Flexible composite material skin and preparation method thereof

Abstract

The invention provides a flexible composite material skin and a preparation method thereof. The flexible composite material skin comprises a zero Poisson's ratio skeleton, a negative Poisson's ratio filler and an elastic surface layer, the zero-Poisson-ratio framework is provided with a plurality of filling areas; the negative Poisson's ratio filler is arranged in the filling area; the elastic surface layer is attached to the upper surface and / or the lower surface of the zero-Poisson-ratio framework with the negative-Poisson-ratio filler. According to the flexible composite material skin provided by the invention, the surface can be kept continuous, smooth and free of concave-convex fluctuation in the deformation process, and the stealth performance and aerodynamic performance of a corresponding aircraft structure prepared from the flexible composite material skin can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and more particularly to a flexible composite material skin and a preparation method thereof. Background Art

[0002] Variant technology is one of the characteristics of future fighter jets. In order to improve the maneuverability of the aircraft while ensuring the stealth and aerodynamic performance of the aircraft, it is necessary to achieve adaptive continuous variation of the wings, which is a key technology for the high performance of future variant aircraft.

[0003] Traditional fixed geometry aircraft all use rigid skins. When the deformable wings such as variable swept wings and folding wings are deformed, the rigid skins deform discontinuously, and large gaps will be generated on the wing surface, resulting in unacceptable reduction in stealth performance. At the same time, the cost of structural weight and reliability is required, which cannot meet the aerodynamic and stealth performance requirements of the new generation of deformable aircraft. In 2008, the US Air Force magazine published an article entitled "Fighter Generations", which summarized hypersonic flight, dual-mode engines and adaptive deformation as the three most revolutionary technologies of the fifth-generation fighter. The "deformability" and "smart skin" mentioned in the article are the basis of the adaptive shape technology of the deformable aircraft. "Deformability" means that the aircraft continuously and adaptively adjusts the wing shape according to the flight mission and changes in the external environment to maintain the best flight attitude, and "smart skin" is a flexible skin that can both normally bear the aerodynamic load during flight and can undergo continuous, seamless and smooth deformation within the surface. It is a key material for improving the stealth and aerodynamic performance of structures such as adaptive wings.

[0004] The skin in the prior art does not have the ability to deform, or when the flexible skin undergoes a large deformation, its flexible base material undergoes tensile deformation, resulting in uneven surface, which has an adverse effect on the stealth performance. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is that the skin in the prior art has no deformation capability or the surface of the flexible skin is prone to produce unevenness when it is deformed.

[0007] (II) Technical solution

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] In a first aspect, the present invention provides a flexible composite skin, comprising a zero Poisson's ratio skeleton, a negative Poisson's ratio filler and an elastic surface layer; the zero Poisson's ratio skeleton has a plurality of filling areas; the negative Poisson's ratio filler is arranged in the filling area; the elastic surface layer is attached to the upper surface and / or lower surface of the zero Poisson's ratio skeleton having the negative Poisson's ratio filler.

[0010] Preferably, the zero Poisson's ratio skeleton comprises a plurality of support rods and a plurality of tensile units, the plurality of support rods are arranged at intervals along the X direction, a tensile unit is connected between two adjacent support rods, and the plurality of tensile units extend at intervals along the Y direction.

[0011] Preferably, the tensile unit comprises a first tensile plate and a second tensile plate, the first tensile plate and the second tensile plate have the same structure and are mirror-imaged with the X direction as the axis of symmetry.

[0012] Preferably, the shapes of the first tensile plate include Ω-shape, V-shape, cosine curve shape, U-shape, T-shape, trapezoid, L-shape and rectangle.

[0013] Preferably, the negative Poisson's ratio filler fills the entire space within the filling area, or the negative Poisson's ratio filler fills a portion of the space within the filling area.

[0014] Preferably, the material of the negative Poisson's ratio filler includes at least one of polyurethane, polyethylene, polyvinyl chloride, polyamide, organic fluorine thermoplastic resin and copolymers thereof.

[0015] Preferably, the material of the zero Poisson's ratio skeleton includes at least one of carbon fiber / polyetheretherketone, polyetheretherketone, polyurethane, and carbon fiber / polyurethane.

[0016] Preferably, the material of the elastic surface layer includes at least one of thermosetting resin, thermoplastic resin, rubber and polyurethane elastomer.

[0017] Preferably, the elastic surface layer is adhesively connected to the negative Poisson's ratio filler, and / or the elastic surface layer is sutured to the negative Poisson's ratio filler.

