Composite thin-wall tubular extension arm based on flexible layer and manufacturing method of composite thin-wall tubular extension arm

Abstract

The invention provides a composite thin-wall tubular extension arm based on a flexible layer and a manufacturing method of the composite thin-wall tubular extension arm. The stretching arm is composed of vertically-symmetrical fiber layers and a flexible layer located in the middle, the flexible layer stores elastic potential energy, the height of the section of the structure is increased, the flexural rigidity is effectively enhanced, and meanwhile the flattening performance and the rapid unfolding capacity of the stretching arm during rolling are guaranteed. According to the manufacturing method, hot press forming is adopted, the fiber layer, the flexible layer and the silica gel inner core are sequentially stacked in a female die to be formed, and high precision and good interface combination of the structure are achieved. The flexible layer is made of high-elasticity rubber or thermoplastic elastomer and has elasticity recovery performance and durability. According to the invention, the defects of the traditional inflatable and directly manufactured composite thin-wall tubular extension arm with high section height are overcome, the stability and reliability of the extension arm are improved, the service life of the extension arm is prolonged, and the extension arm is suitable for the field of space deployable structures.

Description

Technical Field

[0001] The present invention relates to the technical field of tubular extension arm manufacturing, and in particular to a composite thin-wall tubular extension arm based on a flexible layer and a manufacturing method thereof. Background Art

[0002] In the field of deployable structures in space, thin-walled tubular extension arms have become a potential alternative to traditional complex and heavy folding mechanisms due to their low mass, compact structure, and high stability. They are widely used in space missions such as solar sails. Currently, this type of structure is developing towards multifunctionality (such as bending, support, and sensing), lightweighting (grid-like, composite materials), and adaptability. However, how to significantly improve its bending and compressive stiffness while maintaining good curling performance remains a key challenge in the design of thin-walled tubular extension arms.

[0003] In the mechanical design of thin-walled tubular extension arms, bending stiffness is a key indicator to measure its ability to resist bending deformation, which directly affects the stability and load-bearing performance of the structure. According to classical beam theory, bending stiffness is proportional to the elastic modulus of the material and the geometric moment of inertia of the structural section. Among them, the moment of inertia is closely related to the cross-sectional shape, and is particularly sensitive to the cross-sectional height. For a typical rectangular or tubular cross-section, the moment of inertia is proportional to the cube of the cross-sectional height, which means that with the material usage remaining basically unchanged, appropriately increasing the cross-sectional height can significantly improve the bending performance without significantly increasing the mass. For thin-walled tubular extension arms with high stiffness and deformation control requirements, optimizing the cross-sectional height can effectively improve their bending stiffness, which is an important path to achieve high-performance lightweight design.

[0004] Traditional methods for improving the bending stiffness of thin-walled tubular extension arms include inflatable structures and molded high-cross-section structures. Inflatable tubular extension arms achieve their higher cross-sectional height through gas expansion, but they are highly dependent on gas pressure, making them prone to structural instability after decompression and resulting in poor reliability. High-cross-section structures molded in a single step, while offering high bending stiffness, are prone to significant compressive stress and buckling risk when flattened, impacting service life and repeatability. Therefore, striking a balance between high cross-sectional height and good stability, compressibility, and recoverability has become a key technical challenge in the design of thin-walled tubular extension structures. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a composite thin-walled tubular extension arm based on a flexible layer and a manufacturing method thereof.

[0006] The present invention provides a composite thin-walled tubular extension arm based on a flexible layer, comprising two fiber layers arranged symmetrically in a vertical direction, with a flexible layer disposed between the two fiber layers to form a sandwich structure. A convex arc portion is provided in the middle of the fiber layer, with concave arc portions and straight portions provided on either side. At a certain manufacturing height of the fiber layer, the flexible layer stores a certain amount of elastic potential energy in advance, and utilizes its inward elastic force to further increase the cross-sectional height of the fiber layer, thereby improving the overall bending stiffness without causing excessive stress in the fiber layer when flattened. Furthermore, due to the flexible layer's excellent elongation and recovery capabilities, the composite thin-walled tubular extension arm based on the flexible layer can be flattened, rolled up, and quickly deployed.

