CN117863588A - A weaving needle punching forming method for a deployable structural preform - Google Patents

Abstract

The present invention discloses a weaving needling forming method for a deployable structural preform, comprising: determining a rigid bearing area of the deployable structural preform; placing a mesh tire on the surface of a preform support core mold; weaving the mesh tire surface as a whole to form a deployable flexible woven layer; laying a mesh tire on the outer layer of the flexible woven layer, determining the needling area corresponding to the rigid bearing area in the preform composed of all mesh tires and the flexible woven layer for needling; expanding the preform, repeating the weaving needling process until the thickness of the preform reaches the requirement; expanding the preform until the inner diameter of the preform reaches the requirement, needling the selected rigid needling area, and obtaining a deployable structural preform. During the preform weaving process, the inner diameter of the weaving needling preform is gradually increased to make the fabric layer more sparse, and at the same time, the rigidity of the rigid area is improved by increasing the fabric thickness and staggered needling, so that the formed rigid area is more rigid and the flexible area is more flexible, thereby improving the rigid-flexible coupling characteristics of the deployable structural preform.

Description

A weaving needle punching forming method for a deployable structural preform

Technical Field

The invention relates to the forming of a composite material three-dimensional structure preform, and in particular to a weaving needle punching forming method for an expandable structure preform.

Background technique

Deployable structures can actively adjust their coverage area or volume according to the external environment. They have been successfully applied in aerospace, disaster relief, medical equipment and other fields. Deployable structures usually have very strict requirements on material performance due to their special application scenarios. They need to have performance characteristics such as light weight, high strength, and deformability. These seemingly conflicting performance characteristics make deployable structures face many difficulties in the design and manufacturing process, which greatly hinders the application and development of deployable structures.

In order to overcome these difficulties, people consider using the advantages of carbon fiber reinforced composite materials (CFRP) such as light weight, high strength and good designability to apply them to deployable structures, thereby reducing the weight of the structure and the number of structural parts. CFRP consists of a carbon fiber preform and a matrix. The deployable performance of the preform and the matrix largely determines the deployable performance of CFRP components. In recent years, people have tried to prepare deployable CFRP by cleverly designing the preform and the matrix. It is worth noting that current research has made the rigid-flexible coupling resin matrix the main factor for the function of deployable CFRP, while the preform as a reinforcement of CFRP has not played its due role in the deployment function of CFRP. This directly leads to the fact that the existing deployable CFRP requires multiple resin curing processes and preform splicing processes to be prepared, and the entire process is extremely costly. Therefore, it is necessary to explore new deployable CFRP preform forming technology, which is the only way to reduce the manufacturing cost of deployable CFRP and promote the application of deployable structures.

Summary of the invention

Purpose of the invention: In view of the above shortcomings, the present invention provides a knitting needle forming method for improving the performance of a deployable structural preform.

Technical solution: To solve the above problems, the present invention adopts a knitting needle punching forming method for a deployable structure preform, comprising the following steps:

(1) Determine the rigid bearing area of the deployable structural preform;

(2) placing a mesh tire on the surface of the preform supporting core mold;

(3) Weaving the entire surface of the web to form an expandable flexible woven layer;

(4) laying a mesh tire on the outer layer of the flexible woven layer, determining the needle-punching area corresponding to the rigid bearing area in the preform composed of all the mesh tires and the flexible woven layer, and needle-punching the needle-punching area;

(5) expanding the preform, increasing the inner diameter of the preform, and repeating steps (3) to (5) until the preform thickness reaches the required value;

(6) expanding the preform until the inner diameter of the preform reaches the requirement, determining the needle-punching area of the preform corresponding to the rigid bearing area described in step (1), and needle-punching the needle-punching area to obtain an expandable structural preform.

Furthermore, in step (4) and step (6) of each cycle, when the acupuncture area is acupunctured, the acupuncture positions of each two cycles are staggered with each other, the arc length range corresponding to the inner circle in the acupuncture area of each cycle remains unchanged, and the rigidity of the rigid bearing area is ensured by the acupuncture process.

Furthermore, the radius of the preform supporting core mold is adjustable, and the preform can be enlarged by increasing the radius of the preform supporting core mold.

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

Furthermore, the deployable structural preform comprises a rigid bearing area and a flexible deployment area, the rigid bearing area is used for bearing the force of the deployable composite material component, and the flexible deployment area is used for folding, unfolding and deforming the deployable composite material component.

