A biomimetic titanium-based mechanical metamaterial and its preparation method

Abstract

This invention provides a biomimetic titanium-based mechanical metamaterial, comprising a lattice structure. The lattice structure includes multiple lattice unit cells arranged periodically and interconnected in three-dimensional space. Each lattice unit cell includes a central block and multiple connecting blocks. One end of each connecting block is connected to the central block. Each connecting block extends from the central block in a direction away from the central block, and the included angle between two adjacent connecting blocks is greater than 0. Each connecting block includes 3n prisms, where n ≥ 1. The 3n prisms are spaced apart around an axis extending from the connecting block, and the planes containing the 3n prisms intersect the axis. The titanium-based mechanical metamaterial provided in this application, with its lattice unit cell structure, enables the transfer of stress from the lattice structure to the center of the connecting blocks, reducing the stress at the nodes of the lattice structure.

Description

Technical Field

[0001] This invention relates to the field of mechanical metamaterials technology, and in particular to a titanium-based mechanical metamaterial based on biomimetic design and its preparation method. Background Technology

[0002] Lattice mechanical metamaterials are a type of man-made material with special properties. These materials achieve their theoretically predicted isotropic ultimate stiffness by designing their internal structure, such as the evolution of lattice unit cells, to reduce stress concentration within the structure. Lattice mechanical metamaterials are lightweight, multifunctional materials with high specific strength, high specific stiffness, and explosion-resistant energy absorption characteristics, showing broad application prospects in aerospace, medical implants, heat transfer, and vehicle collision avoidance. Therefore, developing lattice structures with high specific strength and strong energy absorption is of great significance.

[0003] Lattice structures include lattice unit cells, which can be divided into plate-like lattice unit cells and rod-like lattice unit cells. Multiple plate-like lattice unit cells arranged periodically in three-dimensional space form a plate-like lattice structure, and multiple rod-like lattice unit cells arranged periodically in three-dimensional space form a rod-like lattice structure. Plate-like lattice unit cells are generally cubic structures formed by stacking multiple plates. The plates have a large area, which can usually disperse stress and avoid stress concentration. However, multiple plates often form closed internal cavities within the lattice unit cell, leading to powder accumulation that cannot be removed after additive manufacturing. Furthermore, the plates occupy a significant amount of volume space. Under conditions of low lattice structure volume fraction (e.g., 15%), the mechanical properties of plate-like lattice unit cells will significantly decrease. Rod-like lattice structures do not have closed internal cavities, and their mechanical properties do not significantly decrease at low volume fractions. However, due to stress concentration at their node connections, the lattice structure may fail prematurely, resulting in a decrease in its mechanical properties. For example, the existing Chinese patent CN202010990661.9 invented a rounded lattice structure. The rounding of the rods reduces the stress concentration at the nodes of the BCC lattice. However, (i) the rounding of the rods changes the three-dimensional spatial symmetry of the original BCC lattice structure, resulting in more obvious anisotropy of the structural mechanical properties; (ii) the rod-shaped structural design still cannot eliminate the stress concentration at the nodes of the lattice structure. Summary of the Invention

[0004] To address the issue that existing rod-shaped lattice structures suffer from stress concentration at node connections when the volume fraction of the lattice structure is low, resulting in poor mechanical properties, this application provides a titanium-based mechanical metamaterial based on biomimetic design.

[0005] In a first aspect, the present invention provides a titanium-based mechanical metamaterial based on biomimetic design, comprising a lattice structure, wherein the lattice structure comprises a plurality of lattice unit cells arranged periodically and regularly in three-dimensional space and interconnected with each other, wherein the lattice unit cell comprises a central block and a plurality of connecting blocks, one end of the connecting block is connected to the central block, each connecting block extends from the central block in a direction away from the central block, and the included angle between two adjacent connecting blocks is greater than 0.

[0006] Each of the connecting blocks includes 3n prisms, where n ≥ 1. The 3n prisms are spaced apart around an axis extending from the connecting block, and the planes containing the 3n prisms intersect the axis.

[0007] Preferably, when n=1, the cross-section of the connecting block is Y-shaped, and the length of the long side of the cross-section of each rib is... The length of the shorter side of the cross-section of each prism is L is the edge length of the lattice unit cell;

[0008] The volume fraction V of the lattice structure satisfies relation 1:

[0009] Relation 1

[0010] Where 0 < A < 0.4, 0 < B < 0.7.

[0011] Preferably, 0 < V ≤ 90%.

[0012] Preferably, the included angle between any two adjacent prisms is the same.

