Three-dimensional structure construction method based on mesh division and variable cross-section curved rod connection

Abstract

The application discloses a three-dimensional structure construction method based on grid division and variable cross-section curved rod connection, and comprises the following steps: determining three-dimensional model parameters of a target three-dimensional curved rod porous structure; acquiring grid information; setting curved rod parameters required by the target three-dimensional curved rod porous structure; combining the grid information and the curved rod parameters required by the target three-dimensional curved rod porous structure, and generating geometric parameters of the target three-dimensional curved rod porous structure by using a parameterized curved rod structure generation algorithm; and generating the target three-dimensional curved rod porous structure when the geometric parameters of the target three-dimensional curved rod porous structure are in a preset range. Therefore, not only can the three-dimensional structure connected by the curved rod with variable cross-section be generated, but also the related parameters of the curved rod can be regulated according to the target requirement, so that the designability and universality of the three-dimensional structure construction method based on the grid division and the curved rod connection with variable cross-section are remarkably improved.

Description

A 3D Structure Construction Method Based on Mesh Generation and Variable Cross-Section Curved Rod Connection Technical Field

[0001] This invention relates to the field of porous structure design technology, and in particular to a method for constructing three-dimensional structures based on mesh generation and variable cross-section curved rod connections. Background Technology

[0002] Porous structures are networked systems composed of interconnected solid edges and walls. Their unique pore distribution characteristics give them a combination of high strength ratio, high stiffness ratio, and excellent impact resistance and vibration reduction performance, thus making them widely used in mechanical engineering, building structures, aerospace and biomedicine.

[0003] Chinese patent (publication number: CN120339505A; publication date: 2025-07-18) discloses a method, system, device, and medium for constructing a three-dimensional gear structure. This application discloses a method, system, device, and medium for constructing a three-dimensional gear structure. This method acquires at least two sets of regional point cloud data of the gear to be tested and the corresponding gear rotation angles of the regional point cloud data. The regional point cloud data is obtained by scanning with a laser scanner based on the gear rotation angle adjusted by a multi-axis rotation clamping mechanism. The gear rotation angles corresponding to any two sets of regional point cloud data are different. The rotation center axis of the gear to be tested is calculated based on all regional point cloud data. Based on the rotation center axis and the gear rotation angles corresponding to the regional point cloud data, each pair of adjacent regional point cloud data is registered to obtain registered regional point cloud data. Based on the registered regional point cloud data, the pose map structure of the gear to be tested is constructed to obtain the three-dimensional structure of the gear to be tested. This method can comprehensively scan helical tooth surfaces with complex curved surfaces and achieve non-contact, efficient, and high-precision detection of gears.

[0004] A Chinese patent (publication number: CN114078183B; publication date: 2023-06-20) discloses a method for reconstructing the three-dimensional structure of porous media. This application discloses a method for reconstructing the three-dimensional structure of porous media. It obtains a three-dimensional structure reconstruction model by learning the three-dimensional rock sample sedimentary arrangement features and training the generative adversarial neural network based on sample slice data of three-dimensional image samples of porous media. Since the model introduces the three-dimensional rock sample sedimentary arrangement feature learning and feature transfer training links in the training process, it can obtain more realistic three-dimensional structure information of porous media based on two-dimensional digital core images, thereby improving the efficiency of the three-dimensional structure reconstruction process of porous media and making the reconstructed three-dimensional structure more valuable for reference.

[0005] Although the two patent documents mentioned above can successfully construct three-dimensional structures, they cannot generate three-dimensional structures based on variable cross-section curved rods. Moreover, the three-dimensional structure generation technology has problems such as high geometric complexity, high design difficulty, high manufacturing requirements and low experimental accuracy. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a method for constructing three-dimensional structures based on mesh generation and variable cross-section curved bar connections. This method is not only simpler but also allows for precise control of the relevant parameters of the curved bars in the generated target three-dimensional curved bar porous structure.

