Titanium-based mechanical metamaterial based on bionic design and preparation method thereof

Abstract

The titanium-based mechanical metamaterial comprises a lattice structure, the lattice structure comprises a plurality of lattice unit cells which are periodically and regularly arranged in a three-dimensional space and connected with one another, each lattice unit cell comprises a center block and a plurality of connecting blocks, one end of each connecting block is connected with the center block, and the other end of each connecting block is connected with the center block; each connecting block extends from the center block to the direction far away from the center block, and the included angle between every two adjacent connecting blocks is larger than 0; each connecting block comprises 3n edge plates, n is larger than or equal to 1, the 3n edge plates are arranged around an axis in the extending direction of the connecting blocks at intervals, and the planes where the 3n edge plates are located intersect at the axis; according to the titanium-based mechanical metamaterial provided by the invention, the stress of the lattice structure can be transferred to the middle part of the connecting block through the lattice unit cell structure, so that the stress at the node of the lattice structure is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical metamaterials, and in particular to a titanium-based mechanical metamaterial based on bionic design and a preparation method thereof. Background Art

[0002] Lattice mechanics metamaterial is a kind of artificial material with special properties. It is a kind of metamaterial. This material is designed by its internal structure, such as the evolution of the basic unit of the lattice unit cell, to reduce the stress concentration inside the structure and achieve the theoretically predicted isotropic limit stiffness. Lattice mechanics metamaterial is a lightweight multifunctional material with high specific strength, high specific stiffness, anti-explosion energy absorption and other characteristics. It has broad application prospects in aerospace, medical implants, heat transfer and vehicle collision avoidance. Therefore, it is of great significance to develop a lattice structure with high specific strength and strong energy absorption.

[0003] The lattice structure includes lattice cells, which can be divided into plate-like lattice cells and rod-like lattice cells. Multiple plate-like lattice cells are arranged regularly and periodically in three-dimensional space to form a plate-like lattice structure, and multiple rod-like lattice cells are arranged regularly and periodically in three-dimensional space to form a rod-like lattice structure. Plate-like lattice cells are generally formed by stacking multiple plates to form a cubic structure. The plates have a large area and can usually disperse stress to avoid stress concentration. However, multiple plates usually form an internal cavity of a closed lattice cell, resulting in the inability to remove powder accumulation after additive manufacturing, and the plates occupy a large volume space. Under the condition of a low volume fraction of the lattice structure (for example, 15%), the mechanical properties of the plate-like lattice cell will be significantly reduced. The rod-like lattice structure has no closed internal cavity, and its mechanical properties will not be significantly reduced at a lower volume fraction. However, due to the stress concentration at its node connection, the lattice structure will be destroyed prematurely, and the mechanical properties of the lattice structure will be reduced accordingly. For example, the existing Chinese patent CN202010990661.9 invented a rounded lattice structure, which reduces the stress concentration at the BCC lattice nodes. However, (i) the rounded design 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 lattice structure nodes. Summary of the invention

[0004] In view of the problem that the existing rod-shaped lattice structure has stress concentration at the node connection when the volume fraction of the lattice structure is low, and the mechanical properties of the lattice structure are still poor, the present application provides a titanium-based mechanical metamaterial based on bionic design.

[0005] In a first aspect, the present invention provides a titanium-based mechanical metamaterial based on bionic design, including a lattice structure, wherein the lattice structure includes a plurality of lattice unit cells that are periodically arranged and interconnected in a three-dimensional space, wherein the lattice unit cell includes a central block and a plurality of connecting blocks, wherein one end of the connecting block is connected to the central block, each of the connecting blocks extends from the central block in a direction away from the central block, and an angle between two adjacent connecting blocks is greater than 0; Each of the connecting blocks comprises 3n edge plates, where n≥1, and the 3n edge plates are arranged at intervals around an axis in the extending direction of the connecting block, and the planes where the 3n edge plates are located intersect the axis.

[0006] 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 edge plate is , the length of the short side of each edge plate section is , L is the edge length of the lattice unit cell; The volume fraction V of the lattice structure satisfies the relationship 1: , relation 1 Among them, 0<A<0.4, 0<B<0.7.

[0007] Preferably, 0<V≤90%.

[0008] Preferably, the angles between every two adjacent edge plates are the same.

[0009] 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 one 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 three edge plates among the 3n edge plates are respectively fitted with the three edges in a one-to-one correspondence.

