A method for generating a three-dimensional closed pore structure

Abstract

The present invention discloses a method for generating a three-dimensional closed pore structure, belonging to the technical field of porous structure design, and comprising the following steps: S1: determining the three-dimensional model parameters of the target porous structure, namely the geometric information of the three-dimensional configuration; S2: setting the size range of the tetrahedral mesh size and selecting a suitable finite element mesh generation algorithm to perform tetrahedral mesh generation on the three-dimensional structure; S3: determining the porosity distribution of the target three-dimensional closed pore structure; S4: using a closed pore structure generation algorithm to generate the geometric information of the target porous structure. Based on the finite element mesh generation topology algorithm, the present invention can regenerate a three-dimensional closed pore porous structure for any complex three-dimensional geometric configuration, and the size of the structure holes can be adjusted according to the distribution of the target porosity. The generation method is simple and has strong scalability, and can save time.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous structure design, and particularly relates to a method for generating a three-dimensional closed pore structure. Background Art

[0002] A porous structure is an interconnected network formed by solid rods or fixed plates with edges and walls that form pores. Due to its high strength ratio, high stiffness ratio, strong impact resistance, good shock absorption and other characteristics, the porous structure is widely used in the fields of machinery, architecture, aerospace, medical treatment, etc.

[0003] Among them, the modeling methods of porous structures are divided into regular porous structure design methods and irregular porous structure design methods. The modeling of irregular porous structures is difficult and the controllability is poor. The design of regular porous structures is relatively simple and can be used for performance analysis in aspects such as mechanics. However, there are few methods to generate any complex three-dimensional structures using regular hole structures, and the controllability of the porosity is also very limited.

[0004] Currently, for the three-dimensional porous structures generated from complex three-dimensional models, the voronoi method is more commonly used. However, the structures generated by this method are irregular open hole structures, and the porosity distribution is difficult to accurately control. At the same time, there are also many regular hole structures developed using algorithmic programs, but most of them are for regular three-dimensional configurations. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for generating a three-dimensional closed pore structure, which can adjust the distribution of the porosity according to the target requirements, greatly improving the designability of the porous structure. At the same time, this design method is applicable to any complex three-dimensional structure and has strong expansibility and applicability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for generating a three-dimensional closed pore structure, comprising the following steps:

[0008] S1: Determine the three-dimensional model parameters of the target porous structure, that is, the geometric information of the three-dimensional configuration;

[0009] S2: Set the size range of the tetrahedral mesh size and select a suitable finite element mesh generation algorithm to perform tetrahedral mesh generation on the three-dimensional structure;

[0010] S3: Determine the porosity distribution of the target three-dimensional closed pore structure;

[0011] S4: Use a closed pore structure generation algorithm to generate the geometric information of the target porous structure.

[0012] Further, step S1 specifically includes: determining the geometric parameters of the target three-dimensional configuration and saving them in the three-dimensional model file format.

[0013] Further, step S2 specifically includes the following steps:

[0014] S21: Import the three-dimensional model file into the finite element mesh generation software Gmesh;

[0015] S22: Select a suitable finite element mesh generation algorithm in Gmesh and set the minimum and maximum tetrahedral mesh sizes;

[0016] S23: After the settings are completed, perform tetrahedral mesh generation on the three-dimensional model to obtain the element and node information of each tetrahedron.

[0017] Further, step S3 determines the porosity distribution of the target three-dimensional closed-cell structure, specifically including the following steps:

[0018] First, set the porosity of each tetrahedral element to n is the number of tetrahedral elements divided by the finite element algorithm, C i is a constant greater than or equal to 0 and less than 1, i represents the i-th tetrahedron, and the porosity distribution is expressed by the following formula:

[0019]

[0020] Further, the closed-cell structure generation algorithm in step S4 specifically includes the following steps:

[0021] S41: Read and process the obtained tetrahedral node coordinates and element information;

[0022] S42: According to the porosity distribution, keep the centroid of each tetrahedral element unchanged and scale the vertex coordinates of the large tetrahedron to obtain the vertex coordinates of the new small tetrahedron;

[0023] S43: According to the eight vertex coordinates of each large tetrahedron and small tetrahedron unit, first divide a closed - pore tetrahedron hole structure into two parts. That is, select a vertex of a large tetrahedron at will, and then start from this vertex to perform a bisecting cut on the closed - pore tetrahedron to form two non - pore solid three - dimensional structures. Then perform triangulation on the surface of this structure, that is, the surface of each solid three - dimensional structure is composed of 12 triangular units. The other half of the solid three - dimensional structure is also generated according to this method, that is, each closed - pore tetrahedron unit is composed of two non - pore solid three - dimensional structures, and the surface of each solid three - dimensional structure is composed of 12 triangular units. Then process all the tetrahedron units through the above process to obtain a plurality of triangular units and node information, and read this unit and node information into an obj file at the same time to realize the generation of a three - dimensional closed - pore structure using 3D printing, and this three - dimensional closed - pore structure has the characteristic of the target porosity distribution;

[0024] S44: Finally, import the obj file of the generated three - dimensional porous structure into three - dimensional modeling software to view its porous structure. If it meets the requirements, a porous structure that meets the needs is generated. If it does not meet the requirements, adjust the tetrahedron unit size range and porosity distribution through step S2.

