Composite material rapid melting interface microstructure and design method thereof

Abstract

The invention belongs to the technical field of composite material rapid melting interface design and manufacturing, and particularly relates to a composite material rapid melting interface microstructure and a design method thereof.The composite material rapid melting interface microstructure comprises a planar film microstructure, and a plurality of through holes are formed in the planar film microstructure; a plurality of through holes are arranged in an array, the distance between every two adjacent through holes is equal, a plurality of micro-supporting structures are arranged in the circumferential direction of the through holes, the micro-supporting structures are perpendicular to the planar thin film microstructure, and the micro-supporting structures are symmetrically arranged on the upper side and the lower side of the planar thin film microstructure respectively. According to the self-designed net-shaped planar microstructure, good contact between the microstructure and the composite material is promoted in the forming process, the surface of the composite material is completely wetted, a more uniform interface is formed, no pore area exists, and therefore the forming quality of the composite material structure is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of design and manufacturing of composite material rapid melting interfaces, and in particular relates to a composite material rapid melting interface microstructure and a design method thereof. Background Art

[0002] Advanced composite materials (CFRP) with carbon fiber as reinforcing fiber have been widely used in aerospace, energy industry, automobile, sports and many other fields due to their good dimensional stability, high specific strength, good corrosion resistance and fatigue fracture resistance. In recent years, the development of composite material integrated molding technology has been particularly rapid, but in some major engineering fields such as aerospace, the demand for composite material connection technology continues to exist, and new connection technologies continue to optimize factors such as improving the overall strength of the structure, cost savings and lightweight. Therefore, it also fully reflects the necessity of developing composite material manufacturing technology. At present, composite material connection manufacturing technology is mainly divided into three methods: mechanical connection, adhesive bonding and fusion connection molding. Among them, mechanical connection is the earliest and most mature connection method, which has been widely used in aerospace, but because CFRP has a special network structure, when making bolt holes, it will cut and destroy the internal carbon fiber, reducing the fiber continuity. Due to the interruption of force conduction, a new critical destructive force value will be generated when loading, thereby reducing the bearing capacity of the system. The adhesive bonding process has also developed rapidly. Both mechanical connection and mechanical connection are suitable for thermoplastic and thermosetting matrices. Adhesive bonding can effectively reduce the weight of the structure, while reducing manufacturing costs and improving damage tolerance. However, the process may introduce foreign materials, which may risk contaminating the interface and add additional weight to the joint.

[0003] Melt connection molding refers to heating the resin at the interface to a viscous state, allowing the resin matrix to diffuse with each other, and cooling to form a connection joint. Its molding process does not require flux and external heating, has little damage to the composite material, has a short molding time (generally less than 1s), has high structural strength and small residual strain, and is easy to automate. It is considered to be one of the most promising connection molding technologies for advanced composite materials. During the melt molding process of composite materials, a resin-based microstructure needs to be placed at the connection interface, which is usually used to increase energy transfer, shorten molding time, and reduce edge stress concentration. This microstructure is a resin protrusion or an artificial protrusion on the surface of the composite material. Due to the presence of the microstructure, friction heat can be preferentially generated on the resin surface at the connection interface, and viscoelastic heat is generated between molecular chains due to friction. Therefore, the resin-based microstructure has an important influence on the interface bonding and mechanical properties of the connection molding.

