Non-equal-wall-thickness lightweight carbon fiber honeycomb core and preparation method thereof

Abstract

The invention provides a non-equal-wall-thickness lightweight carbon fiber honeycomb core and a preparation method thereof. The carbon fiber honeycomb core is a non-equal-wall-thickness carbon fiber honeycomb core. The carbon fiber honeycomb core is formed by assembling a plurality of discretized same polygonal cell units in an array; the boundary dimension of the carbon fiber honeycomb core can be infinitely expanded by adopting the polygonal cell units; the structure of each polygonal cell unit is a hollow structure penetrating through the upper and lower ends. According to the carbon fiber honeycomb core assembled by the discrete array, the carbon fiber honeycomb core with any structural size can be obtained as required, the breadth of the carbon fiber honeycomb core can be expanded infinitely, and the size requirement of a large-aperture satellite antenna reflector is met.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite antennas and relates to a carbon fiber honeycomb core, and in particular to a unequal wall thickness lightweight carbon fiber honeycomb core and a preparation method thereof. Background Art

[0002] Honeycomb sandwich structure is the most common sandwich structure for satellite antenna reflectors due to its outstanding advantages such as high specific stiffness and specific strength. The most common one is the carbon fiber panel aluminum honeycomb sandwich structure. However, in the extreme high and low temperature environment of space, the thermal performance mismatch between the structure composed of carbon fiber panel and aluminum honeycomb core is prominent. Due to the thermal expansion coefficient of aluminum honeycomb core material (10 -5 Scale) and carbon fiber panel material (10 -6 There is a big difference in the magnitude of carbon fiber panels and aluminum honeycomb cores. In extreme service environments, high thermal stress will be generated between the carbon fiber panels and the aluminum honeycomb core, resulting in large thermal deformation of the satellite antenna reflector surface. The surface error of the "carbon panel + aluminum honeycomb" structure due to thermal deformation is 3 times that of the "carbon panel + carbon honeycomb" structure. In addition, during the manufacturing process of the satellite antenna reflector, due to the thermal mismatch between the aluminum honeycomb core and the carbon fiber panel, the curing residual stress is large and the manufacturing surface accuracy is poor. After curing, the "carbon panel + carbon honeycomb" reflector has a surface accuracy that is 3.5 times better than the "carbon panel + aluminum honeycomb" satellite antenna reflector. Therefore, in order to meet the requirements of the new generation of satellite payloads for high surface accuracy and high thermal stability of the antenna, and to solve the problem of thermal mismatch between the satellite antenna reflector panel and the honeycomb core, a sandwich structure design must be carried out using a carbon fiber honeycomb core that matches the carbon fiber panel.

[0003] At present, the existing carbon fiber honeycomb core design and preparation methods are:

[0004] First, the locking structure method: According to the slots on the long-size carbon fiber laminate structure panel, it is assembled into a locking structure with equal wall thickness in two-axis and three-axis directions, but it has the disadvantages of large assembly stress and stress concentration. At the same time, the degree of industrialization is low and the processing cycle is long, making it difficult to produce on the shelf. The locking structure cell units are mostly triangular and quadrilateral structures. However, under the same boundary constraints, the density of the triangular structure cell unit is 2.87 times that of the hexagonal structure cell unit, and the thermal stability is 1.27 times worse than that of the hexagonal structure cell unit.

[0005] Second, the zigzag bonding method: a number of long carbon fiber zigzag strips are assembled and bonded to form a shape. The forming size is limited by the forming tooling and cannot be expanded infinitely. The zigzag bonding method cell units are mostly hexagonal structures.

[0006] Third, the discrete array method: It is assembled and bonded by a number of thin-walled circular tube arrays. It has simple molding and its thermal stability is comparable to that of the hexagonal structural cell unit. However, under the same boundary constraint conditions, the density of the thin-walled circular tube structural cell unit is 1.62 times that of the hexagonal structural cell unit. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a non-uniform wall thickness lightweight carbon fiber honeycomb core and a preparation method to solve the technical problem that the carbon fiber honeycomb core in the prior art is difficult to simultaneously take into account high thermal stability, unlimited scalability and lightweight.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0009] A carbon fiber honeycomb core, wherein the carbon fiber honeycomb core is a carbon fiber honeycomb core with unequal wall thickness.

[0010] The carbon fiber honeycomb core is assembled by arraying a plurality of discrete identical polygonal cell units.

