A method for preparing composite material special-shaped curved honeycomb

Abstract

A method for preparing composite material irregularly shaped curved honeycombs relates to the field of flat and curved honeycomb fabrication. This invention addresses the problem of existing composite material irregularly shaped curved honeycombs lacking a suitable molding technology. The method comprises the following steps: Step 1: Material selection and pretreatment; Step 2: Prepreg strip folding; Step 3: High-temperature curing; Step 4: Demolding and arrangement and assembly; Step 5: Finishing. This method is used to prepare irregularly shaped curved honeycomb structures.

Description

Technical Field

[0001] The invention relates to the field of plane and curved honeycomb preparation, and in particular to a method for preparing a composite material special-shaped curved honeycomb. Background Art

[0002] Composite honeycomb structures have excellent mechanical properties such as light weight, high specific stiffness and high specific strength, and are widely used in aerospace structures. Honeycomb structures are not only used in flat plate structures, but can also form complex curved structures to adapt to various curved shapes. However, the forming technology of composite curved honeycomb structures is still imperfect. The existing curved honeycomb manufacturing processes mainly include natural bending, clamp cable technology, 3D printing technology, fiber winding technology, 3D printing technology and origami technology. The first five technologies are not suitable for composite materials or are not suitable for modern industrial production. The folding method (publication number: CN114055825A) is mainly aimed at honeycomb shell structures, and has poor adaptability to any upper and lower surfaces, and cannot adapt to all upper and lower surfaces. Summary of the Invention

[0003] In order to solve the problem that there is no suitable forming technology for existing composite material arbitrary curved surface honeycombs, the present invention further proposes a preparation method for composite material special-shaped curved surface honeycombs.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A method for preparing a composite material irregular curved honeycomb includes the following steps:

[0006] Step 1: Material selection and pretreatment: Composite material prepreg strips are selected as the preparation material. The size, shape and quantity of the composite material prepreg strips required are calculated according to the different upper and lower curved surface structures. The composite material prepreg strips include upper prepreg strips and lower prepreg strips. A high-precision CNC cutting machine is used to cut the composite material prepreg according to the calculated predetermined size and shape to obtain multiple composite material prepreg strips, which are numbered one by one.

[0007] Step 2: Folding the prepreg strips: Lay the composite material prepreg strips on the corresponding wave-shaped mold and fold them. During the folding process, the edges of the composite material prepreg strips are aligned with the turning points of the wave-shaped mold, and the composite material prepreg strips and the wave-shaped mold are tightly attached without wrinkles.

[0008] Step 3: High-temperature curing: Set the temperature, pressure, and time parameters of the hot press according to the curing requirements of the composite prepreg. Place the fixed wave-shaped mold and the composite prepreg strips on it into the hot press. Start the hot press and perform the curing process according to the preset temperature, pressure, and time parameters.

[0009] Step 4: Demolding and Arrangement: After the composite prepreg strips are completely solidified and cooled, the wavy mold is removed. After demoulding, the composite prepreg strips are arranged according to the numbers, first arranging the lower layer prepreg strips, and then inserting the upper layer prepreg strips one by one on top of the lower layer prepreg strips. The upper layer prepreg strips are staggered with the lower layer prepreg strips to form a mosaic curved honeycomb.

[0010] Step 5: Trimming: After the arrangement and combination is completed, check whether there are defects at the intersection of the composite material prepreg strips, and fix and trim the defects.

[0011] Furthermore, the composite material prepreg strip in step one includes a supporting structure and a matching structure, the shape and size of the supporting structure are set according to the shape of the upper and lower curved surfaces and the size of the honeycomb unit cell, the upper edge of the matching structure cutting figure in the lower prepreg strip is consistent with the lower edge of the matching structure cutting figure in the upper prepreg strip, and the shape and size of the lower edge of the matching structure cutting figure in the lower prepreg strip and the upper edge of the matching structure cutting figure in the upper prepreg strip are set according to the shape of the upper and lower curved surfaces and the size of the honeycomb unit cell.

[0012] Furthermore, in the second step, the corner of the wave-shaped mold coincides with the junction of the support structure and the matching structure, and the turning angle of the wave-shaped mold corner matches the angle required for matching different honeycomb unit cell structures.

[0013] Furthermore, the honeycomb unit cell of the irregular curved honeycomb is a triangle, a hexagon, an octagon or a negative Poisson's ratio unit cell.

