Design method of bionic spherical lattice structure with artificially set mechanical property distribution

Abstract

The present invention belongs to the field of design of advanced structural materials for additive manufacturing, and relates to a method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, including: designing a spherical cell surface according to a lattice stacking pattern; designing a bionic multi-level topological segmentation network; Boolean segmenting of spherical cells through a topological segmentation network; achieving a lattice distribution of artificially designed mechanical properties through performance matching based on mechanical property distribution requirements and comparison of bionic multi-level spherical cells with different design parameters; and forming and manufacturing the material using additive manufacturing technology. Based on the complex structure forming and design capabilities provided by additive manufacturing technology, the present invention proposes a design method for different stacking connections and bionic multi-level surface topologies of cells in a spherical lattice structure, and realizes a method for achieving an artificially designed material mechanical property distribution through a combination of bionic multi-level topological spherical lattice cells by matching the mechanical properties of the cells with the material property distribution requirements.

Description

Technical Field

[0001] The present invention belongs to the field of design of advanced structural materials for additive manufacturing, and relates to a method for designing a bionic spherical lattice structure that can be formed by additive manufacturing technology by artificially combining and arranging spherical cells with different structural design parameters based on a bionic multi-level design of the surface topology of the spherical cells and matching the mechanical property distribution requirements with the mechanical properties of the cells determined by the structural design parameters. Background Art

[0002] Additive Manufacturing (AM) fabricates structures by adding materials layer by layer. This unique manufacturing method allows for the free "growth" of highly complex structures, greatly expanding the design "space" and providing a powerful tool for the preparation of new structures and materials. Topology optimization uses optimization techniques to determine where and what materials should be placed within a structure to achieve optimal performance while ensuring certain constraints. The integration of topology optimization (an advanced design technology) with additive manufacturing (an advanced manufacturing technology) to develop innovative design technologies holds great promise and has attracted widespread attention in academia.

[0003] Lattice structures are complex metamaterials composed of cells with periodic connectivity. Due to their unique mechanical properties, such as high specific strength, high energy absorption, negative Poisson's ratio, shock absorption, and crack resistance, lattice structures have broad application prospects in aerospace, biomedicine, and customized design. Among the various lattice or porous structure designs, spherical lattice structures composed of periodically arranged hollow spheres or spherical porous structures formed by simple bonding have been found to have high impact resistance and energy absorption properties due to their long stress plateau periods. However, due to their uniformly distributed structure and mechanical properties, uncontrollable localized failures often occur in practical applications, preventing the full energy absorption effect of the structure. To further enhance the mechanical properties of lattice structures, some research works have designed spherical lattice structures with gradient thicknesses or used a combination of spheres of different thicknesses to further enhance the impact or energy absorption performance of the structure. However, because these design methods rely on variations in the thickness of the spherical connectors and lack a universal cellular connection design method, they suffer from limitations such as limited flexibility in mechanical property combinations and difficulty connecting cellular structures. This ultimately limits the manipulability of the material's mechanical property distribution using traditional design methods. Therefore, designing a new spherical lattice structure with highly manipulable mechanical property distribution, while further enhancing its performance advantages, such as energy absorption and impact resistance, has become a highly worthy research topic in this field. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a bionic spherical lattice structure design method for artificially setting the distribution of mechanical properties, so as to further enhance the performance advantages of the spherical lattice structure and the flexibility of artificial mechanical property design, realize flexible and controllable artificial distribution of mechanical properties of structural materials, thereby further enhancing the application value of the spherical lattice structure and solving the shortcomings of the existing technology.

[0005] In order to achieve the above object, the purpose of the present invention is achieved through the following technical solutions:

[0006] A method for designing a bionic spherical lattice structure with artificially set mechanical property distribution is provided, comprising the following steps:

[0007] S1. Design spherical cellular surface based on lattice stacking properties;

[0008] S2, bionic multi-level topology segmentation network design;

[0009] S3, Boolean segmentation of spherical cells through topological segmentation network;

[0010] S4. Comparison of bionic multi-level spherical cells based on mechanical property distribution requirements and different design parameters, and achieving artificially designed mechanical property lattice distribution through performance matching;

[0011] S5. Use additive manufacturing technology to shape and manufacture materials.

