Splicing structure of carbon skin aluminum honeycomb sandwich plate and preparation method of splicing structure

Abstract

The splicing structure of the carbon skin aluminum honeycomb sandwich plates is connected between every two adjacent carbon skin aluminum honeycomb sandwich plates, and each sandwich plate comprises a main body honeycomb and partitioned carbon skins fixed to the upper side and the lower side of the main body honeycomb through adhesive films. The splicing structure comprises a splicing position honeycomb located between the main body honeycombs of the two adjacent sandwich plates, and the upper surface and the lower surface of the main body honeycombs located on the two sides of the same splicing position honeycomb are flush with each other. The inner reinforcing skins are fixed to the upper side and the lower side of the honeycomb at the splicing position through adhesive films, the surfaces of the sides, back on to the honeycomb at the splicing position, of the inner reinforcing skins on the upper side and the lower side are flush with the upper surface and the lower surface of the main honeycomb correspondingly, the centers of the inner reinforcing skins are located at the splicing seam of every two adjacent block carbon skins, and the inner reinforcing skins and the block carbon skins are fixed through the adhesive films; and the foaming adhesive tape is filled in a gap between the main body honeycomb and the honeycomb at the abutted seam. The blocking carbon skin can be prepared from raw materials with small sizes, and the cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of composite material forming, and in particular to a splicing structure of a carbon-skinned aluminum honeycomb sandwich panel and a preparation method thereof. Background Art

[0002] Honeycomb sandwich structure is a composite material composed of three basic materials: upper and lower skins, honeycomb core and adhesive. Honeycomb sandwich structure has the characteristics of high specific strength and specific stiffness, good fatigue resistance and excellent designability, and is widely used in the aerospace field. When the size of the composite material structure becomes larger and larger, the width or length of the skin material will be insufficient and need to be spliced ​​to meet the product size requirements.

[0003] For the preparation of large-sized carbon-skinned aluminum honeycomb sandwich structure products, there are two main existing technical solutions:

[0004] One is to use the hot melt method to prepare pre-impregnated non-woven fabric. The length of the pre-impregnated non-woven fabric is not limited, and large-sized carbon skins can be laid as a whole without splicing. Specifically, the hot melt method refers to a method of heating and melting the resin into a flowing state and using it to impregnate fibers or fabrics. There are two main methods for preparing pre-impregnated non-woven fabrics by the hot melt method: a one-step method and a two-step method. The one-step method requires good fluidity of the resin matrix and is mainly used to prepare narrow-band pre-impregnated non-woven fabrics. The prepared material has a low resin content and poor product quality; the two-step method can accurately control the glue content in the prepreg, and the volatile content is low. The hot melt method requires the use of high-temperature and high-pressure equipment and melting equipment to prepare prepregs, and the equipment use and maintenance costs are high. Although the hot melt method can achieve the preparation of long prepregs, it requires large-sized process templates and large-sized curing equipment when laying large-sized carbon skins. The quality control and curing costs during the overall skin molding process are relatively large, which does not meet the current product cost reduction and efficiency improvement requirements.

[0005] Another method is to splice the pre-impregnated non-woven fabric of the carbon skin, stagger the seams of each layer, and enlarge the skin size by splicing during the laying process. The fault splicing in the carbon skin laying process needs to consider the stress concentration and the residual strength after the fault splicing. Many scholars at home and abroad have conducted mechanical analysis and experimental verification on composite materials with spliced ​​plies, and obtained the conclusion that the shorter the length of the staggered splicing of the plies, the higher the degree of local stress concentration, and the failure mode of the tensile spliced ​​laminate containing plies is interlaminar shear failure and fiber fracture. When the laminated material containing spliced ​​plies is subjected to external loads, it is easy to cause single-layer failure at the splicing seam and induce crack propagation, resulting in a reduction in the actual mechanical properties of the structural parts. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, the present invention proposes a splicing structure of a carbon skin aluminum honeycomb sandwich panel and a preparation method thereof, designs reinforcement at the skin splicing position, and designs the process parameters of the honeycomb sandwich panel to ensure the molding quality of the sandwich structure after the skin splicing, ensure that the flatness, mechanical properties and environmental adaptability of the entire panel meet the requirements, and greatly reduce the product manufacturing cost.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A first aspect of the present invention provides a splicing structure of a carbon skin aluminum honeycomb sandwich panel, wherein the splicing structure is connected between two adjacent carbon skin aluminum honeycomb sandwich panels, each of which includes a main honeycomb and a segmented carbon skin fixed to the upper and lower sides of the main honeycomb by an adhesive film, and the splicing seam of the two adjacent segmented carbon skins is consistent with the length direction of the carbon skin aluminum honeycomb sandwich panel. The splicing structure includes:

[0010] The honeycomb at the joint is located between the main honeycombs of two adjacent carbon-skinned aluminum honeycomb sandwich panels, and the upper and lower surfaces of the main honeycombs located on both sides of the honeycomb at the same joint are flush respectively;

[0011] The inner reinforcing skin is fixed to the upper and lower sides of the honeycomb at the joint by means of adhesive film, and the surfaces of the inner reinforcing skin on the upper and lower sides facing away from the honeycomb at the joint are respectively flush with the upper and lower surfaces of the main honeycomb, the center of the inner reinforcing skin is located at the joint of two adjacent segmented carbon skins, and the inner reinforcing skin is fixed to the segmented carbon skins by means of adhesive film;

[0012] The foam strip is filled in the gap between the main honeycomb and the honeycomb at the joint.

[0013] In some embodiments, the segmented carbon skin and the inner reinforcement skin are both laminated structural parts formed by using carbon fiber prepreg.

[0014] In some embodiments, the width of the inner reinforced skin is determined based on the principle that the bonding shear failure load of the adhesive at the splicing reinforcement position of the segmented carbon skin is greater than the tensile failure load of the segmented carbon skin when the carbon-skinned aluminum honeycomb sandwich panel is tensilely damaged, and the length of the inner reinforced skin needs to completely cover the length of the splicing seam.

[0015] In some embodiments, the width of the inner reinforcing skin is determined according to the following formula:

[0016] σ×b1×t1×b f ≥σ f ×t f ×b f

[0017] Wherein, σ is the shear strength of the adhesive, t1 is the thickness of the inner reinforced skin, b1 is the width of the inner reinforced skin on one side of the joint, and the width of the inner reinforced skin is 2×b1; σ f is the tensile strength of the segmented carbon skin, t f and b f are the thickness and width of the segmented carbon skin respectively.

[0018] In some embodiments, the thickness of the inner reinforcement skin is equal to the thickness of the segmented carbon skin.

[0019] In some embodiments, the height of the honeycomb at the joint is determined according to the following formula:

[0020] H2=H1-2×t1-2×h2×δ

[0021] Among them, H2 is the height of the honeycomb at the joint, H1 is the height of the main honeycomb, t1 is the thickness of the inner reinforcement skin, h2 is the thickness of the adhesive film, and δ is the compression ratio of the adhesive film after curing to its original thickness.

[0022] In some embodiments, one side of the main honeycomb in contact with the inner reinforcement skin is compressed by two honeycomb cells; and two honeycomb cells are compressed on both sides of the honeycomb at the joint in contact with the segmented carbon skin.

[0023] A second aspect of the present invention provides a method for preparing a splicing structure according to any embodiment of the first aspect of the present invention, comprising the following steps:

[0024] 1) cutting carbon fiber prepreg flat fabric according to the size and laying angle of the segmented carbon skin and the inner reinforcement skin, laying the carbon fiber prepreg flat fabric according to the designed number of layers and laying angle to obtain the first structure and the second structure after laying, vacuum packaging and curing the structures to obtain the blanks of the segmented carbon skin and the inner reinforcement skin;

[0025] 2) Cutting the block carbon skin and the inner reinforcement skin according to the size and splicing position of the carbon skin aluminum honeycomb sandwich panel to obtain the block carbon skin and the inner reinforcement skin;

[0026] 3) milling the honeycombs at the joints of the main honeycombs according to the size of the carbon-skinned aluminum honeycomb sandwich panels, and stretching them into a regular hexagonal form;