[0014] Furthermore, the negative Poisson's ratio unit cell includes a concave hexagon, a double trapezoid and a star.

[0015] Furthermore, in the step 2, when the honeycomb unit cell of the irregular curved honeycomb is a triangle, the turning angle at the corner of the wavy mold is 60°; when the honeycomb unit cell of the irregular curved honeycomb is a hexagon, the turning angle at the corner of the wavy mold is 120°; when the honeycomb unit cell of the irregular curved honeycomb is an octagon, the turning angle at the corner of the wavy mold is repeated in a cycle of 135°, 270°, 270°, 135°, 225°, 90°, 90°, and 225°.

[0016] Furthermore, in the step 2, when the honeycomb unit cell of the special-shaped curved honeycomb is a concave hexagon, the turning angle of the wavy mold corner of the lower prepreg strip is 120°, and the turning angle of the wavy mold corner of the upper prepreg strip is 60°; when the honeycomb unit cell of the special-shaped curved honeycomb is a double trapezoid, the turning angle of the wavy mold corner of the lower prepreg strip is (180°-α), and the turning angle of the wavy mold corner of the upper prepreg strip is (180°-β).

[0017] Furthermore, in the step 2, the bending direction of the composite material prepreg strip during the folding process is set according to the matching mode between the upper layer prepreg strip and the lower layer prepreg strip.

[0018] Furthermore, in step one, the lower layer prepreg strips include lower layer middle prepreg strips and lower layer edge prepreg strips, and the upper layer prepreg strips include upper layer middle prepreg strips, upper layer one side edge prepreg strips and upper layer other side edge prepreg strips.

[0019] Furthermore, when the lower layer prepreg strips are arranged in step four, the lower layer middle prepreg strips and the lower layer edge prepreg strips are arranged alternately, and when the upper layer prepreg strips are inserted into the lower layer prepreg strips one by one, the upper layer prepreg strips are arranged in sequence from the upper left corner to the upper layer middle prepreg strips and the upper layer edge prepreg strips on one side, and the upper layer edge prepreg strips on the other side are arranged in sequence from top to bottom.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Propose a set of molding technology for preparing composite material curved honeycomb structure. The present invention adopts a new molding process to prepare composite material honeycomb structure, which is simple to prepare and easy to achieve batch production.

[0022] 2. This forming method can not only form hexagonal honeycomb structures, but also triangle, octagon and negative Poisson's ratio honeycomb structures.

[0023] 3. This molding method can be applied to the molding of any known upper and lower surface honeycomb structure and has low requirements on the properties of the composite material.

[0024] 4. Composite materials are lightweight materials that effectively reduce the overall weight of the honeycomb structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the upper end face of the hexagonal honeycomb structure of the present invention;

[0026] Figure 2 It is an axonometric view of the hexagonal honeycomb molding structure of the present invention;

[0027] Figure 3 It is a schematic diagram of the upper end surface of the triangular honeycomb forming structure of the present invention;

[0028] Figure 4 It is a first axonometric view of the triangular honeycomb forming structure of the present invention;

[0029] Figure 5 is a second axonometric view of the triangular honeycomb structure of the present invention;

[0030] Figure 6Schematic diagram of the upper end face of the concave hexagonal honeycomb structure of the present invention;

[0031] Figure 7 It is a first axonometric view of the concave hexagonal honeycomb molding structure of the present invention;

[0032] Figure 8 It is a second axonometric view of the concave hexagonal honeycomb molding structure of the present invention;

[0033] Figure 9 It is a schematic diagram of the upper end face of the double trapezoidal honeycomb forming structure of the present invention;

[0034] Figure 10 This is a first axonometric view of the double trapezoidal honeycomb molding structure of the present invention;

[0035] Figure 11 It is a second axonometric view of the double trapezoidal honeycomb molding structure of the present invention;

[0036] Figure 12 Schematic diagram of the cutting pattern of the lower layer prepreg strips of the present invention;

[0037] Figure 13 Schematic diagram of the cutting pattern of the upper prepreg strip in the present invention;

[0038] Figure 14 Schematic diagram of the support structure and matching structure of the composite material prepreg strip in the present invention;

[0039] Figure 15 Schematic diagram of the first method of combining the upper prepreg strips and the lower prepreg strips in the present invention;

[0040] Figure 16 Schematic diagram of the second method of combining the upper prepreg strips and the lower prepreg strips in the present invention;