[0010] Preferably, the central block is a central point.

[0011] Preferably, the edge length of the lattice unit cell is L, and the fitting length of the edge plate and the edge is .

[0012] In a second aspect, the present application provides a method for preparing the titanium-based mechanical metamaterial based on bionic design as described above, comprising the following steps: using Ti6Al4V alloy as a raw material and using a laser powder bed melting process to prepare; In the laser powder bed melting process, the slice layer thickness is 30 μm, the laser power is 230 W, the scanning speed is 100 mm / s, and the scanning interval is 1200 μm.

[0013] The titanium-based mechanical metamaterial based on bionic design provided in the present application has the following effects: 1) Combining the characteristics of the rod-like lattice structure and the plate-like lattice structure, the structure of the lattice unit cell can transfer the stress of the lattice structure to the middle of the connecting block, thereby reducing the stress at the nodes of the lattice structure; 2) The connecting block includes 3n edges, and the 3n edges are arranged at intervals around an axis in the extension direction of the connecting block, and the planes where the 3n edges are located intersect at the axis, and the 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, so that the stress distribution of the lattice structure is more uniform, and the mechanical properties of the lattice structure are significantly improved; 3) The structure of the lattice unit cell enables the lattice structure to still obtain excellent mechanical properties at a lower volume fraction (such as 15% and below). In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which is conducive to the removal of powder accumulation after additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the BCC lattice unit cell in Comparative Example 1; Figure 2 This is the exploded diagram of the BCC lattice unit cell in comparative example 1; Figure 3 This is a schematic diagram of the lattice structure formed by the arrangement of BCC lattice unit cells in Comparative Example 1; Figure 4 This is a schematic diagram of a lattice unit cell of a titanium-based mechanical metamaterial based on bionic design when n=1 according to Example 1 of the present application; Figure 5 This is an exploded diagram of a titanium-based mechanical metamaterial-lattice unit cell based on biomimetic design according to Example 1 of the present application; Figure 6 This is a schematic diagram of the cross-sectional structure of a titanium-based mechanical metamaterial-connecting block based on bionic design according to Example 1 of the present application; Figure 7 This is a schematic diagram of a titanium-based mechanical metamaterial-lattice structure based on biomimetic design according to Example 1 of the present application; Figure 8 This is a curve diagram of parameter A and parameter B changes of titanium-based mechanical metamaterial-lattice structure based on bionic design in Example 1 of the present application; Fig. 9 It is a schematic diagram of a titanium-based mechanical metamaterial-lattice structure based on biomimetic design according to Examples 1-3, 5, and 7 of the present application; Fig.10 2 are the compressive stress-strain curves of the lattice structure of Example 1 and the lattice structure of Comparative Example 1 along the Z direction; Fig.11 This is the cross-sectional diagram of the Mises stress distribution of the lattice unit cell of Example 1 compressed along the Z direction; Fig.12is a cross-sectional diagram of the Mises stress distribution of the lattice unit cell of Example 1 along the Z direction; Fig.13 is the Mises stress curve of the lattice unit cell along the rod direction of Example 1 and Comparative Example 1; Fig.14 This is a schematic diagram of a lattice unit cell of a titanium-based mechanical metamaterial based on bionic design provided in this application when n=2.

[0015] 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; 2. Lattice unit cell; 20. Connection block; 21. Center block; 201. Connection block No. 1; 202. Connection block No. 2; 203. Connection block No. 3; 204. Connection block No. 4; 205. Connection block No. 5; 206. Connection block No. 6; 207. Connection block No. 7; 208. Connection block No. 8. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0018] like Figure 4-14 As shown, the present application provides a titanium-based mechanical metamaterial based on bionic design, including a lattice structure, wherein the lattice structure includes a plurality of lattice unit cells 2 that are periodically arranged and interconnected in a three-dimensional space. Figure 7 As shown, in three-dimensional space, four lattice unit cells 2 are arranged in the x-axis direction, the y-axis direction and the z-axis direction respectively; it can be understood that the number of lattice unit cells 2 arranged in the x-axis direction, the y-axis direction and the z-axis direction is not limited in this application, and the lattice unit cells 2 arranged in each direction in the x-axis direction, the y-axis direction and the z-axis direction may be equal or unequal.

[0019] 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 angle between two adjacent connecting blocks 20 is greater than 0.