[0027] 4) Pasting adhesive film on the bonding surface between the segmented carbon skin and the main honeycomb, pasting adhesive film on the bonding surface between the inner reinforcement skin and the honeycomb at the joint, placing the segmented carbon skin side by side on the process board according to the size of the carbon skin aluminum honeycomb sandwich panel, with the side pasted with adhesive film facing upward; laying the inner reinforcement skin in the center of the joint seam of the segmented carbon skin, with the side pasted with adhesive film facing upward;

[0028] 5) placing the opened main honeycomb on the segmented carbon skin with adhesive film, covering the segmented carbon skin and compressing two honeycomb grids on the side in contact with the inner reinforcement skin; pasting the foam strip used in conjunction with the adhesive film on the sides of the main honeycomb and the honeycomb at the joint; placing the opened honeycomb at the joint on the inner reinforcement skin with adhesive film, covering the inner reinforcement skin and compressing two honeycomb grids on both sides in contact with the segmented carbon skin; pressing all honeycombs to the adhesive film for bonding;

[0029] 6) Place foam sticks in the honeycomb grids on both sides of the honeycomb joint seam, and place them in pairs on the left and right sides;

[0030] 7) The inner reinforcing skin with adhesive film attached is placed above the honeycomb at the joint, with one side of the adhesive film attached facing downward; the segmented carbon skin with adhesive film attached is placed above the main honeycomb, with one side of the adhesive film attached facing downward; the joint seam of the segmented carbon skin is located at the center of the width of the inner reinforcing skin, to obtain a honeycomb sandwich panel blank;

[0031] 8) vacuum packaging and curing the honeycomb sandwich panel blank to obtain the splicing structure of the carbon skin aluminum honeycomb sandwich panel.

[0032] In some embodiments, in step 1), when curing the first structure and the second structure, the applied pressure is 0.4 MPa to 0.5 MPa, the curing temperature is 165° C. to 175° C., and the curing time is 3 h to 4 h.

[0033] In some embodiments, in step 8), when curing the honeycomb sandwich panel blank, the applied pressure is 0.15MPa to 0.2MPa, the curing temperature is 125°C to 135°C, and the curing time is 120min to 180min.

[0034] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0035] The present invention proposes a splicing structure of a carbon-skinned aluminum honeycomb sandwich panel and a preparation method thereof. For a large-sized carbon-skinned aluminum honeycomb sandwich structure, the skin is spliced ​​and a reinforced structure is designed at the splicing position to enhance the bending strength of the splicing position and the bending stiffness of the whole panel; the process parameters of the honeycomb sandwich and the adhesive at the splicing position are designed, including the design of the carbon panel splicing form and the reinforcement panel parameters, the bonding form, etc., to ensure the molding quality of the whole panel, and to ensure that the flatness, mechanical properties and environmental adaptability of the whole panel meet the requirements. Specifically:

[0036] 1) The present invention solves the problem of limited size of raw materials used to prepare large-sized carbon skins, and can use smaller raw materials to prepare block carbon skins, saving the cost of raw material production and the cost of large-sized carbon skin molding and curing equipment.

[0037] 2) The present invention designs a splicing and reinforcement structure in the sandwich panel, which can ensure the flatness of the entire panel, improve the rigidity of the entire panel, and has a high practical application value.

[0038] 3) The method of the present invention is simple and highly feasible, and the large-sized carbon-skinned aluminum honeycomb sandwich panels produced have good processability and a high success rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic cross-sectional view of a splicing structure of a carbon skinned honeycomb sandwich panel provided in an embodiment of the first aspect of the present invention.

[0040] Figure 2 yes Figure 1 Schematic diagram of the honeycomb structure in the spliced ​​structure shown.

[0041] Figure 3 It is a flow chart of a process for preparing a splicing structure of a carbon skinned honeycomb sandwich panel provided in an embodiment of the second aspect of the present invention.