Furthermore, when the preform is expanded, the flexible braided layer satisfies the following conditions:

Among them, _Sc is the braiding yarn coverage factor, θ is the braiding angle, _bf is the braiding yarn width, n is the number of braiding yarns, and D is the inner circle diameter of the preform after expansion.

Furthermore, when the preform is expanded, the web meets the following conditions:

Wherein, σ is the mass surface density of the web during the expansion of the preform, D ₀ is the inner ring diameter of the initial preform, and σ ₀ is the mass surface density of the initial preform.

Furthermore, the expandable structural preform includes a number of rigid load-bearing areas uniformly distributed circumferentially and a number of flexible expansion areas uniformly distributed circumferentially, the rigid load-bearing areas and the flexible expansion areas are alternated, the rigid areas are needle-punched to ensure their rigidity, and the flexible areas are not needle-punched, and their flexibility is ensured by the flexibility of the fabric itself and the expansion of the preform, the arc length corresponding to each rigid load-bearing area before and after needling is the same, and the needling positions are staggered each time.

Furthermore, when the preform is expanded, the arc length increment ΔL corresponding to the flexible expansion area is:

Wherein, D is the inner diameter of the expanded preform, _D0 is the inner diameter of the initial preform, and Q is the number of flexible expansion areas in the expandable structural preform.

Beneficial effects: Compared with the prior art, the significant advantage of the present invention is that the inner diameter of the woven needle-punched preform is gradually increased during the preform weaving process. The fabric layer can be made sparser by increasing the preform diameter. At the same time, the rigidity of the rigid zone can be effectively improved by increasing the fabric thickness and staggered needling, so that the forming can achieve the goal of making the rigid zone more rigid and the flexible zone more flexible, thereby improving the rigid-flexible coupling characteristics of the deployable structure preform. In addition, the rigid-flexible zoning forming of the deployable structure preform can be carried out through the weaving needling cycle, and the folding area, thickness and unfolding range of the deployable structure preform can be controlled. The method proposed in this invention provides theoretical guidance for the woven needle-punched composite forming of the deployable structure preform, and the customized forming of the deployable structure composite material preform can be realized by this method. This method provides a new way for the forming of deployable structure composite materials, which can simplify the manufacturing process of deployable composite material components and reduce the forming cost of deployable composite materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow chart of the knitting needle punching forming method of the present invention.

FIG. 2 is a schematic diagram showing a structural comparison between a preform of the first knitting needling cycle and a preform of an expandable structure after the knitting needling cycle in the present invention.

FIG. 3 is a schematic diagram of structural parameters of the flexible braided layer in the present invention.

FIG. 4 is a schematic structural diagram of the mesh tire before and after expansion in the present invention.

FIG. 5 is a schematic diagram of the unfolded and folded state of the unfoldable structural preform in the present invention.

Detailed ways

As shown in FIG1 , a braided needling forming method for a deployable structure preform in this embodiment includes the following steps:

(1) According to the degree of expansion and functional requirements of the expandable structural preform, the flexible expansion area 5 and the rigid bearing area 3 of the expandable structural preform are determined. As shown in FIG5 , the rigid bearing area 3 is formed by a needle punching process, and the woven layer 2 and the web layer 1 in this area are connected by interlayer fibers and have a certain rigidity. The flexible expansion area 5 does not adopt the needle punching process and is composed of the woven layer 2 and the web layer 1 separated from each other;

(2) tightly attaching the web layer 1 to the surface of the preform supporting core mold;

(3) The surface of the web layer 1 is integrally woven to form an expandable flexible 2.5D biaxial woven layer 2; as shown in FIG3 and FIG4, the biaxial 2.5D woven layer has good expandability. The web layer is regarded as an in-plane isotropic material. During the expansion of the woven needle-punched preform, the mass of the web remains unchanged, and the structural parameters during the expansion process satisfy the following equations:

Wherein, θ is the braiding angle, _bf is the braiding yarn width, n is the number of braiding yarns, _Sc is the braiding yarn coverage factor (the ratio of the area of the braided fiber bundle covering the web to the total area of the web layer), D is the expandable structure diameter, σ is the mass surface density of the web during the expansion of the preform, _D0 is the initial preform inner ring diameter, and _σ0 is the mass surface density of the initial preform.

