A method of braided needle punching a preform for an expandable structure

Abstract

The application discloses a kind of weaving needle punching forming methods for deployable structure preform, comprising: determining the rigid load area of deployable structure preform;Net tire is pasted on the surface of preform support core mold;Overall weaving is carried out on the surface of net tire to form deployable flexible woven layer;Net tire is laid on the outer layer of flexible woven layer, and the needle punching area corresponding to the rigid load area in the preform combined with all net tires and flexible woven layer is needle punched;The preform is expanded, and the above weaving needle punching process is repeated until the thickness of the preform reaches the requirement;The preform is expanded until the inner diameter of the preform reaches the requirement, and the selected rigid needle punching area is needle punched to obtain the deployable structure preform.In the weaving process of preform, the inner diameter of the woven needle punching preform is gradually increased, the fabric layer is more sparse, and the rigidity of the rigid area is improved by increasing the fabric thickness and staggered needle punching, so that the formed rigid area is more rigid, the flexible area is more flexible, so as to improve the rigid-flexible coupling characteristics of the deployable structure preform.

Description

Technical Field

[0001] This invention relates to the forming of three-dimensional structural preforms of composite materials, specifically to a braiding needle punching forming method for deployable structural preforms. Background Technology

[0002] Deployable structures can actively adjust their coverage area or volume according to the external environment, and have been successfully applied in aerospace, disaster relief, and medical equipment. Due to their special application scenarios, deployable structures usually have very demanding requirements for material properties, needing to possess lightweight, high strength, and deformability simultaneously. These seemingly conflicting properties pose many challenges in the design and manufacturing process of deployable structures, greatly hindering their application and development.

[0003] To overcome these challenges, researchers are considering leveraging the advantages of carbon fiber reinforced polymer (CFRP) – its lightweight, high strength, and excellent designability – for use in deployable structures, thereby reducing structural weight and the number of components. CFRP consists of a carbon fiber preform and a matrix. The deployability of the preform and matrix largely determines the deployability of the CFRP component. In recent years, researchers have attempted to fabricate deployable CFRP through clever design of the preform and matrix. Notably, current research has made the rigid-flexible coupled resin matrix the primary factor in the functionality of deployable CFRP, while the preform, acting as a reinforcement, has not played its due role in the deployment process. This directly leads to the requirement of multiple resin curing processes and preform splicing techniques for the production of existing deployable CFRP, resulting in extremely high costs. Therefore, exploring novel deployable CFRP preform forming technologies is essential to reducing the manufacturing cost of deployable CFRP and promoting the application of deployable structures. Summary of the Invention

[0004] Purpose of the invention: To address the above-mentioned shortcomings, the present invention provides a braided needle punching forming method for improving the performance of deployable prefabricated structures.

[0005] Technical solution: To solve the above problems, the present invention employs a weaving needle punching forming method for deployable prefabricated structures, comprising the following steps:

[0006] (1) Determine the rigid load-bearing zone of the deployable prefabricated structure;

[0007] (2) Attach a mesh template to the surface of the precast support core mold;

[0008] (3) The mesh surface is woven as a whole to form a flexible woven layer that can be unfolded;

[0009] (4) Lay a mesh on the outer layer of the flexible woven layer, determine the needled area corresponding to the rigid load-bearing area in all prefabricated bodies that combine the mesh and the flexible woven layer, and needle the needled area.

[0010] (5) Expand the precast body and increase the inner diameter of the precast body. Repeat steps (3)-(5) until the thickness of the precast body meets the requirements.

[0011] (6) Expand the precast body until the inner diameter of the precast body reaches the requirement, determine the needled area in the precast body corresponding to the rigid bearing area described in step (1), needle the needled area, and obtain the deployable precast structure.

[0012] Furthermore, in each cycle of steps (4) and (6), when the needled area is needled, the needled positions of each two cycles are staggered, and the arc length range corresponding to the inner circle of the needled area in each cycle remains unchanged. The stiffness of the rigid bearing area is guaranteed by the needled process.

[0013] Furthermore, the radius of the preform support core mold is adjustable, and the preform can be enlarged by increasing the radius of the preform support core mold.

[0014] Furthermore, the flexible braided layer is a flexible 2.5D biaxial braided layer.

[0015] Furthermore, the deployable prefabricated structure includes a rigid load-bearing area and a flexible deployment area. The rigid load-bearing area is used for bearing the load of the deployable composite material component, and the flexible deployment area is used for the folding and unfolding deformation of the deployable composite material component.