[0020] Specifically, the lattice unit cell 2 includes a plurality of connection blocks 20, one end of each connection block 20 is connected to the central block 21, and the connection block 20 extends from the central block 21 to a direction away from the central block 21. For example, when the lattice unit cell 2 is a body-centered cube, the end of the connection 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 cube, one end of a portion of the connection blocks 20 away from the central block 21 extends to the vertex of the cube, and another end of the connection blocks 20 away from the central block 21 extends to the face center of the cube. Depending on the structure of the lattice unit cell 2, the extension direction and extension position of the end of the connection block 20 away from the central block 21 are different.

[0021] Limiting the angle between two adjacent connection blocks 20 to be greater than 0 enables each connection block 20 extending from the central block 21 to be connected to a vertex, edge, or face of the cube structure, thereby playing the role of supporting the lattice unit cell 2.

[0022] Each of the connection blocks 20 includes 3n edge plates, where n≥1 and n is a positive integer. The 3n edge plates are arranged at intervals around an axis in the extending direction of the connection block 20 , and the planes where the 3n edge plates are located intersect the axis.

[0023] Specifically, the connecting block 20 includes 3n edges, and the 3n edges are arranged at intervals around an axis in the extension direction of the connecting block 20, and the planes where the 3n edges are located intersect with the axis, and the angle between two adjacent connecting blocks 20 is greater than 0. The lattice unit cell 2 combines the characteristics of the rod-like lattice structure and the plate-like lattice structure. The structure of this lattice unit cell 2 is conducive to transferring the stress of the lattice structure to the middle part 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.

[0024] like Figure 4 , 14 As shown, Figure 4 is the lattice unit cell diagram corresponding to the structure of the connection block 20 when n=1, Fig.14 When n=2, the lattice unit cell diagram corresponding to the structure of the connection block 20. Specifically, the 3n ribs are arranged at intervals around an axis in the extending direction of the connection block 20, which means that the side surfaces of the 3n ribs intersect to form a central axis with the axis in the extending direction of the connection block 20 as the center, and all the ribs are arranged at intervals around the central axis, each rib extends in a direction away from the central axis to form the width of the rib, and each rib extends to the central block 21 in a direction parallel to the central axis.

[0025] The titanium-based mechanical metamaterial based on bionic design provided in the present application has the following effects: 1) Combining the characteristics of the rod-like lattice structure and the plate-like lattice structure, the structure of the lattice unit cell 2 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; 2) The connecting block 20 includes 3n edges, and the 3n edges are arranged at intervals around an axis in the extension direction of the connecting block 20, and the planes where the 3n edges are located intersect at the axis, and the 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, so that the stress distribution of the lattice structure is more uniform, and the mechanical properties of the lattice structure are significantly improved; 3) The structure of the lattice unit cell 2 enables the lattice structure to still obtain excellent mechanical properties at a lower volume fraction (such as 15% and below). In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which is conducive to the removal of powder accumulation after additive manufacturing.

[0026] 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 edge plate is , the length of the short side of each edge plate section is , L is the edge length of the lattice unit cell 2; The volume fraction V of the lattice structure satisfies the relationship 1: , relation 1 Among them, 0<A<0.4, 0<B<0.7.

[0027] Specifically, n=1, and the corresponding connecting block 20 has three edges, such as Figure 6 As shown, the cross section of the connecting block 20 is Y-shaped.

[0028] like Fig. 9 As shown, a schematic diagram of a lattice structure block with different parameter A and B values ​​is selected. As parameter A increases, the length of the long side of the cross section of each rib in the connecting block 20 gradually increases, and the lattice unit cell 2 tends to form a plate-like lattice unit cell 2, and the corresponding lattice structure tends to form a plate-like lattice structure. As parameter B increases, the length of the short side of the cross section of each rib in the connecting block 20 gradually increases, and the lattice unit cell 2 tends to form a rod-like lattice unit cell 2, and the corresponding lattice structure tends to form a rod-like lattice structure. Specifically, A can be 0.1, 0.15, 0.2, 0.25, 0.3 or 0.35, etc., as long as the value of A is within the range of 0<A<0.4. The value of 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, 0.65, etc., as long as the value of B is within the range of 0<A<0.7.

[0029] The volume fraction V of the lattice structure is an important parameter that directly affects the mechanical properties and functional characteristics of the lattice structure. The volume fraction V of the lattice structure refers to the ratio of the volume fraction of solid materials in the lattice structure to the total volume.