[0042] In the figure: 1. Block carbon skin; 2. Inner reinforced skin; 3. Main honeycomb; 4. Honeycomb at the joint; 5. Adhesive film; 6. Foam strip; 7. Foam stick. DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] In order to enable those skilled in the art to better understand the disclosed solution, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] See also Figure 1 , Figure 2 The first aspect of the present invention provides a splicing structure of a carbon skin aluminum honeycomb sandwich panel, which is connected between two adjacent carbon skin aluminum honeycomb sandwich panels. Each carbon skin aluminum honeycomb sandwich panel includes a main honeycomb 3 and a segmented carbon skin 1 fixed to the upper and lower sides of the main honeycomb 3 by an adhesive film 5. The joint between the two adjacent segmented carbon skins 1 is consistent with the length direction of the carbon skin aluminum honeycomb sandwich panel. The splicing structure of this embodiment includes:

[0046] The honeycomb 4 at the joint is located between the main honeycombs 3 of two adjacent carbon-skinned aluminum honeycomb sandwich panels, and the upper and lower surfaces of the main honeycombs 3 located on both sides of the honeycomb 4 at the same joint are flush with each other;

[0047] The inner reinforcing skin 2 is fixed to the upper and lower sides of the honeycomb 4 at the joint by means of adhesive films 5, and the surfaces of the inner reinforcing skin 2 on the upper and lower sides facing away from the honeycomb 4 at the joint are flush with the upper and lower surfaces of the main honeycomb 3 respectively, the center of the inner reinforcing skin 2 is located at the joint of the two adjacent segmented carbon skins 1, and the inner reinforcing skin 2 is fixed to the segmented carbon skins 1 by means of adhesive films 5;

[0048] The foam strip 6 is filled in the gap between the main honeycomb 3 and the honeycomb 4 at the joint to seal and bond the two together.

[0049] In some embodiments, the segmented carbon skin 1 and the inner reinforcement skin 2 are both laminated structural parts formed using carbon fiber prepreg, and are located on the upper and lower surfaces of the sandwich panel.

[0050] The number of blocks and the size of a single block of the segmented carbon skin 1 should be determined according to the size of the carbon fiber prepreg and the size of the carbon skin aluminum honeycomb sandwich panel. When the size of the carbon skin aluminum honeycomb sandwich panel is larger than the size of the carbon fiber prepreg, the carbon skin needs to be divided into 2 or more blocks, and the size of a single block should be evenly divided on the premise that it is not larger than the size of the carbon fiber prepreg.

[0051] For the inner reinforced skin 2, the thickness and size of the inner reinforced skin 2 should be determined according to the parameters of the adhesive used and the skin material parameters. Specifically: based on the principle that the bonding shear failure load of the adhesive at the splicing reinforcement position of the segmented carbon skin when the carbon skin aluminum honeycomb sandwich panel is tensilely damaged is greater than the tensile failure load of the segmented carbon skin, the tensile strength of the segmented carbon skin 1 is taken as σ f , the thickness of the block carbon skin 1 is t f The segmented carbon skin 1 is spliced ​​in the length direction, that is, the splicing seam is perpendicular to the length direction of the segmented carbon skin 1, and the width of the segmented carbon skin 1 is b f ; The shear strength of the adhesive is σ; the inner reinforced skin 2 and the segmented carbon skin 1 are made of the same material and process. The thickness of the inner reinforced skin 2 is t1. To facilitate the process operation, t1 is generally taken to be the same thickness as the segmented carbon skin 1. The width of the inner reinforced skin 2 on one side of the joint is b1, that is, the width of the inner reinforced skin 2 is 2×b1. According to σ×b1×t1×b f ≥σ f ×t f ×b f The width of the inner reinforcing skin 2 is preliminarily calculated as 2×b1, and the length of the inner reinforcing skin 2 needs to completely cover the length of the splicing seam.

[0052] The number of plies and the ply angle of the segmented carbon skin 1 and the inner reinforcement skin 2 should be determined based on the structural design and mechanical analysis of the carbon skin aluminum honeycomb sandwich panel.

[0053] In a specific embodiment of the present application, the thickness of the segmented carbon skin 1 is 0.5 mm, the tensile strength of the segmented carbon skin 1 is 400 MPa, the shear strength of the adhesive is 10 MPa, the thickness t1 of the inner reinforced skin 2 is 0.5 mm, and the calculation shows that the width on both sides of the splicing seam is 40 mm, and the width of the inner reinforced skin 2 is 80 mm. The carbon fiber prepreg flat cloth is cut according to the laying angle of the carbon skin, and 4 layers are laid on the process board. The laying angles are [0 / +45 / 90 / -45] from bottom to top. After laying, vacuum packaging is carried out and cured in an autoclave to obtain the cured segmented carbon skin 1 and the inner reinforced skin 2.

