Efficient energy-absorbing lattice mechanical metamaterial based on heterostructure optimization design and additive manufacturing

Abstract

The invention discloses an efficient energy-absorbing lattice mechanical metamaterial based on heterostructure optimization design and additive manufacturing. The efficient energy-absorbing lattice mechanical metamaterial comprises a plurality of lattice unit cell cuboids which are periodically and regularly arranged in a three-dimensional space and are connected with one another, the lattice unit cell cuboid comprises a first center connecting node, a second center connecting node, a first vertex node, a second vertex node, a third vertex node, a first connecting rod and a second connecting rod, and the first center connecting node is connected with the first vertex node and the second vertex node through the first connecting rod to form a cubic structure; the second center connecting node is connected with the second vertex node and the third vertex node through the second connecting rod to form a cuboid structure. According to the efficient energy-absorbing dot matrix mechanical metamaterial, the stress distribution of the BCC dot matrix metamaterial is optimized while the stress at the nodes of the dot matrix metamaterial is reduced, and the mechanical property of the BCC dot matrix metamaterial is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical metamaterials, and in particular to a high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing. Background Art

[0002] As a kind of porous material, lattice mechanical metamaterial has excellent properties such as high specific strength, high specific stiffness, light weight, and strong energy absorption. These properties make it show a wide range of application potential in aerospace, medical implants, heat transfer and vehicle collision avoidance. Therefore, the development of lattice mechanical metamaterials with high specific strength and strong energy absorption performance is not only of great research significance for improving its application efficiency in these fields, but also provides a new development direction for achieving high efficiency, low resource consumption and environmental protection goals of materials.

[0003] The deformation mode of traditional body-centered cubic (BCC) lattice mechanical metamaterials is bending-dominated. When subjected to compressive loads, the deformation is mainly concentrated in the bending of the rods at the nodes. In this deformation mode, since the rods are not unstable, the stress-strain curve of the structure shows an obvious "flat" stress platform, that is, after the yield point, the material can withstand large plastic deformation without a sharp increase in stress, achieving effective energy absorption and reducing secondary impact on the protected object. However, the material utilization efficiency of this structure is relatively low, such as Figure 1 and Figure 2 The uniform BCC lattice metamaterial shown has eight vertex nodes and one central node, and eight circular cross-section rods connect the eight vertex nodes and one central node respectively. The main reason is that the deformation is mainly concentrated in the node area, while the rods in other parts hardly participate in the stress transfer and deformation process. This "localized" deformation mode causes a large amount of material to fail to play its due role under load, resulting in unnecessary waste of resources. Especially in the design of efficient energy-absorbing metamaterials, how to effectively utilize the potential of all structural units has become an urgent problem to be solved. Summary of the invention

[0004] In order to overcome the problems existing in the existing uniform BCC lattice metamaterials, the present invention provides a high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing, which solves the above-mentioned traditional problems, improves its characteristics through structural innovation, thereby improving the utilization efficiency of various parts of the material, making the stress distribution of the material more uniform, and significantly improving the mechanical properties of the material.

[0005] The present invention is implemented by the following technical solutions: A high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing, including a plurality of lattice unit cell cuboids that are periodically arranged and interconnected in a three-dimensional space, the lattice unit cell cuboids including a first central connecting node, a second central connecting node, a plurality of first vertex nodes, a plurality of second vertex nodes, a plurality of third vertex nodes, a plurality of first connecting rods and a plurality of second connecting rods, the first central connecting node is respectively connected to the first vertex node and the second vertex node through the first connecting rod to form a cubic structure, and the second central connecting node is respectively connected to the second vertex node and the third vertex node through the second connecting rod to form a cuboid structure.

[0006] Preferably, the length of the rectangular parallelepiped structure is 1.5-3 times the length of the cubic structure.

[0007] Preferably, the length of the rectangular parallelepiped structure is twice the length of the cubic structure.

[0008] Preferably, the length of the second connecting rod is greater than the length of the first connecting rod.

[0009] Preferably, the length of the second connecting rod is 1.2-2 times the length of the first connecting rod.

[0010] Preferably, the length of the second connecting rod is 1.35-1.8 times the length of the first connecting rod.

[0011] Preferably, the first connecting rod and the second connecting rod are rods with circular cross-sections. Preferably, the diameter of the first connecting rod is equal to the diameter of the second connecting rod. Preferably, the lattice unit cell cuboids are arranged repeatedly in a regular pattern along the three directions of x, y and z, and the arranged lattice metamaterial unit cell cuboids are tightly connected and have spatial symmetry in the x and y directions.

