Fiber continuous longitudinal and transverse reinforced integral composite material skin structure and forming method

Abstract

The invention relates to a fiber continuous longitudinal and transverse reinforced integral composite material skin structure which is formed by co-bonding an upper skin (3), a lower skin (1) and a longitudinal and transverse reinforced structure (2). The invention further relates to a forming method of the fiber continuous longitudinal and transverse reinforced integral composite material skin structure. The forming method comprises the step of forming the longitudinal and transverse reinforced structure (2). Paving the skin and positioning the longitudinal and transverse reinforcing structure (2); and curing the paved fiber continuous longitudinal and transverse reinforced integral composite material skin structure, machining a circular opening in each of the left side and the right side of the longitudinal and transverse reinforced structure (2), and completing the whole forming process of the fiber continuous longitudinal and transverse reinforced integral composite material skin structure. The skin structure is light in weight and continuous in fiber, the structural strength is effectively enhanced through integral structure cementing co-curing forming, the integral structure is more excellent in rigidity performance, and the embedded longitudinal and transverse reinforcing structure is high in size and position precision.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a fiber continuous longitudinal and transverse reinforced integral composite material skin structure and a molding method. Background Art

[0002] Continuous fiber reinforced composite materials have outstanding mechanical properties and designability, and are widely used in the aerospace field. Among them, the aircraft composite cabin structure is relatively thin. In order to enhance its load-bearing performance, it is necessary to arrange reinforcement ribs to increase the strength, stiffness and stability of the thin-walled structure. The longitudinal and transverse reinforcement rib structure, as the main load-bearing component of the thin-walled structure, can effectively enhance the mechanical properties of the overall structure. At present, most of the composite material longitudinal and transverse reinforcement rib structures select continuous longitudinal / transverse ribs based on the main load-bearing direction, and the reinforcement ribs in the vertical direction need to be cut off. This method does not give full play to the advantages of fiber-reinforced composite materials, and the mechanical properties of the reinforcement rib structure are not outstanding. Especially for composite thin-walled structures with large openings, local reinforcement near the opening is required, but the conventional method has limited structural reinforcement effect within the limited reinforcement space. It is necessary to develop a fiber-continuous longitudinal and transverse reinforced integral composite skin structure. Summary of the invention

[0003] The purpose of the present invention is: in order to solve the above-mentioned technical problems, the present invention provides a fiber continuous longitudinal and transverse reinforced integral composite material skin structure and molding method, the structure is light in weight, the fiber is continuous, and the overall structure is glued and co-cured to effectively enhance the structural strength.

[0004] The technical solution of the present invention is:

[0005] A fiber continuous longitudinal and transverse reinforced integral composite material skin structure, formed by gluing an upper skin 3, a lower skin 1 and a longitudinal and transverse reinforcement structure 2;

[0006] The longitudinal and transverse reinforcement structure 2 includes two transverse reinforcement ribs and one longitudinal reinforcement rib. The upper skin 3 and the lower skin 1 cover the longitudinal and transverse reinforcement structure 2 on the upper and lower surfaces respectively. The upper skin 3 and the lower skin 1 are both rounded rectangles of the same size, with the longitudinal and transverse reinforcement structure 2 in the middle. The longitudinal and transverse reinforcement structure 2 has a circular opening on the left and right sides.

[0007] A method for forming a fiber continuous longitudinal and transverse reinforced integral composite material skin structure comprises the following steps:

[0008] 1) Forming of the longitudinal and transverse reinforcement structure 2: The longitudinal and transverse reinforcement structure paving surfaces 4 are formed by making a mold, and 7 ply groups are laid on the 7 longitudinal and transverse reinforcement structure paving surfaces 4, wherein the 7 longitudinal and transverse reinforcement structure paving surfaces 4 include a longitudinal paving surface, 4 "L"-shaped paving surfaces, and 2 "U"-shaped paving surfaces. On one longitudinal paving surface is a ply group 4 5, and the ply group 4 5 includes 5 layers of prepreg. On the 4 "L"-shaped paving surfaces and the 2 "U"-shaped paving surfaces is a ply group 3 6, and the ply group 3 6 includes 10 layers of prepreg. After the ply laying is completed, the longitudinal and transverse reinforcement structure 2 is cured and formed, and then machined to the required thickness;

[0009] 2) Skin laying and positioning of longitudinal and transverse reinforcement structures 2: a skin laying surface 7 is formed by making a mold, the lower skin 1 is laid on the skin laying surface 7, the transverse reinforcement structure 3 is wrapped with a laying film, and then the transverse reinforcement structure 3 is laid in the center of the lower skin 1, and positioned on the skin 2 to ensure the position accuracy of the transverse reinforcement structure 3, and finally the upper skin 3 is laid on the transverse reinforcement structure 3 and the lower skin 1 to complete the skin laying;

[0010] 3) The fiber-laid continuous longitudinal and transverse reinforced integral composite material skin structure is solidified, and a circular opening is machined on the left and right sides of the longitudinal and transverse reinforcement structure 2 to complete the entire molding process of the fiber-laid continuous longitudinal and transverse reinforced integral composite material skin structure.