[0018] In a second aspect, the present invention further provides a method for preparing a flexible composite material skin, comprising the following steps:

[0019] According to the deformation and load required by the skin, the structure of the zero Poisson's ratio skeleton is simulated, calculated and designed, and the zero Poisson's ratio skeleton is prepared;

[0020] placing a zero Poisson's ratio skeleton within the filling mold;

[0021] According to the deformation range required by the skin, a preset filling ratio of the negative Poisson's ratio filler required for the filling area is simulated and calculated, and the negative Poisson's ratio filler is filled in the filling area according to the preset filling ratio, and the negative Poisson's ratio filler and the zero Poisson's ratio skeleton are connected;

[0022] The elastic surface layer is attached to the upper surface and / or lower surface of the zero Poisson's ratio skeleton having the negative Poisson's ratio filler;

[0023] After curing, a flexible composite skin is obtained.

[0024] (III) Beneficial effects

[0025] The above technical solution of the present invention has at least the following advantages:

[0026] 1. In the present invention, the zero Poisson's ratio skeleton has the characteristics of normal load-bearing and large in-plane deformation, so that the skin has the ability to be deformed. The zero Poisson's ratio skeleton is filled with a negative Poisson's ratio filler, and the tensile expansion effect of the negative Poisson's ratio filler during the deformation process is utilized to effectively solve the problem of surface unevenness existing in the deformation process of the current flexible skin; and the elastic surface layer is attached to the upper surface and / or the lower surface of the zero Poisson's ratio skeleton with the negative Poisson's ratio filler. Through the combination of the three structures, the flexible composite material skin can maintain a continuous, smooth and non-undulating surface during the deformation process, thereby improving the stealth performance and aerodynamic performance of the corresponding aircraft structure prepared using the flexible composite material skin.

[0027] 2. In the present invention, the preparation method of the flexible composite material skin provided by the present invention adopts a filling mold to control the filling ratio of the negative Poisson's ratio filler, thereby avoiding deformation of the zero Poisson's ratio skeleton during the molding process, and the operation process is simple and the molding quality is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the structure of the flexible composite material skin provided in Example 1 of the present invention.

[0030] Figure 2 It is a schematic diagram of the structure of the flexible composite material skin provided in the second embodiment of the present invention.

[0031] Figure 3 It is a structural schematic diagram of a zero Poisson's ratio skeleton provided in Example 3 of the present invention.

[0032] Figure 4 It is a structural schematic diagram of a zero Poisson's ratio skeleton provided in Example 4 of the present invention.

[0033] Figure 5 It is a schematic diagram of the structure of a zero Poisson's ratio skeleton provided in Example 5 of the present invention.

[0034] Figure 6 It is a schematic diagram of the structure of a zero Poisson's ratio skeleton provided in Example 6 of the present invention.

[0035] The reference numerals in the figures are:

[0036] 1. Zero Poisson's ratio skeleton; 2. Negative Poisson's ratio filler; 3. Elastic surface layer; 11. Filling area; 12. Support rod; 13. Tensile unit; 131. First tensile plate; 132. Second tensile plate. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly located on the other element or indirectly located on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0039] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention, and do not indicate that a device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating relative importance or indicating the number of technical features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The specific implementation of the present invention is described in more detail below in conjunction with specific embodiments:

[0041] like Figure 1 and Figure 2As shown, an embodiment of the present invention provides a flexible composite skin, including a zero Poisson's ratio skeleton 1, a negative Poisson's ratio filler 2, and an elastic surface layer 3; the zero Poisson's ratio skeleton 1 has a plurality of filling areas 11; the negative Poisson's ratio filler 2 is arranged in the filling area 11; the elastic surface layer 3 is attached to the upper surface and / or lower surface of the zero Poisson's ratio skeleton 1 having the negative Poisson's ratio filler 2. Specifically, the elastic surface layer 3 is arranged on the aerodynamic surface side of the corresponding aircraft prepared by using the flexible composite skin, which can be the upper surface, or the lower surface, or the upper surface and the lower surface.

[0042] In one of the embodiments, the zero Poisson's ratio skeleton 1 includes a plurality of support rods 12 and a plurality of tensile units 13, wherein the plurality of support rods 12 are arranged at intervals along the X direction, and a tensile unit 13 is connected between two adjacent support rods 12, and the plurality of tensile units 13 extend at intervals along the Y direction. The zero Poisson's ratio skeleton 1 can realize the function of bearing in the normal direction, and can also realize large deformation in the plane. The zero Poisson's ratio skeleton 1 is a zero Poisson's ratio structure in the plane, and can realize that when the plane is deformed in the Y direction, the size in the X direction remains unchanged. The skin prepared by using the zero Poisson's ratio skeleton 1 has the characteristics of normal bearing and large deformation in the plane, so that the skin has the ability to be deformed, so that the aspect ratio of the wing covered with the skin remains unchanged when deformed, thereby ensuring its aerodynamic performance and stealth performance.