[0012] Preferably, the highly efficient energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing is prepared by the following steps: Aluminum alloy is selected as the material, and laser powder bed melting technology is used to complete the processing and preparation of lattice metamaterials. The process parameters of the laser powder bed melting technology used are: slice layer thickness 30μm, laser power 330w, scanning speed 600mm / s, and scanning spacing 100μm.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing of the present invention forms a new rectangular unit cell by combining a cubic structure and a rectangular parallelepiped structure, which reduces the stress at the nodes of the lattice metamaterial and optimizes the stress distribution of the BCC lattice metamaterial, thereby significantly improving the mechanical properties of the BCC lattice metamaterial. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of a unit cell structure of a uniform BCC lattice metamaterial in the prior art; Figure 2 for Figure 1 Block schematic diagram of uniform BCC lattice metamaterial shown; Figure 3 A schematic diagram of a unit cell structure of a highly efficient energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing of the present invention; Figure 4 for Figure 3 Block diagram of a highly efficient energy-absorbing lattice mechanical metamaterial based on heterostructure optimization design and additive manufacturing is shown; Figure 5 Compressive stress-strain curves in the Z direction for uniform BCC and BCC lattice metamaterials optimized for heterogeneous structures.

[0015] In the figure: 10, first central connection node; 20, second central connection node; 30, first vertex node; 40, second vertex node; 50, third vertex node; 60, first connecting rod; 70, second connecting rod. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0017] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0018] In the description of the present invention, it should be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be intermediate elements at the same time. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0019] See also Figure 3 and Figure 4 , which is a highly efficient energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing in a preferred embodiment of the present invention, and which makes structural innovation on the basis of the traditional uniform lattice structure to improve its characteristics. Specifically, the highly efficient energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing includes a plurality of lattice unit cell cuboids that are periodically arranged and interconnected in a three-dimensional space, and the lattice unit cell cuboids include a first central connection node 10, a second central connection node 20, a plurality of first vertex nodes 30, a plurality of second vertex nodes 40, a plurality of third vertex nodes 50, a plurality of first connecting rods 60 and a plurality of second connecting rods 70, the first central connection node 10 is respectively connected to the first vertex node 30 and the second vertex node 40 through the first connecting rod 60 to form a cubic structure, and the second central connection node 20 is respectively connected to the second vertex node 40 and the third vertex node 50 through the second connecting rod 70 to form a cuboid structure.

[0020] In one embodiment, the length of the cuboid structure is 1.5-3 times the length of the cubic structure, preferably, the length of the cuboid structure is 2 times the length of the cubic structure, and the cubic unit cell in the existing uniform BCC lattice metamaterial is combined with the new cuboid unit cell to form a new cuboid unit cell while keeping the unit cell volume fraction unchanged. By merging three cubic unit cells in the uniform BCC lattice metamaterial into a new cuboid unit cell, the stress at the node of the lattice metamaterial is reduced, and the stress distribution of the BCC lattice metamaterial is optimized; through heterogeneous structure optimization, the three cubic unit cells in the uniform BCC lattice metamaterial are merged into a new cuboid unit cell and fused and arranged, which significantly improves the mechanical properties of the BCC lattice metamaterial.

[0021] In this embodiment, the cubic structure formed by the first central connecting node 10 and the first connecting rod 60, the first vertex node 30, and the second vertex node 40 is the original uniform BCC lattice metamaterial unit cell, and the rectangular structure formed by the second central connecting node 20, the second connecting rod 70, the second vertex node 40, and the third vertex node 50 is based on the original uniform BCC lattice metamaterial unit cell, and the angle between the connecting rod and the vertical line of the central connecting node is adjusted. It is connected through the second vertex node 40 and combined with the cubic structure to make the stress distribution of each part of the material more uniform, thereby improving the bearing capacity of the structure, wherein the length of the second connecting rod 70 is greater than the length of the first connecting rod 60. Preferably, the length of the second connecting rod 70 is 1.2-2 times the length of the first connecting rod 60. Preferably, the length of the second connecting rod 70 is 1.35-1.8 times the length of the first connecting rod 60.

[0022] In one embodiment, the first connecting rod 60 and the second connecting rod 70 are rods with circular cross-sections, and the diameter of the first connecting rod 60 is equal to the diameter of the second connecting rod 70 .

