Pre-buried metal joint composite material airfoil structure and paving method

Abstract

The invention relates to the field of composite materials, in particular to an embedded metal joint composite material airfoil structure and a paving method. Comprising a composite material skin, foam, a main beam, a main joint and carbon filaments, besides the mechanical interface, the metal joint is completely coated in the composite material skin, so that the cementing area between the metal joint and the composite material skin is greatly increased, and the integrity of the airfoil structure is improved; the metal joint does not have a redundant structure required for maintaining the pneumatic shape, so that the design and manufacturing difficulty of the joint is reduced, and the manufacturing cost and the structural weight are effectively reduced; and the carbon filaments are filled in the groove at the sleeving part of the metal joint and the composite material main beam, so that the connection strength between the metal joint and the composite material main beam is effectively improved, and the stripping failure risk between the metal joint and the composite material main beam under the impact load is reduced.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a pre-embedded metal joint composite wing surface structure and a paving method. Background Art

[0002] Composite materials have the advantages of high specific strength, high specific modulus, and strong performance designability, and are widely used in the aerospace field. Among them, the composite wing surface structure mainly includes joints, composite main beams, composite skins, PMI foam and other structures. During the use of the wing surface structure, it is necessary to meet multiple mechanical movements such as folding and unfolding, locking pins, etc. There will be local stress concentration at the connection between the wing root skin and the joint, and all dynamic and static loads of the wing surface need to be transferred to the joint through here, so the joint is usually machined from high-strength aluminum alloy or titanium alloy and other metal materials. There are many ways to connect metal joints with composite main beams and composite skins. The simple adhesive connection method is prone to peeling failure between the metal joints and the composite main beams and composite skins under impact loads, and the simple mechanical connection method is prone to stress concentration near the screws. Therefore, most composite wing surface structures use a hybrid connection mode of adhesive and mechanical connection. This connection mode requires that after the wing structure is glued and assembled, nails or screws are used to reinforce the metal joints and the composite main beams and composite skin sleeves. This involves many process flows and has low production and assembly efficiency. In addition, as the number of nails and screws used increases, the weight reduction advantages of composite materials are not fully utilized.

[0003] In addition, the metal joints need to meet the connection consistency between the wing structure and the aerodynamic shape of the fuselage in the folded and unfolded state, so the structure of the metal joints is often more complicated and the materials are redundant, and multiple complex curved surfaces and lightening grooves need to be processed, which violates the design concept of weight reduction and cost reduction. Therefore, under the constraints of the aerodynamic shape, in order to meet the overall strength and stiffness of the composite wing structure, with low cost and lightweight as the design goals, it is necessary to develop a composite wing structure with embedded metal joints. Summary of the invention

[0004] Purpose of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a pre-embedded metal joint composite wing structure, which is mainly formed by pure adhesive bonding and co-curing of metal joints, composite main beams and composite skins. The wing cross-sectional structure is as follows: Figure 1 shown.

[0006] Technical Solution

[0007] A pre-embedded metal joint composite wing structure, comprising a composite material skin, foam, a main beam, a main joint, and carbon filaments; the main joint is an integrally formed machine-added part, the main joint comprises a skin covering area and a main beam covering area, a mechanical interface is provided on the skin covering area; a plurality of grooves are provided on the main beam covering area, carbon filaments are wound inside the grooves to form a carbon filament filling area;

[0008] The skin covering area of ​​the main joint is entirely covered inside the composite material skin except for the mechanical interface area. The main beam covering area of ​​the main joint is inserted into the main beam, and the gap between the main beam and the composite material skin is filled with foam.

[0009] Furthermore, the foam is specifically polymethacrylimide (PMI) foam.

[0010] Furthermore, the main joint is made of metal material.

[0011] Furthermore, the metal material is specifically aluminum alloy.

[0012] Furthermore, it also includes a lightening groove, which is opened on the side wall of the skin covering area.

[0013] Furthermore, it also includes a lightening hole, wherein the lightening hole is opened on the end surface of the carbon filament filling area;

[0014] Furthermore, a boss is provided on the mechanical interface. When the wing surface rotates, the locking pin contacts the boss and slides on the boss to avoid contact between the metal locking pin and the composite material, thereby preventing scratches on the composite material surface.