[0030] Compared with the rod-like lattice structure formed by simple rod-like lattice unit cells, or the plate-like lattice structure formed by plate-like lattice unit cells, the titanium-based mechanical metamaterial based on bionic design provided by the present application, when n=1, the volume fraction V of the formed lattice structure satisfies the relationship 1. As the parameters A and B change, the volume fraction V of the corresponding lattice structure also changes, which greatly broadens the design freedom of the lattice structure and realizes the conversion between the plate-like lattice structure and the rod-like lattice structure well. The lattice structure can still obtain excellent mechanical properties at a lower volume fraction (such as 15% and below). In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which is conducive to the removal of powder accumulation after additive manufacturing, and is suitable for additive manufacturing technology.

[0031] 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 lower volume fraction (such as 15% and below). In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which helps to remove powder accumulation after additive manufacturing and is suitable for additive manufacturing technology.

[0032] When n is greater than 1, such as Fig.14 As shown in FIG. 1 , it is a structural diagram of a lattice unit cell 2 with n=2. The lattice unit cells 2 formed are arranged periodically and regularly in three-dimensional space and connected to each other to obtain a lattice structure. Although the relationship satisfied by the volume fraction V of the lattice structure needs to be slightly changed accordingly, the obtained lattice structure still has excellent mechanical properties at a lower volume fraction. In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which is helpful for removing powder accumulation after additive manufacturing, and is suitable for the effect of additive manufacturing technology.

[0033] In some embodiments, 0<V≤90%.

[0034] Specifically, the volume fraction V of the lattice structure refers to the ratio of the volume fraction of the solid material in the lattice structure to the total volume. The titanium-based mechanical metamaterial based on bionic design provided in the present application, the inventor combines the characteristics of the rod-shaped lattice structure and the plate-shaped lattice structure, and designs a connecting block 20 with a Y-shaped cross-section. At the same time, with the central block 21 as the center, the connecting block 20 extends from one end of the central block 21 to a direction away from the central block 21, and the angle between two adjacent central blocks 21 is greater than 0°. Each of the connecting blocks 20 includes 3n edges, n≥1, and the 3n edges are spaced apart around an axis in the extension direction of the connecting block 20, and the planes where the 3n edges are located intersect at the axis, forming the following: Figure 4 , 14 The lattice unit cell 2 structure shown in the figure has a volume fraction V of the lattice structure formed by arranging multiple lattice unit cells 2 in three-dimensional space in the range of 0<V≤90%. The lattice structure can still obtain excellent mechanical properties at a lower volume fraction (such as 15% and below). At the same time, it also improves the design freedom of the lattice structure and has no internal closed space, which is conducive to the removal of powder accumulation after additive manufacturing and is suitable for additive manufacturing technology.

[0035] In some embodiments, the angles between every two adjacent ribs are the same.

[0036] Specifically, the connecting block 20 includes 3n edge plates, and the angles between each two adjacent edge plates are the same, which is conducive to forming a structure in which two relative connecting blocks 20 are symmetrically arranged with the center of the cube, and 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. At the same time, it can also make the stress distribution of the lattice structure more uniform, significantly improving the mechanical properties of the lattice structure.

[0037] In some preferred embodiments, when n=1, the cross section of the connecting block 20 is formed Figure 6 The cross-sectional structure of the connecting block 20 is defined as a first edge plate, a second edge plate, and a third edge plate; Figure 6 The cross-sectional structure is Y-shaped, and the cross-sections of the first edge plate, the second edge plate, and the third edge plate are correspondingly defined as the first cross-sectional edge plate, the second cross-sectional edge plate, and the third cross-sectional edge plate. Figure 6 In the embodiment, the angle between the first section rib and the second section rib is 120°, the angle between the first section rib and the third section rib is 120°, and the angle between the second section rib and the third section rib is 120°.

[0038] 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 to the vertex of the cube, and one end of the connecting block 20 away from the central block 21 abuts against the vertex of the cube; One vertex of the cube is connected to three edges, and three edge plates among the 3n edge plates are respectively fitted with the three edges in a one-to-one correspondence.

[0039] Specifically, Figure 4 , 5 As shown, when the lattice unit cell 2 is a cubic structure, the connection block 20 extends from the central block 21 toward a vertex of the cube, and the end of the connection 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 connection blocks 20, each vertex is abutted against a connection block 20, and the eight connection blocks 20 extend from the vertex of the cube toward the body center of the cube and intersect at the body center of the cube, forming the central block 21.

