Fabricated negative Poisson's ratio structure based on mortise and tenon connection and assembling method of fabricated negative Poisson's ratio structure

Abstract

The invention relates to the technical field of metamaterials or superstructures, in particular to an assembly type negative Poisson's ratio structure based on mortise and tenon connection and an assembly method thereof, the assembly type negative Poisson's ratio structure is composed of a plurality of annular parts and plate-shaped parts, and tenons of the plate-shaped parts and mortises of the annular parts are mutually embedded. According to the structure disclosed by the invention, under the condition that an additional connecting means is not needed, stable connection is formed by mutual embedding of the mortise and the tenon, and the limitation that a traditional integrated negative Poisson's ratio structure depends on a 3D printing process is overcome. Due to the high assembling freedom degree, expansion in any direction in a plane can be achieved, and assembling can be conducted according to actual requirements in engineering. The modularized part design can adapt to a traditional manufacturing process, the production cost and the maintenance cost of the structure are reduced, and large-batch production is achieved. The structure is suitable for engineering structures for protection, shock resistance and noise reduction.

Description

Technical Field

[0001] The invention relates to the field of metamaterials or metastructures, and in particular to an assembled negative Poisson's ratio structure based on mortise and tenon connection and an assembly method thereof. Background Art

[0002] Metamaterials or metastructures refer to materials whose microstructures are purposefully designed to achieve special functions. Since the concept of metamaterials was proposed, researchers from various countries have conducted extensive research on metamaterials. Metamaterials have gradually become an important branch of the field of new materials and new structures. The excellent performance of metamaterials makes them have broad application prospects in aerospace, biomedicine, civil engineering and other fields.

[0003] Negative Poisson's ratio structure is an important branch of metamaterials. This structure will expand laterally when stretched, so it is also called tensile structure. Compared with traditional honeycomb structure, negative Poisson's ratio structure has better energy absorption, impact resistance, shear resistance and shock absorption performance.

[0004] However, most of the research progress on negative Poisson's ratio structures remains at the theoretical and experimental stage. Although negative Poisson's ratio structures have broader application prospects than traditional honeycomb structures, very few can actually be used in actual engineering. On the one hand, the existing negative Poisson's ratio structures have complex configurations, and most of the reported negative Poisson's ratio structures are manufactured using 3D printing technology. On the other hand, the existing 3D printing technology is immature. The high manufacturing cost and unstable performance of 3D printing technology limit the large-scale application of negative Poisson's ratio structures.

[0005] Discretizing a one-piece structure into several parts is a common design method for engineering structures. The modular design method allows each component of the structure to remain independent, thereby achieving mass production. However, the connection points between parts are usually the weak points of the structure, and maintaining the connection points of the structure also requires a lot of resources.

[0006] The traditional mortise and tenon structure originated from the ancient Hemudu cultural site in China more than 7,000 years ago. The nodes in the ancient building structure rely on the mortise and tenon connection method, which can be used for a long time in the natural environment without much maintenance. The reliability and durability of the mortise and tenon connection method have been tested by history.

[0007] At present, the negative Poisson's ratio structure is mainly an integrated structure. Considering its production, processing, transportation and maintenance and other factors, the existing integrated negative Poisson's ratio structure is difficult to meet the existing engineering needs. Summary of the invention

[0008] In view of the current problem that negative Poisson's ratio structures are difficult to produce and difficult to achieve large-scale application, the present invention provides an assembled negative Poisson's ratio structure based on mortise and tenon connection and an assembly method thereof, combining the mortise and tenon structure with the negative Poisson's ratio structure, using metal as raw material, producing parts through cutting and stamping processes, and then assembling to form a structure. The structure proposed by the present invention has a high degree of freedom in assembly, can freely expand the size of the structure according to actual conditions, effectively solves the problem of difficulty in large-scale production and application of negative Poisson's ratio structures, and the modular design can effectively improve production efficiency and reduce manufacturing and transportation costs.

