8.

[0045] S5. Lay the lower panel fiber material 6 on the metal frame 8 and the polyurethane core mold 7, and lay the upper panel fiber material 2 on the mold 1.

[0046] S6. Flexible fabric 3 is laid on both the bottom panel fiber material 6 and the top panel fiber material 2. The mold 1, the top panel fiber material 2 and the flexible fabric 3 form a first structure. The metal skeleton 8, the polyurethane core mold 7, the bottom panel fiber material 6 and the flexible fabric 3 form a pre-structure.

[0047] During the molding process, due to the presence of the flexible fabric 3, the resin can more easily penetrate into every corner of the connection area, thereby effectively improving the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0048] S7. After installing the prefabricated connecting area body and the first core material 9 on the pre-structure body, the second structure body is formed to prepare for the subsequent molding process.

[0049] S8. The second structure is attached to the first structure and integrally formed.

[0050] The warp and weft weaving density of the flexible fabric 3 is reduced by 50% to 80% compared with the upper panel fiber material 2 and the lower panel fiber material 6, and the weight of the flexible fabric 3 is increased by 20% to 50% compared with the upper panel fiber material 2 and the lower panel fiber material 6. This design gives the flexible fabric 3 good flexibility and extensibility, and can adjust the gap between the prefabricated body of the connection area and the upper panel fiber material 2 and the lower panel fiber material 6.

[0051] The present invention discloses a method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness. Steps S1 to S8 are interconnected and inseparable, serving multiple functions: First, it effectively avoids the unevenness of gaps between the preform in the connection area and the lower panel fiber material 6 and the upper panel fiber material 2, thereby avoiding the problem of uneven resin flow rate during vacuum infusion, and thus avoiding molding defects. There are no missing glue, bubbles or white spots with a diameter greater than 4mm inside the composite material of the upper and lower panels at the laminate preform 5; Second, the resin can more easily penetrate into all corners of the connection area, effectively improving the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8; Third, the connection method is simple, the materials are readily available, and the cost is low.

[0052] Specifically, the flexible fabric 3 has a thickness of 1 to 5 mm, which reduces production costs while ensuring that it can effectively adjust gaps and improve the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0053] Specifically, the flexible fabric 3, the upper panel fiber material 2, and the lower panel fiber material 6 are of the same material system, which can ensure their compatibility and bonding force, thereby further improving the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0054] Specifically, such as Figure 1 and Figure 2 As shown, the flexible fabric 3 includes a first fabric 31 and a second fabric 32. The first fabric 31 is laid on the top plate fiber material 2, and the second fabric 32 is laid on the bottom plate fiber material 6.

[0055] More specifically, in step S6, flexible fabric 3 is laid at the corresponding position of the preform in the connection area of ​​the lower panel fiber material 6 and the upper panel fiber material 2. This reduces production costs while ensuring that the fabric can effectively adjust gaps and improve the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0056] Specifically, the thickness of the composite material is 1 to 10 mm.

[0057] Specifically, the flexible fabric 3, the upper panel fiber material 2, and the lower panel fiber material 6 are at least one of glass fiber, carbon fiber, and aramid fiber material systems.

[0058] Specifically, the metal frame 8 is made of at least one of steel, aluminum alloy, magnesium alloy, copper alloy and titanium alloy.

[0059] Specifically, the mold 1 is made of at least one of metal, wood, and composite materials.

[0060] Specifically, the matrix resin of the composite material and laminate preform 5 is at least one of unsaturated polyester resin, vinyl resin, phenolic resin, epoxy resin and bismaleimide resin.

[0061] Specifically, the molding process of the composite material and laminate preform 5 is one of liquid molding, prepreg molding, and hand lay-up molding.

[0062] Specifically, the core material 4 in the transition region and the first core material 9 are made of at least one of polyurethane foam, polymethacrylamide foam, polyetherimide foam, polystyrene foam, polyvinyl chloride foam, polyethylene foam, and acrylonitrile-styrene foam.

[0063] Specifically, the core material 4 of the transition area is bonded to both sides of the laminate preform 5 using an adhesive, wherein the adhesive is at least one of epoxy, polyurethane, acrylic and vinyl adhesives.

[0064] More specifically, the upper panel fiber material 2 and the lower panel fiber material 6 are at least one of fiber fabric and chopped strand mat.

[0065] Example 1

[0066] This embodiment proposes a method for connecting composite materials and metal skeletons based on unequal thickness mold cavities.

[0067] The metal frame 8 is made of steel, specifically Q355D steel. Figure 2 and Figure 3 As shown, the frame cross-section of the metal skeleton 8 is an I-beam structure, the composite material shell plate is a glass fiber foam sandwich composite material, and the thickness of the first core material 9 is 50mm.

