Composite material bidirectional self-locking structure design and preparation method

Abstract

The invention relates to a design and preparation method of a bidirectional self-locking structure of a composite material. The bidirectional self-locking structure is formed by interlocking a plurality of unit cell structures; the unit cell structure is formed by six basic units which are perpendicular to one another and form a concave interlocking area through twice axial symmetry in sequence, and expansibility of the whole structure is guaranteed. The whole structure is formed by interlocking a plurality of unit cell structures, and the unit cell structures cannot fall off due to interlocking among cell elements when the tensile and compressive loads are borne. The structure is prepared by adopting a fiber reinforced composite material mold hot press molding process, the mold is divided into four parts, after the mold is assembled, prepreg is wound and vulcanized according to requirements, a unit cell structure can be prepared, and the unit cell structure is subjected to interlocking assembly to form a bidirectional self-locking structure. In addition, unit cell structures with different wall thicknesses and different characteristics can be prepared by adjusting gaps and sizes of mold components.

Description

Technical Field

[0001] The invention belongs to the technical field of material processing structures, and in particular relates to a composite material bidirectional self-locking structure design and a preparation method. Background Art

[0002] The cells of the self-locking structure can be interlocked with adjacent cells without additional constraints. Compared with the traditional sandwich structure, it has the characteristics of good expandability, convenient assembly, and replaceable after damage. However, the common self-locking structure can only achieve self-locking performance in a single direction. When the other directions are subjected to loads, the basic units of the structure will sputter in all directions, which not only cannot play the role of bearing and impact resistance and energy absorption, but also cause secondary damage due to the sputtering of the structure. The present invention proposes a design and preparation method of a bidirectional self-locking structure of a composite material. Different from the traditional self-locking structure, the bidirectional self-locking structure proposed in the present invention has excellent symmetry performance, can achieve all-round interlocking within the plane, and when loaded outside the plane, the self-locking within the plane can also be effectively extended to the outside of the plane, which can give full play to the self-locking design. In addition, the present invention proposes that the self-locking structure is prepared by the fiber-reinforced composite material compression molding process, which gives full play to the characteristics of light weight and high strength of the composite material. Summary of the invention

[0003] In order to overcome the shortcoming that the traditional self-locking structure has the self-locking performance in only one direction and has better mechanical properties in the field of load-bearing and impact resistance, the present invention designs a bidirectional self-locking structure and provides a preparation method thereof.

[0004] The present invention provides a basic unit of a composite material bidirectional self-locking structure, which is composed of six plates of the same length and thickness. The first plate, the third plate and the fifth plate are arranged vertically, and the second plate, the fourth plate and the sixth plate are arranged horizontally. The long side of the upper end of the first plate is in contact with the long side of the left side of the second plate, the long side of the right side of the second plate is in contact with the long side of the upper end of the third plate, the long side of the lower end of the third plate is in contact with the long side of the right side of the fourth plate, the long side of the left side of the fourth plate is in contact with the long side of the upper end of the fifth plate, and the long side of the lower end of the fifth plate is in contact with the long side of the left side of the sixth plate. The width of the six plates is l 1 ,l 2 ,l 3 ,l 4 ,l 5 ,l 6 And the thickness t satisfies:

[0005] l 2 = l 6 , l 3 = l 5 , l 1 >l 3 +l 5 +t,l 2 >l 4 +t.

[0006] The present invention also provides a unit cell composed of basic units of a composite material bidirectional self-locking structure. The unit cell structure as a whole is a rectangular structure with concave locking areas on upper and lower sides. The basic unit as a whole is first symmetrical about the horizontal plane where the lower end of the first plate is located, and then symmetrical about the vertical plane where the right end of the sixth plate is located.

[0007] The present invention further provides a bidirectional self-locking structure composed of a composite material bidirectional self-locking structure unit cell, which is formed by multiple unit cell structures through interlocking, and the four corners of the unit cell structure are respectively embedded in the interlocking areas of other unit cell structures to form self-locking.