[0041] Figure 17 Schematic diagram of the matching mode of the upper layer prepreg strips and the lower layer prepreg strips when the honeycomb unit cell of the present invention is hexagonal;

[0042] Figure 18 Schematic diagram of the matching mode of the upper layer prepreg strips and the lower layer prepreg strips when the honeycomb unit cell is triangular in the present invention;

[0043] Figure 19 Schematic diagram of the matching mode of the upper layer prepreg strips and the lower layer prepreg strips when the honeycomb unit cell is octagonal in the present invention;

[0044] Figure 20 Schematic diagram of the matching mode of the upper layer prepreg strips and the lower layer prepreg strips when the honeycomb unit cell of the present invention is a concave hexagon;

[0045] Figure 21Schematic diagram of the matching mode of the upper layer prepreg strips and the lower layer prepreg strips when the honeycomb unit cell of the present invention is a double trapezoid;

[0046] Figure 22 Schematic diagram of the cutting pattern of the lower middle prepreg strip when the honeycomb unit cell of the present invention is hexagonal;

[0047] Figure 23 Schematic diagram of the cutting pattern of the lower edge prepreg strip when the honeycomb unit cell is hexagonal in the present invention;

[0048] Figure 24 This is a schematic diagram of the cutting pattern of the upper middle prepreg strip when the honeycomb unit cell is hexagonal in the present invention;

[0049] Figure 25 This is a schematic diagram of the cutting pattern of the prepreg strip on one edge of the upper layer when the honeycomb unit cell is hexagonal in the present invention;

[0050] Figure 26 Schematic diagram of the cutting pattern of the prepreg strip at the other edge of the upper layer when the honeycomb unit cell is hexagonal in the present invention;

[0051] Figure 27 Schematic diagram of the arrangement of the lower layer prepreg strips after curing when the honeycomb unit cell of the present invention is hexagonal;

[0052] Figure 28 Schematic diagram of the arrangement of the upper layer of prepreg strips after curing when the honeycomb unit cell of the present invention is hexagonal;

[0053] Figure 29 Schematic diagram of the coordination of the lower prepreg strip and the single upper prepreg strip after curing when the honeycomb unit cell of the present invention is hexagonal;

[0054] Figure 30 Schematic diagram of the coordination of the lower layer prepreg strips and the upper layer middle prepreg strips after curing when the honeycomb unit cell of the present invention is hexagonal;

[0055] Figure 31 Schematic diagram of the coordination of the lower layer prepreg strips, the upper layer middle prepreg strips, and the upper layer edge prepreg strips after curing when the honeycomb unit cell of the present invention is hexagonal;

[0056] Figure 32 This is a schematic diagram of the coordination of the lower layer prepreg strips and the upper layer prepreg strips after curing when the honeycomb unit cell in the present invention is hexagonal.

[0057] Among them, 1-1 is the middle prepreg strip of the lower layer, 1-2 is the edge prepreg strip of the lower layer, 2-1 is the middle prepreg strip of the upper layer, 2-2 is the edge prepreg strip of one side of the upper layer, and 2-3 is the edge prepreg strip of the other side of the upper layer. DETAILED DESCRIPTION

[0058] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to 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.

[0059] Specific implementation method 1: Combination Figures 1 to 32 This embodiment describes a method for preparing a composite material irregular curved honeycomb, including the following steps:

[0060] Step 1: Material selection and pretreatment: Composite material prepreg strips are selected as the preparation material. The size, shape and quantity of the composite material prepreg strips required are calculated according to the different upper and lower curved surface structures. The composite material prepreg strips include upper prepreg strips and lower prepreg strips. A high-precision CNC cutting machine is used to cut the composite material prepreg according to the calculated predetermined size and shape to obtain multiple composite material prepreg strips, which are numbered one by one.

[0061] Step 2: Folding the prepreg strips: Lay the composite material prepreg strips on the corresponding wave-shaped mold and fold them. During the folding process, the edges of the composite material prepreg strips are aligned with the turning points of the wave-shaped mold, and the composite material prepreg strips and the wave-shaped mold are tightly attached without wrinkles.

[0062] Step 3: High-temperature curing: Set the temperature, pressure, and time parameters of the hot press according to the curing requirements of the composite prepreg. Place the fixed wave-shaped mold and the composite prepreg strips on it into the hot press. Start the hot press and perform the curing process according to the preset temperature, pressure, and time parameters.

