Composite sandwich structure and method for manufacturing thereof

Abstract

The application provides a composite sandwich structure and a preparation method thereof, which comprises a core material, a first panel, a second panel and a deformation compensation layer; the first panel is connected to a first side of the core material; the second panel is connected to a second side of the core material, and the first side and the second side are oppositely arranged; the deformation compensation layer is connected to a side of the second panel away from the core material; wherein the thermal expansion coefficient of the first panel is greater than the thermal expansion coefficient of the second panel, and the thermal expansion coefficient of the deformation compensation layer is not less than the thermal expansion coefficient of the first panel. The application has strong designability, simple operation and high efficiency, and can effectively reduce the overall deformation of the composite sandwich structure without changing the sandwich structure.

Description

Technical Field

[0001] This invention relates to the field of aerospace composite material manufacturing technology, and more specifically, to a composite material sandwich structure and its preparation method. Background Technology

[0002] Composite materials, due to their high specific strength, high specific stiffness, strong designability, good fatigue fracture resistance, corrosion resistance, good dimensional stability, and ease of large-area integral molding, have become one of the most important structural materials in modern aerospace applications. Honeycomb sandwich composite materials are currently known as the most material-efficient structural material with the highest strength-to-weight ratio. Compared to solid materials, honeycomb sandwich composite materials use only 1% to 5% of the material being replaced. Therefore, in developed aerospace countries, honeycomb sandwich composite materials are widely used in the primary and secondary load-bearing structures of aircraft, such as the fuselage, tail, and rudder.

[0003] With the development of composite sandwich structure design and manufacturing technology, the surface of composite sandwich structures is becoming increasingly complex, and the materials of the outer panels are becoming more diversified. However, the differences in the physical properties of the outer panel materials and the complex shape of the sandwich structure inevitably lead to deformation. For example, if one side of the outer panel is made of carbon fiber and the other side is made of glass fiber, the huge difference in the coefficients of thermal expansion during the bonding process results in significant deformation and internal stress in the entire sandwich structure. Sometimes, this internal stress can even cause the core material to debond from the outer panel. Currently, there is no simple and effective means to control the deformation of composite sandwich structures. How to invent a method that is highly designable, easy to operate, and efficient, and can effectively reduce the overall deformation of composite sandwich structures without changing the sandwich structure, remains a challenge. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] The technical problem to be solved by the present invention is that in the existing dissimilar material sandwich structure, due to the huge difference in the coefficient of thermal expansion during the bonding process, the entire sandwich structure has large deformation and internal stress. Sometimes, this internal stress can even cause the core material of the sandwich structure to debond from the outer panel.

[0006] (II) Technical Solution

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

[0008] This invention provides a composite sandwich structure, including a core material, a first panel, a second panel, and a deformation compensation layer; the first panel is connected to a first side of the core material; the second panel is connected to a second side of the core material, with the first side and the second side disposed opposite to each other; the deformation compensation layer is connected to the side of the second panel away from the core material; wherein, the coefficient of thermal expansion of the first panel is greater than that of the second panel, and the coefficient of thermal expansion of the deformation compensation layer is not less than that of the first panel.

[0009] Preferably, the deformation compensation layer is formed by laminating multiple layers of resin-based prepreg on the outer surface of the second panel.

[0010] Preferably, when the thickness of the second panel is not greater than 3 mm, the number of layers of the resin-based prepreg is 1-4; when the thickness of the second panel is greater than 3 mm, the number of layers of the resin-based prepreg is 4 to 2n, where n is the thickness of the second panel, and the unit of thickness is millimeters.

[0011] Preferably, the resin-based prepreg is a full lay-up or a partial intercalation, and the shape of the resin-based prepreg is a grid, stripe, or radial pattern.

[0012] Preferably, it further includes a first adhesive film, which adhesively connects the core material to the first panel.

[0013] Preferably, it further includes a second adhesive film, which adhesively connects the core material to the second panel.

[0014] Preferably, the first panel is made of a first material, the second panel is made of a second material, and the first material is different from the second material.

[0015] Preferably, the core material is a honeycomb panel, a foam core material, or a dot matrix structure.

[0016] Secondly, the present invention also provides a method for preparing the composite material sandwich structure according to any of the above technical solutions, comprising the following steps:

[0017] The first panel, core material, second panel and deformation compensation layer are stacked in sequence and then co-cured into a single unit.

[0018] Alternatively, the first panel, the core material, and the second panel can be integrally co-cured and formed, and then the deformation compensation layer can be laid and formed on the side of the second panel opposite to the core material.

[0019] Preferably, the preparation method further includes the following step: locally grinding away the deformation compensation layer.