[0016] Furthermore, when expanding the precast structure, the flexible woven layer meets the following conditions:

[0017]

[0018] Among them, S c Here, θ is the yarn coverage factor, θ is the weaving angle, and b is the yarn coverage factor. f Where n is the width of the braided yarn, n is the number of braided yarns, and D is the inner diameter of the preform after stretching.

[0019] Furthermore, when expanding the precast structure, the mesh tire must meet the following conditions:

[0020]

[0021] Where σ is the mass surface density of the mesh during the expansion of the precast body, D0 is the inner diameter of the initial precast body, and σ0 is the mass surface density of the initial precast body.

[0022] Furthermore, the deployable prefabricated structure includes several circumferentially uniformly distributed rigid load-bearing areas and several circumferentially uniformly distributed flexible deployable areas. The rigid load-bearing areas and flexible deployable areas alternate. The rigid areas are needled to ensure their rigidity, while the flexible areas are not needled and are made flexible by the flexibility of the fabric itself and the expansion of the prefabricated structure. The arc lengths corresponding to the needled areas before and after each needled area are the same, and the needled positions are staggered from each other each time.

[0023] Furthermore, when the precast structure is expanded, the arc length increment ΔL corresponding to the flexible unfolding zone is:

[0024]

[0025] Where D is the inner diameter of the expanded precast body, D0 is the inner diameter of the initial precast body, and Q is the number of flexible deployment zones in the deployable precast structure.

[0026] Beneficial Effects: Compared with existing technologies, the significant advantage of this invention is that it gradually increases the inner diameter of the woven needle-punched preform during the preform weaving process. Increasing the preform diameter allows for a sparser fabric layer, while increasing fabric thickness and using staggered needle punching effectively enhances the stiffness of the rigid regions. This results in a more rigid and flexible structure, improving the rigid-flexible coupling characteristics of the deployable preform. Furthermore, the cyclic weaving needle punching allows for the formation of rigid-flexible zones within the deployable preform, enabling control over the unfolding area, thickness, and range. The method proposed in this invention provides theoretical guidance for the composite forming of deployable preforms using weaving needle punching, enabling customized forming of deployable composite material preforms. This method provides a new approach to the forming of deployable composite materials, simplifying the manufacturing process and reducing the forming cost. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the knitting needle punching forming method of the present invention.

[0028] Figure 2 This is a structural comparison diagram of the preform of the first weaving and punching cycle and the unfoldable preform after the weaving and punching cycle is completed in this invention.

[0029] Figure 3 This is a schematic diagram of the structural parameters of the flexible braided layer in this invention.

[0030] Figure 4 This is a schematic diagram of the structure of the tire mesh before and after the expansion of the tire support in this invention.

[0031] Figure 5 This is a schematic diagram of the unfolded and folded state of the unfoldable prefabricated structure in this invention. Detailed Implementation

[0032] like Figure 1 As shown, a braiding needle punching forming method for a deployable prefabricated structure in this embodiment includes the following steps:

[0033] (1) Based on the unfolding degree and functional requirements of the deployable precast structure, determine the flexible unfolding zone 5 and the rigid load-bearing zone 3 of the deployable precast structure, such as... Figure 5 As shown, the rigid load-bearing area 3 is formed by needle punching. The braided layer 2 and the mesh layer 1 in this area are linked by interlayer fibers and have a certain rigidity. The flexible unfolding area 5 is not formed by needle punching and is composed of the braided layer 2 and the mesh layer 1 that are separated from each other.

[0034] (2) The mesh layer 1 is tightly attached to the surface of the precast support core mold;

[0035] (3) A flexible 2.5D biaxially woven layer 2 is integrally woven on the surface of the mesh layer 1; such as Figure 3 and Figure 4 As shown, the biaxial 2.5D braided layer has good unfolding properties. The mesh layer is considered to be an in-plane isotropic material. During the unfolding process of the braided needle-punched preform, the mass of the mesh remains unchanged, and its structural parameters during the unfolding process satisfy the following equations:

[0036]

[0037]

[0038] Where θ is the weaving angle, b f Where n is the width of the braided yarn, n is the number of braided yarns, and S is the width of the braided yarn. c σ is the weaving yarn coverage factor (the ratio of the area of ​​the weaving fiber bundle covering the mesh to the total area of ​​the mesh layer), D is the diameter of the expandable structure, σ is the mass surface density of the mesh during the expansion of the precast body, D0 is the inner diameter of the initial precast body, and σ0 is the mass surface density of the initial precast body.