[0013] Preferably, the lattice unit cell is a cubic structure, the central block is located at the body center of the cube, the connecting block extends from the central block to the vertex of the cube, and the end of the connecting block away from the central block abuts against the vertex of the cube;

[0014] One vertex of the cube is connected to three edges, and among the 3n edge plates, three edge plates are respectively attached to the three edges.

[0015] Preferably, the center block is the center point.

[0016] Preferably, the edge length of the lattice unit cell is L, and the contact length between the edge plate and the edge is [missing information]. .

[0017] Secondly, this application provides a method for preparing the above-mentioned biomimetic titanium-based mechanical metamaterial, comprising the following steps: using Ti6Al4V alloy as raw material and fabricating it using laser powder bed melting process;

[0018] In the laser powder bed melting process, the slice layer thickness is 30μm, the laser power is 230W, the scanning speed is 100mm / s, and the scanning interval is 1200μm.

[0019] The biomimetic titanium-based mechanical metamaterial provided in this application has the following effects: 1) Combining the characteristics of rod-shaped and plate-shaped lattice structures, the structure of the lattice unit cell allows the stress of the lattice structure to be transferred to the middle of the connecting block, reducing the stress at the nodes of the lattice structure; 2) The connecting block includes 3n prisms, which are spaced apart around an axis extending from the connecting block, and the planes of the 3n prisms intersect the axis. The included angle between two adjacent connecting blocks is greater than 0. The structure of the connecting block does not change the three-dimensional spatial symmetry of the lattice structure, making the stress distribution of the lattice structure more uniform and significantly improving the mechanical properties of the lattice structure; 3) The structure of the lattice unit cell allows the lattice structure to still obtain excellent mechanical properties at a low volume fraction (such as 15% and below). In addition, it increases the design freedom of the lattice structure and has no internal enclosed space, which helps to remove powder accumulation after additive manufacturing. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the BCC lattice unit cell in Comparative Example 1;

[0021] Figure 2 This is an exploded diagram of the BCC lattice unit cell in Comparative Example 1;

[0022] Figure 3 This is a schematic diagram of the lattice structure formed by the arrangement of BCC lattice unit cells in Comparative Example 1.

[0023] Figure 4 This is a schematic diagram of the lattice unit cell of the biomimetic titanium-based mechanical metamaterial with n=1 in Embodiment 1 of this application;

[0024] Figure 5 This is an exploded view of a lattice unit cell of a titanium-based mechanical metamaterial based on biomimetic design, as described in Embodiment 1 of this application.

[0025] Figure 6 This is a schematic diagram of the cross-sectional structure of the biomimetic titanium-based mechanical metamaterial-connector block in Embodiment 1 of this application;

[0026] Figure 7 This is a schematic diagram of the titanium-based mechanical metamaterial-lattice structure based on biomimetic design in Embodiment 1 of this application;

[0027] Figure 8 This is a graph showing the variation of parameters A and B of the titanium-based mechanical metamaterial lattice structure based on biomimetic design in Embodiment 1 of this application.

[0028] Figure 9These are schematic diagrams of the biomimetic titanium-based mechanical metamaterial-lattice structure in embodiments 1-3, 5, and 7 of this application;

[0029] Figure 10 These are the compressive stress-strain curves along the Z-direction of the lattice structure in Example 1 and the lattice structure in Comparative Example 1.

[0030] Figure 11 This is a cross-sectional view of the compressive Mises stress distribution along the Z-direction of a lattice unit cell in Comparative Example 1.

[0031] Figure 12 This is a cross-sectional view of the compressive Mises stress distribution along the Z-direction of a lattice unit cell in Example 1;

[0032] Figure 13 These are the Mises stress curves of the lattice unit cells along the rod direction for Example 1 and Comparative Example 1.

[0033] Figure 14 This is a schematic diagram of the lattice unit cell of the biomimetic titanium-based mechanical metamaterial with n=2 provided in this application.

[0034] 1. BCC lattice unit cell; 10. Connecting rod; 101. Round rod No. 1; 102. Round rod No. 2; 103. Round rod No. 3; 104. Round rod No. 4; 105. Round rod No. 5; 106. Round rod No. 6; 107. Round rod No. 7; 108. Round rod No. 8;

[0035] 2. Lattice unit cell; 20. Connector block; 21. Center block; 201. Connector block 1; 202. Connector block 2; 203. Connector block 3; 204. Connector block 4; 205. Connector block 5; 206. Connector block 6; 207. Connector block 7; 208. Connector block 8. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] To illustrate the technical solution of the present invention, specific embodiments are described below.