[0040] 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; the 3n edge panels of the connecting block 20 include at least three edge panels, wherein the three edge panels correspond one to one with the three edges respectively, and the three edge panels that correspond to the three edge panels are defined as the first edge panel, the second edge panel and the third edge panel.

[0041] like Figure 5 As shown, the end of the first prism away from the center block 21 is in contact with the first edge, the end of the second prism away from the center block 21 is in contact with the second edge, and the end of the third prism away from the center block 21 is in contact with the third edge; when external force acts on the lattice structure, the structure of the first prism, the second prism and the third prism in a single lattice unit cell 2 can transfer the stress in the lattice structure to the middle of the first prism, the middle of the second prism and the middle of the third prism, thereby 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 close to the middle and the middle attachment between the center block 21 and the vertex, the middle of the second prism also refers to the position close to the middle and the middle attachment between the center block 21 and the vertex, and the middle of the third prism also refers to the position close to the middle and the middle attachment between the center block 21 and the vertex.

[0042] In some embodiments, the center block 21 is a center point.

[0043] like Figure 4 , 5 As shown, eight connection blocks 20 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 block 21. At this time, the central block 21 is the center of the cube, and also the center point.

[0044] In some embodiments, two adjacent connecting blocks 20 are respectively defined as a first connecting block and a second connecting block, and end surfaces of two adjacent edge plates in the first connecting block and the second connecting block are fitted with each other toward the center point.

[0045] like Figure 4 , 5 As shown in Figures 7, in the direction toward the central block 21, as each adjacent first connecting block and second connecting block gradually approaches the central block 21, the end faces of the two edge plates of the first connecting block and the second connecting block gradually fit together, so that the multiple connecting blocks 20 can be stably connected to form the central block 21, thereby improving the stability of the central block 21 and the mechanical properties of the central node of the lattice structure.

[0046] In some embodiments, the edge length of the lattice unit cell 2 is L, and the fitting length of the edge plate and the edge is .

[0047] 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. The present 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.

[0048] The connecting block 20 includes 3n ribs, each of which has a cross-sectional area of ​​a long side of The three edges of each connecting block 20 are respectively fitted with the three edges extending from a vertex of the cube, and the fitting length is the length of the long side of the cross section of the corresponding edge plate. .

[0049] In some embodiments, the connecting block 20 includes a first edge plate, a second edge plate, and a third edge plate, and the fitting length between the first edge plate and the first edge is ; The fitting length between the second edge plate and the second edge is ; The fitting length between the third ridge plate and the third edge is .

[0050] like Figure 5 As shown, the first edge plate is a structure that fits the first edge of the cube, the second edge plate is a structure that fits the second edge of the cube, and the third edge plate is a structure that fits the third edge of the cube; the fitting length is the length of the long side of the cross section of the edge plate . The length of the long side of the cross section of the first edge plate , then the corresponding fitting length between the first edge plate and the first edge is , the fitting length between the second edge plate and the second edge is , the fitting length between the third edge plate and the third edge is .

[0051] 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.

[0052] The range of B is 0<B<0.7, It is the result of multiplying the value of B by the value of L.

[0053] In a second aspect, the present application provides a method for preparing a titanium-based mechanical metamaterial based on bionic design, comprising the following steps: using Ti6Al4V alloy as a raw material and using a laser powder bed melting process to prepare the material; In the laser powder bed melting process, the slice layer thickness is 30 μm, the laser power is 230 W, the scanning speed is 100 mm / s, and the scanning interval is 1200 μm.

[0054] Specifically, Ti6Al4V alloy is used as raw material and laser powder bed melting technology is used to construct a three-dimensional lattice structure to prepare a titanium-based mechanical metamaterial based on bionic design.

[0055] In the laser powder bed melting process, Ti6Al4V alloy powder particles are used as raw materials, the slice layer thickness is 30μm, the laser power is 230W, the scanning speed is 100mm / s, the scanning interval is set to 1200μm, and the slice layer is scanned according to the predetermined path.

[0056] The present application provides a method for preparing a titanium-based mechanical metamaterial based on bionic design, which has a simple preparation process and low cost.

[0057] The present invention is further described below by way of examples.