[0007] Preferably, the fiber layer is a fiber composite material with a thickness of 0.08-0.6 mm, and a thermosetting or thermoplastic matrix can be selected. The reinforcing material includes carbon fiber, glass fiber, etc. The structural form can be a sheet structure, a mesh structure or a porous structure to meet the dual requirements of strength and deformation coordination.

[0008] Preferably, the flexible layer has a thickness of 0.03–0.1 mm and is made of a highly elastic material such as natural rubber, synthetic rubber, or thermoplastic elastomer (TPE). It is shaped like a sheet, a mesh, or a porous structure. This flexible layer gives the extendable arm a higher cross-sectional height and ensures high stability and shape retention during multiple flattening and unfolding cycles.

[0009] Preferably, the present invention also provides a method for manufacturing a composite thin-walled tubular extension arm based on a flexible layer, comprising the following steps:

[0010] Step S1: preparing two fiber layers by a molding method;

[0011] Step S2: preparing a flexible layer by a molding method for standby use;

[0012] Step S3: preparing two halves of a silicone inner core by a molding method, which are used to support and define the inner cavity shape of the structure during the hot pressing molding process, ensuring that the thin-walled tubular extension arm after molding has a predetermined geometric size and cross-sectional shape;

[0013] Step S4: preparing two concave molds of identical shapes by a molding method, one of which serves as a lower concave mold and the other as an upper concave mold, for defining the shape and molding range of the molding material;

[0014] Step S5: Setting key parameters of the hot press according to material properties and process requirements, including applied pressure, molding temperature, and holding time, to ensure molding accuracy while avoiding excessive deformation;

[0015] Step S6: The prepared fiber layer, flexible layer, silicone core, and concave mold are stacked in the following order: lower concave mold, one fiber layer, half of the silicone core, the stretched flexible layer, another fiber layer, the other half of the silicone core, and upper concave mold. The entire assembly is placed in a hot press, and the hot pressing process is initiated for molding.

[0016] Step S7: After the hot pressing is completed, the composite material is slowly cooled to room temperature by furnace cooling to reduce internal stress and warping deformation, and then the mold is opened to take out the composite thin-walled tubular extension arm based on the flexible layer with complete shape and accurate size.

[0017] Preferably, the fiber layer can be prepared by a variety of molding techniques to meet different structural performance and manufacturing requirements. Specifically, the fiber layer can be prepared using multi-layer prepreg compression molding technology. This process involves stacking multiple layers of resin-impregnated prepreg in the designed direction and curing them under high temperature and high pressure conditions to obtain a dense, uniform composite fiber layer with excellent mechanical properties. At the same time, continuous fiber 3D printing molding technology can also be used. This technology can achieve the manufacture of complex shapes and high-performance fiber composite materials by precisely controlling the laying path of continuous fibers, significantly improving manufacturing flexibility and material utilization.

[0018] Preferably, the preparation of the flexible layer also supports multiple molding methods. The flexible layer material can be selected from natural rubber, synthetic rubber, and thermoplastic elastomer (TPE), which can be obtained by compression molding or 3D printing respectively. The compression molding technology of natural rubber and synthetic rubber can ensure the uniformity of the material and excellent elastic recovery performance, and is suitable for the preparation of highly elastic flexible layers; while the 3D printing of thermoplastic elastomer (TPE) not only achieves a high degree of customization of the material morphology and structure, but also improves the preparation efficiency and design freedom.

[0019] Compared with the related art, the composite thin-walled tubular extension arm based on the flexible layer and the manufacturing method thereof provided by the present invention have the following beneficial effects:

[0020] 1. Compared with the traditional composite thin-wall tubular extension arm, the present invention introduces a flexible layer, which significantly increases the cross-sectional height of the extension arm while ensuring lightweight and winding performance, thereby improving the bending resistance.

[0021] 2. Compared with the inflatable thin-walled tubular extension arm, the present invention has higher stability. Compared with the thin-walled tubular extension arm directly manufactured with a higher cross-sectional height, the stress of the fiber layer is smaller when flattened and rolled, and the material is less likely to be damaged.

[0022] 3. The flexible materials used in the flexible layer of the present invention, such as natural rubber, synthetic rubber, and thermoplastic elastomer (TPE), exhibit excellent elasticity and recovery properties, enabling the extension arm to quickly recover after being subjected to external forces, thereby enhancing the reliability and safety of the extension arm. When the extension arm is retracted, the flexible layer can store a large amount of elastic potential energy, enabling the extension arm to deploy more quickly.