[0011] The outer dimensions of the carbon fiber honeycomb core can be infinitely expanded by using polygonal cell units.

[0012] The structure of the polygonal cell unit is a hollow structure that runs through the upper and lower ends.

[0013] The present invention also has the following technical features:

[0014] Specifically, the structures of the polygonal cell units are all thin-walled cylindrical structures; the cross-sections of the polygonal cell units are regular polygons, and the thickness of each side wall of the same polygonal cell unit is equal.

[0015] Preferably, each side wall of the polygonal cell unit is evenly distributed with a plurality of air holes penetrating through both sides of the side wall.

[0016] The present invention also protects a method for preparing the carbon fiber honeycomb core as described above, wherein a plurality of identical polygonal cell units are assembled into an array by bonding, and the carbon fiber honeycomb core is obtained after curing.

[0017] Preferably, the method specifically comprises the following steps:

[0018] Step 1: Using a rigid rod-shaped mold as a molding tool, using carbon fiber composite materials, laying out layers according to a polygonal cell design for laying and curing molding, and obtaining a polygonal cell blank with a hollow thin-walled cylindrical structure.

[0019] Step 2: Cut and process the air holes of the polygonal cell unit blank obtained in step 1 as needed to obtain a polygonal cell unit.

[0020] Step three, coating the outer surface of the side wall of the polygonal cell unit obtained in step two with an adhesive, coating the outer surface of the side wall of the auxiliary tooling with a release agent, assembling a plurality of identical polygonal cell units in an array with the auxiliary tooling and then curing them, removing the auxiliary tooling after curing and forming, and obtaining a carbon fiber honeycomb core preform.

[0021] Step 4: Perform high and low temperature aging treatment on the carbon fiber honeycomb core preform obtained in step 3 to finally obtain a carbon fiber honeycomb core.

[0022] Specifically, in step three, the structural dimensions of the auxiliary tooling are the same as the structural dimensions of the polygonal cell unit.

[0023] Specifically, in step three, the array is assembled in a manner that the sidewall of each auxiliary tooling is wrapped by a plurality of polygonal cell units.

[0024] Preferably, in step 4, the carbon fiber honeycomb core is bonded with a pin at the node of the carbon fiber honeycomb core, the side wall of the pin is provided with a plurality of slots, each slot is adapted to one or more polygonal cell units, and a threaded hole is also provided on the top of each pin.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (I) The carbon fiber honeycomb core assembled by discrete arrays in the present invention can obtain a carbon fiber honeycomb core of any structural size as needed, and the width of the carbon fiber honeycomb core can be infinitely expanded to meet the size requirements of large-diameter satellite antenna reflectors.

[0027] (II) The non-uniform wall thickness regular hexagonal carbon fiber honeycomb core of the present invention has better thermal stability than the triangular and circular cell unit honeycomb cores, and its weight is reduced by 32% compared with the uniform wall thickness regular hexagonal carbon fiber honeycomb core.

[0028] (III) The present invention not only avoids the problems of residual stress and stress concentration of the locking structure by bonding and forming the polygonal cell units of the discrete array, but also has good air permeability and repairability.

[0029] (IV) Due to the flexibility of cutting the polygonal cell units in the present invention, it can be produced on the shelf without having to wait until the satellite antenna reflector structure design is completed before production, thus shortening the processing cycle and improving production efficiency.

[0030] (V) The method for preparing the carbon fiber honeycomb core of the present invention can be used for various composite material functional structures with high precision and high thermal stability requirements. The application fields include but are not limited to the development of high-precision reflectors such as earth observation satellites, communication and broadcasting satellites, and deep space exploration satellites. It can also be applied to the development of high-precision ground reflectors, meeting the needs of high-precision satellite antenna reflectors for surface manufacturing accuracy and thermal stability.

[0031] (VI) The external connection design and embedded parts design of the honeycomb sandwich structure prepared by the carbon fiber honeycomb core of the present invention have the advantages of flexible design, simple structure and good thermal stability compared with the traditional foam filling method. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1( a ) is a schematic diagram of the structure of a carbon fiber honeycomb core in the present invention.

[0033] FIG. 1( b ) is a schematic diagram of the partial structure of the top of the carbon fiber honeycomb core of the present invention.

[0034] Figure 2 Schematic diagram of the structure of the hexagonal cell unit in the present invention.

[0035] Figure 3 This is a front view of the hexagonal cell unit blank laid on the forming tool in the present invention.