[0012] The method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, in step S1, includes the following steps:

[0013] S11. Select the connector position corresponding to the cell according to the lattice stacking characteristics;

[0014] S12. Based on the connector size l, the spherical cell radius R, and the connector cross-sectional arc radius r, a connecting curved surface with a circular arc cross-section and smooth connection positions is designed;

[0015] Generate a cross-section arc object based on the connector size l, connector position, and spherical cell radius R. Use the Revolve command in Rhino to rotate the object along the O1O2 axis to form a connecting surface.

[0016] S13. According to the connection surface design and the selected connector position, the original spherical surface and the connection surface are subjected to Boolean segmentation and reorganization. The spherical surface inside the closed intersection line of the connection surface and the spherical surface is cut and deleted, and combined with the connection surface to form a spherical cell. The spherical cell surface is smooth everywhere.

[0017] As described in the bionic spherical lattice structure design method for artificially setting the mechanical property distribution, the lattice stacking characteristics include FCC, HCP and BCC.

[0018] The method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, in step S2, includes the following steps:

[0019] S21. Based on the selected topology type and the number of topological faces N, use the Rhino Polyhedron plug-in to generate a topological polyhedron consisting of N planar topological units;

[0020] S22. Design the radius R of the spherical cell and use the Rhino Pull Command to map the topological polyhedron boundary to the spherical surface, forming a spherical topological polyhedron network composed of N surface topological unit edges.

[0021] S23, Boolean segmentation of the spherical curve into a set of N discrete topological surfaces based on the spherical topological polyhedron network;

[0022] S24, the size of the local structural rod d, use Rhino Paneling Tools to offset the discrete topological surface boundary based on the center of the surface, and use the FilletCorners command to round the offset boundary line to obtain the final topological segmentation network.

[0023] As described in the bionic spherical lattice structure design method for artificially setting the mechanical property distribution, in step S3, the original spherical topological segmentation network is mapped to the cellular spherical surface part of the non-connected area, and the part is Boolean segmented, and the bionic multi-level topological spherical surface obtained after the segmentation is recombined with the connected surface to form a bionic multi-level topological spherical cell.

[0024] The method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, in step S4, includes the following steps:

[0025] S41. Analyze the mechanical properties of bionic spherical cells with different design parameters and establish a model of the relationship between design parameters and mechanical properties;

[0026] S42. According to the actual mechanical property distribution requirements, the cellular mechanical properties are matched and distributed, thereby realizing a bionic multi-level spherical lattice structure with artificially designed mechanical property distribution.

[0027] As described in the method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, in step S5, the bionic multi-level spherical lattice structure with artificially designed mechanical property distribution is formed by 3D printing.

[0028] The beneficial effects of the technical solution of the present invention are:

[0029] The innovative design method provided by the present invention improves the functional design flexibility and overall mechanical properties of the spherical lattice structure (improving the structural performance advantages such as energy absorption and impact resistance), and designs a spherical lattice stacking connection method and mechanical property distribution that can be artificially designed. The bionic multi-level topological spherical lattice design method realized by additive manufacturing technology realizes flexible and controllable artificial distribution of mechanical properties of structural materials, thereby further enhancing the application value of the spherical lattice structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To further illustrate the above-mentioned objectives, structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Figure 1 Show the overall design process of the present invention;

[0032] Figures 2a to 2d The design of spherical lattice cell surface is shown using simple stacking as an example: FIG2a shows the selection of connector positions based on simple stacking; Figure 2b Designed for spherical cellular surface connectors; Figure 2c The designed spherical cellular surface; Figure 2d are two adjacent connected spherical cells;

[0033] Figure 3 The design process of bionic multi-level spherical topology segmentation network is shown, taking the triangle topology structure as an example;

[0034] Figure 4 The Boolean segmentation process of spherical cells is shown using a triangle topology as an example;

[0035] Figure 5 The paper shows a method for achieving artificially designed lattice distribution of mechanical properties by performance matching based on the mechanical property distribution requirements and the mechanical properties of bionic multi-level spherical cells with different design parameters.

