A negative poisson's ratio metamaterial structure with a biomimetic structure

Abstract

This invention belongs to the field of metamaterials technology, specifically a negative Poisson's ratio metamaterial structure with a biomimetic structure. The negative Poisson's ratio metamaterial structure includes at least one basic unit structure, which comprises an outer frame and supporting rods. The outer frame includes a first frame at the upper end and a second frame at the lower end. Four bent rods are fixedly connected between the first and second frames. The first frame consists of four first connecting rods, and the second frame consists of four second connecting rods. Both the first and second frames are made of negative Poisson's ratio metamaterials, and the supporting rods are made of biomimetic glass sponge material. The mechanical metamaterial of this invention is a cubic structure composed of multiple basic unit structures arranged in an orderly manner. The negative Poisson's ratio mechanical metamaterial can be customized by changing the ratio of its thickness to its side length. The biomimetic mechanical metamaterial exhibits a layered fracture mechanism with transverse fracture, a high elastic modulus, and multi-segment energy absorption characteristics.

Description

Technical Field

[0001] This invention belongs to the field of metamaterials technology, specifically a negative Poisson's ratio metamaterial structure with a biomimetic structure. Background Technology

[0002] Mechanical metamaterials, also known as mechanical metamaterials, refer to metamaterials with special mechanical properties composed of artificially designed microscopic physical structures. Mechanical metamaterials are typically composed of periodically arranged unit structures and can significantly improve the mechanical properties of the original material. Among them, negative Poisson's ratio metamaterials, as a type of mechanical metamaterial, exhibit tensile properties different from traditional positive Poisson's ratio structures. When a negative Poisson's ratio material is compressed under axial force, it exhibits lateral tensile properties. These negative Poisson's ratio metamaterials can improve the lateral and vertical load-bearing capacity of materials. Compared with traditional materials, negative Poisson's ratio metamaterials possess superior fracture resistance, impact resistance, energy absorption capacity, and vibration isolation performance.

[0003] Biological structures, due to their unique mechanical properties, often provide inspiration for the design of high-performance mechanical structures. Incorporating some functions or characteristics of biological organisms into new materials, devices, and structures can enhance the toughness of existing designs. The toughening properties of biomimetic structures make them widely used in energy absorption systems, such as aircraft wings and defensive armor, in aerospace and military fields. Glass sponges, formed by a unique periodic arrangement of intersecting and non-intersecting units, possess complex geometries and excellent mechanical properties, such as lightweight, high strength, and energy absorption characteristics.

[0004] Currently, there are not many studies on biomimetic mechanical metamaterials, and even fewer studies on the influence of biomimetic structures on the mechanical properties and energy absorption characteristics of mechanical metamaterials. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, this invention proposes a negative Poisson's ratio metamaterial structure with a biomimetic structure.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A biomimetic negative Poisson's ratio metamaterial structure, characterized in that the negative Poisson's ratio metamaterial structure includes at least one basic unit structure, the basic unit structure including an outer frame and a support rod;

[0008] The outer frame has the following structure: the upper end of the outer frame consists of a first frame composed of four first connecting rods, and the lower end of the outer frame consists of a second frame composed of four second connecting rods. The first and second frames have the same shape and size. Four bent rods are fixedly connected between the first and second frames. The connection position of the bent rods to the first frame is the junction of two adjacent first connecting rods of the first frame. The connection position of the bent rods to the second frame is the junction of two adjacent first connecting rods of the second frame. A support rod is disposed between adjacent first connecting rods and bent rods, and both ends of the support rod are fixedly connected to the side ends of the first connecting rods and the bent rods, respectively. The support rod is disposed between adjacent second connecting rods and bent rods, and both ends of the support rod are fixedly connected to the side ends of the second connecting rods and the bent rods, respectively.

[0009] Furthermore, the first connecting rod and the second connecting rod have the same shape and the same length.

[0010] Furthermore, the length of both the first connecting rod and the second connecting rod is 8mm, and the width and thickness of both the first connecting rod and the second connecting rod are 0.5mm.

[0011] Furthermore, the bending angle at the bend of the bending rod is 120°.

[0012] Furthermore, the first connecting rod, the second connecting rod, and the bending rod are all made of Ti6Al4V (64 titanium), a negative Poisson's ratio metamaterial with a density of 4.5 g / cm3f, a Young's modulus of 110000 MPa, and a Poisson's ratio of 0.3.

[0013] Furthermore, the support rod is made of biomimetic glass sponge material.

[0014] Furthermore, the biomimetic negative Poisson's ratio metamaterial structure is a cubic structure composed of multiple basic unit structures arranged in an orderly manner.