[0009] The present invention achieves the above-mentioned object through the following technical scheme: an assembled negative Poisson's ratio structure based on mortise and tenon connection, which is composed of a plurality of annular parts and plate-like parts, wherein a trapezoidal mortise groove is provided at the annular ring of the annular part, a tenon is provided at the end of the plate-like part, the tenon of the plate-like part is embedded in the mortise groove of the annular part, the annular part is embedded in the other end of the plate-like part, and the plate-like parts are arranged in an annular array along the mortise groove provided on the annular part, and the negative Poisson's ratio structure is formed according to this assembly rule;

[0010] When the structure is subjected to tension or compression, the plate-like parts will bend and deform, and the plate-like parts will drive the annular parts to rotate clockwise or counterclockwise. Under the rotation of the annular parts, the plate-like parts will stretch or shrink along the direction of rotation of the annular parts. Under this action, the structure will expand or shrink in a direction perpendicular to the load, thereby achieving a negative Poisson's ratio effect.

[0011] The annular part has 6 tenons in total, and the spacing between the tenons is 60 degrees.

[0012] The middle part of the plate-like part is provided with two bends, the tenon size of the plate-like part is smaller than the tenon groove size of the annular part, and the thicknesses of the two parts are the same.

[0013] The radius R of the annular part is between 15 times the thickness T1 and 60 times the thickness T1, that is, 15T1>R>60T1, wherein the thickness T1 of the annular part 1 is the same as the thickness T2 of the plate-like part 2, and the mortise and tenon spacing θ of the annular part 1 satisfies: θ=60°, the mortise and tenon is a trapezoid, wherein the short side dimension A satisfies: A>2.5T2, and the long side dimension B satisfies: B>2A.

[0014] The tenon of the plate-like part is an equilateral triangle, the side length C of which satisfies: C≤B, and the angles β of the two bends in the middle section satisfy: 90°<β<180°.

[0015] The assembly method of the assembled negative Poisson's ratio structure based on mortise and tenon joints comprises the following steps:

[0016] (1) Insert the tenon at one end of the plate-like part into the tenon groove of the ring-like part. The front side of the plate-like part should be on the same plane as the front side of the ring-like part to ensure that the tenon is fully inserted into the tenon groove. Use this method to fill the remaining tenons of the ring-like part.

[0017] (2) Based on step (1), the tenon at the other end of the plate-like part is inserted into the tenon groove of the next ring-like part. When the tenon and the tenon groove are completely engaged, the assembled parts will present a hexagonal component with the center of the ring-like part as the corner point;

[0018] (3) Based on step (2), the plate-like part is embedded into the remaining tenon groove of the annular part, and the above three steps are repeated to fit the plate-like part and the annular part together until the entire assembly is completed.

[0019] The principle of the present invention is:

[0020] The modular design idea is adopted to discretize the traditional complex negative Poisson's ratio structure into several simple parts, and the parts are connected by mortise and tenon joints. The mortise and tenon joint connection method can reduce the assembly complexity of the structure and does not require additional connection means.

[0021] When the assembled negative Poisson's ratio structure is stretched or compressed, the plate-like part will bend and deform. The plate-like part drives the ring-like part to rotate clockwise or counterclockwise. Under the rotation of the ring-like part, the plate-like part will stretch or shrink in the direction of the ring-like part's rotation. Under this action, the structure will expand or shrink in the direction perpendicular to the load.

[0022] The present invention has the following beneficial effects over the existing technology:

[0023] The proposed prefabricated negative Poisson's ratio structure based on mortise and tenon joints will expand / contract in the direction perpendicular to the load under uniaxial tension / compression. Compared with the performance of the traditional one-piece structure, the proposed prefabricated structure retains all the characteristics and mechanical properties of the traditional structure.

[0024] 2. The modular assembly design method is combined with the design method of the traditional negative Poisson's ratio structure, and the modularization of the traditional negative Poisson's ratio structure is realized based on the mortise and tenon connection method. Compared with the traditional integrated structure, the modular design can better adapt to the traditional manufacturing method, thereby achieving low-cost and large-scale production.

[0025] The structure proposed in 3 has good energy absorption characteristics and can be applied to protective facilities. In addition, the modular design adopted by the present invention can effectively reduce the maintenance cost of the structure.

[0026] 4 The proposed structure has a wide range of controllable mechanical properties and can be adjusted according to the needs of actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the annular part 1 of the assembled negative Poisson's ratio structure based on mortise and tenon connection according to the present invention.