[0008] The present invention further provides a mold for preparing a composite material bidirectional self-locking structure unit cell, the mold comprising four plates A, B, C, and D; the A plate is an L-shaped structure, the B plate is a rectangular parallelepiped structure, the C plate is a rectangular parallelepiped structure with a protruding platform in the middle, and the D plate is a rectangular parallelepiped structure with protruding platforms on both sides; the A, B, C, and D plates are combined to form a top component, a bottom component, and a filling component; the top component and the bottom component include the D plate; the filling component includes the B plate and the A plate located around the B plate; the C plate is arranged in the area formed by the A and B plates, and the C plate is located on the left and right sides of the B plate; the filling component is arranged on the non-protruding platform of the D plate; the mold as a whole is symmetrical about the horizontal plane of the C plate; gaps are provided between the A, B, C, and D plates, and the gap width is the thickness of the plate constituting the unit cell structure.

[0009] Furthermore, the number of the A plates is four, the number of the B plates is one, the number of the C plates is two, and the number of the D plates is two.

[0010] Furthermore, the A section: A1 = l 1 -2t,l A2 = l 3 +l 5 -t,l A3 = l 4 , l A4 = l 3 -2t; where l A1 is the height of plate A, l A2 is the width of plate A, l A3 is the height of the protruding platform of plate A, l A4 is the width of the protruding platform of plate A;

[0011] The B section: l B1 =2×(l 2 +l 6 -l 4 ), l B2=2×l 1 -2t; where l B1 is the width of the rectangular block of plate B, l B2 is the height of the cuboid of plate B;

[0012] The C plate: l C1 = l 5 -2t,l C2 =2×(l 6 -t), l C3 =2l 1 +l 3 , l C4 = l 4 ; Among them, l C1 is the height of the rectangular parallelepiped of plate C, l C2 is the width of the rectangular parallelepiped of plate C, l C3 is the height of the protruding platform of plate C, l C4 It is the width of the platform that does not protrude on one side of the C plate;

[0013] The D plate: l D1 =2l 1 , l D2 = l 2 , l D3 =2l 1 , l D4 =2l 2 ; Among them, l D1 is the width of the platform where the D plate does not protrude, l D2 is the height of the protruding platform of plate D, l D3 is the width of the protruding platform of plate D, l D4 is the height of the D plate cuboid and the protruding platform.

[0014] Furthermore, the lengths of the A, B, C, and D plates are equal and greater than the length of the plate in the unit cell structure.

[0015] Furthermore, the C plate and the D plate in the mold are provided with through holes for positioning by positioning pins.

[0016] The present invention further provides a method for preparing a composite bidirectional self-locking structure, comprising the following steps:

[0017] Step 1: Make a unit cell mold according to the size of the basic unit;

[0018] Step 2: Select fiber-reinforced composite material prepreg as raw material, cut the prepreg according to the unit cell structure size, and lay the layers at a set angle. When laying the prepreg, each layer needs to be laid in an offset manner to form a prepreg laminate;

[0019] Step 3: The mold is heated and coated with a release agent, the prepreg laminate is wrapped around the mold, and then the mold is heated and shaped;

[0020] Step 4: After vulcanization is completed, wait for the mold to cool naturally, remove the mold and trim the residual edge of the self-locking structure to obtain a unit cell structure;

[0021] Step 5: Multiple unit cell structures are assembled through the interlocking region to form a bidirectional self-locking structure.

[0022] Furthermore, in step 3, the heating and shaping is performed by pressurizing a vulcanizer, the pressure of the vulcanizer is set to 1 MPa, the temperature is first set to 90° C., and after heating for 30 minutes, the temperature is raised to 120° C. and the heating time is 90 minutes.

[0023] The beneficial effects of the present invention are:

[0024] 1. The overall structure of the bidirectional self-locking device of the present invention is formed by assembling a number of unit cell structures through interlocking areas. When subjected to tensile and compressive loads, the interlocking between the cells prevents the structure from falling off, thus achieving a self-locking effect.