[0068] The connection method includes the following steps:

[0069] Specifically, the method for connecting the composite material and the metal skeleton based on the unequal thickness mold cavity includes the following steps:

[0070] S1. Make a corresponding mold 1 according to the shape of the composite shell plate. The shape of mold 1 is offset outward according to the shape of the skeleton to determine the thickness of the composite shell plate.

[0071] S2. Fabricate precast laminated slabs for the connection area 5;

[0072] S3. Bond the transition area core material 4 onto the laminated precast body 5 to make the connection area precast body, and reduce the thickness of the connection area precast body by 1mm.

[0073] S4. Fill the polyurethane core mold 7 within the metal skeleton 8 frame.

[0074] S5. Lay the lower panel fiber material 6 on the metal frame 8 and the polyurethane core mold 7, and lay the upper panel fiber material 2 on the mold 1.

[0075] S6. Flexible fabric 3 is laid on both the bottom panel fiber material 6 and the top panel fiber material 2. The mold 1, the top panel fiber material 2 and the flexible fabric 3 form a first structure. The bottom panel fiber material 6 and the flexible fabric 3 are laid on the metal skeleton 8 and the polyurethane core mold 7 to form a pre-structure.

[0076] S7. After installing the prefabricated connecting area body and the first core material 9 on the pre-structure, the second structure is formed;

[0077] S8. The second structure is attached to the first structure and vacuum-assisted integrated molding is performed. After curing at room temperature for 48 hours, the structure is demolded.

[0078] The warp and weft weaving density of the flexible fabric is reduced by 65% ​​compared with the upper panel fiber material 2 and the lower panel fiber material 6, and the weaving weight of the flexible fabric is increased by 35% compared with the upper panel fiber material 2 and the lower panel fiber material 6.

[0079] Specifically, the thickness of the flexible fabric 3 is 1 mm.

[0080] Specifically, the flexible fabric 3, the upper panel fiber material 2, and the lower panel fiber material 6 are of the same material system; the flexible fabric 3, the upper panel fiber material 2, and the lower panel fiber material 6 are all glass fiber fabrics.

[0081] Specifically, the flexible fabric 3 includes a first fabric 31 and a second fabric 32. The first fabric 31 is laid on the top plate fiber material 2, and the second fabric 32 is laid on the bottom plate fiber material 6.

[0082] Step S2 is as follows: when making the laminate preform 5, 55 layers of high-strength glass fiber fabric are laid. After the laying is completed, vacuum sealing is performed, and vacuum infusion is completed using matrix resin. After curing at room temperature for 24 hours, the laminate preform 5 with a thickness of 11mm is demolded.

[0083] Specifically, step S3 includes the following steps:

[0084] S31. Adhesive is used to bond a trapezoidal transition area core material 4 with a length of 120mm to both sides of the laminate prefabricated body 5 to create a connection area prefabricated body.

[0085] S32. Reduce the thickness of the precast body in the connection area by 1mm.

[0086] Specifically, the adhesive is a vinyl adhesive.

[0087] Step S5 specifically involves laying a lower panel fiber material 6 on the metal skeleton 8 and the polyurethane core mold 7, and laying an upper panel fiber material 2 on the mold 1. The upper panel fiber material 2 and the lower panel fiber material 6 are high-strength glass fiber fabrics with 25 layers, and the thickness of the upper panel fiber material 2 and the lower panel fiber material 6 is 5mm.

[0088] Step S6 specifically involves laying flexible fabric 3 on both the bottom panel fiber material 6 and the top panel fiber material 2. The flexible fabric 3 is a high-strength glass fiber fabric with three layers and a thickness of 1 mm.

[0089] More specifically, in step S6, flexible fabric 3 is laid at the corresponding position of the preform in the connection area of ​​the lower panel fiber material 6 and the upper panel fiber material 2. This reduces production costs while ensuring that the fabric can effectively adjust gaps and improve the molding quality and structural strength of the connection structure between the composite material and the metal skeleton 8.

[0090] Specifically, the core material 4 in the transition region and the first core material 9 are made of polyurethane foam.

[0091] Specifically, the mold 1 is made of wood.

[0092] Specifically, the matrix resin of the composite material and laminate preform 5 is vinyl resin.

[0093] Specifically, the molding process of the composite material and laminate preform 5 is a liquid molding process.

[0094] More specifically, in this embodiment, the molding process of the composite material and laminate preform 5 is a vacuum-assisted molding process of liquid molding.

[0095] Example 2

[0096] In this embodiment, unlike in embodiment 1,

[0097] In step S2, the thickness of the prefabricated body in the connection area is reduced by 5 mm.