[0007] A method for constructing a three-dimensional structure based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention includes: determining the three-dimensional model parameters of a target three-dimensional curved bar porous structure; setting the size range of a tetrahedral mesh, and performing tetrahedral mesh generation on the three-dimensional model parameters of the target three-dimensional curved bar porous structure using a corresponding finite element mesh generation algorithm to obtain mesh information; setting the required curved bar parameters for the target three-dimensional curved bar porous structure; combining the mesh information and the required curved bar parameters for the target three-dimensional curved bar porous structure, generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm; determining whether the geometric parameters of the target three-dimensional curved bar porous structure are within a preset range; when the geometric parameters of the target three-dimensional curved bar porous structure are not within the preset range, adjusting the required curved bar parameters and / or the mesh information for the target three-dimensional curved bar porous structure; and generating the target three-dimensional curved bar porous structure when the geometric parameters of the target three-dimensional curved bar porous structure are within the preset range.

[0008] Therefore, not only can 3D structures with arbitrary variable cross-section curved bar connections be generated, but the relevant parameters of the curved bar can also be adjusted according to the target requirements, significantly improving the designability and universality of the 3D structure construction method based on mesh generation and variable cross-section curved bar connections.

[0009] In some examples of the present invention, the step of setting the size range of the tetrahedral mesh further includes, before the step of setting the size range of the tetrahedral mesh, determining the geometric parameters of the target three-dimensional configuration and saving them as a three-dimensional model file; importing the three-dimensional model file into a finite element meshing software, and performing tetrahedral meshing on the three-dimensional model parameters of the target three-dimensional curved bar porous structure using a corresponding finite element meshing algorithm, wherein the finite element meshing software stores the corresponding finite element meshing algorithm.

[0010] In some examples of the present invention, the steps of setting the size range of the tetrahedral mesh and performing tetrahedral meshing on the three-dimensional model parameters of the target three-dimensional curved bar porous structure using a corresponding finite element meshing algorithm to obtain mesh information include: selecting a corresponding finite element meshing algorithm in the finite element meshing software; setting the minimum and maximum tetrahedral mesh sizes; and after setting, performing tetrahedral meshing on the structure using the corresponding finite element meshing algorithm to obtain the element and node information of each tetrahedron.

[0011] In some examples of the present invention, the required crank parameters for the target three-dimensional crank porous structure include: the shape of the crank. And the radius parameter R(t) of the curved bar cross section.

[0012] In some examples of this invention, when the central axis of the crank is a sine wave, the formula for setting the shape of the crank is:

[0013] ,in, Let P(t) be the spatial parametric equation of the crank axis, and P(t) be the original linear parametric equation. δ is the direction vector, t is the offset distance, and t is the normalized path parameter between the two endpoints, used to control the distribution of the curved rod shape along its length, t∈[0,1].

[0014] In some examples of the present invention, the step of generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm, combining the mesh information and the curved bar parameters required for the target three-dimensional curved bar porous structure, includes: reading and processing the obtained tetrahedral node coordinates and element information; defining edges using node numbers, fixing the endpoint and midpoint positions of each bar, and offsetting one of the two quarter points centrifugally relative to the tetrahedral center and the other centripetally relative to the tetrahedral center to obtain the coordinates of five points on each edge; connecting the five points on each edge to form a sine line, and processing all edges as described above to obtain a solid constructed from the sine line; and determining the cross-sectional radius of the curved bar in the solid constructed from the sine line.

[0015] In some examples of this invention, when the central axis of the crank is a helix and the two ends of the crank are smoothly connected, the formula for setting the shape of the crank is as follows:

[0016] ,in,

[0017] in, The spatial parametric equation for the axis of the crankshaft is given. It is a piecewise function, in and hour, =0, the two parts of the curved rod on each side construct a straight rod; in hour, The curved rods on each side form the helical rod. Let the coordinates be the starting coordinates of each edge. The distance from the starting point to the ending point. is a unit direction vector and r is the radius of the crank screw helix. The number of turns of the crank screw. and It is perpendicular to The unit vector is t, which is the normalized path parameter between the two endpoints and is used to control the distribution of the curved rod shape along its length, t∈[0,1].