[0043] In one embodiment, the tensile unit 13 includes a first tensile plate 131 and a second tensile plate 132. The first tensile plate 131 and the second tensile plate 132 have the same structure and are mirror-imaged with the X direction as the symmetry axis. The first tensile plate 131 and the second tensile plate 132 are mirror-imaged with the symmetry axis, so that the tensile unit 13 can achieve the function of maintaining the X-direction dimension unchanged when the plane is deformed along the Y direction.

[0044] In one embodiment, the shape of the first tensile plate 131 includes an Ω shape, a V shape, a cosine curve shape, a U shape, a T shape, a trapezoid, an L shape, and a rectangle. The shape of the first tensile plate 131 is the same as the shape of the second tensile plate 132. Specifically, the specific shape of the first tensile plate 131 and the specific shape of the second tensile plate 132 can be determined according to the specific design requirements of the skin structure and obtained through topological optimization. Figure 3 As shown, the zero Poisson's ratio skeleton 1 is a skeleton having an Ω-shaped first tensile plate 131; Figure 4 As shown, the zero Poisson's ratio skeleton 1 is a skeleton having a V-shaped first tensile plate 131; Figure 5 As shown, the zero Poisson's ratio skeleton 1 is a skeleton having a trapezoidal first tensile plate 131; Figure 6 As shown, the zero Poisson's ratio skeleton 1 is a skeleton having a rectangular first tensile plate 131 .

[0045] In one embodiment, the negative Poisson's ratio filler 2 fills the entire space in the filling area 11, or the negative Poisson's ratio filler 2 fills a portion of the space in the filling area 11. Figure 1 The negative Poisson's ratio filler 2 is shown to fill part of the space in the filling area 11. Figure 2 It is shown that the negative Poisson's ratio filler 2 fills the entire space in the filling area 11. Specifically, the filling ratio of the negative Poisson's ratio filler 2 required can be simulated and calculated according to the range of the deformation required for the final design of the skin, and the filling area 11 can be filled according to the filling ratio. By utilizing the tensile expansion effect of the negative Poisson's ratio filler 2 during deformation, the surface unevenness problem existing in the deformation process of the current flexible skin can be effectively solved.

[0046] In one embodiment, the material of the negative Poisson's ratio filler 2 includes at least one of polyurethane, polyethylene, polyvinyl chloride, polyamide, organic fluorine thermoplastic resin and copolymers thereof.

[0047] In one embodiment, the material of the zero Poisson's ratio skeleton 1 includes at least one of carbon fiber / polyetheretherketone (CF / PEEK), polyetheretherketone (PEEK), polyurethane (PU), and carbon fiber / polyurethane (CF / PU).

[0048] In one embodiment, the material of the elastic surface layer 3 includes at least one of thermosetting resin, thermoplastic resin, rubber, and polyurethane elastomer.

[0049] In one embodiment, the elastic surface layer 3 is connected to the negative Poisson's ratio filler 2 by adhesive bonding, and / or the elastic surface layer 3 is connected to the negative Poisson's ratio filler 2 by sewing.

[0050] In a second aspect, the present invention further provides a method for preparing a flexible composite material skin, comprising the following steps:

[0051] According to the deformation and load required by the skin, the structure of the zero Poisson's ratio skeleton 1 is simulated, calculated and designed, and the zero Poisson's ratio skeleton 1 is prepared; specifically, according to the deformation and load required by the skin, the structural unit parameters of the zero Poisson's ratio skeleton 1 are simulated, calculated and designed, and the zero Poisson's ratio skeleton 1 is prepared by 3D printing.

[0052] The zero Poisson's ratio skeleton 1 is placed in a filling mold (not shown); specifically, the filling mold can achieve the closure of part of the space in the filling area 11, so that the area of ​​the closed area in the filling area 11 matches the preset filling ratio of the negative Poisson's ratio filler 2, thereby facilitating the filling of the negative Poisson's ratio filler 2 and avoiding deformation of the zero Poisson's ratio skeleton during the molding process.

[0053] According to the deformation range required by the skin, the preset filling ratio of the negative Poisson's ratio filler 2 required for the filling area is simulated and calculated, and the negative Poisson's ratio filler 2 is filled in the filling area 11 according to the preset filling ratio, and the negative Poisson's ratio filler 2 and the zero Poisson's ratio skeleton 1 are connected; specifically, the negative Poisson's ratio filler 2 is connected to the inner wall of the zero Poisson's ratio skeleton 1 by a high-flexibility adhesive.