[0015] A paving method for a composite wing structure with embedded metal joints,

[0016] First, the main beam uses its internal foam and metal joint sleeve part to lay prepreg on the main beam laying mold to complete the positioning relationship between the main joint and the main beam; then, the main joint is constrained by the locating pin of the wing surface forming mold to determine the position of the main joint and the composite main beam assembly in the wing surface forming mold; multiple sections of foam are filled in the gap between the wing surface forming mold and the main joint and the main beam to complete the assembly of the composite skin positive mold (main joint, main beam, main beam external foam) assembly; prepreg is laid on the surface of the positive mold according to the designed layup table. During the layup process, vacuum pre-compaction is required for multiple times to ensure that the prepreg layup group fits the positive mold assembly as completely as possible; and the negative mold is closed.

[0017] The wing structure is formed and solidified according to the process flow, and the demoulding and deburring post-processing are completed; finally, non-destructive inspection is carried out on the main joint and skin glue joint, the main joint and main beam glue joint, and the main beam and skin glue joint area.

[0018] Furthermore, the mold body is heated to 80°C±5°C at a heating rate of ≤3°C / min, kept at that temperature for 30min±5min, then pressurized until the mold is closed, and then heated to 125°C±5°C at a heating rate of ≤3°C / min, kept at that temperature for 90min-120min. Finally, under the pressure-maintaining condition, the pressure is released at a cooling rate of ≤2°C / min or naturally cooled to below 60°C.

[0019] Furthermore, the bonding surfaces between metal and composite materials, composite materials and foam, and the bonding sections between different materials and foam splicing sections need to be covered with a corresponding amount of adhesive film according to the actual situation to ensure the strength of the bonding interface. The beneficial effects of this application are:

[0020] Except for the mechanical interface, the metal joint is completely covered inside the composite skin, which greatly increases the bonding area between the metal joint and the composite skin and improves the integrity of the wing structure. The metal joint does not have the redundant structure required to maintain the aerodynamic shape, which reduces the difficulty of joint design and manufacturing, and effectively reduces the manufacturing cost and structural weight. The grooves at the joints between the metal joint and the composite main beam are filled with carbon filaments, which effectively improves the connection strength between the metal joint and the composite main beam and reduces the risk of peeling failure between the metal joint and the composite main beam under impact load. The composite main beam and the composite skin are co-cured, which reduces the process flow compared to co-bonding and effectively improves the bonding strength between the main beam and the skin. PMI foam is filled between the composite skin and the metal joint and the composite main beam, which effectively improves the overall strength of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the cross section of the wing structure joint section;

[0022] Figure 2 Schematic diagram of metal joint structure;

[0023] Among them: 1 composite skin, 2 PMI foam, 3 main beam, 4 metal main joint, 5 carbon filament filling, 6 mechanical interface, 7 skin covering area, 8 main beam covering area, 9 carbon filament filling area, 10 lightening groove, 11 lightening hole. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail in combination with the embodiment of the present invention. In the example, the same or similar reference numerals throughout represent the same or similar originals or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of them. The embodiments described below by reference are exemplary and intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention. The following is a detailed description in combination with the embodiments of the present invention.

[0025] Example

[0026] The pre-embedded metal joint composite wing structure comprises a composite material skin 1, foam 2, a main beam 3, a main joint 4, and carbon filaments 5; the main joint 4 is an integrally formed machine-added part, and the main joint 4 comprises a skin covering area 7 and a main beam covering area 8, and a mechanical interface 6 is provided on the skin covering area 7; a plurality of grooves are provided on the main beam covering area 8, and carbon filaments 5 are wound inside the grooves to form a carbon filament filling area;

[0027] The skin covering area 7 of the main joint 4 is entirely covered inside the composite material skin 1 except for the mechanical interface area. The main beam covering area 8 of the main joint 4 is inserted into the main beam 3. The gap between the main beam 3 and the composite material skin 1 is filled with foam 2.

[0028] In a certain embodiment of the present invention, the foam 2 is specifically polymethacrylimide PMI foam

[0029] In a certain implementation case of the present invention, the main joint 4 is made of metal material.