[0018] In some examples of the present invention, the step of generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm, combining the mesh information and the curved bar parameters required for the target three-dimensional curved bar porous structure, includes: reading and processing the obtained tetrahedral node coordinates and element information; defining edges using node numbers, taking one-fifth to one-fifth and four-fifths of each edge, setting the area between the starting point and one-fifth of the point, and between four-fifths and the ending point as straight bars, setting the area between one-fifths and four-fifths as helical bars, smoothing the transition between the helical bars and the straight bars, and generating small balls at the starting and ending points of each bar, so as to construct a solid by processing all edges as described above; determining the cross-sectional radius of the curved bar and the diameter of the small ball in the constructed solid, wherein the diameter of the small ball is 1.5 times the maximum diameter of the bar.

[0019] In some examples of the present invention, the radius of the curved bar cross section includes at least one of constant, linear variation, nonlinear variation, regular variation, and irregular variation.

[0020] In some examples of the present invention, the step of determining the cross-sectional radius of the curved rod in the constructed entity includes: when the radius is a fixed radius, directly setting the radius value of the cross-section of the curved rod, i.e., R(t) = A; when the radius is a variable radius, first setting the fixed radius values ​​of the cross-sections at both ends of the curved rod, and the change in the radius between the two ends of the curved rod is determined by the... Function control, Let be the radius of the cross section at the starting point of the curved rod. Let B be the radius of the cross-section at the end of the curved rod; when the radius is variable, set one end of the curved rod cross-section to a fixed radius value B, and the radius of the curved rod cross-section changes from one end to the other in the direction of extension. Function control.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 is a flowchart of a three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention;

[0024] Figure 2 is one of the partial flowcharts of a three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention;

[0025] Figure 3 is a partial flowchart of a three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention;

[0026] Figure 4 is a partial flowchart of a three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention;

[0027] Figure 5 is a partial flowchart of the three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention;

[0028] Figure 6 is a solid figure of a curved rod whose center line of each side is constructed from a sine curve according to an embodiment of the present invention.

[0029] Figure 7 is a solid figure of the curved rod shape constructed by the position function P(k) for the center line of each side of the curved rod according to an embodiment of the present invention. Detailed Implementation

[0030] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0031] The following describes a three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention, with reference to Figures 1-7.

[0032] Referring to Figures 1-7, the three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to the present invention mainly includes the following steps:

[0033] S1. Determine the three-dimensional model parameters of the target three-dimensional curved bar porous structure;

[0034] S2. Set the size range of the tetrahedral mesh, and use the corresponding finite element meshing algorithm to perform tetrahedral meshing on the three-dimensional model parameters of the target three-dimensional curved bar porous structure to obtain mesh information;

[0035] S3. Set the crank parameters required for the target three-dimensional curved bar porous structure;

[0036] S4. Combining the mesh information and the crank parameters required for the target three-dimensional curved bar porous structure, a parametric curved bar structure generation algorithm is used to generate the three-dimensional curved bar porous structure.

[0037] S5. Determine whether the geometric parameters of the three-dimensional curved bar porous structure are within the preset range;

[0038] S6. When the geometric parameters of the three-dimensional curved bar porous structure are not within the preset range, adjust the bar parameters and / or mesh information required for the three-dimensional curved bar porous structure.

[0039] S7. When the geometric parameters of the three-dimensional curved bar porous structure are within the preset range, the target three-dimensional curved bar porous structure is generated.

[0040] Specifically, in existing technologies, the Voronoi method is a commonly used approach for generating three-dimensional curved bar cell structures that adapt to shape changes and possess robust functionality. However, this method lacks the precise control over key parameters defining variable cross-section curved bars, such as the central axis and cross-sectional shape dimensions and their continuous changes. Consequently, it cannot generate curved bars with variable cross-sections, nor can it adjust the curvature and diameter of the curved bars.