[0039] (4) Lay a mesh on the outer layer of the woven prefabricated body of the woven layer 2, and perform relay needle punching in the corresponding determined rigid bearing area 3 to form a local relay needle punching area 6.

[0040] (5) After the needle is inserted, the preform is expanded to increase its expandability.

[0041] The above steps are called a weaving needle punching cycle. The needle punching positions in each cycle are staggered from those in the previous cycle to ensure the rigidity of the needle punching rigid zone. For example... Figure 2As shown, after one weaving and punching cycle, the diameter of the preform is D1. After two weaving and punching cycles, the diameter of the preform increases to D2. During this process, the arc length of the flexible area of ​​the weaving and punching preform increases from L1 to L2. The above steps are repeated until the thickness of the preform reaches the design requirements.

[0042] The degree of unfolding is determined by the diameter D of the unfoldable prefabricated structure and the number of equal parts Q into which the unfoldable structure is divided. The position of the rigid needle-punched area remains unchanged each time, while the flexible unfolding area of ​​the woven needle-punched prefabricated structure increases with the increase of the unfolding diameter D. The corresponding arc length increment ΔL of the flexible unfolding area can be expressed as:

[0043]

[0044] (6) Refer to the expansion steps of the preform during the weaving needle punching cycle, expand the preform until the expansion degree of the preform reaches the design value, and needle punch reinforcement is carried out on the original rigid needle punching area.

Claims

1. A method for weaving and needle-punching prefabricated structures, characterized in that, Includes the following steps: (1) Determine the rigid load-bearing zone of the deployable prefabricated structure; (2) Attach a mesh template to the surface of the precast support core mold; (3) The mesh surface is woven as a whole to form a flexible woven layer that can be unfolded; (4) Lay a mesh on the outer layer of the flexible woven layer, determine the needled area corresponding to the rigid load-bearing area in all prefabricated bodies that combine the mesh and the flexible woven layer, and needle the needled area. (5) Expand the precast body and increase the inner diameter of the precast body. Repeat steps (3)-(5) until the thickness of the precast body meets the requirements. (6) Expand the precast body until the inner diameter of the precast body reaches the requirement, determine the needled area in the precast body corresponding to the rigid bearing area described in step (1), needle the needled area, and obtain the deployable precast structure.

2. The knitting needle punching forming method according to claim 1, characterized in that, In each cycle, during steps (4) and (6), when the needled area is needled, the needled positions of each two cycles are staggered. The arc length range corresponding to the inner circle of the needled area in each cycle remains unchanged, and the stiffness of the rigid bearing area is guaranteed by the needled process.

3. The knitting needle punching forming method according to claim 1, characterized in that, The radius of the preform support core mold is adjustable, and the preform can be enlarged by increasing the radius of the preform support core mold.

4. The knitting needle punching forming method according to claim 1, characterized in that, The flexible braided layer is a flexible 2.5D biaxial braided layer.

5. The knitting needle punching forming method according to claim 1, characterized in that, The deployable prefabricated structure includes a rigid load-bearing area and a flexible deployment area. The rigid load-bearing area is used for bearing the load of the deployable composite material component, and the flexible deployment area is used for the folding and unfolding deformation of the deployable composite material component.

6. The knitting needle punching forming method according to claim 1, characterized in that, When expanding the precast structure, the flexible woven layer must meet the following conditions: Among them, S c Here, θ is the yarn coverage factor, θ is the weaving angle, and b f Where n is the width of the braided yarn, n is the number of braided yarns, and D is the inner diameter of the preform after stretching.

7. The knitting needle punching forming method according to claim 6, characterized in that, When expanding the precast structure, the mesh tire must meet the following conditions: Where σ is the mass surface density of the mesh during the expansion of the precast body, D0 is the inner diameter of the initial precast body, and σ0 is the mass surface density of the initial precast body.

8. The knitting needle punching forming method according to claim 5, characterized in that, The deployable prefabricated structure includes several circumferentially uniformly distributed rigid load-bearing areas and several circumferentially uniformly distributed flexible deployable areas, which are alternately distributed.

9. The knitting needle punching forming method according to claim 7, characterized in that, When the precast structure is expanded, the arc length increment ΔL corresponding to the flexible unfolding zone is: Where D is the inner diameter of the expanded precast body, D0 is the inner diameter of the initial precast body, and Q is the number of flexible deployment zones in the deployable precast structure.

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