[0054] The elastic surface layer 3 is attached and connected to the upper surface and / or lower surface of the zero Poisson's ratio skeleton 1 having the negative Poisson's ratio filler 2; specifically, the elastic surface layer 3 and the negative Poisson's ratio filler 2 are connected by means of a high-flexibility adhesive, high-flexibility fiber positioning, etc.

[0055] After curing, demoulding is performed to obtain a flexible composite material skin.

[0056] The following is a specific implementation method provided by this application:

[0057] First, a zero Poisson's ratio skeleton 1 having a first tensile plate 131 and a second tensile plate 132 in the shape of a cosine curve is prepared by 3D printing of CF / PEEK material, and the zero Poisson's ratio skeleton 1 is placed in a filling mold, and a polyurethane matching primer is coated on the inner wall of the zero Poisson's ratio skeleton 1, and the cut negative Poisson's ratio filler 2 (specifically a polyurethane elastic foam material) is filled into the filling area 11 of the zero Poisson's ratio skeleton 1, and the negative Poisson's ratio filler 2 is bonded to the inner wall of the zero Poisson's ratio skeleton 1. After the bonding is completed, a high-flexibility adhesive is used to apply the elastic surface layer 3 (polyurethane) to the upper and lower surfaces of the zero Poisson's ratio skeleton 1 filled with the negative Poisson's ratio filler 2, and it is taken out after curing to obtain a flexible composite material skin. According to the test, the in-plane tensile deformation of the flexible composite material skin reaches 35%, and the skin can achieve seamless, continuous and smooth deformation, meeting the aerodynamic performance requirements and stealth performance requirements of the corresponding structure.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible composite material skin, characterized in that: include: zero Poisson's ratio skeleton with multiple infill regions; A negative Poisson's ratio filler is disposed in the filling area; The elastic surface layer is attached to the upper surface and / or lower surface of the zero Poisson's ratio skeleton having the negative Poisson's ratio filler.

2. The flexible composite material skin according to claim 1, characterized in that: The zero Poisson's ratio skeleton comprises a plurality of support rods and a plurality of tensile units, wherein the plurality of support rods are arranged at intervals along the X direction, a tensile unit is connected between two adjacent support rods, and the plurality of tensile units extend at intervals along the Y direction.

3. The flexible composite skin according to claim 2, characterized in that: The tensile unit comprises a first tensile plate and a second tensile plate. The first tensile plate and the second tensile plate have the same structure and are mirror-imaged with the X direction as the axis of symmetry.

4. The flexible composite skin according to claim 3, characterized in that: The shapes of the first tensile plate include Ω-shape, V-shape, cosine curve shape, U-shape, T-shape, trapezoid, L-shape and rectangle.

5. The flexible composite skin according to claim 1, characterized in that: The negative Poisson's ratio filler fills the entire space within the filling area, or the negative Poisson's ratio filler fills a portion of the space within the filling area.

6. The flexible composite skin according to claim 1, characterized in that: The material of the negative Poisson's ratio filler includes at least one of polyurethane, polyethylene, polyvinyl chloride, polyamide, organic fluorine thermoplastic resin and copolymers thereof.

7. The flexible composite skin according to claim 1, characterized in that: The material of the zero Poisson's ratio skeleton includes at least one of carbon fiber / polyetheretherketone, polyetheretherketone, polyurethane, and carbon fiber / polyurethane.

8. The flexible composite skin according to claim 1, characterized in that: The material of the elastic surface layer includes at least one of thermosetting resin, thermoplastic resin, rubber and polyurethane elastomer.

9. The flexible composite skin according to claim 1, characterized in that: The elastic surface layer is adhesively connected to the negative Poisson's ratio filler, and / or the elastic surface layer is sutured to the negative Poisson's ratio filler.

10. A method for preparing a flexible composite material skin, characterized in that: The following steps are involved: According to the deformation and load required by the skin, the structure of the zero Poisson's ratio skeleton is simulated, calculated and designed, and the zero Poisson's ratio skeleton is prepared; placing a zero Poisson's ratio skeleton within the filling mold; According to the deformation range required by the skin, a preset filling ratio of the negative Poisson's ratio filler required for the filling area is simulated and calculated, and the negative Poisson's ratio filler is filled in the filling area according to the preset filling ratio, and the negative Poisson's ratio filler and the zero Poisson's ratio skeleton are connected; The elastic surface layer is attached to the upper surface and / or lower surface of the zero Poisson's ratio skeleton having the negative Poisson's ratio filler; After curing, a flexible composite skin is obtained.

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