[0004] At present, extensive studies have shown that different microstructure shapes have a significant impact on the temperature of the welding interface. Triangular and semicircular structures can achieve higher interface temperatures, but due to the asymmetric structure, they can also cause local overheating or local cold welding at the interface. The planar structure may remain in part of the weld in the form of an original film due to insufficient melting, which significantly reduces the welding strength and leads to uneven welds. In order to improve the structural strength of composite materials, a more adaptable structural design is required, while meeting the rigid requirements of simplicity, effectiveness, ease of implementation, and process feasibility. Summary of the invention

[0005] The purpose of the present invention is to provide a composite material rapid melting interface microstructure and a design method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above-mentioned purpose, the present invention provides a composite material rapid melting interface microstructure, including a planar film microstructure, wherein a plurality of through holes are opened on the planar film microstructure, wherein the plurality of through holes are arranged in an array, and the distance between two adjacent through holes is equal, and a plurality of micro-support structures are arranged along the circumference of the through holes, wherein the micro-support structures are arranged perpendicular to the planar film microstructure, and the plurality of micro-support structures are symmetrically arranged on the upper and lower sides of the planar film microstructure.

[0007] Preferably, the through hole is a circular hole or a regular polygonal hole.

[0008] Preferably, the plurality of through holes are arranged in a rectangular array, and four adjacent through holes are arranged at equal intervals along the circumference of the micro-support structure.

[0009] Preferably, when the through hole is a regular polygonal hole, a plurality of the micro-support structures are respectively arranged at the vertices of the regular polygonal hole.

[0010] Preferably, when the through hole is a circular hole, a plurality of the micro-support structures are arranged at equal intervals along the circumference of the through hole.

[0011] Preferably, the micro-support structure is one of a hemispherical micro-structure, a regular pyramidal micro-structure or a regular prism-shaped micro-structure.

[0012] The present invention provides a method for designing a composite material rapid melting interface microstructure, comprising the following steps:

[0013] Step 1: Determine the outline size of the planar film microstructure according to the area of ​​the composite material molding interface and cut it;

[0014] Step 2, determining the hole shape of the through hole and opening the hole in the planar film microstructure;

[0015] Step 3: According to the hole shape of the through hole, the micro-support structure is fixed on the surface of the planar thin film micro-structure.

[0016] Preferably, before drilling holes on the planar film microstructure, the hole positions are determined and marked on the planar film microstructure; before fixing the micro-support structure on the planar film microstructure, the fixing position of the micro-support structure is determined and marked on the planar film microstructure.

[0017] Preferably, when the micro-support structure is fixedly connected to the planar thin film micro-structure, the large surface end of the micro-support structure is fixedly connected to the planar thin film micro-structure.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] 1. The fast melting interface microstructure of a composite material provided by the present invention takes advantage of various simple solid configuration microstructures, and has the advantages of fast melting and short welding time while maintaining high strength.

[0020] 2. The independently designed mesh planar microstructure of the present invention promotes good contact between the microstructure and the composite material during the molding process, completely wets the surface of the composite material, forms a more uniform interface without pore areas, and thus improves the molding quality of the composite material structure.

[0021] 3. The interface microstructure proposed by the present invention can realize the large-scale molding process of advanced composite materials. Under the pressure applied by the welding head, the more flexible microstructure will experience greater deformation, which will promote better contact with the composite material and thus improve the melting of the interface. In addition, the uniform deformation of the interface microstructure can bond the entire interface, thereby reducing the interface gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0023] Figure 1 A schematic diagram of a rapid melting interface microstructure of a composite material proposed by the present invention;

[0024] Figure 2 Schematic diagram of a regular pyramidal microstructure in the present invention;

[0025] Figure 3 It is a schematic diagram of the hemispherical microstructure in the present invention;

[0026] Figure 4Schematic diagram of a regular pyramidal microstructure in the present invention;

[0027] Figure 5 This is a schematic diagram of the microstructure of the rapid melting interface of the composite material in Example 3 of the present invention;

[0028] Wherein: 1. planar thin film microstructure; 2. micro support structure; 3. through hole; 101. hole; 201. connecting column; 202. mounting hole. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1:

[0032] Reference Figures 1 to 4 As shown, the present invention provides a composite material rapid melting interface microstructure, including a planar film microstructure 1, a plurality of through holes 3 are opened on the planar film microstructure 1, the plurality of through holes 3 are arranged in an array, and the distance between two adjacent through holes 3 is equal, and a plurality of micro-support structures 2 are arranged along the circumference of the through holes 3, the micro-support structures 2 are arranged perpendicular to the planar film microstructure 1, and the plurality of micro-support structures 2 are symmetrically arranged on the upper and lower sides of the planar film microstructure 1.