[0058] Example 1 This embodiment provides a titanium-based mechanical metamaterial based on bionic design and a preparation method thereof.

[0059] The preparation method of titanium-based mechanical metamaterial based on bionic design includes the following steps: The material is Ti6Al4V alloy, and the preparation method is laser powder bed fusion (LPBF) technology. The LPBF preparation process parameters are selected as follows: 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.

[0060] The structure of the prepared lattice unit cell 2 is as follows Figures 4 to 7As shown, the lattice unit cell 2 is a body-centered cubic structure, the center 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 connection blocks 20, each vertex is abutted with a connection block 20, and the connection block 20 extends from one end of the center block 21 to the vertex of the cube, so that the end of the connection block 20 away from the center block 21 abuts the vertex of the cube, and the other end of the connection block 20 is connected to the center block 21, and the angle between two adjacent connection blocks 20 is greater than 0°. In the lattice unit cell 2, each connection block 20 includes three edges, which are defined as the first edge plate, the second edge plate and the third edge plate. The three edges are centered on an axis in the extension direction of the connection block 20. The sides of the first edge plate, the second edge plate and the third edge plate intersect to form a central axis. The first edge plate, the second edge plate and the third edge plate all extend from the vertex of the cube in a direction parallel to the central axis to the center block 21; the first edge plate, the second edge plate and the third edge plate all extend in a direction away from the central axis to form the width of the edge plate. .

[0061] The cross section of the connecting block 20 is Y-shaped, and the cross sections of the first edge plate, the second edge plate and the third edge plate are defined as the first section edge plate, the second section edge plate and the third section edge plate, respectively. The corresponding angle between the first section edge plate and the second section edge plate is 120°, the angle between the first section edge plate and the third section edge plate is 120°, and the angle between the second section edge plate and the third section edge plate is 120°.

[0062] The cross section of the connecting block 20 is Y-shaped, and the length of the long side of each edge plate is , the length of the short side of each edge plate section is , L is the edge length of the lattice unit cell 2, and L is 8mm.

[0063] A is 0.132, B is 0.065, substitute into equation 1 , relation 1 The volume fraction V of the obtained lattice structure is 14.9%.

[0064] The size of the lattice unit cell 2 prepared in Example 1 is 8×8×8mm 3 The lengths of the long sides of the cross sections of the first edge plate, the second edge plate, and the third edge plate are all 0.132×8=1.056mm, and the lengths of the short sides of the cross sections of the first edge plate, the second edge plate, and the third edge plate are all 0.065×8=0.52mm.

[0065] The positions of the eight connection blocks 20 in the lattice unit cell 2 of Example 1 in the cube structure are as follows: one end of the No. 1 connection block 201 abuts against the vertex at the upper left front of the cube, and the other end of the No. 1 connection block 201 is connected to the central block 21; one end of the No. 2 connection block 202 abuts against the vertex at the upper left rear of the cube, and the other end of the No. 2 connection block 202 is connected to the central block 21; one end of the No. 3 connection block 203 abuts against the vertex at the upper right rear of the cube, and the other end of the No. 3 connection block 203 is connected to the central block 21; one end of the No. 4 connection block 204 abuts against the vertex at the upper right front of the cube, and the No. 4 connection block The other end of connection block No. 204 is connected to the center block 21; one end of connection block No. 5 205 abuts against the vertex at the lower right rear of the cube, and the other end of connection block No. 5 205 is connected to the center block 21; one end of connection block No. 6 206 abuts against the vertex at the lower right front of the cube, and the other end of connection block No. 6 206 is connected to the center block 21; one end of connection block No. 7 207 abuts against the vertex at the lower left front of the cube, and the other end of connection block No. 7 207 is connected to the center block 21; one end of connection block No. 8 208 abuts against the vertex at the lower left rear of the cube, and the other end of connection block No. 8 208 is connected to the center block 21.

[0066] In order to verify the excellent mechanical properties of the lattice structure at low density, the volume fraction is selected as 14.9%, and the edge length L of the lattice unit cell 2 is set to 8 mm. In order to avoid the unit cell size effect and ensure the mechanical properties of the lattice structure, the number of lattice unit cells 2 arranged along the x, y, and z directions is designed to be 4, thus forming an overall size of 32×32×32 mm. 3 The three-dimensional solid lattice structure, such as Figure 7 shown.