[0025] The beneficial effects of the present invention are as follows: Based on the finite - element mesh - generation topology algorithm, the present invention can regenerate a three - dimensional closed - pore structure for any complex three - dimensional geometric configuration, and the size of the structure holes can be adjusted according to the distribution of the target porosity. The generation method is simple and has strong scalability, and it can save time.

[0026] Other advantages, objectives and features of the present invention will be described in the subsequent specification, and to some extent, they are obvious to those skilled in the art, or those skilled in the art can obtain teachings from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the present invention provides the following drawings for description:

[0028] Figure 1 It is a flowchart of the method for generating the three - dimensional porous structure described in the present invention;

[0029] Figure 2 It is a specific process diagram of the method for generating the three - dimensional porous structure in the embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of the porous structure under different porosity distributions of the same configuration in the present invention;

[0031] Figure 4Schematic diagram of the porous structure under different configurations and different porosity distributions of the present invention. Detailed implementation manners

[0032] As Figures 1 to 4 shown, a method for generating a three-dimensional porous structure of the present invention can adjust the distribution of porosity according to the target requirements, greatly improving the designability of the porous structure. At the same time, this design method is applicable to any complex three-dimensional structure, with strong scalability and applicability. This method includes the following steps:

[0033] Step 1: Determine the geometric parameters of the target three-dimensional configuration and save them in the three-dimensional model file format, such as the stp format.

[0034] Step 2: Import the three-dimensional model file into the finite element mesh generation software Gmesh.

[0035] Step 3: Select a suitable finite element mesh generation algorithm in Gmesh and set the minimum and maximum tetrahedral mesh sizes. After setting, perform tetrahedral mesh generation on the structure to obtain the element and node information of each tetrahedron.

[0036] Step 4: According to the target requirements, set the porosity distribution on the three-dimensional configuration. There are various ways to set the porosity distribution of the three-dimensional model. For example, the formula method can be used to set it. That is, first set the porosity of each tetrahedral element as n is the number of tetrahedral elements divided by the finite element algorithm, C i is a constant greater than or equal to 0 and less than 1, and i represents the i-th tetrahedron. Then the porosity distribution can be expressed by the following formula:

[0037] In addition to the above method of using mathematical analytical expressions to set the porosity distribution, other methods such as random numbers can also be used to set the porosity distribution.

[0038] Step 5: Import the node and element information of the tetrahedron obtained after finite element mesh generation into the algorithm for generating a three-dimensional closed-cell structure.

[0039] Step 6: Use the obj file generation algorithm to generate a three-dimensional closed-cell structure that meets the target porosity distribution.

[0040] The specific design process of the algorithm includes the following steps:

[0041] Read and process the obtained tetrahedral node coordinates and element information.

[0042] According to the porosity distribution, keep the centroid of each tetrahedral element unchanged, and then scale the vertex coordinates of the large tetrahedron to obtain the vertex coordinates of the new small tetrahedron.

[0043] There are many types of format files for three-dimensional configurations. To quickly generate closed-cell structures and porous structures that can be 3D printed, in this embodiment, a method of directly writing an obj file is adopted to generate porous structures. According to the eight vertex coordinates of each large tetrahedron and small tetrahedron unit obtained above, first, a closed-cell tetrahedron hole structure is divided into two parts, that is, an arbitrary vertex of a large tetrahedron is selected, and then the closed-cell tetrahedron is bisected starting from this vertex, thereby forming two non-porous solid three-dimensional structures. Then, triangulation is performed on the surface of this structure, that is, the surface of each solid three-dimensional structure can be composed of 12 triangular units, and the other half of the solid three-dimensional structure can also be generated according to the above method, that is, each closed-cell tetrahedron unit can be composed of two non-porous solid three-dimensional structures, and the surface of each solid three-dimensional structure can be composed of 12 triangular units. Then, all tetrahedron units are processed through the above process to obtain a lot of triangular unit information. Reading these unit and node information into an obj file at the same time will realize a three-dimensional closed-cell structure that can be generated using 3D printing, and this three-dimensional closed-cell structure has the characteristic of a target porosity distribution.