[0041] Therefore, in some embodiments of the present invention, the three-dimensional model parameters of the target three-dimensional curved bar porous structure are first divided into tetrahedral meshes using a finite element mesh generation algorithm to obtain mesh information. Then, by setting the required curved bar parameters for the target three-dimensional curved bar porous structure, the geometric parameters of the target three-dimensional curved bar porous structure can be generated using a parametric curved bar structure generation algorithm, combining the mesh information and the required curved bar parameters. This makes the generated target three-dimensional curved bar porous structure simpler and more direct, and reduces the difficulty of generating the target three-dimensional curved bar porous structure.

[0042] Furthermore, after generating the geometric parameters of the target three-dimensional curved bar porous structure using the parametric curved bar structure generation algorithm, it is necessary to determine whether the geometric parameters of the target three-dimensional curved bar porous structure are within a preset range. If the geometric parameters of the target three-dimensional curved bar porous structure are not within the preset range, the required curved bar parameters and / or mesh information of the target three-dimensional curved bar porous structure are adjusted. If the geometric parameters of the target three-dimensional curved bar porous structure are within the preset range, the target three-dimensional curved bar porous structure is generated. With this setting, the three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection of this embodiment of the invention can also precisely control the parameters of the target three-dimensional curved bar porous structure according to requirements. This can further significantly improve the designability and universality of the three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection of this embodiment of the invention, and make the designed target three-dimensional curved bar porous structure more accurate.

[0043] In some embodiments of the present invention, after generating the geometric parameters of the target three-dimensional curved bar porous structure using a parameterized curved bar structure generation algorithm, determining whether the geometric parameters of the target three-dimensional curved bar porous structure are within a preset range specifically refers to determining whether the porosity of the target three-dimensional curved bar porous structure is within a preset range, whether all the curved bars in the target three-dimensional curved bar porous structure are connected as a whole, whether the dimensions of the curved bars in the target three-dimensional curved bar porous structure meet the requirements of minimum diameter and maximum length, whether the topological structure of the target three-dimensional curved bar porous structure meets the requirements of periodicity, randomness, and symmetry, and whether the target three-dimensional curved bar porous structure meets the requirements of strength, stiffness, and toughness.

[0044] Additionally, it should be noted that when determining whether the target three-dimensional curved bar porous structure meets the requirements for strength, stiffness, toughness, etc., it is necessary to verify it through finite element simulation.

[0045] Furthermore, generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm includes the following steps:

[0046] Extract the structural skeleton based on Voronoi diagrams or Delaunay diagrams, or construct a path diagram based on grid cell centers;

[0047] Smooth the skeleton path and control the curvature, length, and connection method of the path;

[0048] Generate a curved rod with a certain cross-section along the skeleton path;

[0049] All curved rods are merged into a single unit using Boolean operations (union), and nodes or connecting structures are added at the intersections of the curved rods to generate the geometric parameters of the target three-dimensional curved rod porous structure.

[0050] Referring to Figure 2, the tetrahedral mesh size range is set, and the three-dimensional model parameters of the target three-dimensional curved bar porous structure are tetrahedral meshed using the corresponding finite element meshing algorithm. Before obtaining the mesh information, the following steps are also included: determining the geometric parameters of the target three-dimensional configuration and saving them as a three-dimensional model file; importing the three-dimensional model file into the finite element meshing software, and tetrahedral meshing of the three-dimensional model parameters of the target three-dimensional curved bar porous structure is performed using the corresponding finite element meshing algorithm. The finite element meshing software stores the corresponding finite element meshing algorithm.

[0051] In some specific embodiments of the present invention, the three-dimensional model file format can be STP format.

[0052] In some specific embodiments of the present invention, the finite element mesh generation software can be Hypermesh software, which is a mature software in the prior art and will not be described in detail here.

[0053] Referring to Figure 3, the size range of the tetrahedral mesh is set, and the three-dimensional model parameters of the target three-dimensional curved bar porous structure are divided into tetrahedral meshes using the corresponding finite element meshing algorithm. The steps to obtain mesh information include: selecting the corresponding finite element meshing algorithm in the finite element meshing software; setting the minimum and maximum tetrahedral mesh sizes; and after setting, performing tetrahedral meshing on the structure using the corresponding finite element meshing algorithm to obtain the element and node information of each tetrahedron.