[0036] Figure 6 Showing the honeycomb-shaped bionic multi-level cell design with increasing topological density from (a) to (d);

[0037] Figure 7 Shows an example of cellular finite element simulation;

[0038] Figure 8a 、 Figure 8b Shows a honeycomb lattice with gradient mechanical properties: Figure 8a For design purposes, Figure 8b This is an illustration of the finished print. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0040] See Figure 1 As shown, the present invention provides a method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, comprising the following steps: S1, designing a spherical cellular surface according to lattice stacking properties; S2, designing a bionic multi-level topological segmentation network; S3, Boolean segmenting the spherical cells through the topological segmentation network; S4, based on the mechanical property distribution requirements and comparison of bionic multi-level spherical cells with different design parameters, achieving artificially designed mechanical property lattice distribution through performance matching; S5, forming and manufacturing the material using additive manufacturing technology.

[0041] The specific implementation steps are:

[0042] In the spherical cell surface design according to the lattice stacking pattern in step S1, it refers to Figure 2a 、 Figure 2b The method shown in the figure is to segment the original spherical surface and reassemble the connected surfaces using a given radius R of the spherical surface, a connected surface size l, and a set lattice stacking mode. The steps specifically include:

[0043] S11. Select the connector position corresponding to the cell according to the lattice stacking characteristics.

[0044] S12, based on Figure 2a 、 Figure 2b The connector size l and spherical cell radius R are shown, and the design cross section is an arc, and the connection position is smooth at all connection surfaces. Figure 2b The design solution generates a cross-section arc line object, which is rotated along the O1O2 axis using the Revolve command in Rhino to form the following Figure 2c and the connecting surface shown in Figure 2d.

[0045] S13. According to the connection surface design and the selected connector position, the original spherical surface and the connection surface are subjected to Boolean segmentation and reorganization, that is, the spherical surface inside the closed intersection line of the link surface and the spherical surface is cut and deleted, and then combined with the connection surface.

[0046] The lattice stacking characteristics include but are not limited to various existing lattice cell stacking methods, such as FCC, HCP, BCC, etc. A simple stacking method is used in the specification for ease of understanding and is not intended to limit the scope of the present invention.

[0047] The bionic multi-level topology segmentation network design in step S2 is as follows: Figure 3 As shown, based on a given topology type and the number of topological faces N, a topological segmentation network with reduced stress concentration fillets that can be used to segment a cellular spherical surface is generated. The steps specifically include:

[0048] S21. Based on the selected topology type and the number of topological faces N, use the Rhino Polyhedron plug-in to generate a topological polyhedron consisting of N planar topological units.

[0049] S22. Design the radius R of the spherical cell and use the Rhino Pull Command to map the boundary of the topological polyhedron to the spherical surface, forming a spherical topological polyhedron network composed of the edges of N surface topological units.

[0050] S23. The spherical curve is Boolean segmented into a set of N discrete topological surfaces based on the spherical topological polyhedron network.

[0051] S24, the size of the local structural rod d, use Rhino Paneling Tools to offset the discrete topological surface boundary based on the center of the surface, and use the FilletCorners command to round the offset boundary line to obtain the final topological segmentation network.

[0052] The Boolean segmentation of the spherical cells by the topological segmentation network in step S3 refers to the following: Figure 4 The spherical topological segmentation network shown is mapped to the cellular spherical surface part of the non-connected area of the spherical cell, and the part is Boolean segmented. The bionic multi-level topological spherical surface obtained after the segmentation is recombined with the connected surface to form a design method for bionic multi-level topological spherical cells.

[0053] The comparison of the bionic multi-level spherical cells based on the mechanical performance distribution requirements and different design parameters in step S4 realizes the lattice distribution of artificially designed mechanical properties by performance matching, which means that Figure 5 The design process shown includes:

[0054] S41. Analyze the mechanical properties of bionic spherical cells with different design parameters, and establish a model of the relationship between design parameters and mechanical properties.

[0055] S42. According to the actual mechanical property distribution requirements, the cellular mechanical properties are matched and distributed, thereby realizing a bionic multi-level spherical lattice structure with artificially designed mechanical property distribution.

[0056] The forming and manufacturing of the structure by using the additive manufacturing technology in step S5 refers to the process of forming and processing the bionic multi-level spherical lattice structure with artificially designed mechanical property distribution by means of 3D printing.

[0057] The present invention provides a method for designing a bionic multi-level topological spherical lattice that can artificially design the distribution of mechanical properties and realize it through additive manufacturing technology. The following describes a specific embodiment of the present invention by taking the design of a structural material with a gradient mechanical property distribution for energy absorption design as an example. The method specifically includes the following steps:

[0058] According to the impact requirements, the honeycomb topology with better energy absorption characteristics is selected as the multi-level topology structure. Figure 5 The steps shown in the figure generate a honeycomb topology polyhedron segmentation network with a relative density topological face number N ranging from 80 to 260 and a spherical cell with a simple stacking connection attribute; and finally obtain the following by topological segmentation: Figure 6 A series of spherical cells with different structures and properties are shown.