[0030] In a certain implementation case of the present invention, the metal material is specifically an aluminum alloy.

[0031] In a certain embodiment of the present invention, the main connector 4 is provided with

[0032] In a certain embodiment of the present invention, a lightening groove 10 is further included, and the lightening groove 10 is opened on the side wall of the skin covering area 7.

[0033] In a certain embodiment of the present invention, a lightening hole 11 is further included, and the lightening hole 11 is opened on the end surface of the carbon filament filling area 9;

[0034] In one embodiment of the present invention, a boss is provided on the mechanical interface 6. When the wing surface rotates, the locking pin contacts the boss and slides on the boss to avoid contact between the metal locking pin and the composite material, thereby preventing scratches on the composite material surface.

[0035] A paving method for a composite wing structure with embedded metal joints,

[0036] First, the main beam uses its internal foam and metal joint sleeve part to lay prepreg on the main beam laying mold to complete the positioning relationship between the main joint and the main beam; then, the main joint is constrained by the positioning pin of the wing surface forming mold to determine the position of the main joint and the composite main beam assembly in the wing surface forming mold; multiple sections of foam are filled in the gap between the wing surface forming mold and the main joint and the main beam to complete the assembly of the composite skin positive mold (main joint, main beam, main beam external foam) assembly; prepreg is laid on the surface of the positive mold according to the designed laying table, and vacuum pre-compaction is required multiple times during the laying process to ensure that the prepreg laying group fits the positive mold assembly as completely as possible; the female mold is closed, the temperature is raised to 80℃±5℃ at a heating rate of ≤3℃ / min, and the temperature is kept for 30min±5min, and then pressurized to the mold closing, and then the temperature is raised to 125℃±5℃ at a heating rate of ≤3℃ / min, and the temperature is kept for 90min~120min. Finally, under the condition of maintaining pressure, the pressure is released at a cooling rate of ≤2℃ / min or by naturally cooling to below 60℃.

[0037] The wing structure is formed and solidified according to the process flow, and the demoulding and deburring post-processing are completed; finally, non-destructive inspection is carried out on the main joint and skin glue joint, the main joint and main beam glue joint, and the main beam and skin glue joint area.

[0038] In a certain embodiment of the present invention, the bonding surfaces between metal and composite materials, composite materials and foam, and the bonding surfaces between different materials and the foam splicing sections need to be covered with a corresponding amount of adhesive film according to actual conditions to ensure the strength of the bonding interface.

[0039] See also Figure 1The wing structure is from the inside to the outside. First, the composite main beam uses its internal PMI foam and metal joint sleeve part to lay prepreg on the main beam laying mold to complete the positioning relationship between the metal joint and the composite main beam; then, the metal joint is constrained by the positioning pin of the wing forming mold to determine the position of the metal joint and the composite main beam assembly in the wing forming mold; multiple sections of PMI foam are filled in the gap between the wing forming mold and the metal joint and the composite main beam to complete the composite skin positive mold (metal joint, composite The main material beam and the main beam external PMI foam) assembly are assembled; prepreg is laid on the male mold surface according to the designed layup table. Because the wing surface shape is relatively complex, multiple vacuum pre-compactions are required during the layup process to ensure that the prepreg layup group fits the male mold assembly as completely as possible; the female mold is closed, heated and pressurized, the wing surface structure is formed and solidified according to the process flow, and post-processing such as demoulding and deburring is completed; finally, non-destructive inspection is performed on key areas such as the main joint and skin adhesive surface, the main joint and main beam adhesive surface, and the main beam and skin adhesive surface. In addition, it should be noted that in addition to the interface between composite parts, the adhesive surfaces between different materials such as metal and composite materials, composite materials and foam, and the foam splicing section need to be covered with a corresponding amount of adhesive film according to actual conditions to ensure the strength of the adhesive interface.

[0040] Except for the mechanical interface, all metal joints are covered inside the composite skin. There is no redundant structure to maintain the aerodynamic shape. The composite wing structure does not use pins or screws required for mechanical connection. PMI foam is filled in the gap between the composite skin and the metal joints and the composite main beam, which effectively reduces the weight of the wing structure and improves the integrity of the wing structure.