[0038] like Figure 4-14 As shown, this application provides a titanium-based mechanical metamaterial based on biomimetic design, comprising a lattice structure, wherein the lattice structure includes multiple lattice unit cells 2 arranged periodically and interconnected in three-dimensional space. Figure 7As shown, in three-dimensional space, four lattice unit cells 2 are arranged in the x-axis, y-axis and z-axis directions respectively. It can be understood that the number of lattice unit cells 2 arranged in the x-axis, y-axis and z-axis directions is not limited in this application. For the x-axis, y-axis and z-axis directions, the number of lattice unit cells 2 arranged in each direction can be equal or unequal.

[0039] The lattice unit cell 2 includes a central block 21 and a plurality of connecting blocks 20. One end of each connecting block 20 is connected to the central block 21. Each connecting block 20 extends from the central block 21 in a direction away from the central block 21, and the included angle between two adjacent connecting blocks 20 is greater than 0.

[0040] Specifically, the lattice unit cell 2 includes multiple connecting blocks 20, one end of which is connected to the central block 21. The connecting blocks 20 extend from the central block 21 in a direction away from it. For example, when the lattice unit cell 2 is a body-centered cubic, the end of the connecting block 20 away from the central block 21 extends to the vertex of the cube; when the lattice unit cell 2 is a face-centered cubic, some connecting blocks 20 extend to the vertex of the cube, while others extend to the face centers. Depending on the structure of the lattice unit cell 2, the direction and position of the extension of the end of the connecting block 20 away from the central block 21 vary.

[0041] Limiting the included angle between two adjacent connecting blocks 20 to be greater than 0 enables each connecting block 20 extending from the central block 21 to be connected to the vertex, edge, or face of the cube structure, thus supporting the lattice unit cell 2.

[0042] Each of the connecting blocks 20 includes 3n prisms, where n ≥ 1 and n is a positive integer. The 3n prisms are spaced apart around an axis extending from the connecting block 20, and the planes containing the 3n prisms intersect the axis.

[0043] Specifically, the connecting block 20 includes 3n prisms, which are spaced apart around an axis extending from the connecting block 20. The planes containing the 3n prisms intersect the axis, and the angle between two adjacent connecting blocks 20 is greater than 0. The lattice unit cell 2 combines the characteristics of rod-shaped and plate-shaped lattice structures. The structure of this lattice unit cell 2 is beneficial for transferring the stress of the lattice structure to the middle of the connecting block 20, reducing the stress at the nodes of the lattice structure. At the same time, the structure of the connecting block 20 does not change the three-dimensional spatial symmetry of the lattice structure, so that the mechanical properties of the lattice structure have three-dimensional spatial symmetry, making the stress distribution of the lattice structure more uniform and significantly improving the mechanical properties of the lattice structure.

[0044] like Figure 4 ,14 As shown, Figure 4 This is the lattice unit cell diagram corresponding to the structure of connecting block 20 when n=1. Figure 14 This is the lattice unit cell diagram corresponding to the structure of connecting block 20 when n=2. Specifically, the 3n prisms are spaced apart around an axis extending from the connecting block 20. This means that, with the axis extending from the connecting block 20 as the center, the sides of the 3n prisms intersect to form a central axis, and all prisms are spaced apart around this central axis. Each prism extends away from the central axis to form its width, and each prism extends to the central block 21 in a direction parallel to the central axis.

[0045] The biomimetic titanium-based mechanical metamaterial provided in this application has the following effects: 1) Combining the characteristics of rod-shaped and plate-shaped lattice structures, the structure of the lattice unit cell 2 enables the stress of the lattice structure to be transferred to the middle of the connecting block 20, reducing the stress at the nodes of the lattice structure; 2) The connecting block 20 includes 3n prisms, which are spaced apart around an axis extending from the connecting block 20, and the planes of the 3n prisms intersect the axis. The included angle between two adjacent connecting blocks 20 is greater than 0. The structure of the connecting block 20 does not change the three-dimensional spatial symmetry of the lattice structure, making the stress distribution of the lattice structure more uniform and significantly improving the mechanical properties of the lattice structure; 3) The structure of the lattice unit cell 2 allows the lattice structure to still obtain excellent mechanical properties at a low volume fraction (such as 15% and below). In addition, it increases the design freedom of the lattice structure and has no internal enclosed space, which helps to remove powder accumulation after additive manufacturing.

[0046] In some embodiments, when n=1, the cross-section of the connecting block 20 is Y-shaped, and the length of the long side of the cross-section of each rib is... The length of the shorter side of the cross-section of each prism is L is the edge length of lattice unit cell 2;

[0047] The volume fraction V of the lattice structure satisfies relation 1:

[0048] Relation 1

[0049] Where 0 < A < 0.4, 0 < B < 0.7.

[0050] Specifically, when n=1, the corresponding connecting block 20 has three prisms, such as... Figure 6 As shown, the cross-section of the connecting block 20 is Y-shaped.