[0011] It is characterized in that the lower skin 1 is laid up with 8 layers at different laying angles, the lowermost prepreg is glass cloth fabric prepreg, and the inner side is carbon fiber fabric prepreg.

[0012] It is characterized in that the upper skin 3 is laid up in three layers at different laying angles, the uppermost prepreg is a glass cloth fabric prepreg, and the inner side is a carbon fiber fabric prepreg.

[0013] It is characterized in that the ply group three 6 uses different ply angles to perform 10 plies, and the ply material is carbon fiber fabric prepreg.

[0014] It is characterized in that the layup group four 5 uses different layup angles to perform 5-layer layup, and the layup material is carbon fiber fabric prepreg.

[0015] The feature of the invention is that when the longitudinal and transverse reinforcement structure 2 is formed, the triangular areas formed between different ply groups are filled with unidirectional tape prepreg 8 .

[0016] It is characterized in that unidirectional prepreg 8 is attached to the bottom corners around the longitudinal and transverse reinforcement structures 2 to prevent the formation of cavities in the right-angle transition zone formed with the longitudinal and transverse reinforcement structures 2 when the upper skin 3 is laid.

[0017] The feature of the invention is that lines are drawn on the skin 2 or positioning clamps are made thereon to ensure the position accuracy of the transverse reinforcement structure 3 .

[0018] The advantages of the present invention are:

[0019] The fiber-continuous longitudinal and transversely reinforced integral composite material skin structure of the present invention adopts continuous longitudinal and transverse reinforcement structure fiber plies, which fully exerts the mechanical properties of continuous fiber reinforced composite materials. The longitudinal and transverse reinforcement structures are divided into multiple ply groups, which can be finely designed according to working conditions and size requirements. The longitudinal and transverse reinforcement structures are first cured and formed, and unidirectional tape prepreg is filled around the longitudinal and transverse reinforcement structures, and adhesive film is pasted on the contact surface with the skin, and then the structure is embedded in the skin plies and bonded and co-cured to form the whole structure. The overall structure has better strength and stiffness performance, and the size and position accuracy of the embedded longitudinal and transverse reinforcement structures are high. A fiber-continuous longitudinal and transversely reinforced integral composite material skin structure is light in weight, the fibers are continuous, and the overall structure is bonded and co-cured to effectively enhance the structural strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Composite material longitudinal and transverse reinforced integral skin structure

[0021] Figure 2 Vertical and horizontal reinforcement structure paving diagram

[0022] Figure 3 Paving split diagram DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0024] See attached Figure 1 This composite material longitudinal and transverse reinforced integral skin structure is formed by bonding and co-curing the skin 2, the skin 5 and the longitudinal and transverse reinforcement structure 2. The longitudinal and transverse reinforcement structure 2 can ensure the position accuracy by marking on the skin 2 or making positioning card plates; the main direction of all fibers of the longitudinal and transverse reinforcement structure 2 is continuous, and the triangular area formed at the corners of different laying groups is filled with unidirectional tape prepreg. The bottom corners of the longitudinal and transverse reinforcement structure 2 are affixed with unidirectional tape prepreg 8 to transition in the right angle area to prevent bridging to form a resin-rich area when the skin 5 is laid. See attached Figure 2 The longitudinal and transverse reinforcement structure 2 includes 7 paving groups 6-12 and 7 paving surfaces 13. The triangular matching areas of different paving groups are filled with unidirectional tape prepreg. The required thickness of the longitudinal and transverse reinforcement structure 2 after curing and molding; see the attached Figure 3 After the overall structure is solidified, a large circular opening is machined to complete the entire process of composite material production.

[0025] The fiber continuous longitudinal and transverse reinforced integral composite skin structure of the present invention is formed by co-curing and bonding the cured longitudinal and transverse reinforcement structure and the thin-walled skin. The longitudinal and transverse reinforcement structure ensures the continuity of fibers in all directions by designing multiple paving surfaces, and there are more fibers along the main load-bearing direction. After the longitudinal and transverse reinforcement structure is cured, it needs to be machined to the specified rib height. The longitudinal and transverse reinforcement structure can adjust the number and position of the longitudinal / transverse reinforcement distribution according to the structural force transmission characteristics and large opening characteristics, and ensure that each longitudinal / transverse staggered form is an open form, and the continuity of the fiber can be guaranteed by increasing the paving surface. In the skin paving process, the longitudinal and transverse reinforcement structure is embedded in the middle layer of the skin paving, and the longitudinal and transverse reinforcement structure needs to be paved with adhesive film on the upper and lower contact surfaces between the longitudinal and transverse reinforcement structure and the adjacent skin paving layer, and the bottom corners around the longitudinal and transverse reinforcement structure are filled with unidirectional tape prepreg to prevent the subsequent paving of the skin from bridging to generate resin-rich areas and affect the quality of the structure. After the pre-embedding and paving are completed, the co-curing is formed, and the required openings are machined to complete the preparation of the composite material parts. Take the paving groups in Tables 1 and 2 as an example.