[0036] Figure 4 It is a structural schematic diagram of the cutting of hexagonal cell unit blank and the processing of air holes in the present invention.

[0037] Figure 5 It is a top view of the assembly of the hexagonal cell unit and the auxiliary tooling array in the present invention.

[0038] Figure 6 It is a schematic diagram of the structure of the latch in the present invention.

[0039] Figure 7 It is a schematic diagram of the assembly structure of the latch on the carbon fiber honeycomb core in the present invention.

[0040] Figure 8 It is a schematic diagram of the structure of the honeycomb interlayer and the external mechanical connection port in the present invention.

[0041] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0042] It should be noted that the raw materials and equipment used in the present invention, unless otherwise specified, are all raw materials and equipment known in the prior art. For example, the material of the polygonal cell unit is a carbon fiber composite material, and the carbon fiber composite material is a known carbon fiber composite material.

[0043] In the present invention, discretization means that the carbon fiber honeycomb core is integrated from polygonal cell units.

[0044] In the present invention, the carbon fiber honeycomb node refers to the top of the edges where a plurality of polygonal cell units intersect.

[0045] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0046] Example:

[0047] This embodiment provides a carbon fiber honeycomb core, which is a carbon fiber honeycomb core with unequal wall thickness.

[0048] As shown in Figure 1(a), the carbon fiber honeycomb core is assembled by an array of multiple identical discrete polygonal cell units; as shown in Figure 1(b), if the thickness of each side wall of a single polygonal cell unit is a, the thickness of the two polygonal cell units at the overlap of the side walls is 2a, that is, the carbon fiber honeycomb core has non-uniform wall thickness.

[0049] The outer dimensions of the carbon fiber honeycomb core can be infinitely expanded using polygonal cell units.

[0050] The structure of the polygonal cell unit is a hollow structure that runs through the upper and lower ends.

[0051] The structures of the polygonal cell units are all thin-walled cylindrical structures; the cross-section of the polygonal cell unit is a regular polygon, and the thickness of each side wall of the same polygonal cell unit is equal.

[0052] Each side wall of the polygonal cell is evenly distributed with multiple air holes that penetrate both sides of the side wall, such as Figure 2 shown.

[0053] In this embodiment, the polygonal cell unit is a hexagonal cell unit, and the cross section of the polygonal cell unit is a regular hexagon.

[0054] The preparation method of the carbon fiber honeycomb core in this embodiment is to assemble a plurality of identical hexagonal cell units in an array by bonding, and obtain the carbon fiber honeycomb core after curing.

[0055] The method for preparing the carbon fiber honeycomb core in this embodiment specifically includes the following steps:

[0056] Step 1, such as Figure 3 As shown, a rigid rod-shaped mold is used as a molding tool, and a carbon fiber composite material is adopted. Layers are laid out according to a hexagonal cell design for placement and curing molding, so as to obtain a hexagonal cell blank with a hollow thin-walled cylindrical structure.

[0057] Step 2: Cut the hexagonal cell unit blank obtained in step 1 and process the air holes as needed to obtain a hexagonal cell unit, such as Figure 4 shown.

[0058] Step 3: Apply adhesive to the outer surface of the side wall of the hexagonal cell unit obtained in step 2, and apply a release agent to the outer surface of the side wall of the auxiliary tooling, such as Figure 5 As shown, a plurality of identical hexagonal cell units are discretely assembled in an array with auxiliary tooling and then solidified. After solidification and forming, the auxiliary tooling is removed to obtain a carbon fiber honeycomb core preform.

[0059] The structural dimensions of the auxiliary tooling are the same as those of the hexagonal cell unit. The auxiliary tooling can be used for array assembly together with the hexagonal cell unit, and can also apply a certain curing pressure to the surrounding hexagonal cell units when the carbon fiber honeycomb core preform is bonded and formed.

[0060] The array is assembled in a manner that the side wall of each auxiliary tool is wrapped by six hexagonal cell units. During the array assembly, each side wall of each auxiliary tool is bonded to the side wall of a hexagonal cell unit.

[0061] Step 4: Perform high and low temperature aging treatment on the carbon fiber honeycomb core preform obtained in step 3, and finally obtain a carbon fiber honeycomb core, as shown in Figure 1(a). The carbon fiber honeycomb core preform is subjected to high and low temperature aging treatment to release the residual stress of the carbon fiber honeycomb core preform.