[0025] 2. The present invention overcomes the disadvantage of the traditional structure of self-locking in a single direction, and realizes the self-locking of the structure in all directions within the plane through the design of the inner concave lock, and can also be freely expanded in the out-of-plane direction. In addition, combined with the light weight and high strength characteristics of fiber-reinforced composite materials, the structure is prepared by the compression molding process, so that the structure has more excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a bidirectional self-locking structure of a composite material according to the present invention and a coordinate schematic diagram, wherein 1 is a unit cell structure;

[0027] Figure 2 A schematic diagram of the unit cell structure dimensions and local coordinate system marking of a composite bidirectional self-locking structure according to the present invention;

[0028] Figure 3 It is a schematic diagram of the process of assembling a composite bidirectional self-locking structure unit cell structure into a self-locking structure according to the present invention;

[0029] Figure 4 A schematic diagram of preparing mold parts and assembling a composite bidirectional self-locking structure according to the present invention;

[0030] Figure 5 A schematic diagram of the dimensions of mold parts for preparing a composite material bidirectional self-locking structure according to the present invention;

[0031] Figure 6 This is a schematic diagram of the preparation, assembly and vulcanization preparation of a composite material bidirectional self-locking structure described in the present invention. DETAILED DESCRIPTION

[0032] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0034] The invention discloses a composite material bidirectional self-locking structure such as Figure 1 As shown, it contains several unit cell structures such as Figure 2 As shown in the figure, the unit cell structure is formed by two axial symmetry steps of the basic unit. The basic unit consists of six plates that are perpendicular to each other and form an interlocking region. The concave interlocking region in the unit cell structure is embedded in the concave interlocking region of other unit cells, such as Figure 3 After assembly, a bidirectional self-locking structure is formed.

[0035] The unit cell structure is first 1 Not with l 2 The connected side is symmetrical about the XZ plane, and then 6 Not with l 5 The connected side is symmetrical about the YZ plane (or first 6 Not with l 5 The connected side is symmetrical about YZ, and then 1 Not with l 2 The adjacent sides are symmetrical about the XZ plane).

[0036] Unit cell structure 3 = l 5 , l 2 = l 6 , l 1 > 3 +l 5 +t,l 2 > 4 +t, L length is not limited and can be designed according to actual working conditions, and the wall thickness of the unit cell structure is consistent at all locations.

[0037] Establish a local coordinate system for the basic structure. Take the global coordinate system as the reference. Rotate from the positive direction of the X axis to the positive direction of the Y axis. The angle is positive. Rotate from the positive direction of the Y axis to the negative direction of the X axis. The angle is positive. 1 The angle between the positive direction of the X axis and the positive direction of the X axis is 90°. 2 The angle with the positive direction of the Y axis is -90°, 3The angle with the positive direction of the X axis is -90°, 4 The angle between the positive direction of the Y axis and the positive direction of the Y axis is 90°. 5 The angle with the positive direction of the X axis is -90°, 6 The angle with the positive direction of the Y axis is 90°.

[0038] The unit cell structure is made of fiber reinforced composite material wrapped around a mold by hot pressing. Figure 4 , 5 As shown, the mold consists of four parts with a total of 9 parts, including four parts A, one part B, two parts C, and two parts D. The size of part A in the mold meets l A1 = l 1 -2t,l A2 = l 3 +l 5 -t,l A3 = l 4 , l A4 = l 3 -2t. The size of part B in the mold meets l B1 =2×(l 2 +l 6 -l 4 ), l B2 =2×l 1 -2t. The size of the C part in the mold meets l C1 = l 5 -2t,l C2 =2×(l 6 -t), l C3 =2l 1 +l 3 , l C4 = l 4 The D dimension of the part in the mold meets l D1 =2l 1 , l D2 = l 2 , l D3 =2l 1 , l D4 =2l 2 Mold part C and mold part D should have through holes so that they can be positioned with locating pins. The position of the through holes should comply with the basic principles of mechanical design. The dimensions of all parts in the mold in the Z direction must be consistent and greater than L.