[0044] Finally, the obj file of the generated three-dimensional porous structure is imported into three-dimensional modeling software to view its porous structure. If it meets the requirements, a porous structure that meets the needs is generated. If it does not meet the requirements, the size range of the tetrahedron unit and the porosity distribution can be adjusted through steps 3-4.

[0045] As Figure 3 shown is a schematic diagram of the porous structure under different porosity distributions of the same configuration in this embodiment. For example, for a regular hexahedron three-dimensional configuration, the porosity distribution can be set from different dimensions. Among them represents that the porosity distribution of the regular hexahedron gradually increases along the positive x-axis direction, represents that the porosity distribution of the regular hexahedron gradually increases along the positive x-axis and y-axis directions respectively, represents that the porosity distribution of the regular hexahedron gradually increases along the positive x-axis, y-axis and z-axis directions. The range of the set porosity is 0.1 to 0.9. The centroid coordinates of each tetrahedron unit are C ij , (j = 1, 2, 3) respectively represent the coordinate values in the x, y, and z coordinate axis directions, and i represents the i-th tetrahedron. x min , x max , y min , y max , z min , z max respectively represent the minimum and maximum values among the centroid coordinates of all tetrahedrons. By setting different porosity distributions, different porous structures can be obtained as Figure 3as shown

[0046] As Figure 4 Shown are schematic diagrams of the porous structure of different configurations of this embodiment under different porosity distributions. By selecting different three-dimensional configurations, such as setting the three-dimensional configurations of spheres, cylinders, tigers, and giraffes and setting the corresponding porosity distributions, the corresponding three-dimensional closed-cell structures can be obtained.

[0047] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for generating a three-dimensional closed-cell structure, Features: The following steps are involved: S1: Determine the three-dimensional model parameters of the target porous structure, that is, the geometric information of the three-dimensional configuration; S2: Set the size range of the tetrahedral mesh and select an appropriate finite element meshing algorithm to perform tetrahedral meshing on the three-dimensional structure; S3: determining the porosity distribution of the target three-dimensional closed-cell structure; S4: Generate geometric information of the target porous structure using a closed-cell structure generation algorithm; the closed-cell structure generation algorithm in step S4 specifically includes the following steps: S41: Read and process the obtained tetrahedron node coordinates and unit information; S42: According to the porosity distribution, the body center of each tetrahedron unit is kept unchanged, and the vertex coordinates of the large tetrahedron are scaled to obtain the vertex coordinates of the new small tetrahedron; S43: According to the eight vertex coordinates of each large tetrahedron and small tetrahedron unit, firstly, a closed-cell tetrahedron hole structure is divided into two parts, that is, a vertex of a large tetrahedron is selected, and then the closed-cell tetrahedron is bisected from the vertex to form two non-hole solid three-dimensional structures; then the surface of the structure is triangulated, that is, the surface of each solid three-dimensional structure is composed of 12 triangular units, and the other half of the solid three-dimensional structure is also generated according to this method, that is, each closed-cell tetrahedron unit is composed of two non-hole solid three-dimensional structures, and the surface of each solid three-dimensional structure is composed of 12 triangular units; then all tetrahedron units are processed through the above process to obtain multiple triangular units and node information, and these units and node information are simultaneously read into an obj file to realize the three-dimensional closed-cell structure generated by 3D printing, and the three-dimensional closed-cell structure has the characteristics of target porosity distribution; S44: Finally, the obj file of the generated three-dimensional porous structure is imported into the three-dimensional modeling software to view its porous structure. If it meets the requirements, a porous structure that meets the requirements is generated. If it does not meet the requirements, the tetrahedral unit size range and porosity distribution are adjusted through step S2.

2. The method for generating a three-dimensional closed-cell structure according to claim 1, Features: Step S1 specifically includes: determining the geometric parameters of the target three-dimensional configuration and saving them in a three-dimensional model file format.

3. The method for generating a three-dimensional closed-cell structure according to claim 1, Features: Step S2 specifically includes the following steps: S21: Import the 3D model file into the finite element meshing software Gmesh; S22: Select the appropriate finite element meshing algorithm in Gmesh and set the minimum and maximum tetrahedral mesh sizes; S23: After the setting is completed, the three-dimensional model is divided into tetrahedral meshes to obtain the unit and node information of each tetrahedron.

4. The method for generating a three-dimensional closed-cell structure according to claim 1, Features: Step S3 determines the porosity distribution of the target three-dimensional closed-cell structure, specifically comprising the following steps: First, set the porosity of each tetrahedral element to n is the number of tetrahedral elements divided by the finite element algorithm, C i is a constant greater than or equal to 0 and less than 1. i represents the i-th tetrahedron, and the porosity distribution is expressed by the following formula:

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