[0067] Embodiment 2-8 Most of the steps in Example 2-8 are the same as those in Example 1, except that the values ​​of A and B are different. The specific values ​​are shown in Table 1. The lattice structure formed in Example 2-5 is as follows Fig. 9 shown.

[0068] Comparative Example 1 Comparative Example 1 is an existing BCC lattice structure block, including a plurality of BCC lattice unit cells 1 that are periodically arranged and interconnected in a three-dimensional space; Figure 1 The figure shows the schematic diagram of the existing BCC lattice unit cell 1 structure. Figure 3 Schematic diagram of the lattice structure formed by BCC lattice unit cell 1. Figure 2As shown, it is an exploded view of the existing BCC lattice unit cell 1 structure. The BCC lattice unit cell 1 includes a central node and a connecting rod 10. The connecting rod 10 includes a No. 1 round rod 101, a No. 2 round rod 102, a No. 3 round rod 103, a No. 4 round rod 104, a No. 5 round rod 105, a No. 6 round rod 106, a No. 7 round rod 107 and a No. 8 round rod 108. The BCC lattice unit cell 1 is a cubic structure. In the BCC lattice unit cell 1, the central node is located at the body center of the cube. One end of the No. 1 round rod 101 is abutted against the vertex at the upper left front of the cube, and the other end of the No. 1 round rod 101 is connected to the central node; one end of the No. 2 round rod 102 is abutted against the vertex at the upper left rear of the cube, and the other end of the No. 2 round rod 102 is connected to the central node; one end of the No. 3 round rod 103 is abutted against the vertex at the upper right rear of the cube, and the other end of the No. 3 round rod 103 is connected to the central node; one end of the No. 4 round rod 104 is abutted against the vertex at the upper right front of the cube , the other end of the No. 4 round rod 104 is connected to the central node; one end of the No. 5 round rod 105 is abutted against the vertex at the lower right rear of the cube, and the other end of the No. 5 round rod 105 is connected to the central node; one end of the No. 6 round rod 106 is abutted against the vertex at the lower right front of the cube, and the other end of the No. 6 round rod 106 is connected to the central node; one end of the No. 7 round rod 107 is abutted against the vertex at the lower left front of the cube, and the other end of the No. 7 round rod 107 is connected to the central node; one end of the No. 8 round rod 108 is abutted against the vertex at the lower left rear of the cube, and the other end of the No. 8 round rod 108 is connected to the central node. The first round bar 101, the second round bar 102, the third round bar 103, the fourth round bar 104, the fifth round bar 105, the sixth round bar 106, the seventh round bar 107 and the eighth round bar 108 all extend from the vertices of the cube to the center of the cube and intersect at the center of the cube to form a central node.

[0069] The BCC lattice structure of Comparative Example 1 is also prepared by laser powder bed fusion (LPBF) technology, the material is Ti6Al4V alloy, and the LPBF preparation process parameters are selected as follows: 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.

[0070] Examples 9-11 Most of the steps of Examples 9-11 are the same as those of Example 1, except that the values ​​of A and B are different. The specific values ​​are shown in Table 1.

[0071] The elastic modulus of each embodiment and comparative example was tested, and the specific test results are shown in Table 2.

[0072] Table 1 Table 2 Fig.10 The compressive stress-strain curves of the titanium-based mechanical metamaterial based on bionic design prepared in Example 1 and the BCC lattice structure prepared in Comparative Example 1 in the Z direction are shown; the results show that there is a large difference in the mechanical properties of the lattice structure before and after the improvement, wherein the elastic modulus of the BCC lattice structure of Comparative Example 1 is 0.15 GPa and the compressive strength is 9.8 MPa, and the elastic modulus of the lattice structure of Example 1 is 0.31 GPa and the compressive strength is 17.4 MPa, that is, relative to Comparative Example 1, the elastic modulus of the lattice structure of Example 1 is increased by 106% and the compressive strength is increased by 77%; Fig.11 and Fig.12 The cross-sectional diagrams of the Mises stress distribution of the lattice unit cell 2 of the comparative example 1 and the embodiment 1 along the Z direction are respectively shown. By comparison, it is found that the stress distribution of the lattice structure of the embodiment 1 is more uniform.