[0063] Step 4: Demolding and Arrangement: After the composite prepreg strips are completely solidified and cooled, the wavy mold is removed. After demoulding, the composite prepreg strips are arranged according to the numbers, first arranging the lower layer prepreg strips, and then inserting the upper layer prepreg strips one by one on top of the lower layer prepreg strips. The upper layer prepreg strips are staggered with the lower layer prepreg strips to form a mosaic curved honeycomb.

[0064] Step 5: Trimming: After the arrangement and combination is completed, check whether there are defects at the intersection of the composite material prepreg strips, and fix and trim the defects.

[0065] The present invention performs customized cutting and trimming of composite material prepregs, forms the composite material prepregs into the desired strip structure, and then undergoes folding, curing, demoulding, and arrangement and combination processes. The method is simple and easy to implement in batch production, has low requirements on the properties of the composite material, and can form any known upper and lower surface honeycomb shell structure.

[0066] Multiple composite prepreg strips of varying curvature and size are calculated based on the different upper and lower curved surface structures. Each composite prepreg strip has a unique shape and is assigned a specific number. During cutting, ensure smooth, burr-free edges to ensure quality subsequent assembly.

[0067] When folded, the composite prepreg strip is attached to the mold on both sides.

[0068] During curing, it should be ensured that there is no bending or deformation in the structure when the composite prepreg strips are placed in the hot press.

[0069] When dismantling, apply force gently and evenly to avoid sudden or excessive force that may cause deformation or damage to the structure. After demoulding, arrange and combine the parts according to the sequence number marked on the design drawing.

[0070] After the arrangement and combination is completed, check whether the intersection of the prepreg strips is flat, fits well, and has no protrusions or gaps. If necessary, use glue or other fixing structures to fix the prepreg strips.

[0071] The darker areas in the image are the upper prepreg strips, and the lighter areas are the lower prepreg strips. The intersection of the dark and light colors is the common area between the upper and lower layers, with each layer occupying half.

[0072] The width of the upper and lower prepreg strips in the non-overlapping part of the top view is determined by the upper and lower surfaces, and the common part of the upper and lower layers each occupies 1 / 2 of the height between the upper and lower surfaces, and should fit together after molding.

[0073] Specific implementation method 2: Combination Figures 1 to 32 To explain this embodiment, the composite material prepreg strip in step one described in this embodiment includes a supporting structure and a matching structure. The shape and size of the supporting structure are set according to the shapes of the upper and lower curved surfaces and the size of the honeycomb unit cell. The upper edge of the matching structure cutting figure in the lower prepreg strip is consistent with the lower edge of the matching structure cutting figure in the upper prepreg strip. The shapes and sizes of the lower edge of the matching structure cutting figure in the lower prepreg strip and the upper edge of the matching structure cutting figure in the upper prepreg strip are set according to the shapes of the upper and lower curved surfaces and the size of the honeycomb unit cell.

[0074] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0075] Specific implementation method three: Combination Figures 1 to 32 To illustrate this embodiment, the corner of the wavy mold in step 2 of this embodiment coincides with the junction of the support structure and the matching structure, and the turning angle of the wavy mold corner matches the angle required for matching different honeycomb unit cell structures.

[0076] The undisclosed technical features in this embodiment are the same as those in the second embodiment.

[0077] Specific implementation method four: Combination Figures 1 to 32 To illustrate this embodiment, the honeycomb unit cell of the irregular curved honeycomb in this embodiment is a triangle, a hexagon, an octagon or a negative Poisson's ratio unit cell.

[0078] The undisclosed technical features in this embodiment are the same as those in the third embodiment.

[0079] Specific implementation method five: Combination Figures 1 to 32 This embodiment will be described. The negative Poisson's ratio unit cells in this embodiment include concave hexagons, double trapezoids, and stars.

[0080] The undisclosed technical features in this embodiment are the same as those in the fourth embodiment.

[0081] Specific implementation method six: combination Figures 1 to 32 To illustrate this embodiment, in step 2 described in this embodiment, when the honeycomb unit cell of the irregular curved honeycomb is a triangle, the turning angle at the corner of the wavy mold is 60°; when the honeycomb unit cell of the irregular curved honeycomb is a hexagon, the turning angle at the corner of the wavy mold is 120°; when the honeycomb unit cell of the irregular curved honeycomb is an octagon, the turning angle at the corner of the wavy mold is repeated in a cycle of 135°, 270°, 270°, 135°, 225°, 90°, 90°, and 225°.