[0051] like Figure 9As shown, this diagram illustrates a lattice structure block with different values ​​of parameters A and B. As parameter A increases, the length of the long side of the cross-section of each prism in the connecting block 20 gradually increases, and the lattice unit cell 2 tends to form a plate-shaped lattice unit cell 2, resulting in a plate-shaped lattice structure. Conversely, as parameter B increases, the length of the short side of the cross-section of each prism in the connecting block 20 gradually increases, and the lattice unit cell 2 tends to form a rod-shaped lattice unit cell 2, resulting in a rod-shaped lattice structure. Specifically, A can be 0.1, 0.15, 0.2, 0.25, 0.3, or 0.35, as long as the value of A is within the range of 0 < A < 0.4. Similarly, B can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, or 0.65, as long as the value of B is within the range of 0 < A < 0.7.

[0052] The volume fraction V of a lattice structure is an important parameter that directly affects the mechanical properties and functional characteristics of the lattice structure. The volume fraction V of a lattice structure refers to the proportion of the solid material volume in the total volume of the lattice structure.

[0053] Compared to rod-shaped lattice structures formed by simple rod-shaped lattice units or plate-shaped lattice units, the biomimetic titanium-based mechanical metamaterial provided in this application, when n=1, results in a lattice structure volume fraction V that satisfies Equation 1. As parameters A and B change, the corresponding lattice structure volume fraction V also changes, greatly expanding the design freedom of the lattice structure and effectively realizing the conversion between plate-shaped and rod-shaped lattice structures. The lattice structure can still obtain excellent mechanical properties at lower volume fractions (such as 15% and below). In addition, the improved design freedom of the lattice structure and the absence of internal enclosed spaces facilitate the removal of powder deposits after additive manufacturing, making it suitable for additive manufacturing technology.

[0054] It should be noted that when n=1, the volume fraction V of the lattice structure satisfies Equation 1, which has the following effects: the lattice structure can still obtain excellent mechanical properties at a low volume fraction (such as 15% and below). In addition, it improves the design freedom of the lattice structure and has no internal closed space, which facilitates the removal of powder accumulation after additive manufacturing and is suitable for additive manufacturing technology.

[0055] When n is greater than 1, such as Figure 14As shown, this is a diagram of a lattice unit cell 2 structure with n=2. The lattice unit cells 2 are periodically arranged and interconnected in three-dimensional space to form a lattice structure. Although the relationship satisfied by the volume fraction V of the lattice structure needs to be slightly modified accordingly, the resulting lattice structure still has excellent mechanical properties at a low volume fraction. In addition, it increases the design freedom of the lattice structure and has no internal closed space, which facilitates the removal of powder accumulation after additive manufacturing and is suitable for additive manufacturing technology.

[0056] In some embodiments, 0 < V ≤ 90%.

[0057] Specifically, the volume fraction V of the lattice structure refers to the proportion of the solid material volume in the lattice structure to the total volume. The biomimetic titanium-based mechanical metamaterial provided in this application combines the characteristics of rod-shaped and plate-shaped lattice structures, designing a connecting block 20 with a Y-shaped cross-section. Centered on a central block 21, the connecting block 20 extends from one end of the central block 21 in a direction away from it, with the included angle between two adjacent central blocks 21 greater than 0°. Each connecting block 20 includes 3n prisms, n≥1. The 3n prisms are spaced apart around an axis extending from the connecting block 20, and the planes containing the 3n prisms intersect the axis, forming a structure as shown in the image. Figure 4 , 14 The lattice unit cell 2 structure shown has a volume fraction V ranging from 0 to 90% when multiple lattice unit cells 2 are arranged in three-dimensional space. The lattice structure can still obtain excellent mechanical properties at a low volume fraction (such as 15% and below). It also improves the design freedom of the lattice structure and has no internal closed space, which helps to remove powder accumulation after additive manufacturing and is suitable for additive manufacturing technology.

[0058] In some embodiments, the included angle between any two adjacent prisms is the same.

[0059] Specifically, the connecting block 20 includes 3n prisms, with the same included angle between each pair of adjacent prisms. This facilitates the formation of a structure in which the two connecting blocks 20 are symmetrically arranged with respect to the body center of the cube, without altering the three-dimensional spatial symmetry of the lattice structure. This results in the mechanical properties of the lattice structure having three-dimensional spatial symmetry, while also making the stress distribution of the lattice structure more uniform, significantly improving the mechanical properties of the lattice structure.

