CN117863588A - Knitting and needling forming method for expandable structure preform - Google Patents
Knitting and needling forming method for expandable structure preform Download PDFInfo
- Publication number
- CN117863588A CN117863588A CN202311716808.5A CN202311716808A CN117863588A CN 117863588 A CN117863588 A CN 117863588A CN 202311716808 A CN202311716808 A CN 202311716808A CN 117863588 A CN117863588 A CN 117863588A
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- China
- Prior art keywords
- preform
- needling
- flexible
- knitting
- rigid
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- 238000009940 knitting Methods 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000009954 braiding Methods 0.000 claims abstract description 17
- 239000002131 composite material Substances 0.000 claims description 11
- 239000004744 fabric Substances 0.000 abstract description 6
- 230000008878 coupling Effects 0.000 abstract description 3
- 238000010168 coupling process Methods 0.000 abstract description 3
- 238000005859 coupling reaction Methods 0.000 abstract description 3
- 238000004080 punching Methods 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 17
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/06—Fibrous reinforcements only
- B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
- B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
- B29C70/24—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in at least three directions forming a three dimensional structure
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Mechanical Engineering (AREA)
- Tires In General (AREA)
Abstract
The invention discloses a knitting needle punching forming method for a preform with an expandable structure, which comprises the following steps: determining a rigid load bearing region of the expandable structure preform; pasting a net-laying tire on the surface of the support core mold of the preform; integrally braiding the surface of the net tyre to form an expandable flexible braiding layer; laying a net tire on the outer layer of the flexible braiding layer, and determining needling areas corresponding to the rigid bearing areas in the prefabricated body formed by combining all the net tires and the flexible braiding layer; expanding the preform, and repeating the knitting and needling processes until the thickness of the preform reaches the requirement; and (5) expanding the preform until the inner diameter of the preform meets the requirement, and needling the selected rigid needling area to obtain the preform with the expandable structure. The inner diameter of the knitting needle-punched preform is gradually increased in the process of knitting the preform, so that the fabric layer is sparse, meanwhile, the rigidity of the rigid area is improved through increasing the thickness of the fabric and staggered needling, the formed rigid area is stiffer, the flexible area is softer, and the rigid-flexible coupling characteristic of the expandable structure preform is improved.
Description
Technical Field
The invention relates to forming of a three-dimensional structure prefabricated body of a composite material, in particular to a knitting needling forming method for a prefabricated body of an expandable structure.
Background
The expandable structure can actively adjust the coverage area or volume according to the external environment, and is successfully applied to the fields of aerospace, protection and relief, medical equipment and the like. The expandable structure has very strict requirements on material performance due to the special application scene, and needs to have light weight, high strength, deformability and other performance characteristics, so that the expandable structure faces a plurality of difficulties in the design and manufacturing process due to the seemingly conflicting performance characteristics, and the application and development of the expandable structure are greatly hindered.
In order to overcome these problems, it is considered to use the advantages of the carbon fiber reinforced Composite (CFRP) such as light weight, high strength, and good designability, and apply it to the expandable structure, thereby reducing the weight of the structure and the number of structural parts. CFRP is composed of a carbon fiber preform and a matrix, the spreadability of which largely determines the spreadability of the CFRP member, and attempts have been made in recent years to produce a spreadable CFRP by skillfully designing the preform and matrix. Notably, the current research makes the rigid-flexible coupling resin matrix a main factor for the function of the expandable CFRP, and the preform as a reinforcement of the CFRP does not have the function of expanding the CFRP, which directly results in that the existing expandable CFRP needs a plurality of resin curing processes and preform splicing processes to be prepared, and the whole process has extremely high cost. Therefore, there is a need to explore new expandable CFRP preform forming techniques, which are necessary ways to reduce the manufacturing costs of expandable CFRP and to facilitate the application of expandable structures.
Disclosure of Invention
The invention aims to: in view of the above drawbacks, the present invention provides a method of knitting needle forming that improves the performance of a preform of a deployable structure.
The technical scheme is as follows: in order to solve the problems, the invention adopts a knitting needle punching forming method aiming at a preform with an expandable structure, which comprises the following steps:
(1) Determining a rigid load bearing region of the expandable structure preform;
(2) Pasting a net-laying tire on the surface of the support core mold of the preform;
(3) Integrally braiding the surface of the net tyre to form an expandable flexible braiding layer;
(4) Paving a net tire on the outer layer of the flexible braiding layer, determining needling areas corresponding to the rigid bearing areas in the prefabricated body formed by combining all the net tires and the flexible braiding layer, and needling the needling areas;
(5) Expanding the preform, increasing the inner diameter of the preform, and repeating the steps (3) - (5) until the thickness of the preform reaches the requirement;
(6) And (3) expanding the preform until the inner diameter of the preform meets the requirement, determining a needling area corresponding to the rigid bearing area in the step (1) in the preform, and needling the needling area to obtain the preform with the expandable structure.