[0033] A mesh planar microstructure is formed by opening a plurality of through holes 3 in a planar thin film microstructure 1. In the present embodiment, the planar thin film microstructure has a thickness of 0.4 mm, the through holes 3 are square holes, the cutting length of the square holes is 17.8 mm, and the micro-support structure 2 is a regular tetrahedral microstructure. The regular tetrahedral microstructure is composed of triangular inclined planes with four inclination angles of 45°. The large end of the tetrahedral microstructure is a square with a side length of 4 mm. The height of the tetrahedral microstructure is 2 mm.

[0034] Furthermore, the through hole 3 is a circular hole or a regular polygonal hole.

[0035] Furthermore, a plurality of through holes 3 are arranged in a rectangular array, and four adjacent through holes 3 are arranged at equal intervals along the circumference of the micro-support structure 2 .

[0036] Furthermore, when the through hole 3 is a regular polygonal hole, a plurality of micro-support structures 2 are respectively arranged at the vertices of the regular polygonal hole.

[0037] Furthermore, when the through hole 3 is a circular hole, a plurality of micro-support structures 2 are arranged at equal intervals along the circumference of the through hole 3 .

[0038] Furthermore, the micro-support structure 2 is one of a hemispherical microstructure, a regular pyramidal microstructure or a regular prism-shaped microstructure.

[0039] Embodiment 2:

[0040] Reference Figures 1 to 4 As shown, the present invention provides a method for designing a composite material rapid melting interface microstructure, comprising the following steps:

[0041] Step 1: determining the outline size of the planar film microstructure 1 according to the area of ​​the composite material forming interface and cutting it;

[0042] Step 2, determining the hole shape of the through hole 3 and opening the hole in the planar thin film microstructure 1;

[0043] Step 3: According to the hole shape of the through hole 3 , the micro-support structure 2 is fixed on the surface of the planar thin film micro-structure 1 .

[0044] Furthermore, before opening a hole on the planar film microstructure 1, the hole position is determined and marked on the planar film microstructure 1; before fixing the micro-support structure 2 on the planar film microstructure 1, the fixing position of the micro-support structure 2 is determined and marked on the planar film microstructure 1.

[0045] Furthermore, when the micro-support structure 2 is fixedly connected to the planar thin film micro-structure 1 , the large surface end of the micro-support structure 2 is fixedly connected to the planar thin film micro-structure 1 .

[0046] In this embodiment, the micro-support structure 2 and the planar thin film micro-structure 1 can be fixedly connected by heating.

[0047] When the interface microstructure in the present invention is used, the interface microstructure is clamped between the interfaces of two objects to be connected. It should be noted that the edge contour of the interface microstructure coincides with the connection interface of the two objects and is pressed by auxiliary tooling. The main body of the interface microstructure in the present invention is a mesh structure, which is more flexible and can better fit the interface of the objects to be connected, especially solving the connection of interfaces with concave and convex curved surface features. After being pressed and fixed by auxiliary tooling, ultrasonic welding is used for welding. Since the micro-support structure 2 and the connection interface have less material and are easy to melt, the melted material liquid is quickly filled into the through hole 3 under the capillary action of the through hole 3. It should be noted that since the micro-support structure 2 is a symmetrical structure, it is evenly heated during the welding process, thereby achieving full melting and filling of the through hole 3. The volume and distribution number of the micro-support structure 2 are calculated according to the area of ​​the through hole 3, and then the entire interface microstructure melts to completely wet the surface of the composite material. Finally, wait for complete solidification and remove the object from the auxiliary tooling for inspection.