[0023] In this embodiment, each lattice unit cell cuboid is repeatedly arranged in a regular pattern along the x, y, and z directions. After the arrangement, the lattice metamaterial unit cell cuboids are tightly connected and have spatial symmetry in the x and y directions.

[0024] In order to avoid the size effect of a single BCC lattice metamaterial, the number of the uniform BCC lattice metamaterial unit cell cubes arranged along the x, y, and z directions in this embodiment is designed to be 9, and the size is designed to be 4×4×4mm 3 ; The number of BCC lattice metamaterial unit cell cuboids arranged in the x and y directions is designed to be 9, the number of z-direction arrangements is designed to be 3, and the size is designed to be 4×4×12mm 3 The sample preparation method is laser powder bed fusion (LPBF) technology, the sample preparation material is aluminum alloy, and the LPBF preparation process parameters are: the slice layer thickness is 30μm, the laser power is 330w, the scanning speed is 600mm / s, and the scanning spacing is 100μm.

[0025] The existing uniform BCC structure and the heterogeneous BCC structure of the present invention (the length of the rectangular parallelepiped structure is twice the length of the cubic structure, that is, the three cubic unit cells in the uniform BCC lattice metamaterial are merged into a new rectangular parallelepiped unit cell) are subjected to compression stress tests. The test results are as follows: Figure 5 The Z-direction compressive stress-strain curves of the uniform BCC and heterostructure-optimized BCC lattice metamaterials are shown in Figure 2. Figure 5 It can be seen that the BCC lattice metamaterials with optimized heterostructure can greatly improve the mechanical properties of the lattice metamaterials.

[0026] As a novel type of structural / material features, the heterostructure of the present invention is composed of heterogeneous regions with significantly different physical and chemical properties, and is characterized by significant differences in structure and performance between different domains. Compared with uniform structures, the design of heterostructures can achieve superior functions and mechanical properties. The optimized lattice metamaterials have achieved good results: (i) Compared with uniform BCC lattice metamaterials, the stress distribution of heterostructure-optimized BCC lattice metamaterials is more uniform; (ii) Compared with uniform BCC lattice metamaterials, the mechanical properties of heterostructure-optimized BCC lattice metamaterials are significantly improved.

[0027] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0028] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A highly efficient energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing, characterized in that: It includes a plurality of lattice unit cell cuboids which are periodically arranged and interconnected in a three-dimensional space, wherein the lattice unit cell cuboids include a first central connecting node, a second central connecting node, a plurality of first vertex nodes, a plurality of second vertex nodes, a plurality of third vertex nodes, a plurality of first connecting rods and a plurality of second connecting rods, wherein the first central connecting node is connected to the first vertex node and the second vertex node respectively through the first connecting rod to form a cubic structure, and the second central connecting node is connected to the second vertex node and the third vertex node respectively through the second connecting rod to form a cuboid structure.

2. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 1 is characterized in that: The length of the rectangular parallelepiped structure is 1.5-3 times the length of the cubic structure.

3. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 2 is characterized in that: The length of the rectangular parallelepiped structure is twice the length of the cubic structure.

4. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 1 is characterized in that: The length of the second connecting rod is greater than the length of the first connecting rod.

5. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 4 is characterized in that: The length of the second connecting rod is 1.2-2 times the length of the first connecting rod.

6. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 5 is characterized in that: The length of the second connecting rod is 1.35-1.5 times the length of the first connecting rod.

7. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 1 is characterized in that: The first connecting rod and the second connecting rod are rods with circular cross-sections.

8. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 7 is characterized in that: The diameter of the first connecting rod is equal to the diameter of the second connecting rod.

9. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 1, characterized in that: The lattice unit cell cuboids are respectively and repeatedly arranged in a regular pattern along the three directions of x, y and z. The arranged lattice metamaterial unit cell cuboids are closely connected and have spatial symmetry in the x and y directions.

10. The high-efficiency energy-absorbing lattice mechanical metamaterial based on heterogeneous structure optimization design and additive manufacturing according to claim 1, characterized in that: It is prepared by the following steps: Aluminum alloy is selected as the material, and laser powder bed melting technology is used to complete the processing and preparation of lattice metamaterials. The process parameters of the laser powder bed melting technology used are: slice layer thickness 30μm, laser power 330w, scanning speed 600mm / s, and scanning spacing 100μm.

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