[0054] In some embodiments, the main honeycomb 3 and the honeycomb 4 at the joint are both the middle sandwich layer of the sandwich plate, the main honeycomb 3 is located between the upper and lower block carbon skins 1, and the honeycomb 4 at the joint is located between the upper and lower inner reinforcement skins 2; the adhesive film 5 is located between the block carbon skin 1 and the main honeycomb 3, between the block carbon skin 1 and the inner reinforcement skin 2, and between the inner reinforcement skin 2 and the honeycomb 4 at the joint, and the upper, middle and lower integral structure is formed by adhesive bonding. Let the height of the main honeycomb 3 be H1; calculate the height of the honeycomb 4 at the joint according to the thickness of the inner reinforcement skin 2 and the thickness of the adhesive film 5, take the thickness of the inner reinforcement skin 2 as t1, the thickness of the adhesive film 5 as h2, and assume that the compression ratio of the adhesive film 5 after curing to its original thickness is δ, then the height H2 of the honeycomb 4 at the joint is calculated according to H2=H1-2×t1-2×h2×δ, and the main honeycomb 3 and the honeycomb 4 at the joint need to be pulled apart into a regular hexagonal form.

[0055] In some embodiments, the foam strip 6 is located between the main honeycomb 3 and the honeycomb 4 at the joint, connecting the two honeycombs; the foam stick 7 is located in the honeycomb core cells in the main honeycomb 3 and the honeycomb 4 at the joint, and is used to fill the honeycomb core cell cavity. Two honeycomb cells are compressed on one side of the main honeycomb 3 in contact with the inner reinforcement skin 2; two honeycomb cells are compressed on both sides of the honeycomb 4 at the joint in contact with the segmented carbon skin 1.

[0056] See also Figure 3 The second aspect of the present invention provides a method for preparing a splicing structure of a carbon-skinned aluminum honeycomb sandwich panel, which specifically includes the following steps:

[0057] 1) Cut the carbon fiber prepreg flat cloth according to the size and laying angle of the segmented carbon skin 1 and the inner reinforcement skin 2, lay 4 layers or a specified number of layers on the process board, and the laying angles are [0 / +45 / 90 / -45] or a specified order from bottom to top. After laying, vacuum packaging is performed and cured in an autoclave. The applied pressure is 0.4MPa~0.5MPa, the curing temperature is 165℃~175℃, and the curing time is 3h~4h or the specified pressure, temperature and time to obtain the solidified blanks of the segmented carbon skin 1 and the inner reinforcement skin 2. Among them, the size of the segmented carbon skin 1 and the inner reinforcement skin 2 is determined according to the method described above, which will not be repeated here.

[0058] 2) Cut the solidified carbon skin 1 and inner reinforcement skin 2 according to the size and splicing position of the carbon skin aluminum honeycomb sandwich panel by cutting or machining. After cutting, the edges are neat, the single-side straightness is better than 1 mm, and the verticality of adjacent edges is better than 1.5 mm, so as to obtain the carbon skin 1 and inner reinforcement skin 2.

[0059] 3) According to the size of the carbon skin aluminum honeycomb sandwich panel, the main honeycomb 3 with a height of H1 is milled, and the honeycomb 4 at the joint with a height of H2 is milled, and the main honeycomb 3 and the honeycomb 4 at the joint are pulled apart into a regular hexagonal form.

[0060] 4) Paste a layer of adhesive film 5 on the bonding surface between the segmented carbon skin 1 and the main honeycomb 3, and paste a layer of adhesive film 5 on the bonding surface between the inner reinforcing skin 2 and the honeycomb 4 at the joint. Place the segmented carbon skins 1 side by side on the process board according to the size of the carbon skin aluminum honeycomb sandwich panel, with the side pasted with the adhesive film 5 facing upward; lay the inner reinforcing skin 2 in the center of the joint seam of the segmented carbon skin 1, with the side pasted with the adhesive film 5 facing upward.