[0054] Specifically, the finite element meshing algorithm in finite element meshing software is used to perform tetrahedral meshing on the 3D model parameters of the target 3D curved bar porous structure, thereby obtaining the element and node information of each tetrahedron. It should be noted that the finite element meshing algorithm discretizes the continuous geometric model, that is, the 3D model parameters of the target 3D curved bar porous structure, into a mesh composed of multiple simple shapes (elements) for numerical analysis.

[0055] It should be noted that the minimum tetrahedral mesh size can control the degree of mesh refinement in critical areas (such as the connection of the curved rod), while the maximum tetrahedral mesh size controls the overall mesh density and affects computational efficiency. Together, they determine the local refinement and global coarsening strategies of the mesh.

[0056] In some embodiments of the present invention, the crank parameters required for the target three-dimensional crank porous structure include: the shape of the crank and the size of the crank cross-section radius.

[0057] Furthermore, the parameters of the crank can also include the size of the cross-section and the length of the crank path.

[0058] After determining that the geometric parameters of the target three-dimensional curved bar porous structure are not within the preset range, not only can the required curved bar parameters of the target three-dimensional curved bar porous structure be adjusted, but the mesh information can also be adjusted. Specifically, the size of the mesh can be adjusted, or the region or mesh type can be refined.

[0059] In addition, in some other specific embodiments of the present invention, after determining that the geometric parameters of the target three-dimensional curved bar porous structure are not within the preset range, the parameterized curved bar structure generation algorithm can be adjusted. For example, the skeleton extraction method, path optimization strategy and closed hole connection method of the parameterized curved bar structure generation algorithm can be adjusted.

[0060] In a first embodiment of the present invention, when the central axis of the crank is a sine wave, the formula for setting the shape of the crank is:

[0061] ,

[0062] in Let P(t) be the spatial parametric equation of the crank axis, and P(t) be the original linear parametric equation. δ is the direction vector, t is the offset distance, and t is the normalized path parameter between the two endpoints, used to control the distribution of the curved rod shape along its length, t∈[0,1].

[0063] It should be noted that the shape of the target three-dimensional curved rod porous structure is set according to the requirements of the label. There are multiple ways to set the shape of the target three-dimensional curved rod porous structure. Here, the shape of the curved rod is set using a sine line. Specifically, the original straight path (such as a straight line connecting two points) is disturbed by a sine function to form a wavy curved rod.

[0064] Let the parametric equation of the original line segment be:

[0065] P(t) = P0 + t ,t∈[0,1],

[0066] Where: P0 is the coordinate of the starting point of the line segment. is the direction vector of the two ends of the curved rod; t is the normalized path parameter between the two ends, used to control the distribution of the curved rod shape along its length, 0≤t≤1.

[0067] Based on this, a sinusoidal perturbation is added, that is, a perturbation can be added perpendicular to the direction vector. In the plane, add a sinusoidal offset:

[0068] ,

[0069] Where δ is the offset distance, δ can control the bending amplitude of the crank.

[0070] The radius setting formula is R(t), which can control the radius at different positions of the rod.

[0071] Referring to Figure 4, the steps for generating the geometric parameters of the target 3D curved bar porous structure using a parametric curved bar structure generation algorithm, based on mesh information and the required curved bar parameters, include: reading and processing the obtained tetrahedral node coordinates and element information; defining edges using node numbers, fixing the endpoint and midpoint positions of each edge, and offsetting one of the two quarter points centrifugally relative to the tetrahedral center and the other centripetally relative to the tetrahedral center to obtain the coordinates of five points on each edge; connecting the five points on each edge to form a sine curve, and processing all edges in this way to obtain the solid constructed from the sine curve; and determining the cross-sectional radius of the curved bar in the solid constructed from the sine curve.