[0039] A composite bidirectional self-locking structure is composed of a plurality of identical unit cell structures, wherein the unit cell structure is formed by two-axis symmetry of the basic unit. Therefore, the preparation method of the composite bidirectional self-locking structure is as follows:

[0040] (1) Determine the length of each side of the basic unit according to the requirements;

[0041] (2) Making a unit cell structure mold according to the size of the basic unit;

[0042] (3) Select appropriate prepreg and cut the prepreg into corresponding sizes according to the unit cell size and the preset prepreg laying angle;

[0043] (4) Laying the laminate on the heating table. It is worth noting that the winding method is used to prepare the unit cell structure. Therefore, when laying the prepreg, each layer needs to be laid in an offset manner to avoid discontinuous fiber concentration on the same side and reduce defects in the finished product.

[0044] (5) The mold is evenly coated with a release agent and placed in an oven for preheating at 40°C. After the mold is fully preheated, it is taken out and wrapped with the laid prepreg. Components C and D in the mold are then positioned and fixed with positioning pins.

[0045] (6) Place the mold in a vulcanizer and heat to set the mold. Figure 6 As shown; the pressure setting of the vulcanizer is adjusted according to the size of the sample. In the embodiment, the pressure is set to 1MPa, the temperature is first set to 90°C, the heating time is 30 minutes, then the temperature is raised to 120°C, the heating time is 90 minutes, and then the heating is stopped and the mold is allowed to cool naturally;

[0046] (7) After cooling, disassemble each component in turn and maintain the mold for next use. Cut and polish the sample as needed;

[0047] (8) Prepare multiple samples and assemble them. The size of the bidirectional self-locking structure can be assembled according to the needs by calculating the required unit bodies in each row and column.

[0048] The composite bidirectional self-locking structure described in the present invention is composed of a plurality of interlocking unit cell structures. When subjected to tensile and compressive loads, the interlocking between the units prevents the unit cell structure from falling off. When subjected to out-of-plane loads, the in-plane self-locking can also be effectively extended to the outside of the plane, which can give full play to the self-locking design. The present invention combines the excellent properties of light weight and high strength of fiber-reinforced composite materials, and is prepared by a mold hot pressing molding process. By adjusting the mold gap and size, structures with different wall thicknesses and different properties can be prepared.

[0049] The above contents are only preferred implementation cases of the present invention. For technicians in this technical field, according to the concept of the present invention, there may be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. A composite bidirectional self-locking structural basic unit, characterized in that: It is composed of six plates of the same length and thickness. The first plate, the third plate and the fifth plate are arranged vertically, and the second plate, the fourth plate and the sixth plate are arranged horizontally. The upper long side of the first plate is in contact with the left long side of the second plate, the right long side of the second plate is in contact with the upper long side of the third plate, the lower long side of the third plate is in contact with the right long side of the fourth plate, the left long side of the fourth plate is in contact with the upper long side of the fifth plate, and the lower long side of the fifth plate is in contact with the left long side of the sixth plate. The widths l1, l2, l3, l4, l5, l6 and thickness t of the six plates satisfy: l2=l6, l3=l5, l1>l3+l5+t, l2>l4+t.

2. A unit cell composed of the basic unit of the composite material bidirectional self-locking structure according to claim 1, characterized in that: The unit cell structure is a rectangular parallelepiped structure with upper and lower locking areas, and is formed by the basic unit being symmetrical about the horizontal plane where the lower end of the first plate is located, and then symmetrical about the vertical plane where the right end of the sixth plate is located.

3. A bidirectional self-locking structure composed of a bidirectional self-locking structure unit cell of the composite material according to claim 2, characterized in that: It is formed by multiple unit cell structures through interlocking, and the four corners of the unit cell structure are respectively embedded in the interlocking areas of other unit cell structures to form self-locking.