[0082] The undisclosed technical features in this embodiment are the same as those in the fourth embodiment.

[0083] Specific implementation method seven: combination Figures 1 to 32 To illustrate this embodiment, in step 2 described in this embodiment, when the honeycomb unit cell of the special-shaped curved honeycomb is a concave hexagon, the turning angle of the wavy mold corner of the lower prepreg strip is 120°, and the turning angle of the wavy mold corner of the upper prepreg strip is 60°; when the honeycomb unit cell of the special-shaped curved honeycomb is a double trapezoid, the turning angle of the wavy mold corner of the lower prepreg strip is (180°-α), and the turning angle of the wavy mold corner of the upper prepreg strip is (180°-β).

[0084] The undisclosed technical features in this embodiment are the same as those in the fifth embodiment.

[0085] Specific implementation method eight: combination Figures 1 to 32 To illustrate this embodiment, in step 2 of this embodiment, the bending direction of the composite material prepreg strips during the folding process is set according to the matching mode between the upper prepreg strips and the lower prepreg strips.

[0086] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0087] Specific implementation method nine: combination Figures 1 to 32 To illustrate this embodiment, in step 1 described in this embodiment, the lower layer prepreg strips include the lower layer middle prepreg strips and the lower layer edge prepreg strips, and the upper layer prepreg strips include the upper layer middle prepreg strips, the upper layer one side edge prepreg strips and the upper layer other side edge prepreg strips.

[0088] The undisclosed technical features in this embodiment are the same as those in the first embodiment.

[0089] Specific implementation method ten: Combination Figures 1 to 32 To illustrate this embodiment, when the lower layer prepreg strips are arranged in step four of this embodiment, the lower layer middle prepreg strips and the lower layer edge prepreg strips are arranged alternately, and when the upper layer prepreg strips are inserted into the lower layer prepreg strips one by one, the upper layer prepreg strips are arranged in sequence from left to right with the upper layer middle prepreg strips and the upper layer edge prepreg strips on one side, and the upper layer edge prepreg strips on the other side are arranged in sequence from top to bottom.

[0090] The undisclosed technical features in this embodiment are the same as those in the ninth embodiment.

[0091] Example when honeycomb unit cell is hexagonal

[0092] Step 1: Cutting the composite prepreg

[0093] The composite material prepreg is cut into strip structures of precisely calculated shapes and sizes. According to the shape, length and bending method of the composite material prepreg strips when cut, the composite material prepreg strips can be divided into upper layer prepreg strips and lower layer prepreg strips, wherein the lower layer prepreg strips are divided into two groups, the lower layer middle prepreg strips 1-1 and the lower layer edge prepreg strips 1-2; the upper layer prepreg strips are divided into three groups, the upper layer middle prepreg strips 2-1, the upper layer one side edge prepreg strips 2-2 and the upper layer other side edge prepreg strips 2-3. Each group has a similar shape and the same bending method. The lower layer middle prepreg strips 1-1 and the lower layer edge prepreg strips 1-2 are the same length, the upper layer middle prepreg strips 2-1 have the same length within the group, and the upper layer one side edge prepreg strips 2-2 and the upper layer other side edge prepreg strips 2-3 are all close to the edge and have different lengths. Generally speaking, the upper and lower layer prepreg strips are parallel within the layer and form a certain angle between the layers. Each composite prepreg strip can be divided into a supporting structure and a matching structure, such as Figure 14As shown in the figure, the white part is the supporting structure and the gray part is the matching structure. The shape and size of the supporting structure are determined by the upper and lower surfaces and the size of the honeycomb unit cell, and the matching structure is the key part of the matching of the upper and lower layers, that is, the upper edge of the matching structure cutting pattern of the lower prepreg strip (lower layer middle prepreg strip 1-1 and lower layer edge prepreg strip 1-2) is completely consistent with the lower edge of the matching structure cutting pattern of the upper prepreg strip (upper layer middle prepreg strip 2-1, upper layer one side edge prepreg strip 2-2 and upper layer other side edge prepreg strip 2-3), and can match each other to form an embedded shape. At the same time, the shape and size of the lower edge of the matching structure cutting pattern in the lower prepreg strip and the upper edge of the matching structure cutting pattern in the upper prepreg strip are set according to the shape of the upper and lower curved surfaces and the size of the honeycomb unit cell. For honeycomb structures with different unit cell shapes, the lower middle prepreg strip 1-1 has different length ratios of its single internal supporting structure and matching structure due to the different matching methods between the upper and lower layers. The specific ratios are shown in Table 1.