[0062] The carbon fiber honeycomb core is bonded with pins at the carbon fiber honeycomb core nodes, such as Figure 6 As shown, the side wall of the latch is provided with three slots, such as Figure 7 As shown, each latch slot is matched with a hexagonal cell unit, and a threaded hole is also provided on the top of each latch. The carbon fiber honeycomb core is connected to other external components through screws in the threaded holes.

[0063] The carbon fiber honeycomb core in this embodiment is used as Figure 8 As shown, a lower panel covering the entire bottom of the carbon fiber honeycomb core is bonded to the bottom of the carbon fiber honeycomb core, and an upper panel covering the entire top of the carbon fiber honeycomb core is also bonded to the top of the carbon fiber honeycomb core. The upper panel is provided with through holes penetrating the upper and lower ends of the upper panel at each latch, so that the screws in the threaded holes on the top of the latch can be connected to an external machine. The structure after the carbon fiber honeycomb core, the lower panel and the upper panel are bonded is a honeycomb sandwich structure.

[0064] The carbon fiber honeycomb core in this embodiment is made into a honeycomb sandwich structure and can be applied to the manufacturing of large-caliber high-precision antenna reflector surfaces, meeting the manufacturing accuracy requirements of large-caliber high-precision antenna reflector surfaces and the high thermal stability requirements under extreme high and low temperatures. The manufacturing accuracy of the 2m×1.6m diameter reflector surface reaches 15umRMS, and the thermal stability reaches 8umRMS in the range of -140℃~+120℃.

Claims

1. A carbon fiber honeycomb core, characterized in that: The carbon fiber honeycomb core is a carbon fiber honeycomb core with unequal wall thickness; The carbon fiber honeycomb core is assembled by arraying a plurality of identical discrete polygonal cell units; The outer dimensions of the carbon fiber honeycomb core can be infinitely expanded using polygonal cell units; The structure of the polygonal cell unit is a hollow structure that runs through the upper and lower ends.

2. The carbon fiber honeycomb core according to claim 1, characterized in that: The structures of the polygonal cell units are all thin-walled cylindrical structures; the cross-sections of the polygonal cell units are regular polygons, and the thickness of each side wall of the same polygonal cell unit is equal.

3. The carbon fiber honeycomb core according to claim 2, characterized in that: Each side wall of the polygonal cell unit is evenly distributed with a plurality of air holes penetrating through both sides of the side wall.

4. A method for preparing a carbon fiber honeycomb core according to any one of claims 1 to 3, characterized in that: The method is to assemble a plurality of identical polygonal cell units in an array by bonding, and obtain a carbon fiber honeycomb core after curing.

5. The method for preparing a carbon fiber honeycomb core according to claim 4, characterized in that: The method specifically comprises the following steps: Step 1: using a rigid rod-shaped mold as a molding tool, using a carbon fiber composite material, laying out layers according to a polygonal cell design to perform laying and curing molding, and obtaining a polygonal cell blank with a hollow thin-walled cylindrical structure; Step 2, cutting and processing the vent holes of the polygonal cell unit blank obtained in step 1 as needed to obtain a polygonal cell unit; Step 3: coating the outer surface of the side wall of the polygonal cell unit obtained in step 2 with an adhesive, coating the outer surface of the side wall of the auxiliary tooling with a release agent, assembling a plurality of identical polygonal cell units in an array with the auxiliary tooling and then curing them, and removing the auxiliary tooling after curing and forming to obtain a carbon fiber honeycomb core preform; Step 4: Perform high and low temperature aging treatment on the carbon fiber honeycomb core preform obtained in step 3 to finally obtain a carbon fiber honeycomb core.

6. The method for preparing a carbon fiber honeycomb core according to claim 5, characterized in that: In step three, the structural dimensions of the auxiliary tooling are the same as the structural dimensions of the polygonal cell unit.

7. The method for preparing a carbon fiber honeycomb core according to claim 5, characterized in that: In step three, the array is assembled in a manner that the sidewall of each auxiliary tooling is wrapped by a plurality of polygonal cell units.

8. The method for preparing a carbon fiber honeycomb core according to claim 5, characterized in that: In step 4, a pin is bonded to the carbon fiber honeycomb core at the node of the carbon fiber honeycomb core, and a plurality of slots are arranged on the side wall of the pin, each slot is adapted to one or more polygonal cell units, and a threaded hole is also arranged on the top of each pin.

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