[0015] A method for preparing a biomimetic negative Poisson's ratio metamaterial structure is as follows: it is manufactured using a laser selective melting method.

[0016] The beneficial effects of this invention are:

[0017] The mechanical metamaterial in this invention is a cubic structure composed of multiple mechanical metamaterial units arranged in an orderly manner. The mechanical properties of the negative Poisson's ratio mechanical metamaterial can be customized by changing the ratio of thickness to side length. The biomimetic mechanical metamaterial combines the characteristics of the glass sponge biomimetic prototype and the negative Poisson's ratio structure, namely, the layered fracture mechanism of transverse fracture, high elastic modulus, and multi-segment energy absorption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the basic unit structure of the present invention;

[0019] Figure 2 This is a front view of the basic unit structure of the present invention;

[0020] Figure 3 This is a structural diagram of the mechanical metamaterial of the present invention;

[0021] Figure 4 A comparison of stress-strain curves of mechanical metamaterials and ordinary negative Poisson's ratio structures under quasi-static compression;

[0022] Figure 5 This is a comparison of the energy absorption-strain curves of mechanical metamaterials and ordinary negative Poisson's ratio structures under quasi-static compression.

[0023] Reference numerals in the attached drawings: 1. Outer frame; 2. Support rod; 3. First connecting rod; 4. First frame; 5. Second connecting rod; 6. Second frame; 7. Bending rod. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The present invention will be further described below with reference to embodiments and comparative examples.

[0026] A biomimetic negative Poisson's ratio metamaterial structure, the negative Poisson's ratio metamaterial structure includes at least one basic unit structure, the basic unit structure includes an outer frame 1 and a support rod 2;

[0027] The structure of the outer frame 1 is as follows: the upper end of the outer frame 1 is a first frame 4 composed of four first connecting rods 3, and the lower end of the outer frame 1 is a second frame 6 composed of four second connecting rods. The first frame 4 and the second frame 6 have the same shape and size. Four bent rods 7 are fixedly connected between the first frame 4 and the second frame 6. The connection position of the bent rods 7 and the first frame 4 is the junction of two adjacent first connecting rods 3 of the first frame 4. The connection position of the bent rods 7 and the second frame 6 is the junction of two adjacent first connecting rods 3 of the second frame 6. The support rod 2 is arranged between adjacent first connecting rods 3 and bent rods 7. The two ends of the support rod 2 are fixedly connected to the side ends of the first connecting rods 3 and the bent rods 7, respectively. The support rod 2 is arranged between adjacent second connecting rods 5 and bent rods 7. The two ends of the support rod 2 are fixedly connected to the side ends of the second connecting rods 5 and the bent rods 7, respectively.

[0028] The first connecting rod 3 and the second connecting rod 5 have the same shape and the same length.

[0029] The length of the first connecting rod 3 and the second connecting rod 5 is 8mm, and the width and thickness of the first connecting rod 3 and the second connecting rod 5 are both 0.5mm.

[0030] The bending angle at the bend of the bending rod 7 is 120°.

[0031] The first connecting rod 3, the second connecting rod 5, and the bending rod 7 are all made of Ti6Al4V (64 titanium), a metamaterial with a density of 4.5 g / cm3f, a Young's modulus of 110000 MPa, and a Poisson's ratio of 0.3, which is a negative Poisson's ratio metamaterial. Negative Poisson's ratio structures are often used in environments requiring energy absorption, such as impact and compression. This is because negative Poisson's ratio structures have tensile properties different from positive Poisson's ratio structures, exhibiting multiple plateau regions under pressure, thus improving energy absorption performance. The negative Poisson's ratio metamaterial with a biomimetic structure proposed in this invention improves the strength of the original negative Poisson's ratio structure while having multiple plateau periods.

[0032] The support rod 2 is made of biomimetic glass sponge material. Compared with other common structures, the biomimetic glass sponge structure has stronger compressive performance, elastic modulus, yield strength, and energy absorption. Its unique heterogeneous units enhance the internal connectivity of the negative Poisson's ratio structure frame and reinforce the diagonal of the negative Poisson's ratio structure frame. Both the heterogeneous structure of the biomimetic glass sponge and the negative Poisson's ratio frame exhibit a layer-by-layer fracture mechanism, protecting the internal and overall structural integrity of the metamaterial during quasi-static compression.

[0033] The biomimetic negative Poisson's ratio metamaterial structure is a cubic structure composed of multiple basic unit structures arranged in an orderly manner.

[0034] A method for preparing a biomimetic negative Poisson's ratio metamaterial structure is as follows: it is manufactured using a laser selective melting method.