[0060] In some preferred embodiments, when n=1, the cross-section of the connecting block 20 has formed Figure 6 The cross-sectional structure of the connecting block 20 is defined as the first prism, the second prism, and the third prism. Figure 6The cross-sectional structure is Y-shaped, and the cross-sections of the first, second, and third prisms are defined as the first cross-section prism, the second cross-section prism, and the third cross-section prism, respectively. Figure 6 In the figure, the included angle between the first cross-section prism plate and the second cross-section prism plate is 120°, the included angle between the first cross-section prism plate and the third cross-section prism plate is 120°, and the included angle between the second cross-section prism plate and the third cross-section prism plate is 120°.

[0061] In some embodiments, the lattice unit cell 2 is a cubic structure, the central block 21 is located at the body center of the cube, the connecting block 20 extends from the central block 21 toward the vertex of the cube, and the end of the connecting block 20 away from the central block 21 abuts against the vertex of the cube;

[0062] One vertex of the cube is connected to three edges, and among the 3n edge plates, three edge plates are respectively attached to the three edges.

[0063] Specifically, such as Figure 4 , 5 As shown, when the lattice unit cell 2 is a cube structure, the connecting block 20 extends from the central block 21 toward one of the vertices of the cube, and the end of the connecting block 20 away from the central block 21 abuts against one of the vertices of the cube; the cube has eight vertices, and the corresponding lattice unit cell 2 contains eight connecting blocks 20, each vertex abutting against a connecting block 20. The eight connecting blocks 20 extend from the vertices of the cube toward the body center of the cube and intersect at the body center of the cube, forming the central block 21.

[0064] Specifically, a vertex of the cube is connected to three edges, which are defined as the first edge, the second edge, and the third edge; among the 3n edge plates of the connecting block 20, there are at least three edge plates, and the three edge plates are respectively attached to the three edges, and the three edge plates attached to the three edge plates are respectively defined as the first edge plate, the second edge plate, and the third edge plate.

[0065] like Figure 5As shown, the end of the first prism away from the central block 21 is attached to the first edge, the end of the second prism away from the central block 21 is attached to the second edge, and the end of the third prism away from the central block 21 is attached to the third edge. When an external force is applied to the lattice structure, the structure of the first, second, and third prisms in a single lattice unit cell 2 can transfer the stress in the lattice structure to the middle of the first, second, and third prisms, reducing the stress at the nodes of the lattice structure and improving the mechanical properties of the lattice structure. The middle of the first prism refers to the position near the middle and the middle appendage between the central block 21 and the vertex; the middle of the second prism also refers to the position near the middle and the middle appendage between the central block 21 and the vertex; and the middle of the third prism also refers to the position near the middle and the middle appendage between the central block 21 and the vertex.

[0066] In some embodiments, the central block 21 is the center point.

[0067] like Figure 4 , 5 As shown, eight connecting blocks 20 extend from the vertices of the cube toward the center of the cube and intersect at the center of the cube, forming a central block 21. At this time, the central block 21 is the center of the cube and also the center point.

[0068] In some embodiments, two adjacent connecting blocks 20 are defined as a first connecting block and a second connecting block, respectively, and the end faces of two adjacent prisms in the first connecting block and the second connecting block are in contact with each other in the direction of the center point.

[0069] like Figure 4 , 5 As shown in Figure 7, in the direction towards the central block 21, the end faces of the two prisms of each adjacent first connecting block and second connecting block gradually come into contact with the central block 21 as they gradually approach the central block 21. This allows multiple connecting blocks 20 to be stably connected to form the central block 21, improving the stability of the central block 21 and enhancing the mechanical properties of the central node of the lattice structure.

[0070] In some embodiments, the edge length of the lattice unit cell 2 is L, and the contact length between the prism plate and the edge is [missing information]. .

[0071] Specifically, L is the edge length of the lattice unit cell 2. When the lattice unit cell 2 is a cubic structure, the corresponding L is the edge length of the cube. This application does not limit the length of the edge length L of the lattice unit cell 2, and lattice unit cells 2 with different edge lengths can be prepared according to actual needs.

[0072] Connecting block 20 includes 3n prisms, each prism having a long side length of its cross-section. Each connecting block 20 has three edges that fit into the three edges extending from a vertex of the cube, and the length of the fit is the length of the longer side of the corresponding edge's cross-section. .

[0073] In some embodiments, the connecting block 20 includes a first prism plate, a second prism plate, and a third prism plate, wherein the contact length between the first prism plate and the first edge is [missing information]. ;

[0074] The fitting length between the second prism plate and the second edge is ;

[0075] The fitting length between the third prism plate and the third edge is .

[0076] like Figure 5 As shown, the first edge plate fits snugly against the first edge of the cube, the second edge plate fits snugly against the second edge of the cube, and the third edge plate fits snugly against the third edge of the cube; the length of the fit is the length of the longer side of the edge plate's cross-section. The length of the longer side of the cross-section of the first prism plate. Then the corresponding fitting length between the first prism plate and the first edge is The fitting length between the second prism plate and the second edge is The fitting length between the third prism plate and the third edge is .