Further, in the step (4) and the step (6) of each cycle, when the needling area is needled, needling positions of every two cycles are staggered, the corresponding arc length range of the inner ring of the needling area of each cycle is unchanged, and the rigidity of the rigid bearing area is ensured by a needling process.
Further, 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.
Further, the flexible braid is a flexible 2.5D biaxial braid.
Further, the expandable structural preform comprises a rigid bearing zone for bearing the stress of the expandable composite member and a flexible expansion zone for folding, expanding and deforming the expandable composite member.
Further, when the preform is enlarged, the flexible braid satisfies the following condition:
wherein S is c For the knitting yarn coverage factor, θ is the knitting angle, b f For knitting yarn width, n is the number of knitting yarns, and D is the inner ring diameter of the enlarged preform.
Further, when the preform is enlarged, the web tire satisfies the following conditions:
wherein sigma is the mass area density of the net tyre in the process of expanding the prefabricated body, D 0 For initial preform inner circle diameter, σ 0 Is the mass areal density of the initial preform.
Further, the expandable structure prefabricated body comprises a plurality of rigid bearing areas which are uniformly distributed in the circumferential direction and a plurality of flexible expansion areas which are uniformly distributed in the circumferential direction, the rigid bearing areas and the flexible expansion areas are alternated, the rigidity of the rigid areas is ensured by needling, the flexible areas are not needled, the flexibility of the fabric is ensured by the flexibility of the fabric and the prefabricated body is expanded, the corresponding arc lengths of each rigid bearing area before and after needling are the same, and the needling positions of each time are staggered.
Further, when the preform is expanded, the arc length increment Δl corresponding to the flexible expansion region is:
wherein D is the diameter of the inner ring of the prefabricated body after being enlarged, D 0 For the initial preform inner ring diameter, Q is the number of flexible deployment regions in the preform in the deployable structure.
The beneficial effects are that: compared with the prior art, the method has the remarkable advantages that the inner diameter of the knitting needle punched preform is gradually increased in the process of knitting the preform, the fabric layer can be made sparse by increasing the diameter of the preform, meanwhile, the rigidity of the rigid region can be effectively improved by increasing the thickness of the fabric and interlacing needle punching, the forming can achieve the aim that the rigid region is stiffer and the flexible region is softer, and the rigid-flexible coupling characteristic of the expandable structure preform is improved. In addition, the rigid and flexible partition forming of the expandable structure preform can be performed through the knitting needling cycle, and the adjustment and control of the folding and unfolding area, thickness and unfolding range of the expandable structure preform are realized. The method provides theoretical guidance for weaving and needling the composite forming expandable structure preform, and can realize customized forming of the expandable structure composite material preform. The method provides a new way for forming the expandable structure composite material, can simplify the manufacturing process of the expandable composite material component and reduce the forming cost of the expandable composite material.
Drawings
FIG. 1 is a schematic flow chart of a knitting needle forming method of the present invention.
FIG. 2 is a schematic diagram showing a structural comparison of a preform from a first knitting and needling cycle and a preform from a deployable structure after the end of the knitting and needling cycle in accordance with the present invention.
FIG. 3 is a schematic view of structural parameters of a flexible braid according to the present invention.
Fig. 4 is a schematic diagram of the structure of the invention before and after the net tire is stretched.
FIG. 5 is a schematic view showing an unfolded and folded state of a preform of an unfolded structure according to the present invention.
Detailed Description
As shown in fig. 1, a knitting needle forming method for a preform of a deployable structure in this embodiment includes the steps of:
(1) According to the unfolding degree and the functional requirement of the unfolding structure prefabricated body, determining a flexible unfolding area 5 and a rigid bearing area 3 of the unfolding structure prefabricated body, wherein as shown in fig. 5, a needling forming process is adopted in the rigid bearing area 3, a braiding layer 2 and a net tire layer 1 are hooked by interlayer fibers in the area, the unfolding area 5 has certain rigidity, and the flexible unfolding area 5 is formed by the braiding layer 2 and the net tire layer 1 which are separated from each other without adopting the needling process;
(2) The net tire layer 1 is tightly attached to the surface of the support core mold of the preform;
(3) Integrally braiding the surface of the net tire layer 1 to form an expandable flexible 2.5D double-shaft braiding layer 2; as shown in fig. 3 and fig. 4, the biaxial 2.5D knitted layer has a better expandable property, the net layer is regarded as an in-plane isotropic material, the net is unchanged in quality during the expanding process of the knitted needled preform, and the structural parameters in the expanding process meet the following equation:
wherein θ is the braiding angle, b f For knitting yarn width, n is the number of knitting yarns, S c For the knitting yarn coverage factor (ratio of the area of the knitting fiber bundles covering the net tire to the total area of the net tire layer), D is the diameter of the expandable structure, sigma is the mass area density of the net tire in the process of expanding the preform, D 0 For initial preform inner circle diameter, σ 0 Is the mass areal density of the initial preform.