[0035] Preferably, the connecting rod is made of biomimetic glass sponge material. Compared with other common structures, the biomimetic glass sponge structure has stronger compressive performance, elastic modulus, yield strength, and energy absorption. Its unique heterogeneous units enhance the internal connectivity of the negative Poisson's ratio structure frame and reinforce the diagonal of the negative Poisson's ratio structure frame. Both the heterogeneous structure of the biomimetic glass sponge and the negative Poisson's ratio structure frame exhibit a layer-by-layer fracture mechanism, protecting the internal and overall structural integrity of the metamaterial during quasi-static compression.

[0036] Example 1

[0037] Quasi-static compression simulation of a negative Poisson's ratio metamaterial with a biomimetic structure was performed using the CAE module of the finite element simulation software Abaqus, and the stress-strain curves were obtained, such as... Figure 4 As shown, from Figure 5 It can be seen that compared with the ordinary negative Poisson's ratio structure, the stress and elastic modulus are significantly improved, and it also has multiple stress plateau regions, with the same number of plateau regions. Furthermore, based on the stress-strain curves, the elastic modulus of the mechanical metamaterial is calculated to be 0.38 GPa, while that of the ordinary negative Poisson's ratio structure is 0.06 GPa. The plateau stress of the mechanical metamaterial is 3.63 MPa, while that of the ordinary negative Poisson's ratio structure is 1.06 MPa. Both the plateau stress and elastic modulus are improved compared to the ordinary negative Poisson's ratio structure, thereby enhancing the structure's energy absorption capacity.

[0038] Example 2

[0039] The specific absorbed energy is calculated based on the integral area of ​​the stress-strain curve, such as... Figure 5 As shown in the figure, the specific absorption energy of the mechanical metamaterial is 0.023 MJ / mm², which can be seen from the comparison of the specific absorption energy of the biomimetic metamaterial and the ordinary negative Poisson's ratio structure. 3 The specific absorption energy of a typical negative Poisson's ratio structure is 0.006 MJ / mm². 3 Compared with ordinary negative Poisson's ratio structures, mechanical metamaterials with biomimetic structures have significantly increased the energy absorbed per unit area.

[0040] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A negative Poisson's ratio metamaterial structure with a biomimetic structure, characterized in that, The negative Poisson's ratio metamaterial structure includes at least one basic unit structure, which includes an outer frame (1) and a support rod (2); The structure of the outer frame (1) is as follows: the upper end of the outer frame (1) is a first frame (4) composed of four first connecting rods (3), and the lower end of the outer frame (1) is a second frame (6) composed of four second connecting rods (5). The first frame (4) and the second frame (6) have the same shape and are equal in size. Four bent rods (7) are fixedly connected between the first frame (4) and the second frame (6). The connection position of the bent rods (7) and the first frame (4) is the junction of two adjacent first connecting rods (3) of the first frame (4). At the junction of the bending rod (7) and the second frame (6), the connection position of the bending rod (7) and the second frame (6) is the junction of the two adjacent first connecting rods (3). The support rod (2) is set between the adjacent first connecting rod (3) and the bending rod (7). The two ends of the support rod (2) are fixedly connected to the side ends of the first connecting rod (3) and the bending rod (7) respectively. The support rod (2) is set between the adjacent second connecting rod (5) and the bending rod (7). The two ends of the support rod (2) are fixedly connected to the side ends of the second connecting rod (5) and the bending rod (7) respectively.

2. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The first connecting rod (3) and the second connecting rod (5) have the same shape and the same length.

3. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The length of the first connecting rod (3) and the second connecting rod (5) is 8mm, and the width and thickness of the first connecting rod (3) and the second connecting rod (5) are both 0.5mm.

4. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The bending angle at the bend of the bending rod (7) is 120°.

5. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The first connecting rod (3), the second connecting rod (5), and the bending rod (7) are all made of Ti6Al4V (64 titanium), a negative Poisson's ratio metamaterial with a density of 4.5 g / cm3f, a Young's modulus of 110000 MPa, and a Poisson's ratio of 0.

3.

6. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The support rod (2) is made of biomimetic glass sponge material.

7. The negative Poisson's ratio metamaterial structure with a biomimetic structure according to claim 1, characterized in that, The biomimetic negative Poisson's ratio metamaterial structure is a cubic structure composed of multiple basic unit structures arranged in an orderly manner.

8. A negative Poisson's ratio metamaterial structure with a biomimetic structure as described in any one of claims 1-7, characterized in that, The method for preparing the biomimetic negative Poisson's ratio metamaterial structure is as follows: it is manufactured using a laser selective melting method.

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