[0061] 5) Place the opened main honeycomb 3 on the segmented carbon skin 1 with the adhesive film 5, the placement range covers the segmented carbon skin 1 and compresses two honeycomb lattices on the side in contact with the inner reinforcement skin 2, the compressed honeycomb lattices can ensure effective bonding during the heating and curing process of the honeycomb sandwich panel, and will not be separated from the main honeycomb 3 due to heating and slippage; paste a layer of foam adhesive strip 6 used in conjunction with the adhesive film 5 on the side of the main honeycomb 3 and the honeycomb 4 at the joint; place the opened honeycomb 4 at the joint above the inner reinforcement skin 2 with the adhesive film 5, the placement range covers the inner reinforcement skin 2 and compresses two honeycomb lattices on both sides in contact with the segmented carbon skin 1; press all the honeycombs to the adhesive film 5 for bonding.

[0062] 6) Place foam rubber sticks 7 in the honeycomb grids on both sides of the honeycomb joint seam, in pairs on the left and right.

[0063] 7) Place the inner reinforcing skin 2 with the adhesive film 5 on top of the honeycomb 4 at the joint, with the side with the adhesive film 5 facing downward; place the segmented carbon skin 1 with the adhesive film 5 on top of the main honeycomb 3, with the side with the adhesive film 5 facing downward; the joint seam of the segmented carbon skin 1 is located at the center of the width of the inner reinforcing skin 2, to obtain a honeycomb sandwich panel blank.

[0064] 8) placing a forming process plate on the honeycomb sandwich panel blank, vacuum packaging and curing in an autoclave, applying a pressure of 0.15 MPa to 0.2 MPa, a curing temperature of 125° C. to 135° C., a curing time of 120 min to 180 min or specifying pressure, temperature and time to obtain a splicing structure of a carbon skinned aluminum honeycomb sandwich panel.

[0065] The skin of the large-sized carbon-skinned aluminum honeycomb sandwich panel prepared in this embodiment has no fault dislocation splicing during layering, no stress concentration, and the cost of preparing the block carbon skin is low; the splicing structure of the carbon-skinned aluminum honeycomb sandwich panel does not affect the flatness of the whole panel and the stiffness of the whole panel is greatly improved, and the production cost of the product is greatly reduced. Specifically, the large-sized carbon-skinned aluminum honeycomb sandwich panel obtained in this example has been applied to the feed array substrate of a certain type of satellite. The flatness of the whole panel with a splicing structure is not reduced compared with the conventional large-sized sandwich panel, and the stiffness of the whole panel is nearly 2 times higher than that of the conventional large-sized sandwich panel; compared with the conventional large-sized sandwich panel, the cost of raw materials and the equipment cost of product production are greatly reduced.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0067] Although embodiments of the present disclosure have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A splicing structure of a carbon-skinned aluminum honeycomb sandwich panel, characterized in that: The splicing structure is connected between two adjacent carbon-skinned aluminum honeycomb sandwich panels, each of which includes a main honeycomb and a segmented carbon skin fixed to the upper and lower sides of the main honeycomb by a film, and the joint between two adjacent segmented carbon skins is consistent with the length direction of the carbon-skinned aluminum honeycomb sandwich panel. The splicing structure includes: The honeycomb at the joint is located between the main honeycombs of two adjacent carbon-skinned aluminum honeycomb sandwich panels, and the upper and lower surfaces of the main honeycombs located on both sides of the honeycomb at the same joint are flush respectively; The inner reinforcing skin is fixed to the upper and lower sides of the honeycomb at the joint by means of adhesive film, and the surfaces of the inner reinforcing skin on the upper and lower sides facing away from the honeycomb at the joint are respectively flush with the upper and lower surfaces of the main honeycomb, the center of the inner reinforcing skin is located at the joint of two adjacent segmented carbon skins, and the inner reinforcing skin is fixed to the segmented carbon skins by means of adhesive film; The foam strip is filled in the gap between the main honeycomb and the honeycomb at the joint.

2. The splicing structure according to claim 1, characterized in that: The segmented carbon skin and the inner reinforced skin are both laminated structural parts formed by using carbon fiber prepreg.

3. The splicing structure according to claim 1, characterized in that: The width of the inner reinforced skin is determined based on the principle that the bonding shear failure load of the adhesive at the splicing reinforcement position of the segmented carbon skin is greater than the tensile failure load of the segmented carbon skin when the carbon-skinned aluminum honeycomb sandwich panel is tensilely damaged, and the length of the inner reinforced skin needs to completely cover the length of the splicing seam.