[0041] In addition, based on the strength analysis results, a local lightening groove was designed for the metal joint. Considering that the bonding strength between the metal joint and the composite material is limited and it is easy to peel off and fail under impact load, a process groove was designed for the metal joint and the main beam sleeve section, such as Figure 2 As shown, the process groove is filled with unidirectional carbon filaments, one side of the unidirectional carbon filaments is confined in the process groove, and the other side is co-solidified with the main beam, which effectively improves the connection strength between the metal joint and the main beam.

[0042] It is understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of ordinary technicians in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and unless defined as here, will not be interpreted with idealized or overly formal meanings. The specific implementation methods described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Within the spirit and principle of the present invention, any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment of equivalent changes for application in other fields, but any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution content of the present invention, any modification, equivalent replacement, improvement, etc., made according to the technical essence of the present invention, should be included in the protection scope of the present invention.

Claims

1. A composite wing structure with embedded metal joints, characterized in that: It includes a composite material skin, foam, a main beam, a main joint, and carbon filaments; the main joint is an integrally formed machine-added part, the main joint includes a skin covering area and a main beam covering area, the skin covering area is provided with a mechanical interface; the main beam covering area is provided with a plurality of grooves, carbon filaments are wound inside the grooves to form a carbon filament filling area; the skin covering area of ​​the main joint, except for the mechanical interface area, is entirely covered in the composite material skin, the main beam covering area of ​​the main joint is inserted into the main beam, and the gap between the main beam and the composite material skin is filled with foam.

2. The airfoil structure according to claim 1, characterized in that: The foam is specifically polymethacrylimide (PMI) foam.

3. The airfoil structure according to claim 1, characterized in that: The main joint is made of metal material.

4. The airfoil structure according to claim 1, characterized in that: The metal material is specifically aluminum alloy.

5. The airfoil structure according to claim 1, characterized in that: It also includes a lightening groove, which is opened on the side wall of the skin covering area.

6. The airfoil structure according to claim 1, characterized in that: The invention also comprises a lightening hole, wherein the lightening hole is opened at the end surface of the carbon filament filling area.

7. The airfoil structure according to claim 1, characterized in that: The mechanical interface is provided with a boss. When the wing surface rotates, the locking pin contacts the boss and slides on the boss to avoid contact between the metal locking pin and the composite material, which may cause scratches on the composite material surface.

8. The paving method of the wing surface structure according to claim 1, characterized in that: First, the main beam uses its internal foam and metal joint sleeve part to lay prepreg on the main beam laying mold to complete the positioning relationship between the main joint and the main beam; then, the main joint is constrained by the positioning pin of the wing surface forming mold to determine the position of the main joint and the composite main beam assembly in the wing surface forming mold; multiple sections of foam are filled in the gap between the wing surface forming mold and the main joint and the main beam to complete the assembly of the composite skin male mold assembly; prepreg is laid on the male mold surface according to the designed layup table, and vacuum pre-compaction is required multiple times during the layup process to ensure that the prepreg layup group fits the male mold assembly as completely as possible; and the female mold is closed; The wing structure is formed and solidified according to the process flow, and the demoulding and deburring post-processing are completed; finally, non-destructive inspection is carried out on the main joint and skin glue joint, the main joint and main beam glue joint, and the main beam and skin glue joint area.

9. The paving method of the wing surface structure according to claim 8, characterized in that: The mold body is: heated to 80℃±5℃ at a heating rate of ≤3℃ / min, kept warm for 30min±5min, then pressurized to mold closing, then heated to 125℃±5℃ at a heating rate of ≤3℃ / min, kept warm and pressurized for 90min~120min; finally, under the pressure holding condition, the pressure is released at a cooling rate of ≤2℃ / min or naturally cooled to below 60℃.

10. The paving method of the wing surface structure according to claim 9, characterized in that: The bonding surfaces between metal and composite materials, composite materials and foam, and the bonding sections between different materials and foam splicing sections need to be covered with a corresponding amount of adhesive film according to the actual situation to ensure the strength of the bonding interface.

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