[0020] (III) Beneficial Effects

[0021] The above-described technical solution of the present invention has at least the following advantages:

[0022] In this invention, the coefficient of thermal expansion of the first panel is greater than that of the second panel. A deformation compensation layer is connected to the side of the second panel facing away from the first panel, where the second panel has a smaller coefficient of thermal expansion. This deformation compensation layer is made of a material with a larger coefficient of thermal expansion. During the bonding process, the deformation compensation layer expands more significantly due to heat, thus compensating for the difference in thermal expansion between the first and second panels and effectively suppressing the deformation of the composite sandwich structure. The deformation compensation layer is co-cured with the second panel using prepreg, and the number of layers, angles, and shapes can be designed as needed to achieve deformation control. The method for preparing the composite sandwich structure provided by this invention is highly designable, simple to operate, and highly efficient. It effectively reduces the overall deformation of the composite sandwich structure without altering the sandwich structure itself. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the flat composite sandwich structure provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the deformation of the flat composite sandwich structure provided in the comparative example of the present invention.

[0026] Figure 3 This is a schematic diagram of the deformation of the U-shaped composite material sandwich structure provided in the comparative example of the present invention.

[0027] Figure 4 This is a schematic diagram of the U-shaped composite material sandwich structure provided in an embodiment of the present invention.

[0028] The labels for the attached figures are as follows:

[0029] 1. Core material; 2. First adhesive film; 3. First panel; 4. Deformation compensation layer; 5. Second adhesive film; 6. Second panel; 11. First side; 12. Second side. Detailed Implementation

[0030] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0032] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments:

[0034] like Figure 1 As shown, this embodiment of the invention provides a composite sandwich structure, including a core material 1, a first panel 6, a second panel 3, and a deformation compensation layer 4; the first panel 6 is connected to a first side 11 of the core material 1; the second panel 3 is connected to a second side 12 of the core material 1, and the first side 11 and the second side 12 are disposed opposite to each other; the deformation compensation layer 4 is connected to the side of the second panel 3 away from the core material 1; wherein, the coefficient of thermal expansion of the first panel 6 is greater than the coefficient of thermal expansion of the second panel 3, and the coefficient of thermal expansion of the deformation compensation layer 4 is not less than the coefficient of thermal expansion of the first panel 6.

[0035] In one embodiment, the deformation compensation layer 4 is formed by laminating multiple layers of resin-based prepreg on the outer surface of the second panel 3. Using resin-based prepreg as the deformation compensation layer 4 is advantageous because it is lightweight and does not significantly increase the weight of the structure. Furthermore, it can be easily laminated onto panels of different shapes, including flat and curved panels.

[0036] In one embodiment, when the thickness of the second panel 3 is no greater than 3 mm, the number of resin-based prepreg layers is 1-4; when the thickness of the second panel 3 is greater than 3 mm, the number of resin-based prepreg layers is 4 to 2n, where n is the thickness of the second panel 3 in millimeters. Depending on the actual design requirements, more layers may be used for areas that may undergo significant deformation, typically 1-4 layers.

[0037] In one embodiment, the resin-based prepreg is a full lay-up or a partial intercalation, and the shape of the resin-based prepreg is a grid, stripe, or radial pattern.

[0038] In one embodiment, a first adhesive film 5 is also included, which adhesively connects the core material 1 and the first panel 6. The core material 1 and the first panel 6 are connected by the first adhesive film 5, and then they are bonded and cured together in a can.

[0039] In one embodiment, a second adhesive film 3 is also included, which adhesively connects the core material 1 and the second panel 3. The core material 1 and the second panel 3 are connected by the second adhesive film 3, and then they are bonded and cured together in a can.

[0040] In one embodiment, the first panel 6 is made of a first material and the second panel 3 is made of a second material, the first material and the second material being different.

[0041] In one embodiment, the core material 1 is a honeycomb panel, a foam core material, or a lattice structure.

[0042] Secondly, the present invention also provides a method for preparing a composite material sandwich structure according to any of the above embodiments, comprising the following steps:

[0043] The first panel 6, the core material 1, the second panel 3, and the deformation compensation layer 4 are stacked in sequence and then integrally cured and molded.

[0044] Alternatively, the first panel 6, the core material 1, and the second panel 3 can be integrally cured and molded, and then the deformation compensation layer 4 can be laid on the side of the second panel 3 away from the core material.

[0045] In one embodiment, the preparation method further includes the following step: locally grinding and removing the deformation compensation layer 4.

[0046] The following are specific embodiments provided by the present invention:

[0047] Example 1

[0048] The dimensions of the flat composite sandwich structure are designed to be 2m*1.5m. The second panel 3 is preferably made of CF3031 / BA9916-2 carbon fiber prepreg, the first panel 6 is preferably made of EW100A / BA9916-2 glass fiber prepreg, and the core material 1 is preferably made of aramid paper honeycomb (NRH 2-48). The second panel 3 and the core material 1 are bonded together by a first adhesive film 5, which is preferably made of J-116A adhesive film. The first panel 6 and the core material 1 are bonded together by a second adhesive film 3, which is preferably made of J-116A adhesive film.