[0023] 4. The present invention tightly combines the fiber layer and the flexible layer through a one-time hot pressing process, thereby improving the interlayer interface performance and enhancing the mechanical consistency of the overall structure. Compared with multiple hot pressing processes, the structural accuracy and integrity are improved.

[0024] 5. The present invention can achieve an optimal balance between performance optimization and process adaptability by reasonably selecting the molding method of the fiber layer and the flexible layer, and meet the diverse needs of different application scenarios for composite thin-walled extension arms. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the structure of a composite thin-walled tubular extension arm based on a flexible layer in an embodiment of the present invention, wherein both the fiber layer and the flexible layer are sheet-like structures;

[0026] Figure 2 Schematic diagram of the structure of a composite thin-walled tubular extension arm based on a flexible layer in another embodiment of the present invention, wherein both the fiber layer and the flexible layer are mesh structures;

[0027] Figure 3 This is a disassembled schematic diagram of the concave mold, fiber layer, silicone inner core, and flexible layer in the present invention, wherein the fiber layer is a sheet structure and the flexible layer is a mesh structure.

[0028] Figure 4 This is a schematic diagram of the hot pressing process of the present invention, showing the state in which the die, fiber layer, silicone core, and flexible layer are compressed in the hot press.

[0029] Figure 5 This is a comparison diagram of the effect of the flexible layer on increasing the cross-sectional height of the composite thin-walled tubular extension arm of the present invention, wherein the cross-sectional height without the flexible layer is 40 mm, and the cross-sectional heights with the flexible layer are 45 mm and 50 mm respectively;

[0030] In the figure: 1-fiber layer, 2-flexible layer, 101-convex arc portion, 102-concave arc portion, 103-straight portion, 3-silicone core, 4-concave mold, 5-hot press DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and examples.

[0032] Example 1

[0033] This embodiment provides a composite thin-walled tubular extension arm composed of a sheet-like flexible layer 2 and a fiber layer 1. Figure 1 As shown. The structure consists of two symmetrical fiber layers 2 and a flexible layer 1 in the middle. The three layers are integrally formed by hot pressing. The fiber layer 1 is made of a thermosetting composite material (such as epoxy carbon fiber prepreg) with a thickness of 0.24mm, and the flexible layer 2 is made of a natural rubber film with a thickness of 0.03mm. After the structure is formed, it can achieve a higher cross-sectional height than a structure without a flexible layer after unfolding without affecting the flattening and curling, thereby improving the bending stiffness of the composite thin-walled tubular extension arm structure.

[0034] Example 2

[0035] In this embodiment, the fiber layer 1 and the flexible layer 2 both adopt a mesh structure, such as Figure 2 As shown in the figure, the fiber layer 1 is a 0.2mm thick thermoplastic composite material (such as carbon fiber / PEEK) produced through a continuous fiber 3D printing process. The flexible layer 2 is a 0.1mm thick TPE elastomer material produced through 3D printing to create a regular pore grid structure. While retaining the advantages of lightweighting, the flexible layer 2's deformability effectively disperses stress concentration during flattening, improving the structure's resilience.

[0036] Example 3

[0037] In order to verify the effect of the thickness of the flexible layer 2 on the structural performance, three samples were prepared: no flexible layer, flexible layer with thickness of 0.1 mm and 0.2 mm, as shown in Figure 2. Figure 5 As shown in the figure, the fiber layer 1 is made of a 0.2mm thick thermoplastic composite material, and the flexible layer 2 is made of a TPE elastomer material, both produced through a 3D printing process. Test results show that when the flexible layer 2 is 0.1mm thick, the unfolded cross-sectional height increases to 45mm, and when it is 0.2mm thick, it increases to 50mm, significantly higher than the 40mm without the flexible layer 2, indicating that the flexible layer 2 has a positive effect in increasing the unfolded cross-sectional height.

[0038] Example 4

[0039] This embodiment provides a specific manufacturing process of a composite thin-walled tubular extension arm based on a flexible layer, including the following steps:

[0040] Step S1: A thermoplastic composite material (such as carbon fiber / PEEK) is selected and 3D printed to produce a fiber layer 1 with a thickness of 0.2 mm that meets the structural dimensions as the upper and lower structural units of the extension arm.