[0028] Figure 2 It is a schematic structural diagram of a plate-like part 2 of an assembled negative Poisson's ratio structure based on mortise and tenon connection according to the present invention.

[0029] Figure 3 It is a schematic diagram of the assembly of the assembled negative Poisson's ratio structure based on mortise and tenon connection described in the present invention.

[0030] Figure 4 This is the quasi-static compression deformation process of the assembled negative Poisson's ratio structure based on mortise and tenon connection described in the present invention.

[0031] Figure 5 The present invention discloses a dynamic impact deformation process of the assembled negative Poisson's ratio structure based on mortise and tenon connection.

[0032] Figure 6 It is a force-displacement curve diagram of quasi-static compression and dynamic impact of the assembled negative Poisson's ratio structure based on mortise and tenon connection described in the present invention. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, the assembled negative Poisson's ratio structure based on mortise and tenon connection described in the present invention is composed of a plurality of annular parts 1 and plate-like parts 2. The annular part 1 is provided with a trapezoidal mortise and tenon groove at the circular ring, and the end of the plate-like part 2 is provided with a tenon. The tenon of the plate-like part 2 is embedded in the mortise and tenon groove of the annular part 1, and the annular part 1 is embedded in the other end of the plate-like part 2. The plate-like parts 1 are arranged in a circular array along the mortise and tenon grooves provided on the annular part 2, and the negative Poisson's ratio structure is formed according to this assembly rule.

[0036] The annular part 1 has a total of 6 tenons, and the spacing between the tenons is 60°.

[0037] The middle part of the plate-like part 2 is provided with two bends, the tenon size of the plate-like part 2 is smaller than the tenon groove size of the annular part 1, and the thickness of the two parts is the same.

[0038] The radius R of the annular part is between 15 times the thickness T1 and 60 times the thickness T1, that is, 15T1>R>60T1, wherein the thickness T1 of the annular part 1 is the same as the thickness T2 of the plate-like part 2, and the mortise and tenon spacing θ of the annular part 1 satisfies: θ=60°, the mortise and tenon is a trapezoid, wherein the short side dimension A satisfies: A>2.5T2, and the long side dimension B satisfies: B>2A.

[0039] The tenon of the plate-like part 2 is an equilateral triangle, the side length C of which satisfies: C≤B, and the angles β of the two bends in the middle section satisfy: 90°<β<180°.

[0040] Example 2

[0041] The assembly method of the assembled negative Poisson's ratio structure based on mortise and tenon joints of the present invention comprises the following steps:

[0042] (1)Reference Figure 3 , insert the tenon at one end of the plate-like part 1 into the tenon groove of the ring-like part 2, and the front of the plate-like part 1 should be on the same plane as the front of the ring-like part 2 to ensure that the tenon is fully inserted into the tenon groove. In this way, fill the remaining tenons of the ring-like part 2.

[0043] (2) Based on step (1), the tenon at the other end of the plate-like part 1 is inserted into the tenon groove of the next ring-like part 2. When the tenon and the tenon groove are completely engaged, the assembled parts will present a hexagonal component with the center of the ring-like part 2 as the corner point.

[0044] (3) Based on step (2), the plate-like part 1 is embedded into the remaining tenon groove of the ring-like part 2. Repeat the above three steps to fit the plate-like part 1 and the ring-like part 2 together. No other connection means are required during the installation process. In addition, the structure has a high degree of assembly freedom. The parts can be assembled according to the pre-designed pattern according to the actual engineering requirements.

[0045] Figure 1 and Figure 2 The mutually nested tenons and tenons formed by the annular part 1 and the plate-like part 2 are shown.

[0046] Figure 3 The figure shows the assembly method of the various parts of the present invention and their positional relationship.

[0047] Figure 4 and Figure 5The responses of the present invention under quasi-static compression and low-speed impact are shown respectively. The present invention exhibits the characteristics of negative Poisson's ratio during the deformation process. During the compression process, the connection at the center of the structure rotates, and the plate connected to the central node will shrink under its rotation. In addition, there are obvious two-stage deformation characteristics during the compression process. The first stage is the overall contraction of the structure, and the second stage is the deformation of the central node after the structure is compacted. Most importantly, during the entire deformation process, the tenon and the mortise always maintain a tight connection.