[0059] See Figure 7 , finite element simulations are performed on different cells as shown, and a relationship model of mechanical properties such as modulus, energy absorption, and relative density with respect to topological density is obtained.

[0060] According to Figure 5 As shown in the actual mechanical properties gradient distribution requirements, the cell combination with the closest mechanical properties to the distribution position is selected and filled with the design space to obtain the final Figure 8a The bionic multi-level honeycomb topology gradient lattice structure design shown in the figure is formed by laser selective melting additive manufacturing, and the final printed product is as follows Figure 8b shown.

[0061] The innovative design method provided by the present invention improves the functional design flexibility and overall mechanical properties of the spherical lattice structure (improving the structural performance advantages such as energy absorption and impact resistance), and designs a spherical lattice stacking connection method and mechanical property distribution that can be artificially designed. The bionic multi-level topological spherical lattice design method realized by additive manufacturing technology realizes flexible and controllable artificial distribution of mechanical properties of structural materials, thereby further enhancing the application value of the spherical lattice structure.

[0062] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing a bionic spherical lattice structure with artificially set mechanical property distribution, characterized in that: The following steps are involved: S1. Design spherical cellular surface based on lattice stacking properties; In step S1, the following steps are included: S11. Select the connector position corresponding to the cell according to the lattice stacking characteristics; S12. Based on the connector size l, the spherical cell radius R, and the connector cross-sectional arc radius r, a connecting curved surface with a circular arc cross-section and smooth connection positions is designed; Generate a cross-section arc object based on the connector size l, connector position, and spherical cell radius R. Use the Revolve command in Rhino to rotate the object along the O1O2 axis to form a connecting surface. S13. Based on the design of the connecting surface and the selected connector position, the original spherical surface and the connecting surface are subjected to Boolean segmentation and reorganization. The spherical surface inside the closed intersection line between the connecting surface and the spherical surface is cut and deleted, and then combined with the connecting surface to form a spherical cell. The spherical cell surface is smooth everywhere. S2, bionic multi-level topology segmentation network design; In step S2, the following steps are included: S21. Based on the selected topology type and the number of topological faces N, use the Rhino Polyhedron plug-in to generate a topological polyhedron consisting of N planar topological units; S22. Design the radius R of the spherical cell and use Rhino Pull Command to map the topological polyhedron boundary to the spherical surface, forming a spherical topological polyhedron network composed of N surface topological unit edges. S23, Boolean segmentation of the spherical curve into a set of N discrete topological surfaces based on the spherical topological polyhedron network; S24, the size of the local structural rod d, uses Rhino Paneling Tools to offset the discrete topological surface boundary based on the center of the surface, and uses the FilletCorners command to round the offset boundary line to obtain the final topological segmentation network; S3, Boolean segmentation of spherical cells through topological segmentation network; In step S3, the original spherical topology segmentation network is mapped to the cellular spherical surface portion of the non-connected area, and the portion is subjected to Boolean segmentation. The bionic multi-level topological spherical surface obtained after segmentation is recombined with the connected surface to form a bionic multi-level topological spherical cell; S4. Comparison of bionic multi-level spherical cells based on mechanical property distribution requirements and different design parameters, and achieving artificially designed mechanical property lattice distribution through performance matching; S5. Using additive manufacturing technology to shape and manufacture materials; In step S4, the following steps are included: S41. Analyze the mechanical properties of bionic spherical cells with different design parameters and establish a model of the relationship between design parameters and mechanical properties; S42. According to the actual mechanical property distribution requirements, the cellular mechanical properties are matched and distributed, thereby realizing a bionic multi-level spherical lattice structure with artificially designed mechanical property distribution.

2. The method for designing a bionic spherical lattice structure with artificially set mechanical property distribution according to claim 1, characterized in that: The lattice stacking characteristics include FCC, HCP and BCC.

3. The method for designing a bionic spherical lattice structure with artificially set mechanical property distribution according to claim 1, characterized in that: In step S5, the bionic multi-level spherical lattice structure with artificially designed mechanical property distribution is formed by 3D printing.

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