[0073] Fig.13 The corresponding horizontal axis normalized distance 0-1.0 refers to Fig.11 , Fig.12 The distance from point A to point B is Fig.13 It can be seen from the curve graph of Example 1 that when the stress at the distance near 0.3 and 0.7 is large, it means that the lattice structure of Example 1 can transfer the stress to the middle of the connecting block 20, while the stress in Comparative Example 1 is close to the central node, and the stress at the central node is high, while the stress at the central node of the lattice structure of Example 1 is small and less than the stress in the middle of the connecting block 20; Figure 3 From the comparison between Example 1 and Comparative Example 1, it can be seen that the lattice structure in the titanium-based mechanical metamaterial based on bionic design provided by the present application transfers the stress to the middle part of the connecting block 20, reducing the stress at the nodes of the lattice structure.

[0074] By comparing Examples 1-8 and Comparative Example 1 in Table 2, it is shown that when the structure of the lattice unit cell 2 of the present application is adopted, and A is in the range of 0<A<0.4, and B is in the range of 0<B<0.7, V satisfies the relationship , the obtained V is in the range of 0<V≤90%, and the elastic modulus of the obtained lattice structure is relatively high, indicating that the structure of the lattice unit cell 2 provided in the present application can transfer the stress of the lattice structure to the middle part of the connecting block 20, thereby reducing the stress at the nodes of the lattice structure. The structure of the lattice unit cell 2 enables the lattice structure to still obtain excellent mechanical properties at a lower volume fraction (such as 15% and below). In addition, the design freedom of the lattice structure is improved and there is no internal closed space, which is conducive to the removal of powder accumulation after additive manufacturing; the structure of the connecting block 20 does not change the three-dimensional spatial symmetry of the lattice structure, so that the stress distribution of the lattice structure is more uniform, which significantly improves the mechanical properties of the lattice structure.

[0075] Comparing Example 1 with Examples 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%, the structure of Example 9-10 cannot be generated, and a lattice unit cell 2 with a closed space inside will be formed. This shows that the relationships of 0<A<0.4, 0<B<0.7, and 0<V≤90% must be satisfied to obtain the structure of the lattice unit cell 2 with a closed space inside provided in the present application.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A titanium-based mechanical metamaterial based on bionic design, characterized in that: It includes a lattice structure, the lattice structure includes a plurality of lattice unit cells that are periodically arranged and connected to each other in a three-dimensional space, the lattice unit cell includes a central block and a plurality of connecting blocks, one end of the connecting block is connected to the central block, each of the connecting blocks extends from the central block in a direction away from the central block, and the angle between two adjacent connecting blocks is greater than 0; Each of the connecting blocks comprises 3n edge plates, where n≥1, and the 3n edge plates are arranged at intervals around an axis in the extending direction of the connecting block, and the planes where the 3n edge plates are located intersect the axis.

2. According to the titanium-based mechanical metamaterial based on bionic design in claim 1, 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 ridge plate is , the length of the short side of each edge plate section is , L is the edge length of the lattice unit cell; The volume fraction V of the lattice structure satisfies the relationship 1: , relation 1 in, 0<A<0.4, 0<B<0.

7.

3. The titanium-based mechanical metamaterial based on bionic design according to claim 2, characterized in that: 0＜V≤90%。 4. The titanium-based mechanical metamaterial based on bionic design according to claim 1, characterized in that: The angle between every two adjacent ribs is the same.

5. The titanium-based mechanical metamaterial based on bionic design according to claim 1, characterized in that: 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 one 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 three edge plates among the 3n edge plates are respectively fitted with the three edges in a one-to-one correspondence.

6. The titanium-based mechanical metamaterial based on bionic design according to claim 5, characterized in that: The central block is the central point.

7. The titanium-based mechanical metamaterial based on bionic design according to claim 6, characterized in that: The two adjacent connection blocks are respectively defined as a first connection block and a second connection block. In the direction toward the center point, the end surfaces of two adjacent edge plates in the first connection block and the second connection block fit each other.

8. The titanium-based mechanical metamaterial based on bionic design according to claim 5, characterized in that: The edge length of the lattice unit cell is L, and the fitting length between the edge plate and the edge is .

9. A method for preparing a titanium-based mechanical metamaterial based on bionic design according to any one of claims 1 to 8, characterized in that: The following steps are involved: It is made of Ti6Al4V alloy and manufactured by laser powder bed fusion process; In the laser powder bed melting process, the slice layer thickness is 30 μm, the laser power is 230 W, the scanning speed is 100 mm / s, and the scanning interval is 1200 μm.

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