[0048] Embodiment three:

[0049] Reference Figure 5 As shown, the difference between this embodiment and the first to second embodiments is that a connecting column 201 is fixedly connected to the middle of the large surface end of one micro-support structure 2 to form an A-type micro-support structure; a mounting hole 202 compatible with the connecting column 201 is opened in the middle of the large surface end of the other micro-support structure 2 to form a B-type micro-support structure. The A-type micro-support structure and the B-type micro-support structure can be integrally formed by injection molding and used as standard parts of different sizes and specifications, thereby improving versatility and reducing processing costs. A hole 101 is opened at a position where a mark of the planar thin film microstructure 1 needs to be fixed. The aperture of the hole 101 is equal to the diameter of the connecting column 201. The connecting column 201 passes through the hole 101 at one end away from the micro-support structure 2 and transitions with the mounting hole 202 to achieve fixed connection between the A-type micro-support structure and the B-type micro-support structure, and the planar thin film microstructure 1 is clamped between the A-type support structure and the B-type support structure, thereby eliminating the process of heating and fixing the connection, thereby improving the consistency and reliability of the connection between the A-type micro-support structure and the B-type micro-support structure on the planar thin film microstructure 1, saving time and reducing costs.

[0050] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] The above embodiments are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A composite material rapid melting interface microstructure, characterized in that: The invention comprises a planar thin film microstructure (1), wherein a plurality of through holes (3) are provided on the planar thin film microstructure (1), wherein the plurality of through holes (3) are arranged in an array, and the distance between two adjacent through holes (3) is equal, and a plurality of micro-support structures (2) are arranged along the circumference of the through holes (3), wherein the micro-support structures (2) are arranged perpendicular to the planar thin film microstructure (1), and the plurality of micro-support structures (2) are symmetrically arranged on the upper and lower sides of the planar thin film microstructure (1).

2. The composite material rapid melting interface microstructure according to claim 1, characterized in that: The through hole (3) is a circular hole or a regular polygonal hole.

3. The composite material rapid melting interface microstructure according to claim 1, characterized in that: A plurality of the through holes (3) are arranged in a rectangular array, and four adjacent through holes (3) are arranged at equal intervals along the circumference of the micro-support structure (2).

4. The composite material rapid melting interface microstructure according to claim 2, characterized in that: When the through hole (3) is a regular polygonal hole, a plurality of the micro-support structures (2) are respectively arranged at the vertices of the regular polygonal hole.

5. The composite material rapid melting interface microstructure according to claim 2, characterized in that: When the through hole (3) is a circular hole, a plurality of the micro-support structures (2) are arranged at equal intervals along the circumference of the through hole (3).

6. The composite material rapid melting interface microstructure according to claim 1, characterized in that: The micro-support structure (2) is one of a hemispherical micro-structure, a regular pyramidal micro-structure or a regular prism-shaped micro-structure.

7. A method for designing a composite material rapid melting interface microstructure according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: determining the outline size of the planar film microstructure (1) according to the area of ​​the composite material molding interface and cutting it; Step 2, determining the hole shape of the through hole (3) and opening the hole in the planar thin film microstructure (1); Step 3: According to the hole shape of the through hole (3), the micro-support structure (2) is fixed on the surface of the planar thin film micro-structure (1).

8. The method for designing a composite material rapid melting interface microstructure according to claim 7, characterized in that: Before opening a hole on the planar thin film microstructure (1), the hole opening position is determined and marked on the planar thin film microstructure (1); before fixing the micro-support structure (2) on the planar thin film microstructure (1), the fixing position of the micro-support structure (2) is determined and marked on the planar thin film microstructure (1).

9. The method for designing a composite material rapid melting interface microstructure according to claim 7, characterized in that: When the micro-support structure (2) is fixedly connected to the planar thin film micro-structure (1), the large surface end of the micro-support structure (2) is fixedly connected to the planar thin film micro-structure (1).

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