[0041] Step S2: Select TPE elastomer material and 3D print to produce a flexible layer 2 with a thickness of 0.1 mm and the same size as the fiber layer 1, which is used as a flexible connecting layer between the two fiber layers 1.

[0042] Step S3: Select an addition-forming two-component silicone rubber (e.g., component A and component B silicone), thoroughly mix them according to the recommended ratio (typically 1:1 or 10:1), pour them into a pre-prepared mold, and use either natural or heat-curing methods to produce two silicone half-cores whose shapes match the structure's internal cavity. After curing, the mold is removed. The resulting silicone core has excellent elasticity, temperature resistance, and dimensional stability, providing effective support during the hot press molding process and preventing structural collapse.

[0043] Step S4: Two concave molds are processed using metal, alloy or heat-resistant composite materials, serving as an upper concave mold and a lower concave mold respectively. The inner cavity of the concave mold is consistent with the shape of the final extension arm, which is used to limit the contour forming of the structure during the hot pressing process.

[0044] Step S5: The pre-set temperature of the hot press is set to 180° C., the pressure is set to 0.5 MPa, and the holding time is set to 10 minutes. The parameters are reasonably set according to the selected fiber material and the thermosetting or thermoplastic properties of the flexible layer.

[0045] Step S6: Place the lower concave mold on the bottom plate of the hot press, and lay a fiber layer, a silicone inner core, a flexible layer in a stretched state, another fiber layer and another silicone inner core in sequence, and finally cover it with the upper concave mold to form a multi-layer structure assembly from bottom to top, and start the hot press for hot pressing molding.

[0046] Step S7: After hot pressing, the furnace is cooled to room temperature. Once the temperature drops to a safe level, the mold is opened and the formed thin-walled tubular composite arm structure is removed. The product has a smooth surface, a complete internal structure, and a well-bonded fiber layer and flexible layer. There are no obvious bubbles or delamination defects.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A composite thin-walled tubular extension arm based on a flexible layer, characterized by: It comprises two fiber layers symmetrically arranged in an upper and lower direction, a convex arc portion is arranged in the middle of the fiber layer, concave arc portions are arranged on both sides of the convex arc portion, a straight portion is arranged on one side of the concave arc portion, and a flexible layer is arranged in the middle of the two symmetrical fiber layers.

2. The composite thin-walled tubular extension arm based on the flexible layer according to claim 1, characterized in that: The fiber layer is a fiber composite material with a thickness of 0.08-0.6 mm. The fiber composite material is one of a thermosetting fiber composite material and a thermoplastic fiber composite material. The shape of the fiber layer is one of a sheet structure, a mesh structure, and a porous structure.

3. The composite thin-walled tubular extension arm based on the flexible layer according to claim 1, characterized in that: The flexible layer is a flexible material with a thickness of 0.03-0.1 mm, and the flexible material is one of natural rubber, synthetic rubber, and thermoplastic elastomer (TPE). The shape of the flexible layer is one of a sheet structure, a mesh structure, and a porous structure.

4. A method for manufacturing a composite thin-walled tubular extension arm based on a flexible layer as claimed in claims 1 to 3, characterized in that: The following steps are involved: S1: Prepare two fiber layers for later use; S2: Prepare a flexible layer for standby use; S3: Make two halves of the silicone core for later use; S4: Make two concave molds with the same shape, one as the upper concave mold and the other as the lower concave mold; S5: Set the hot press parameters, including pressure, temperature, and time; S6: placing the materials prepared in steps S1-S3 in a hot press in the order of a lower concave mold, a fiber layer, half of the silicone inner core, a flexible layer, a fiber layer, half of the silicone inner core, and an upper concave mold from bottom to top and starting hot pressing; S7: After the hot pressing is completed, the furnace is cooled to room temperature, and the mold is opened to take out the composite thin-walled tubular extension arm based on the flexible layer as described in claims 1-3.

5. The method for manufacturing a composite thin-walled tubular extension arm based on a flexible layer according to claim 4, characterized in that: The fiber layer is made by a method selected from the group consisting of multi-layer prepreg molding and continuous fiber 3D printing.

6. The method for manufacturing a composite thin-walled tubular extension arm based on a flexible layer according to claim 4, characterized in that: The flexible layer is made by one of natural rubber compression molding, synthetic rubber compression molding, and thermoplastic elastomer (TPE) 3D printing molding.

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