[0094] Table 1 Ratio of length of single support and matching structure of upper and lower structures of different unit cell shapes

[0095]

[0096] The order of the supporting and matching structures within each group is determined by the matching arrangement of the upper and lower layers of the honeycomb structures of different unit cell shapes. For example, in a regular hexagonal honeycomb structure, the lower layer's center prepreg strips 1-1 and the upper layer's other edge prepreg strips 2-3 form a supporting-matching structure, while the lower layer's edge prepreg strips 1-2, the upper layer's center prepreg strips 2-1, and the upper layer's one edge prepreg strips 2-2 form a matching-supporting structure.

[0097] Step 2: Folding the composite prepreg

[0098] The composite prepreg strips are bonded to a custom mold and folded. During the folding process, the edges of the composite prepreg strips are aligned with the turning points of the wavy mold, ensuring a tight fit and wrinkle-free fit. Both sides of the composite prepreg strips are attached to the mold. The corners of the custom mold for the prepreg material coincide with the junctions between the supporting structure and the mating structure, and the turning angles are related to the angles required for mating of different unit cell structures. The hexagonal structure has a turning angle of 120°, the triangular structure has a turning angle of 60°, and the octagonal structure has a turning angle that cycles through 135°, 270°, 270°, 135°, 225°, 90°, 90°, and 225°. The concave hexagonal lower structure mold has a turning angle of 120°, while the upper structure mold has a turning angle of 60°. The double trapezoidal lower structure mold has a turning angle of (180°-α), while the upper structure mold has a turning angle of (180°-β). During the folding process, the bending direction of each set of composite material strips is related to the matching mode of the upper and lower prepreg strips.

[0099] Step 3: High temperature curing

[0100] Set the heat press's temperature, pressure, and time parameters based on the composite prepreg's curing requirements. Carefully place the secured mold and composite prepreg strips into the press, ensuring the structure is free of warping. Start the press and proceed with the curing process according to the preset temperature, pressure, and time parameters.

[0101] Step 4: Demolding and Arrangement

[0102] After the composite material prepreg strips are demoulded, they are arranged in groups and serial numbers. First, the lower layer prepreg strips are arranged. The lower layer prepreg strips are formed by alternating the lower layer middle prepreg strips 1-1 and the lower layer edge prepreg strips 1-2. Then, the upper layer prepreg strips are fitted into the lower layer arranged structure one by one. The upper layer prepreg strips start from the upper left corner, and the upper layer middle prepreg strips 2-1 and the upper layer one side edge prepreg strips 2-2 are arranged in order from left to right, and the other side edge prepreg strips 2-3 are arranged in order from top to bottom. Taking the hexagon as an example ( Figures 27-32 ), lower prepreg strip ( Figure 27 ) The lower prepreg strips are arranged in parallel with the same spacing, aligned at the ends, and the spacing between the strips is the side length of the hexagonal unit cell; the upper prepreg strips ( Figure 28 ) The upper middle prepreg strip 2-1, the upper side edge prepreg strip 2-2, and the other side edge prepreg strip 2-3 are arranged in parallel and the starting point is aligned with the edge of the lower overall structure. The matching process is as follows Figures 29 to 32 shown.

[0103] Step 5: Connect and fix

[0104] After the arrangement and combination is completed, check whether the intersection of the composite prepreg strips is flat, fits well, and has no protrusions or gaps. If necessary, use glue or other fixing structures to fix the composite prepreg strips.

