Foldable composite panel and method of forming the same

Abstract

The application discloses a foldable composite material plate and a forming method thereof. The foldable composite material plate comprises rigid sections for bearing load and flexible sections for folding deformation. The rigid sections are composed of dense flexible guide three-dimensional woven preforms and high-rigidity matrices. The flexible sections are composed of three-dimensional woven preforms with connecting sections and cavity sections and flexible matrices. The cured rigid plates are embedded in the cavity sections of the flexible plate preforms and connected and packaged with the flexible plate preforms by a three-dimensional stitching process. Then, the whole plate is impregnated with the flexible matrices and cured to obtain a rigid-flexible coupling foldable composite material plate with integrated load bearing and deformation functions.

Description

Technical Field

[0001] This invention relates to the forming of foldable composite materials, specifically to a foldable composite material sheet and its forming method. Background Technology

[0002] Foldable structures, which combine load-bearing and folding functions, have been successfully applied in spacecraft solar panel substrates, bulletproof shields, and morphing aircraft. However, with the further promotion and application of foldable structures, higher requirements are placed on their comprehensive mechanical performance and overall integrity.

[0003] Advanced composite materials possess significant potential for development in the field of foldable structures due to their advantages such as lightweight, high strength, good designability, and integral molding. Composite material structures with rigid-flexible coupling characteristics can achieve functions such as folding and load-bearing. Foldable panels with integrated load-bearing and deformation functions designed based on rigid-flexible coupling theory have great application value and are currently a research hotspot. However, traditional composite foldable panels are generally discrete segmented structures connected by mechanical structures, which limits their engineering applications. Summary of the Invention

[0004] Objective of the Invention: This invention provides a foldable composite material sheet and its forming method, which produces a foldable composite material sheet without employing mechanical structures at the folding points, i.e., without compromising the fabric structure at the folding points; simultaneously, it provides a forming method for this foldable composite material sheet.

[0005] Technical solution: The foldable composite material sheet provided by this invention adopts the following technical solution:

[0006] A rigid-flexible coupled foldable composite material sheet includes several rigid plates and a flexible plate preform for housing the rigid plates; the flexible plate preform includes a cavity section and a connecting section connecting two adjacent cavity sections.

[0007] Furthermore, the rigid plate includes a flexible, guided three-dimensional woven preform woven into a square shape and a rigid resin for curing the flexible, guided three-dimensional woven preform.

[0008] Furthermore, the flexible panel preform is a double-layer corner interlocking woven preform.

[0009] Furthermore, the cavity segment is stitched and fixed to the rigid plate, and the rigid plate and the flexible plate preform are wrapped with flexible resin through impregnation.

[0010] The foldable composite material sheet forming method provided by this invention adopts the following technical solution, including the following steps:

[0011] (1) Obtain a rigid plate; firstly, a dense flexible directional three-dimensional woven preform is woven using a three-dimensional weaving process, and then the flexible directional three-dimensional woven preform is encapsulated and cured with rigid resin.

[0012] (2) Prepare a three-dimensional woven flexible preform including a connecting section and a cavity section, wherein the connecting section is integrally woven between two cavity sections, and the cavity section is a structure woven with fabric on both sides surrounding the middle cavity;

[0013] (3) The rigid plate is encapsulated in the cavity of the cavity section and the rigid plate is fixed in the flexible plate preform by stitching.

[0014] (4) A foldable composite material sheet is obtained by impregnating and curing a rigid plate and a flexible plate preform with flexible resin.

[0015] Furthermore, in step (1), the flexible guided three-dimensional woven prefabricated body should reserve N empty holes without Z-axis yarns during the weaving process, and polish the surface of the component after it is solidified; where N>2.

[0016] Furthermore, after the flexible guided three-dimensional woven prefabricated body described in step (1) has been cured and polished, through holes are drilled along the N empty holes where no Z-axis yarn has been implanted, and the hole walls are ground to serve as channels for introducing the sewing yarn during subsequent sewing, for sewing and fixing the rigid plate and the three-dimensional woven prefabricated body; the radii of the drilled holes satisfy the following relationship:

[0017]

[0018]

[0019] In the formula, r is the radius of the drilled hole; L is the width of the hole in the flexible guide prefabricated body; θ is the geometric shape change coefficient of the width of the hole in the guide prefabricated body before and after the component is cured; h is the thickness of the flexible guide three-dimensional woven rigid plate; and α is the angle between the center line of the drill bit and the center line of the drilled hole.

[0020] Furthermore, in step (2), the three-dimensional woven flexible prefabricated body has a segmented and continuous distribution of connecting sections and cavity sections along the fabric length direction, and the cavity section of the prefabricated body contains a cavity that accommodates a solidified rigid plate.

[0021] Furthermore, the rigid plate encapsulation method described in step (3) involves using fabric and stitching to enclose and sew the two sides of the cavity together, ensuring that the rigid plate is sealed within the three-dimensional woven prefabricated body.

[0022] The present invention also provides composite material sheets manufactured according to the above forming method.