[0072] Specifically, firstly, five points are defined on each side of the tetrahedron: the two endpoints of each side, the center point of each side, and the two quarter points of each side. First, the two endpoints and one center point of each side are fixed. Then, the two quarter points of each side are arranged as described above. The sine parametric equation is subjected to sinusoidal perturbation bias. Specifically, one of the two quarter points of each side is centripetally biased and the other is centrifugally biased. This can introduce a certain asymmetry or specific shape into the generated sine curve path, thereby generating a three-dimensional curved bar porous structure.

[0073] In some specific embodiments of the present invention, while ensuring that one of the two quarter points on a part of the tetrahedron's edge is centrifugally offset and the other is centripetally offset, the two quarter points on the other part of the edge can be centripetally offset or centrifugally offset. This can be selectively set according to specific needs, which can further improve the applicability of the three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection.

[0074] Furthermore, by simultaneously importing the cross-sectional radius of the curved rod in the solid constructed from the sine curve and the sine curve formed by connecting five points on each side into a .dat file, a target three-dimensional curved rod porous structure that can be generated using 3D printing can be achieved. This target three-dimensional curved rod porous structure has the target curved rod shape and cross-sectional radius. Finally, the generated three-dimensional porous structure .dat file is imported into 3D modeling software to view its porous structure. If it meets the requirements, a target three-dimensional curved rod porous structure that meets the requirements is generated. If it does not meet the requirements, the shape and cross-sectional radius of the curved rod can be adjusted.

[0075] The radius control formula can be set to control the distribution of the radius along the extension of the member.

[0076] Furthermore, it should be noted that determining the three-dimensional model parameters of the target three-dimensional curved bar porous structure in step S1 is also determining the geometric information of the three-dimensional configuration. Figure 6 shows the three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to an embodiment of the present invention. After determining the three-dimensional model parameters of the target three-dimensional curved bar porous structure, the method produces the target three-dimensional curved bar porous structure according to different curved bar shapes and cross-sectional radii. The three embodiments in Figure 6 are all curved bar shape entities constructed by sine lines. The five points on each side of the curved bar shape entity are connected to form an irregular wavy sine line.

[0077] In a second embodiment of the present invention, when the central axis of the crank is a helix and the two ends of the crank are smoothly connected, the formula for setting the shape of the crank is:

[0078] ,in,

[0079] ,

[0080] in, The spatial parametric equation for the axis of the crankshaft is given. It is a piecewise function, in and hour, =0, the two parts of the curved rod on each side construct a straight rod; in hour, The curved rods on each side form the helical rod.

[0081] Let the coordinates be the starting coordinates of each edge. The distance from the starting point to the ending point. is a unit direction vector and r is the radius of the crank screw helix. The number of turns of the crank screw. and It is perpendicular to The unit vector is t, which is the normalized path parameter between the two endpoints and is used to control the distribution of the curved rod shape along its length, t∈[0,1].

[0082] Referring to Figure 5, the steps for generating the geometric parameters of the target 3D curved bar porous structure using a parametric curved bar structure generation algorithm, combining mesh information and the required curved bar parameters for the target 3D curved bar porous structure, include:

[0083] Read and process the obtained tetrahedral node coordinates and element information;

[0084] Define edges using node numbers, take one point from the fifth of each edge and one point from the fifth of each edge, set the points between the starting point and the one-fifth point, as well as between the four-fifths point and the ending point, as straight rods, and set the points between the one-fifths point and the four-fifths point as spiral rods. Make the transition between the spiral rods and the straight rods smooth and natural, and generate small balls at the starting point and ending point of each rod, so as to construct a solid by processing all the edges in the above way.

[0085] Determine the cross-sectional radius of the curved rod and the diameter of the small ball in the constructed solid, wherein the diameter of the small ball is 1.5 times the maximum diameter of the rod.

[0086] It should be noted that the straight sections of the curved rods on each side prevent interference between the helical rods of adjacent curved rods, ensuring the structural stability of the curved rods on each side. Furthermore, setting the diameter of the small ball to 1.5 times the maximum diameter of the rod ensures the stability and reliability of the connection between the curved rods of adjacent sides.