[0026] The main directions of all fibers in the longitudinal and transverse reinforcement structures are continuous, and the triangular areas formed at the corners of different laying groups should be filled with unidirectional tape prepreg. The longitudinal and transverse reinforcement structure has 7 longitudinal and transverse reinforcement structure laying surfaces and 7 laying groups. The laying groups are shown in Table 1, and the laying materials are all carbon fiber fabric prepreg.

[0027] Table 1 Reinforcement layer group

[0028]

[0029]

[0030] The thin-walled skin consists of one film surface and one ply group. The ply groups are shown in Table 2. The outermost prepregs of the skin are all glass fabric prepregs. After the longitudinal and transverse reinforcement structures are cured, they are laid between C-P080 and C-P090.

[0031] Table 2 Skin layer group

[0032]

Claims

1. A fiber continuous longitudinal and transverse reinforced integral composite material skin structure, which is formed by gluing an upper skin (3), a lower skin (1) and a longitudinal and transverse reinforcement structure (2); The longitudinal and transverse reinforcement structure (2) includes two transverse reinforcement ribs and one longitudinal reinforcement rib. The upper skin (3) and the lower skin (1) cover the longitudinal and transverse reinforcement structure (2) on the upper and lower surfaces respectively. The upper skin (3) and the lower skin (1) are both rounded rectangles of the same size, with the longitudinal and transverse reinforcement structure (2) in the middle. The longitudinal and transverse reinforcement structure (2) has a circular opening on the left and right sides.

2. A method for forming a fiber-continuous longitudinally and transversely reinforced integral composite material skin structure as claimed in claim 1, comprising the following steps: 1) Forming of the longitudinal and transverse reinforcement structure (2): forming longitudinal and transverse reinforcement structure paving surfaces (4) by making a mold, laying 7 ply groups on the 7 longitudinal and transverse reinforcement structure paving surfaces (4), wherein the 7 longitudinal and transverse reinforcement structure paving surfaces (4) include a longitudinal paving surface, 4 "L"-shaped paving surfaces, and 2 "U"-shaped paving surfaces, and on one longitudinal paving surface there is ply group four (5), and ply group four (5) includes 5 layers of prepreg, and on the 4 "L"-shaped paving surfaces and the 2 "U"-shaped paving surfaces there is ply group three (6), and ply group three (6) includes 10 layers of prepreg. After the ply laying is completed, the longitudinal and transverse reinforcement structure (2) is cured and formed, and then machined to the required thickness; 2) Skin laying and positioning of the longitudinal and transverse reinforcement structures (2): a skin laying surface (7) is formed by making a mold, the lower skin (1) is laid on the skin laying surface (7), the transverse reinforcement structure (3) is wrapped with a laying film, and then the transverse reinforcement structure (3) is laid in the center of the lower skin (1), and positioned on the skin (2) to ensure the position accuracy of the transverse reinforcement structure (3), and finally the upper skin (3) is laid on the transverse reinforcement structure (3) and the lower skin (1) to complete the skin laying; 3) The fiber-laid continuous longitudinal and transverse reinforced integral composite material skin structure is solidified, and a circular opening is machined on the left and right sides of the longitudinal and transverse reinforcement structure (2), thereby completing the entire molding process of the fiber-laid continuous longitudinal and transverse reinforced integral composite material skin structure.

3. The molding method according to claim 2, characterized in that: The lower skin (1) is laid up in 8 layers at different laying angles, the bottom prepreg is glass cloth fabric prepreg, and the inner prepreg is carbon fiber fabric prepreg.

4. The molding method according to claim 3, characterized in that: The upper skin (3) is laminated in three layers at different lamination angles, the uppermost prepreg is a glass cloth fabric prepreg, and the inner side is a carbon fiber fabric prepreg.

5. The molding method according to claim 4, characterized in that: The layup group three (6) uses different layup angles to lay up 10 layers, and the layup material is carbon fiber fabric prepreg.

6. The molding method according to claim 5, characterized in that: Lamination group four (5) uses different lamination angles to perform 5-layer lamination, and the lamination material is carbon fiber fabric prepreg.

7. The molding method according to claim 6, characterized in that: When the longitudinal and transverse reinforcement structure (2) is formed, the triangular areas formed between different ply groups are filled with unidirectional tape prepreg (8).

8. The molding method according to claim 7, characterized in that: The bottom corners of the longitudinal and transverse reinforcement structures (2) are affixed with unidirectional prepreg (8) to prevent the formation of cavities in the right-angle transition zone formed with the longitudinal and transverse reinforcement structures (2) when the upper skin (3) is laid.

9. The molding method according to claim 8, characterized in that: Lines are drawn on the skin (2) or positioning plates are made to ensure the position accuracy of the transverse reinforcement structure (3).

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