4. A mold for preparing the composite bidirectional self-locking structure unit cell according to claim 2, characterized in that: The mold includes four plates, A, B, C, and D; the A plate is an L-shaped structure, the B plate is a rectangular parallelepiped structure, the C plate is a rectangular parallelepiped structure with a protruding platform in the middle, and the D plate is a rectangular parallelepiped structure with protruding platforms on both sides; The four plates A, B, C and D are combined to form a top component, a bottom component and a filling component; the top component and the bottom component include the D plate; the filling component includes the B plate and the A plate located around the B plate; the C plate is arranged in the area formed by the A plate and the B plate, and the C plate is located on the left and right sides of the B plate; the filling component is arranged on the non-protruding platform of the D plate; the mold as a whole is symmetrical about the horizontal plane of the C plate; there is a gap between the four plates A, B, C and D, and the gap width is the thickness of the plate constituting the unit cell structure.

5. The mold of the composite material bidirectional self-locking structure unit cell according to claim 4, characterized in that: The number of the A plates is four, the number of the B plates is one, the number of the C plates is two, and the number of the D plates is two.

6. A composite material bidirectional self-locking structural unit cell mold according to claim 4, characterized in that: The A section: A1 =l1-2t,l A2 =l3+l5-t,l A3 =l4,l A4 =l3-2t; where l A1 is the height of plate A, l A2 is the width of plate A, l A3 is the height of the protruding platform of plate A, l A4 is the width of the protruding platform of plate A; The B section: l B1 =2×(l2+l6-l4), l B2 =2×l1-2t; where l B1 is the width of the rectangular block of plate B, l B2 is the height of the cuboid of plate B; The C plate: l C1 =l5-2t,l C2 =2×(l6-t), l C3 =2l1+l3,l C4 =l4; where l C1 is the height of the rectangular parallelepiped of plate C, l C2 is the width of the rectangular parallelepiped of plate C, l C3 is the height of the protruding platform of plate C, l C4 It is the width of the platform that does not protrude on one side of the C plate; The D plate: l D1 =2l1,l D2 =l2,l D3 =2l1,l D4 =2l2; where l D1 is the width of the platform where the D plate does not protrude, l D2 is the height of the protruding platform of plate D, l D3 is the width of the protruding platform of plate D, l D4 is the height of the D plate cuboid and the protruding platform.

7. The mold of a composite material bidirectional self-locking structure unit cell according to claim 4, characterized in that: The lengths of the A, B, C, and D plates are equal and greater than the length of the plate in the unit cell structure.

8. The mold of a composite material bidirectional self-locking structure unit cell according to claim 4, characterized in that: The C plate and the D plate in the mold are provided with through holes for positioning by positioning pins.

9. A method for preparing the composite bidirectional self-locking structure according to claim 3, characterized in that: The following steps are involved: Step 1: Make a unit cell mold according to the size of the basic unit; Step 2: Select fiber-reinforced composite material prepreg as raw material, cut the prepreg according to the unit cell structure size, and lay the layers at a set angle. When laying the prepreg, each layer needs to be laid in an offset manner to form a prepreg laminate; Step 3: The mold is heated and coated with a release agent, the prepreg laminate is wrapped around the mold, and then the mold is heated and shaped; Step 4: After vulcanization is completed, wait for the mold to cool naturally, remove the mold and trim the residual edge of the self-locking structure to obtain a unit cell structure; Step 5: Multiple unit cell structures are assembled through the interlocking region to form a bidirectional self-locking structure.

10. The method for preparing a composite material bidirectional self-locking structure according to claim 9, characterized in that: In step 3, the vulcanizer is used for heating and shaping, and the pressure of the vulcanizer is set to 1 MPa. The temperature is first set to 90° C., and after heating for 30 minutes, the temperature is raised to 120° C. and the heating time is 90 minutes.

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