[0023] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that it cleverly combines the characteristics of flexible guided three-dimensional weaving, three-dimensional stitching, and three-dimensional machine weaving processes. By using three-dimensional stitching technology to encapsulate and connect the flexible guided three-dimensional woven rigid plate into the cavity of the flexible guided three-dimensional machine woven preform, a multi-process composite forming of foldable plate preforms is achieved without losing the fabric structure. Finally, the flexible matrix is ​​used for curing, which greatly increases the bonding strength of the heterogeneous matrix composite plate. This innovatively realizes the multi-process integrated composite forming of lightweight, load-bearing, and foldable composite plate. Attached Figure Description

[0024] Figure 1 The diagram shown is a flowchart of the foldable composite material sheet forming method of the present invention;

[0025] Figure 2 The diagram shown is a schematic diagram of the rigid plate flexible guide three-dimensional woven prefabricated structure in this invention;

[0026] Figure 3 The image shows the rigid-flexible guide plate of this invention;

[0027] Figure 4 The diagram shown is a schematic of the rigid plate drilling structure in this invention;

[0028] Figure 5 The diagram shown is a schematic diagram of the rigid plate after drilling in this invention;

[0029] Figure 6 The diagram shown is a schematic diagram of the three-dimensional woven prefabricated structure with cavity in this invention;

[0030] Figure 7 The diagram shown is a schematic diagram of the process of embedding a rigid plate into a three-dimensional woven prefabricated body in this invention;

[0031] Figure 8 The diagram shown illustrates the connection and encapsulation of the rigid plate and the flexible three-dimensional woven prefabricated body in this invention.

[0032] Figure 9 The diagram shown is a schematic diagram of the foldable composite material sheet and its folding process in this invention. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0034] Example 1

[0035] To create an integrated foldable composite material sheet that combines lightweight and load-bearing capabilities, and addressing the issues of discrete segments and heavy weight inherent in traditional foldable structures, this invention provides a foldable composite material sheet, such as... Figure 7As shown, the device includes several rigid plates 9 and a flexible prefabricated body for housing the rigid plates 9. The flexible prefabricated body includes a cavity segment 7 and a connecting segment 6 connecting two adjacent cavity segments 7. The cavity segment 7 is woven with fabric on both sides surrounding a central cavity 8. The cavity 8 is used to house the rigid plates 9. The cavity segment 7 is sewn and fixed to the rigid plates 9, and the rigid plates 9 and the flexible prefabricated body are coated with flexible resin through impregnation.

[0036] The rigid plate comprises a flexible, guided three-dimensional woven preform woven into a square shape and a rigid resin for curing the flexible, guided three-dimensional woven preform. For example... Figure 2 As shown, a square flexible guided three-dimensional woven preform is obtained by encapsulating and curing the flexible guided three-dimensional woven preform with rigid resin (not shown) to obtain a rigid plate 9.

[0037] The flexible panel prefabricated body is a double-layer corner interlocking woven prefabricated body.

[0038] Example 2

[0039] This embodiment describes a method for forming a foldable composite material sheet, which specifically includes the following steps:

[0040] (1): Rigid plate 9 is obtained by using a rigid resin-cured, dense, flexible, guided three-dimensional woven prefabricated body, such as... Figure 2 As shown, a flexible, guided three-dimensional woven composite plate-shaped preform is first prepared, and N (N>2, N∈N) is reserved during the weaving process. * N * There are (a natural number > 2) empty holes 2 without Z-axis yarn 1 implantation. In this special case illustration, 9 empty holes 2 without Z-axis yarn 1 implantation are reserved. The plate-shaped flexible guided three-dimensional woven prefabricated body is impregnated with epoxy resin and cured at a heat source. After curing, the flexible guided three-dimensional woven plate is shaped into a regular composite material plate, such as... Figure 3 As shown, the surface of the board is then polished to remove the surface texture caused by the curing process, so that the resin area 3 and fiber texture area 4 on the surface of the component are clearly exposed.

[0041] like Figure 4 and Figure 5 As shown, after the flexible guide component is cured and polished, through holes 5 are drilled along the nine empty holes 2 where no Z-axis yarn 1 is implanted, and the hole walls are ground to serve as channels for introducing the suture yarn during subsequent suturing, for low-damage suturing and fixation of the flexible guide rigid plate 9 and the three-dimensional woven prefabricated body 11. The radius of the drilled through holes 5 should satisfy the following relationship:

[0042]

[0043]

[0044] In the formula, r is the radius of the drilled through hole 5; L is the width of the hole in the flexible guide prefabricated body; θ is the geometric deformation coefficient of the hole width in the flexible guide prefabricated body before and after the component is cured; h is the thickness of the flexible guide three-dimensional woven rigid plate; and α is the angle between the center line of the drill bit and the center line of the drilled through hole 5.