[0077] It should be noted that the range of A is 0 < A < 0.4. It is the result of multiplying the value of A by the value of L.

[0078] The range of B is 0 < B < 0.7. It is the result of multiplying the value of B by the value of L.

[0079] Secondly, this application provides a method for preparing a biomimetic titanium-based mechanical metamaterial, comprising the following steps: using Ti6Al4V alloy as raw material and fabricating it using a laser powder bed melting process;

[0080] In the laser powder bed melting process, the slice layer thickness is 30μm, the laser power is 230W, the scanning speed is 100mm / s, and the scanning interval is 1200μm.

[0081] Specifically, using Ti6Al4V alloy as raw material, laser powder bed melting technology is used to construct a three-dimensional lattice structure and prepare a biomimetic titanium-based mechanical metamaterial.

[0082] In the laser powder bed melting process, Ti6Al4V alloy powder particles are used as raw materials. The thickness of the slice layer is 30μm. The laser power is 230W, the scanning speed is 100mm / s, and the scanning spacing is set to 1200μm. The slice layer is scanned according to a predetermined path.

[0083] This application provides a method for preparing titanium-based mechanical metamaterials based on biomimetic design, which is simple and low in cost.

[0084] The present invention will be further illustrated by the following examples.

[0085] Example 1

[0086] This embodiment provides a biomimetic titanium-based mechanical metamaterial and its preparation method.

[0087] The preparation method of biomimetic titanium-based mechanical metamaterials includes the following steps:

[0088] The material is Ti6Al4V alloy, and the preparation method is laser powder bed melting (LPBF) technology. The LPBF preparation process parameters are selected as follows:

[0089] The slice thickness was 30 μm, the laser power was 230 W, the scanning speed was 100 mm / s, and the scanning interval was set to 1200 μm.

[0090] The structure of the prepared lattice unit cell 2 is as follows Figures 4-7 As shown, the lattice unit cell 2 is a body-centered cubic structure. The central block 21 is located at the body center of the cube. The cube has eight vertices, and the corresponding lattice unit cell 2 contains eight connecting blocks 20. Each vertex abuts against a connecting block 20. The connecting block 20 extends from one end of the central block 21 towards the vertex of the cube, such that the end of the connecting block 20 away from the central block 21 abuts against the vertex of the cube, and the other end of the connecting block 20 connects to the central block 21. The included angle between any two adjacent connecting blocks 20 is greater than 0°. Each connecting block 20 in the lattice unit cell 2 includes three prisms, defined as the first prism, the second prism, and the third prism. The three prisms are centered on an axis along the extension direction of the connecting block 20. The side faces of the first prism, the second prism, and the third prism intersect to form a central axis. The first prism, the second prism, and the third prism all extend from the vertex of the cube in a direction parallel to the central axis to the central block 21. The first prism, the second prism, and the third prism all extend away from the central axis to form the width of the prism.

[0091] The cross-section of the connecting block 20 is Y-shaped. The cross-sections of the first, second, and third prisms are defined as the first cross-section prism, the second cross-section prism, and the third cross-section prism, respectively. The included angle between the corresponding first and second cross-section prisms is 120°, the included angle between the first and third cross-section prisms is 120°, and the included angle between the second and third cross-section prisms is 120°.

[0092] The cross-section of connecting block 20 is Y-shaped, and the length of the long side of the cross-section of each rib is... The length of the shorter side of the cross-section of each prism is L is the edge length of 2 lattice unit cells, and L is 8 mm.

[0093] A is 0.132, B is 0.065, substitute into relation 1

[0094] Relation 1

[0095] The volume fraction V of the obtained lattice structure is 14.9%.

[0096] The lattice unit cell 2 prepared in Example 1 has a size of 8×8×8mm. 3 The length of the long side of the cross-section of the first, second, and third prism plates is 0.132 × 8 = 1.056 mm, and the length of the short side of the cross-section of the first, second, and third prism plates is 0.065 × 8 = 0.52 mm.

[0097] The positions of the eight connecting blocks 20 in the lattice unit cell 2 of Example 1 within the cube structure are as follows: One end of connecting block 201 abuts against the upper left front vertex of the cube, and the other end of connecting block 201 connects to the center block 21; One end of connecting block 202 abuts against the upper left rear vertex of the cube, and the other end of connecting block 202 connects to the center block 21; One end of connecting block 203 abuts against the upper right rear vertex of the cube, and the other end of connecting block 203 connects to the center block 21; One end of connecting block 204 abuts against the upper right front vertex of the cube, and the other end of connecting block 204 connects to the center block 21. The other end of 204 is connected to the center block 21; one end of the fifth connecting block 205 abuts against the bottom right rear vertex of the cube, and the other end of the fifth connecting block 205 is connected to the center block 21; one end of the sixth connecting block 206 abuts against the bottom right front vertex of the cube, and the other end of the sixth connecting block 206 is connected to the center block 21; one end of the seventh connecting block 207 abuts against the bottom left front vertex of the cube, and the other end of the seventh connecting block 207 is connected to the center block 21; one end of the eighth connecting block 208 abuts against the bottom left rear vertex of the cube, and the other end of the eighth connecting block 208 is connected to the center block 21.