[0048] Figure 6 The force-displacement curve of the present invention under quasi-static compression and dynamic impact is shown. It can be seen from the quasi-static force-displacement curve that the force of the structure of the present invention can be maintained in a stable range for a long time during the compression process. The area enclosed by the force-displacement is the energy absorbed by the overall structure. The result of the quasi-static compression force-displacement curve shows that the structure of the present invention can absorb energy smoothly. Unlike the quasi-static compression force-displacement curve, the dynamic impact force-displacement curve has certain fluctuations.

[0049] The quasi-static compression and dynamic impact simulations of the examples of the present invention were performed by ABAQUS software. The material of the finite element simulation only used the Q345 steel plate commonly used in engineering as an example. The simulation analysis results show that the Poisson's ratio of the structure is -0.73 and the elastic modulus is 960.71MPa.

[0050] The above-described example is only one solution of the present invention and is not intended to limit the design of the present invention. The present invention may be subjected to various changes and modifications according to actual needs without departing from the design principle of the present invention.

Claims

1. An assembled negative Poisson's ratio structure based on mortise and tenon joints, characterized in that: It is composed of a plurality of annular parts and plate-like parts. The annular part is provided with a trapezoidal tenon groove at the circular ring, and the end of the plate-like part is provided with a tenon. The tenon of the plate-like part is embedded in the tenon groove of the annular part. The annular part is embedded in the other end of the plate-like part. The plate-like parts are arranged in an annular array along the tenon groove provided by the annular part. According to this assembly rule, a negative Poisson's ratio structure is formed. When the structure is subjected to tension or compression, the plate-like parts will bend and deform, and the plate-like parts will drive the annular parts to rotate clockwise or counterclockwise. Under the rotation of the annular parts, the plate-like parts will stretch or shrink along the direction of rotation of the annular parts. Under this action, the structure will expand or shrink in a direction perpendicular to the load, thereby achieving a negative Poisson's ratio effect.

2. The assembled negative Poisson's ratio structure based on mortise and tenon joints according to claim 1 is characterized in that: The annular part has 6 tenons in total, and the spacing between the tenons is 60 degrees.

3. The assembled negative Poisson's ratio structure based on mortise and tenon joints according to claim 1 is characterized in that: The middle part of the plate-like part is provided with two bends, the tenon size of the plate-like part is smaller than the tenon groove size of the annular part, and the thicknesses of the two parts are the same.

4. The assembled negative Poisson's ratio structure based on mortise and tenon joints according to claim 1 is characterized in that: The radius R of the annular part is between 15 times the thickness T1 and 60 times the thickness T1, that is, 15T1>R>60T1, wherein the thickness T1 of the annular part is the same as the thickness T2 of the plate-shaped part, and the mortise and tenon spacing θ of the annular part satisfies: θ=60°, the mortise and tenon is trapezoidal, wherein the short side dimension A satisfies: A>2.5T2, and the long side dimension B satisfies: B>2A.

5. The assembled negative Poisson's ratio structure based on mortise and tenon joints according to claim 1 is characterized in that: The tenon of the plate-like part is an equilateral triangle, the side length C of which satisfies: C≤B, and the angles β of the two bends in the middle section satisfy: 90°<β<180°.

6. The method for assembling a prefabricated negative Poisson's ratio structure based on mortise and tenon joints according to claim 1, characterized in that: The steps include: (1) Insert the tenon at one end of the plate-like part into the tenon groove of the ring-like part. The front side of the plate-like part should be on the same plane as the front side of the ring-like part to ensure that the tenon is fully inserted into the tenon groove. Use this method to fill the remaining tenons of the ring-like part. (2) Based on step (1), the tenon at the other end of the plate-like part is inserted into the tenon groove of the next ring-like part. When the tenon and the tenon groove are completely engaged, the assembled parts will present a hexagonal component with the center of the ring-like part as the corner point; (3) Based on step (2), the plate-like part is embedded into the remaining tenon groove of the annular part, and the above three steps are repeated to fit the plate-like part and the annular part together until the entire assembly is completed.

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