[0098] In step S6, the thickness of the flexible fabric 3 is 5 mm.

[0099] The warp and weft weaving density of the flexible fabric 3 is reduced by 50% compared with the upper panel fiber material 2 and the lower panel fiber material 6, and the weaving weight of the flexible fabric 3 is increased by 50% compared with the upper panel fiber material 2 and the lower panel fiber material 6.

[0100] Example 3

[0101] In this embodiment, unlike in embodiment 1,

[0102] In step S2, the thickness of the prefabricated body in the connection area is reduced by 3 mm.

[0103] In step S6, the thickness of the flexible fabric 3 is 3 mm.

[0104] The warp and weft weaving density of the flexible fabric 3 is reduced by 80% compared with the upper panel fiber material 2 and the lower panel fiber material 6, and the weaving weight of the flexible fabric 3 is increased by 20% compared with the upper panel fiber material 2 and the lower panel fiber material 6.

[0105] Comparative Example 1

[0106] In this comparative example, unlike Example 1, flexible fabric 3 is not laid on either the bottom panel fiber material 6 or the top panel fiber material 2.

[0107] Performance testing

[0108] The composite material and metal structure connection structures prepared by the method of connecting composite material and metal skeleton based on unequal thickness mold cavity in Examples 1-3 and Comparative Example 1 were tested under the same conditions. The pull-out load between the composite material and metal skeleton in Examples 1-3 and Comparative Example 1 is shown in Table 1.

[0109] Table 1. Pull-off loads between the composite material and the metal skeleton in Examples 1-3 and Comparative Example 1.

[0110]

[0111] As can be seen from Table 1, the pull-out load of the composite material and metal structure connection structure prepared by the method of connecting composite material and metal skeleton based on unequal thickness mold cavity in Examples 1 to 3 of the present invention has a significant improvement of about 35% compared with Comparative Example 1.

[0112] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness, characterized in that, The method for connecting the composite material and the metal skeleton based on the unequal thickness mold cavity includes the following steps: S1. Make the corresponding mold according to the shape of the composite shell plate (1); S2. Fabricate the prefabricated laminated slab in the connection area (5); S3. Bond the trapezoidal transition area core material (4) to both sides of the laminated precast body (5) to make the connection area precast body, and reduce the thickness of the connection area precast body by 1-5mm. S4. Fill the polyurethane core mold (7) within the metal skeleton (8) frame; S5. Lay the lower panel fiber material (6) on the metal frame (8) and polyurethane core mold (7), and lay the upper panel fiber material (2) on the mold (1); S6. Flexible fabric (3) is laid on both the bottom panel fiber material (6) and the top panel fiber material (2). The mold (1), the top panel fiber material (2) and the flexible fabric (3) form a first structure. The metal skeleton (8), the polyurethane core mold (7), the bottom panel fiber material (6) and the flexible fabric (3) form a prestructure. S7. After installing the prefabricated connecting area body and the first core material (9) on the pre-structure, a second structure is formed; S8. The second structure is attached to the first structure and integrally formed. Among them, the warp and weft weaving density of the flexible fabric (3) is reduced by 50% to 80% compared with the upper panel fiber material (2) and the lower panel fiber material (6), and the weight of the flexible fabric (3) is increased by 20% to 50% compared with the upper panel fiber material (2) and the lower panel fiber material (6). The thickness of the flexible fabric (3) is 1-5 mm; The flexible fabric (3), the upper panel fiber material (2), and the lower panel fiber material (6) are all made of the same material system.

2. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The flexible fabric (3) includes a first fabric (31) and a second fabric (32), the first fabric (31) being laid on the top plate fiber material (2) and the second fabric (32) being laid on the bottom plate fiber material (6).

3. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The core material (4) of the transition region and the first core material (9) are made of at least one of polyurethane foam, polymethacrylamide foam, polyetherimide foam, polystyrene foam, polyvinyl chloride foam, polyethylene foam and acrylonitrile-styrene foam.

4. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The flexible fabric (3), the upper panel fiber material (2), and the lower panel fiber material (6) are at least one of glass fiber, carbon fiber, and aramid fiber material systems.

5. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The metal skeleton (8) is made of at least one of steel, aluminum alloy, magnesium alloy, copper alloy and titanium alloy.

6. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The mold (1) is made of at least one of metal, wood and composite materials.

7. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The matrix resin of the composite material and laminate preform (5) is at least one of unsaturated polyester resin, vinyl resin, phenolic resin, epoxy resin and bismaleimide resin.

8. The method for connecting a composite material and a metal skeleton based on a cavity of unequal thickness according to claim 1, characterized in that, The molding process of the composite material and laminate preform (5) is one of the following: liquid molding process, prepreg molding process and hand lay-up molding process.

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