(4) laying a mesh on the outer layer of the woven preform of the woven layer 2, and performing relay needling in the corresponding rigid load-bearing area 3 to form a local relay needling area 6;

(5) After the needling is completed, the preform is stretched to increase the expandability of the preform.

The above steps are called a knitting needling cycle, and the needling positions of each cycle are staggered with the needling positions of the previous cycle to ensure the rigidity of the needling rigid zone. As shown in Figure 2, after one knitting needling cycle, the preform diameter is _D1 , and after two knitting needling cycles, the preform diameter increases to _D2 . In this process, the arc length of the flexible zone of the knitting needling preform increases from _L1 to _L2 . The above steps are repeated until the preform thickness meets the design requirements.

The degree of expansion is determined by the diameter D of the expandable preform structure and the number of equal parts Q into which the expandable structure is divided. The position of the rigid needle punching area remains unchanged each time, and the flexible expansion area of the braided needle punching preform increases with the increase of the expansion diameter D. The arc length increment ΔL corresponding to the corresponding flexible expansion area can be expressed as:

(6) Referring to the step of expanding the preform during the weaving needling cycle, the preform is expanded until the expandable degree of the preform reaches the designed value, and the original rigid needling area is needling reinforced.

Claims (9)

1. A method for forming a woven needle punching body of a deployable structure preform, characterized in that it comprises the following steps: (1) Determine the rigid bearing area of the deployable structural preform; (2) placing a mesh tire on the surface of the preform supporting core mold; (3) Weaving the entire surface of the web to form an expandable flexible woven layer; (4) laying a mesh tire on the outer layer of the flexible woven layer, determining the needle-punching area corresponding to the rigid bearing area in the preform composed of all the mesh tires and the flexible woven layer, and needle-punching the needle-punching area; (5) expanding the preform, increasing the inner diameter of the preform, and repeating steps (3) to (5) until the preform thickness reaches the required value; (6) expanding the preform until the inner diameter of the preform reaches the requirement, determining the needle-punching area of the preform corresponding to the rigid bearing area described in step (1), and needle-punching the needle-punching area to obtain an expandable structural preform. 2. The woven needle punching forming method according to claim 1 is characterized in that, in step (4) and step (6) of each cycle, when the needle punching area is needle punched, the needle punching positions of every two cycles are staggered with each other, the arc length range corresponding to the inner circle in the needle punching area of each cycle remains unchanged, and the rigidity of the rigid bearing area is ensured by the needle punching process. 3. The braided needle punching forming method according to claim 1 is characterized in that the radius of the preform supporting core mold is adjustable, and the preform is enlarged by increasing the radius of the preform supporting core mold. 4. The braided needle punching forming method according to claim 1 is characterized in that the flexible braided layer is a flexible 2.5D biaxial braided layer. 5. The woven needle punching forming method according to claim 1 is characterized in that the expandable structural preform includes a rigid load-bearing area and a flexible expansion area, the rigid load-bearing area is used for the force bearing of the expandable composite material component, and the flexible expansion area is used for the folding, expansion and deformation of the expandable composite material component. 6. The knitting needle punching forming method according to claim 1, characterized in that when the preform is expanded, the flexible knitted layer meets the following conditions: Among them, _Sc is the braiding yarn coverage factor, θ is the braiding angle, _bf is the braiding yarn width, n is the number of braiding yarns, and D is the inner circle diameter of the preform after expansion. 7. The knitting needle forming method according to claim 6, characterized in that when the preform is expanded, the web meets the following conditions: Wherein, σ is the mass surface density of the web during the expansion of the preform, D ₀ is the inner ring diameter of the initial preform, and σ ₀ is the mass surface density of the initial preform. 8. The woven needle punching forming method according to claim 5 is characterized in that the expandable structural preform includes a plurality of circumferentially uniformly distributed rigid load-bearing areas and a plurality of circumferentially uniformly distributed flexible expansion areas, and the rigid load-bearing areas and the flexible expansion areas are alternately distributed. 9. The knitting needle forming method according to claim 7, characterized in that when the preform is expanded, the arc length increment ΔL corresponding to the flexible expansion zone is: Wherein, D is the inner diameter of the expanded preform, _D0 is the inner diameter of the initial preform, and Q is the number of flexible expansion areas in the expandable structural preform.