[0087] The formula for setting the radius parameter of the curved bar section is: ,

[0088] Furthermore, it should be noted that determining the three-dimensional model parameters of the target three-dimensional curved bar porous structure in step S1 is also determining the geometric information of the three-dimensional configuration. Figure 7 shows the target three-dimensional curved bar porous structure produced by the three-dimensional structure construction method based on mesh division and variable cross-section curved bar connection according to an embodiment of the present invention after determining the three-dimensional model parameters of the target three-dimensional curved bar porous structure, based on different curved bar shapes and cross-sectional radii. The three embodiments in Figure 7 are all curved bar shape entities constructed by the centerline position function P(k) of the curved bar on each side.

[0089] In the first and second embodiments of the present invention, the radius of the curved rod cross section includes at least one of constant, linear variation, nonlinear variation, regular variation and irregular variation. The function of the curved rod shape can be selectively adjusted according to the requirements, and the radius of the curved rod cross section can also be selectively adjusted.

[0090] The following examples illustrate the different radii of three curved bar sections:

[0091] In some embodiments, when the radius is a fixed radius, the radius value of the cross section of the curved rod is directly set, i.e., R(t) = A, where A is a constant. For example, the radius of the cross section of the curved rod is a constant 0.2, which corresponds to the target three-dimensional curved rod porous structure generated in the first row of FIG6 of the first embodiment of the present invention and the first row of FIG7 of the second embodiment of the present invention.

[0092] In other embodiments, a fixed radius value for the cross-sections at both ends of the curved rod is first set, and the variation of the radius between the two ends of the curved rod is determined by the... Function control, Let be the radius of the cross section at the starting point of the curved rod. Let be the radius of the cross-section at the end of the curved rod. At this point, the radius of the curved rod changes linearly. For example, the radius at one end of the curved rod cross-section is 0.1, and the radius at the other end is 0.5. The radius change between the two ends of the curved rod is determined by... The function control corresponds to the target three-dimensional curved bar porous structure generated in the second row of Figure 6 of the first embodiment of the present invention and the second row of Figure 7 of the second embodiment of the present invention.

[0093] In some other embodiments, one end of the curved rod cross-section is set to a fixed radius value B, and the radius of the curved rod cross-section varies in the direction extending from one end to the other. Function control is used, where the radius of the crank changes exponentially. For example, if one end of the crank's cross-section is fixed at 0.1, the radius of the crank's cross-section changes exponentially in the direction extending from one end to the other. The function control corresponds to the target three-dimensional curved bar porous structure generated in the third row of Figure 6 of the first embodiment of the present invention and the third row of Figure 7 of the second embodiment of the present invention.

[0094] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0095] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0096] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for constructing a three-dimensional structure based on mesh generation and variable cross-section curved bar connection, characterized in that, Includes the following steps: Determine the three-dimensional model parameters of the target three-dimensional curved bar porous structure; The size range of the tetrahedral mesh is set, and the three-dimensional model parameters of the target three-dimensional curved bar porous structure are divided into tetrahedral meshes using the corresponding finite element mesh generation algorithm to obtain mesh information. The required parameters for setting the target three-dimensional curved bar porous structure are as follows: the curved bar parameters include the shape of the curved bar. The radius parameter R(t) of the curved rod cross-section; when the central axis of the curved rod is a sine line, the formula for setting the shape of the curved rod is: ,in, Let P(t) be the spatial parametric equation of the crank axis, and P(t) be the original linear parametric equation. Let be the direction vector, δ be the offset distance, and t be the normalized path parameter between the two endpoints, used to control the distribution of the curved rod shape along its length, t∈[0,1]. When the central axis of the curved rod is a helix and the two ends of the curved rod are smoothly connected, the formula for setting the shape of the curved rod is: ,in, in, The spatial parametric equation for the axis of the crankshaft is given. It is a piecewise function, in and hour, =0, the two parts of the curved rod on each side construct a straight rod; in hour, The curved rods on each side form the helical rod. Let the coordinates be the starting coordinates of each edge. The distance from the starting point to the ending point. is a unit direction vector and r is the radius of the crank screw helix. The number of turns of the crank screw. and It is perpendicular to The unit vector is t, which is the normalized path parameter between the two endpoints, used to control the distribution of the curved rod shape along the length, t∈[0,1]. Combining the mesh information and the curved rod parameters required for the target three-dimensional curved rod porous structure, a parametric curved rod structure generation algorithm is used to generate the three-dimensional curved rod porous structure. It is determined whether the geometric parameters of the three-dimensional curved rod porous structure are within a preset range. When the geometric parameters of the three-dimensional curved rod porous structure are not within the preset range, the curved rod parameters and / or the mesh information required for the three-dimensional curved rod porous structure are adjusted. When the geometric parameters of the three-dimensional curved rod porous structure are within the preset range, the target three-dimensional curved rod porous structure is generated.