(4) Laying a net tyre on the outer layer of the woven preform of the woven layer 2, and carrying out relay needling in the corresponding determined rigid bearing area 3 to form a local relay needling area 6;
(5) The preform is stretched after needling is completed to increase the degree of stretch of the preform.
The above steps are referred to as a knitting needling cycle, with the needling position of each cycle being offset from the needling position of the previous cycle to ensure the rigidity of the needling stiffness zone. As shown in FIG. 2, the preform diameter after one knitting and needling cycle is D 1 The diameter of the preform increases to D after two knitting and needling cycles are performed 2 The arc length of the flexible area of the knitting needle-punched preform in the process is defined by L 1 Increased to L 2 Repeating the steps until the thickness of the prefabricated body reaches the design requirement.
The expansion degree is determined by the structural diameter D of the expandable preform and the number of parts Q of the expandable structure which are equally divided, the position of each rigid needling area is unchanged, the flexible expansion area of the knitted needled preform can be increased along with the increase of the expansion diameter D, and the arc length increment delta L corresponding to the corresponding flexible expansion area can be expressed as:
(6) And (3) referring to the step of expanding the preform in the knitting and needling circulation process, expanding the preform until the expandable degree of the preform reaches a design value, and performing needling reinforcement on the original rigid needling area.
Claims (9)
1. A method of knitting and needlepunching a preform for a deployable structure, comprising the steps of:
(1) Determining a rigid load bearing region of the expandable structure preform;
(2) Pasting a net-laying tire on the surface of the support core mold of the preform;
(3) Integrally braiding the surface of the net tyre to form an expandable flexible braiding layer;
(4) Paving a net tire on the outer layer of the flexible braiding layer, determining needling areas corresponding to the rigid bearing areas in the prefabricated body formed by combining all the net tires and the flexible braiding layer, and needling the needling areas;
(5) Expanding the preform, increasing the inner diameter of the preform, and repeating the steps (3) - (5) until the thickness of the preform reaches the requirement;
(6) And (3) expanding the preform until the inner diameter of the preform meets the requirement, determining a needling area corresponding to the rigid bearing area in the step (1) in the preform, and needling the needling area to obtain the preform with the expandable structure.
2. The method according to claim 1, wherein in the step (4) and the step (6) of each cycle, the needling positions of each two cycles are staggered, the corresponding arc length range of the inner ring of the needling area of each cycle is unchanged, and the rigidity of the rigid bearing area is ensured by the needling process.
3. The method of knitting and needlepunching as in claim 1, 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 method of claim 1, wherein the flexible braid is a flexible 2.5D biaxial braid.
5. The method of knit needlepunching of claim 1, wherein the preform of the expandable structure includes a rigid load-bearing region for load bearing of the expandable composite member and a flexible expansion region for folding expansion deformation of the expandable composite member.
6. The method of knitting and needlepunching as in claim 1, wherein the flexible knit layer satisfies the following condition when the preform is enlarged:
wherein S is c For the knitting yarn coverage factor, θ is the knitting angle, b f For knitting yarn width, n is the number of knitting yarns, and D is the inner ring diameter of the enlarged preform.
7. The method of knitting and needlepunching as in claim 6, wherein when the preform is enlarged, the web tire satisfies the following condition:
wherein sigma is the mass area density of the net tyre in the process of expanding the prefabricated body, D 0 For initial preform inner circle diameter, σ 0 Is the mass areal density of the initial preform.
8. The method of knitting and needlepunching as in claim 5, wherein the preform includes a plurality of circumferentially uniformly distributed rigid load-bearing regions and a plurality of circumferentially uniformly distributed flexible expansion regions, the rigid load-bearing regions and the flexible expansion regions being alternately distributed.
9. The method of knitting and needlepunching as in claim 7, wherein when the preform is enlarged, the arc length increment Δl corresponding to the flexible deployment region is:
wherein D is the diameter of the inner ring of the prefabricated body after being enlarged, D 0 For the initial preform inner ring diameter, Q is the number of flexible deployment regions in the preform in the deployable structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311716808.5A CN117863588A (en) | 2023-12-14 | 2023-12-14 | Knitting and needling forming method for expandable structure preform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311716808.5A CN117863588A (en) | 2023-12-14 | 2023-12-14 | Knitting and needling forming method for expandable structure preform |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117863588A true CN117863588A (en) | 2024-04-12 |
Family
ID=90593744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311716808.5A Pending CN117863588A (en) | 2023-12-14 | 2023-12-14 | Knitting and needling forming method for expandable structure preform |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117863588A (en) |
-
2023
- 2023-12-14 CN CN202311716808.5A patent/CN117863588A/en active Pending
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