[0098] To verify the excellent mechanical properties of the lattice structure at low density, a volume fraction of 14.9% was selected, and the edge length L of lattice unit cell 2 was set to 8 mm. To avoid unit cell size effects and ensure the mechanical properties of the lattice structure, the number of lattice unit cells 2 arranged along the x, y, and z directions was designed to be 4, resulting in an overall size of 32×32×32 mm. 3 Three-dimensional solid lattice structures, such as Figure 7 As shown.

[0099] Examples 2-8

[0100] Examples 2-8 are largely the same as Example 1, the difference being the different values ​​of A and B, as shown in Table 1. The lattice structure formed in Examples 2-5 is as follows: Figure 9 As shown.

[0101] Comparative Example 1

[0102] Comparative Example 1 is an existing BCC lattice structure block, comprising multiple BCC lattice unit cells 1 arranged periodically and interconnected in three-dimensional space; such as Figure 1 The diagram shown is a schematic of an existing BCC lattice unit cell 1 structure. Figure 3 This is a schematic diagram of the lattice structure formed by unit cell 1 of the BCC lattice. (See diagram below.) Figure 2The figure shown is an exploded view of the existing BCC lattice unit cell 1 structure. The BCC lattice unit cell 1 includes a central node and connecting rods 10. The connecting rods 10 include round rod 101, round rod 102, round rod 103, round rod 104, round rod 105, round rod 106, round rod 107, and round rod 108. BCC lattice unit cell 1 is a cubic structure. In BCC lattice unit cell 1, the central node is located at the body center of the cube. One end of the first circular rod 101 abuts against the upper left front vertex of the cube, and the other end of the first circular rod 101 is connected to the central node. One end of the second circular rod 102 abuts against the upper left rear vertex of the cube, and the other end of the second circular rod 102 is connected to the central node. One end of the third circular rod 103 abuts against the upper right rear vertex of the cube, and the other end of the third circular rod 103 is connected to the central node. One end of the fourth circular rod 104 abuts against the upper right front vertex of the cube. One end of circular rod 104 is connected to the center node; one end of circular rod 105 is connected to the lower right rear vertex of the cube, and the other end of circular rod 105 is connected to the center node; one end of circular rod 106 is connected to the lower right front vertex of the cube, and the other end of circular rod 106 is connected to the center node; one end of circular rod 107 is connected to the lower left front vertex of the cube, and the other end of circular rod 107 is connected to the center node; one end of circular rod 108 is connected to the lower left rear vertex of the cube, and the other end of circular rod 108 is connected to the center node. Round rods 101, 102, 103, 104, 105, 106, 107, and 108 extend from the vertices of the cube toward the center of the cube and intersect at the center of the cube to form a central node.

[0103] The BCC lattice structure in Comparative Example 1 was also prepared using laser powder bed melting (LPBF) technology, with Ti6Al4V alloy as the material. The LPBF preparation process parameters were selected as follows:

[0104] The slice thickness was 30 μm, the laser power was 230 W, the scanning speed was 100 mm / s, and the scanning interval was set to 1200 μm.

[0105] Examples 9-11

[0106] Examples 9-11 are mostly the same as Example 1, except that the values ​​of A and B are different. The specific values ​​are shown in Table 1.

[0107] The elastic modulus of each embodiment and comparative example was tested, and the specific test results are shown in Table 2.

[0108] Table 1

[0109]

[0110] Table 2

[0111]

[0112] Figure 10 The figures show the compressive stress-strain curves in the Z direction of the biomimetic titanium-based mechanical metamaterial prepared in Example 1 and the BCC lattice structure prepared in Comparative Example 1. The results show that there is a significant difference in the mechanical properties of the lattice structures before and after the improvement. The elastic modulus of the BCC lattice structure in Comparative Example 1 is 0.15 GPa and the compressive strength is 9.8 MPa, while the elastic modulus of the lattice structure in Example 1 is 0.31 GPa and the compressive strength is 17.4 MPa. That is, compared with Comparative Example 1, the elastic modulus of the lattice structure in Example 1 increased by 106% and the compressive strength increased by 77%. Figure 11 and Figure 12 The cross-sectional views of the compressive Mises stress distribution along the Z direction of the lattice unit cell 2 of Comparative Example 1 and Example 1 are shown respectively. The comparison shows that the stress distribution of the lattice structure of Example 1 is more uniform.