[0105] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite material irregular curved honeycomb, characterized by: The method includes the following steps: Step 1: Material selection and pretreatment: Composite material prepreg strips are selected as the preparation material. The size, shape and quantity of the composite material prepreg strips required are calculated according to the different upper and lower curved surface structures. The composite material prepreg strips include upper prepreg strips and lower prepreg strips. A high-precision CNC cutting machine is used to cut the composite material prepreg according to the calculated predetermined size and shape to obtain multiple composite material prepreg strips, which are numbered one by one. Step 2: Folding the prepreg strips: Lay the composite material prepreg strips on the corresponding wave-shaped mold and fold them. During the folding process, the edges of the composite material prepreg strips are aligned with the turning points of the wave-shaped mold, and the composite material prepreg strips and the wave-shaped mold are tightly attached without wrinkles. Step 3: High-temperature curing: Set the temperature, pressure, and time parameters of the hot press according to the curing requirements of the composite prepreg. Place the fixed wave-shaped mold and the composite prepreg strips on it into the hot press. Start the hot press and perform the curing process according to the preset temperature, pressure, and time parameters. Step 4: Demolding and Arrangement: After the composite prepreg strips are completely solidified and cooled, the wavy mold is removed. After demoulding, the composite prepreg strips are arranged according to the numbers, first arranging the lower layer prepreg strips, and then inserting the upper layer prepreg strips one by one on top of the lower layer prepreg strips. The upper layer prepreg strips are staggered with the lower layer prepreg strips to form a mosaic curved honeycomb. Step 5: Trimming: After the arrangement and combination is completed, check whether there are defects at the intersection of the composite material prepreg strips, and fix and trim the defects; In step 1, the composite material prepreg strip includes a support structure and a matching structure, the shape and size of the support structure are set according to the shape of the upper and lower curved surfaces and the size of the honeycomb unit cell, the upper edge of the cutting pattern of the matching structure in the lower prepreg strip is consistent with the lower edge of the cutting pattern of the matching structure in the upper prepreg strip, and the shape and size of the lower edge of the cutting pattern of the matching structure in the lower prepreg strip and the upper edge of the cutting pattern of the matching structure in the upper prepreg strip are set according to the shape of the upper and lower curved surfaces and the size of the honeycomb unit cell; In the step 1, the lower layer prepreg strips include the lower layer middle prepreg strips and the lower layer edge prepreg strips, and the upper layer prepreg strips include the upper layer middle prepreg strips, the upper layer one side edge prepreg strips and the upper layer other side edge prepreg strips; When arranging the lower layer prepreg strips in the step 4, the lower layer middle prepreg strips and the lower layer edge prepreg strips are arranged alternately. When the upper layer prepreg strips are inserted into the lower layer prepreg strips one by one, the upper layer prepreg strips are arranged in sequence from the upper left corner to the middle prepreg strips and the upper layer edge prepreg strips on one side, and the upper layer edge prepreg strips on the other side are arranged in sequence from top to bottom.

2. The method for preparing a composite material irregular curved honeycomb according to claim 1, characterized in that: In the second step, the corner of the wave-shaped mold coincides with the junction of the support structure and the matching structure, and the turning angle of the wave-shaped mold corner matches the angle required for matching different honeycomb unit cell structures.

3. The method for preparing a composite material irregular curved honeycomb according to claim 2, characterized in that: The honeycomb unit cell of the special-shaped curved honeycomb is a triangle, a hexagon, an octagon or a negative Poisson's ratio unit cell.

4. The method for preparing a composite material irregular curved honeycomb according to claim 3, characterized in that: The negative Poisson's ratio unit cells include concave hexagons, double trapezoids and stars.

5. The method for preparing a composite material irregular curved honeycomb according to claim 3, characterized in that: In the step 2, when the honeycomb unit cell of the irregular curved honeycomb is a triangle, the turning angle at the corner of the wavy mold is 60°; when the honeycomb unit cell of the irregular curved honeycomb is a hexagon, the turning angle at the corner of the wavy mold is 120°; when the honeycomb unit cell of the irregular curved honeycomb is an octagon, the turning angle at the corner of the wavy mold is repeated in a cycle of 135°, 270°, 270°, 135°, 225°, 90°, 90°, and 225°.

6. The method for preparing a composite material irregular curved honeycomb according to claim 4, characterized in that: In the step 2, when the honeycomb unit cell of the irregular curved honeycomb is a concave hexagon, the turning angle at the corner of the wavy mold of the lower prepreg strip is 120°, and the turning angle at the corner of the wavy mold of the upper prepreg strip is 60°; when the honeycomb unit cell of the irregular curved honeycomb is a double trapezoid, the turning angle at the corner of the wavy mold of the lower prepreg strip is (180°-α), and the turning angle at the corner of the wavy mold of the upper prepreg strip is (180°-β).

7. The method for preparing a composite material irregular curved honeycomb according to claim 1, characterized in that: In the second step, the bending direction of the composite material prepreg strips during the folding process is set according to the matching mode between the upper prepreg strips and the lower prepreg strips.

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