4. The splicing structure according to claim 1, characterized in that: The width of the inner reinforcing skin is determined according to the following formula: σ×b1×t1×b f ≥σ f ×t f ×b f Wherein, σ is the shear strength of the adhesive, t1 is the thickness of the inner reinforced skin, b1 is the width of the inner reinforced skin on one side of the joint, and the width of the inner reinforced skin is 2×b1; σ f is the tensile strength of the segmented carbon skin, t f and b f are the thickness and width of the segmented carbon skin respectively.

5. The splicing structure according to claim 1, characterized in that: The thickness of the inner reinforcement skin is equal to the thickness of the segmented carbon skin.

6. The splicing structure according to claim 1, characterized in that: The height of the honeycomb at the joint is determined according to the following formula: H2=H1-2×t1-2×h2×δ Among them, H2 is the height of the honeycomb at the joint, H1 is the height of the main honeycomb, t1 is the thickness of the inner reinforcement skin, h2 is the thickness of the adhesive film, and δ is the compression ratio of the adhesive film after curing to its original thickness.

7. The splicing structure according to claim 1, characterized in that: Two honeycomb cells are compressed on one side of the main honeycomb in contact with the inner reinforcement skin; and two honeycomb cells are compressed on both sides of the honeycomb at the joint in contact with the segmented carbon skin.

8. A method for preparing a splicing structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) cutting carbon fiber prepreg flat fabric according to the size and laying angle of the segmented carbon skin and the inner reinforcement skin, laying the carbon fiber prepreg flat fabric according to the designed number of layers and laying angle to obtain the first structure and the second structure after laying, vacuum packaging and curing the structures to obtain the blanks of the segmented carbon skin and the inner reinforcement skin; 2) Cutting the block carbon skin and the inner reinforcement skin according to the size and splicing position of the carbon skin aluminum honeycomb sandwich panel to obtain the block carbon skin and the inner reinforcement skin; 3) milling the honeycombs at the joints of the main honeycombs according to the size of the carbon-skinned aluminum honeycomb sandwich panels, and stretching them into a regular hexagonal form; 4) Pasting adhesive film on the bonding surface between the segmented carbon skin and the main honeycomb, pasting adhesive film on the bonding surface between the inner reinforcement skin and the honeycomb at the joint, placing the segmented carbon skin side by side on the process board according to the size of the carbon skin aluminum honeycomb sandwich panel, with the side pasted with adhesive film facing upward; laying the inner reinforcement skin in the center of the joint seam of the segmented carbon skin, with the side pasted with adhesive film facing upward; 5) placing the opened main honeycomb on the segmented carbon skin with adhesive film, covering the segmented carbon skin and compressing two honeycomb grids on the side in contact with the inner reinforcement skin; pasting the foam strip used in conjunction with the adhesive film on the sides of the main honeycomb and the honeycomb at the joint; placing the opened honeycomb at the joint on the inner reinforcement skin with adhesive film, covering the inner reinforcement skin and compressing two honeycomb grids on both sides in contact with the segmented carbon skin; pressing all honeycombs to the adhesive film for bonding; 6) Place foam sticks in the honeycomb grids on both sides of the honeycomb joint seam, and place them in pairs on the left and right sides; 7) The inner reinforcing skin with adhesive film attached is placed above the honeycomb at the joint, with one side of the adhesive film attached facing downward; the segmented carbon skin with adhesive film attached is placed above the main honeycomb, with one side of the adhesive film attached facing downward; the joint seam of the segmented carbon skin is located at the center of the width of the inner reinforcing skin, to obtain a honeycomb sandwich panel blank; 8) vacuum packaging and curing the honeycomb sandwich panel blank to obtain the splicing structure of the carbon skin aluminum honeycomb sandwich panel.

9. The preparation method according to claim 8, characterized in that: In step 1), when curing the first structure and the second structure, the applied pressure is 0.4 MPa to 0.5 MPa, the curing temperature is 165° C. to 175° C., and the curing time is 3 h to 4 h.

10. The preparation method according to claim 8, characterized in that: In step 8), when curing the honeycomb sandwich panel blank, the applied pressure is 0.15MPa-0.2MPa, the curing temperature is 125°C-135°C, and the curing time is 120min-180min.

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