[0113] Figure 13 The corresponding normalized distance on the x-axis (0-1.0) refers to... Figure 11 , Figure 12 The distance from point A to point B is calculated by... Figure 13 The graph of Example 1 shows that the stress is relatively high near distances of 0.3 and 0.7, indicating that the lattice structure of Example 1 can transfer stress to the center of the connecting block 20. In contrast, the stress in Comparative Example 1 is closer to the central node, and the stress at the central node is higher. The stress at the central node of the lattice structure of Example 1 is lower and less than the stress in the center of the connecting block 20. Figure 3 As can be seen from the comparison between Example 1 and Comparative Example 1, the lattice structure in the biomimetic titanium-based mechanical metamaterial provided in this application transfers stress to the middle of the connecting block 20, thereby reducing the stress at the nodes of the lattice structure.

[0114] By comparing Examples 1-8 and Comparative Example 1 in Table 2, it is shown that the structure of the lattice unit cell 2 of this application is adopted, and A is in the range of 0 < A < 0.4, B is in the range of 0 < B < 0.7, and V satisfies the relation. The obtained V is in the range of 0 < V ≤ 90%, and the elastic modulus of the obtained lattice structure is relatively high. This indicates that the structure of the lattice unit cell 2 provided in this application can transfer the stress of the lattice structure to the middle of the connecting block 20, thereby reducing the stress at the nodes of the lattice structure. The structure of the lattice unit cell 2 allows the lattice structure to still obtain excellent mechanical properties at a low volume fraction (such as 15% and below). In addition, it increases the design freedom of the lattice structure and has no internal closed space, which helps to remove powder accumulation after additive manufacturing. The structure of the connecting block 20 does not change the three-dimensional spatial symmetry of the lattice structure, making the stress distribution of the lattice structure more uniform and significantly improving the mechanical properties of the lattice structure.

[0115] Comparing Examples 1 and 9-10, when A is not in the range of 0 < A < 0.4, B is not in the range of 0 < B < 0.7, or V is not in the range of 0 < V ≤ 90%, Examples 9-10 show a situation where the structure cannot be generated, resulting in a lattice unit cell 2 with an internal closed space. This indicates that the relationships 0 < A < 0.4, 0 < B < 0.7, and 0 < V ≤ 90% must also be satisfied in order to obtain the structure of the lattice unit cell 2 with an internal closed space provided in this application.

[0116] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A titanium-based mechanical metamaterial based on biomimetic design, characterized in that, The system includes a lattice structure comprising multiple lattice unit cells arranged periodically and interconnected in a three-dimensional space. Each lattice unit cell includes a central block and multiple connecting blocks. One end of each connecting block is connected to the central block. Each connecting block extends from the central block in a direction away from the central block, and the included angle between two adjacent connecting blocks is greater than 0. Each of the connecting blocks includes 3n prisms, where n ≥ 1. The 3n prisms are spaced apart around an axis extending from the connecting block, and the planes containing the 3n prisms intersect the axis. When n=1, the cross-section of the connecting block is Y-shaped, and the length of the long side of the cross-section of each rib is... The length of the shorter side of the cross-section of each prism is L is the edge length of the lattice unit cell; The volume fraction V of the lattice structure satisfies relation 1: Relation 1 Where 0 < A < 0.4, 0 < B < 0.7; 0＜V≤90%； The lattice unit cell has a cubic structure, the central block is located at the body center of the cube, the connecting block extends from the central block to the vertex of the cube, and the end of the connecting block away from the central block abuts against the vertex of the cube; One vertex of the cube is connected to three edges, and among the 3n edge plates, three edge plates are respectively fitted to the three edges. The central block is the center point; The two adjacent connecting blocks are defined as the first connecting block and the second connecting block, respectively. In the direction of the center point, the end faces of two adjacent prisms in the first connecting block and the second connecting block are in contact with each other. The edge length of the lattice unit cell is L, and the contact length between the edge plate and the edge is... .

2. The biomimetic titanium-based mechanical metamaterial according to claim 1, characterized in that, The included angle between any two adjacent prisms is the same.

3. A method for preparing a biomimetic titanium-based mechanical metamaterial according to any one of claims 1-2, characterized in that, Includes the following steps: It is made from Ti6Al4V alloy using laser powder bed melting process; In the laser powder bed melting process, the slice layer thickness is 30μm, the laser power is 230W, the scanning speed is 100mm / s, and the scanning interval is 1200μm.

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