[0045] (2): A three-dimensional woven prefabricated body with connecting segment 6 and cavity segment 7 was prepared using three-dimensional weaving technology, such as Figure 6 The image shows a double-layer interlocking woven prefabricated body, which can be formed in one step by a three-dimensional weaving machine. It includes segmented, alternating, and continuously distributed connecting sections 6 and cavity sections 7 along the length of the fabric. The cavity area 8 of the prefabricated body should contain enough cavities to accommodate the cured rigid plate.

[0046] (3): The flexible guide rigid plate 9 is encapsulated within the three-dimensional woven prefabricated body 11 and connected to the flexible guide rigid plate 9 using a sewing process with sewing yarn 10, such as... Figure 7 and Figure 8 As shown, firstly, the flexible guide three-dimensional woven rigid plate 9 is inserted into the cavity region 8 of the three-dimensional woven preform. Then, the sewing process is used to pass the sewing yarn 10 through the through hole 5 on the three-dimensional woven preform 11 and the flexible guide rigid plate 9 to achieve the connection between the flexible guide rigid plate 9 and the three-dimensional woven preform 11. At the same time, the carbon cloth 12 is cut according to the cross-sectional size of the cavity region 8 of the three-dimensional woven preform, and the sewing yarn 10 is used to sew the carbon cloth 12 to the side of the cavity region (8) of the three-dimensional woven preform to achieve the encapsulation of the flexible guide three-dimensional woven rigid plate 9.

[0047] (4): A foldable composite material board 13 is obtained by impregnating the entire board with a flexible resin, such as polyurethane, and then insulating and curing it. The actual folding process is as follows: Figure 9 As shown in the figure, the foldable composite material plate 13 includes two foldable and deformable flexible parts 14 and three rigid parts 15 for bearing loads. The structural form of the composite material plate 13 can be adjusted by changing the folding angle of the flexible parts 14.

[0048] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A foldable composite material sheet, characterized in that, The system includes several rigid plates and a flexible plate prefabricated body for housing the rigid plates. The flexible plate prefabricated body includes a cavity section and a connecting section connecting two adjacent cavity sections. The rigid plate includes a flexible guide three-dimensional woven prefabricated body woven into a square shape and a rigid resin for curing the flexible guide three-dimensional woven prefabricated body. The cavity section is sewn and fixed to the rigid plate. The flexible guide three-dimensional woven prefabricated body has N empty holes without Z-axis yarns, where N>2. Through holes are drilled along the N empty holes without Z-axis yarns and the hole walls are ground to serve as channels for introducing the sewing yarn during sewing.

2. The foldable composite material sheet as described in claim 1, characterized in that, The flexible panel prefabricated body is a double-layer corner interlocking woven prefabricated body.

3. The foldable composite material sheet as described in claim 1, characterized in that, Rigid and flexible prefabricated panels are encapsulated in flexible resin through impregnation.

4. A method for forming a foldable composite material sheet, characterized in that, Includes the following steps: (1) Obtaining a rigid plate: First, a dense flexible directional three-dimensional woven preform is woven using a three-dimensional weaving process, and then the flexible directional three-dimensional woven preform is encapsulated and cured with rigid resin. (2) Prepare a three-dimensional woven flexible preform including a connecting section and a cavity section, wherein the connecting section is integrally woven between two cavity sections, and the cavity section is a structure woven with fabric on both sides surrounding the middle cavity; (3) The rigid plate is encapsulated in the cavity of the cavity section and the rigid plate is fixed in the flexible plate preform by stitching process; the rigid plate encapsulation method in step (3) is to use fabric and stitching thread to wrap and sew the two sides of the cavity together to ensure that the rigid plate is sealed in the three-dimensional woven preform. (4) A foldable composite material sheet is obtained by impregnating and curing a rigid plate and a flexible plate preform with flexible resin.

5. The forming method according to claim 4, characterized in that, In step (1), the flexible guided three-dimensional woven prefabricated body should reserve N empty holes without Z-axis yarns during the weaving process, and polish the surface of the component after it is solidified. Where N>2.

6. The forming method according to claim 5, characterized in that, After the flexible guided three-dimensional woven prefabricated body described in step (1) is cured and polished, through holes are drilled along the N empty holes where no Z-axis yarn is implanted, and the hole walls are ground to serve as channels for introducing the sewing yarn during subsequent sewing, for sewing and fixing the rigid plate and the three-dimensional woven prefabricated body; the radius of the drilled holes satisfies the following relationship: ， ， In the formula, r is the radius of the drilled hole; L is the width of the hole in the flexible guide prefabricated body; θ is the geometric shape change coefficient of the width of the hole in the guide prefabricated body before and after the component is cured; h is the thickness of the flexible guide three-dimensional woven rigid plate; and α is the angle between the center line of the drill bit and the center line of the drilled hole.

7. The forming method according to claim 6, characterized in that, In step (2), the three-dimensional woven flexible prefabricated body has a segmented and continuous distribution of connecting sections and cavity sections along the fabric length direction, and the cavity section of the prefabricated body contains a cavity that accommodates a solidified rigid plate.

8. A composite material sheet produced by the molding method according to any one of claims 4 to 7.

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