[0049] The carbon fiber prepreg was laid up in layers [0 / 45 / 45 / 0]S, totaling 8 layers. The glass fiber prepreg was also laid up in layers [0 / 45 / 45 / 0]S, totaling 8 layers. Both the carbon fiber and glass fiber prepregs were cured at 0.6 MPa and 180℃ for 3 hours, respectively. They were then bonded to the aramid paper honeycomb using J-116A adhesive film at 0.2 MPa and 180℃ for 3 hours. After molding, the sandwich structure of the flat composite material deformed by 7mm-10mm. The deformation was as follows: Figure 2 As shown.

[0050] To control the deformation of flat composite sandwich structures, a method for preparing flat composite sandwich structures according to the present invention is used to prepare such structures, as follows: Figure 1 As shown, before the bonding process, based on the aforementioned structure, two layers of glass fiber prepreg are laid on the outside of the second panel 3 in [0 / 0], and bonded together with the core material 1 for curing. After molding, the deformation of the flat composite sandwich structure is reduced to 3mm-6mm.

[0051] Example 2

[0052] Both the second panel 3 and the first panel 6 preferably use CF3031 / BA9916-2 carbon fiber prepreg and aramid paper honeycomb (NRH 2-48) as the core material 1. The second panel 3 and the core material 1 are bonded together by a first adhesive film 5, which is preferably J-116A adhesive film. The first panel 6 and the core material 1 are bonded together by a second adhesive film 3, which is preferably J-116A adhesive film.

[0053] The carbon fiber prepreg is laid up in layers [0 / 45 / 45 / 0]S, totaling 8 layers. The second panel 3 is cured at 0.6 MPa and 180℃ for 3 hours, and then co-bonded with the core material 1 and the uncured first panel 6 using J-116A adhesive film at 0.2 MPa and 180℃ for 3 hours. The resulting U-shaped composite sandwich structure deforms to 10mm-12mm. Figure 3 As shown, the U-shaped composite sandwich structure converges towards the center (the arrow in the figure indicates the direction of deformation).

[0054] To control the deformation of the U-shaped composite sandwich structure, a method for preparing a composite sandwich structure according to the present invention is used to prepare the U-shaped composite sandwich structure. Based on the aforementioned structure, three layers of glass fiber prepreg are laid on the outside of the second panel 3 at [+45 / -45 / +45], and bonded to the core material 1 for co-curing. Figure 4 As shown, the deformation of the U composite sandwich structure is reduced to 6mm-8mm after molding.

[0055] 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 within the protection scope of the present invention.

Claims

1. A composite material sandwich structure, characterized in that, include: core material; The first panel is connected to the first side of the core material; The second panel is connected to the second side of the core material, and the first side and the second side are disposed opposite to each other; A deformation compensation layer is attached to the side of the second panel opposite to the core material; Wherein, the coefficient of thermal expansion of the first panel is greater than that of the second panel, the coefficient of thermal expansion of the deformation compensation layer is not less than that of the first panel, and the deformation compensation layer is formed by laminating multiple layers of resin-based prepreg on the outer surface of the second panel; Wherein, when the thickness of the second panel is not greater than 3mm, the number of layers of the resin-based prepreg is 1-4 layers; when the thickness of the second panel is greater than 3mm, the number of layers of the resin-based prepreg is 4-2n layers, where n is the thickness of the second panel, and the unit of thickness is millimeters; the resin-based prepreg is a full lay-up or a partial intercalation, and the shape of the resin-based prepreg is a grid, stripe, or radial pattern.

2. The composite material sandwich structure as described in claim 1, characterized in that, It also includes a first adhesive film, which adhesively connects the core material to the first panel.

3. The composite material sandwich structure as described in claim 1, characterized in that, It also includes a second adhesive film, which adhesively connects the core material to the second panel.

4. The composite material sandwich structure as described in claim 1, characterized in that, The first panel is made of a first material, and the second panel is made of a second material. The first material and the second material are different.

5. The composite material sandwich structure as described in claim 1, characterized in that, The core material is a honeycomb panel, a foam core material, or a dot matrix structure.

6. A method for preparing a composite material sandwich structure as described in any one of claims 1-5, characterized in that, Includes the following steps: The first panel, core material, second panel and deformation compensation layer are stacked in sequence and then co-cured into a single unit. Alternatively, the first panel, the core material, and the second panel can be integrally co-cured and formed, and then the deformation compensation layer can be laid and formed on the side of the second panel opposite to the core material.

7. The preparation method according to claim 6, characterized in that, It also includes the following steps: The deformation compensation layer is locally removed by grinding.

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