2. The three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection according to claim 1, characterized in that, Before the step of setting the size range of the tetrahedral mesh, the method further includes: determining the geometric parameters of the target three-dimensional configuration and saving them as a three-dimensional model file; importing the three-dimensional model file into a finite element meshing software, and performing tetrahedral meshing on the three-dimensional model parameters of the target three-dimensional curved bar porous structure using a corresponding finite element meshing algorithm, wherein the finite element meshing software stores the corresponding finite element meshing algorithm.

3. The three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection according to claim 1, characterized in that, The steps of setting the size range of the tetrahedral mesh and performing tetrahedral meshing on the three-dimensional model parameters of the target three-dimensional curved bar porous structure using the corresponding finite element meshing algorithm to obtain mesh information include: selecting the corresponding finite element meshing algorithm in the finite element meshing software; setting the minimum and maximum tetrahedral mesh sizes; and after setting, performing tetrahedral meshing on the structure using the corresponding finite element meshing algorithm to obtain the element and node information of each tetrahedron.

4. The three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection according to claim 1, characterized in that, The steps of generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm, combining the mesh information and the required curved bar parameters of the target three-dimensional curved bar porous structure, include: reading and processing the obtained tetrahedral node coordinates and element information; defining edges using node numbers, fixing the endpoint and midpoint positions of each bar, and offsetting one of the two quarter points centrifugally relative to the tetrahedral center and the other centripetally relative to the tetrahedral center to obtain the coordinates of five points on each edge; connecting the five points on each edge to form a sine line, and processing all edges as described above to obtain a solid constructed from the sine line; and determining the cross-sectional radius of the curved bar in the solid constructed from the sine line.

5. The three-dimensional structure construction method based on mesh generation and variable cross-section curved bar connection according to claim 1, characterized in that, The steps of generating the geometric parameters of the target three-dimensional curved bar porous structure using a parametric curved bar structure generation algorithm, combining the mesh information and the required curved bar parameters of the target three-dimensional curved bar porous structure, include: reading and processing the obtained tetrahedral node coordinates and element information; defining edges using node numbers, taking one-fifth to one-fifth and four-fifths of each edge, setting the area between the starting point and one-fifth of the point, and between four-fifths and the ending point as straight bars, setting the area between one-fifths and four-fifths as helical bars, smoothing the transition between the helical bars and the straight bars, and generating small spheres at the starting and ending points of each bar, so that all edges are processed in the above way to construct a solid; determining the cross-sectional radius of the curved bar and the diameter of the small sphere in the constructed solid, wherein the diameter of the small sphere is 1.5 times the maximum diameter of the bar.

6. The three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection according to claim 1, characterized in that, The radius of the curved bar cross section includes at least one of the following: constant, linear variation, nonlinear variation, regular variation, and irregular variation.

7. The three-dimensional structure construction method based on mesh generation and variable cross-section curved rod connection according to claim 1, characterized in that, The step of determining the cross-sectional radius of the curved rod in the constructed entity includes: when the radius is a fixed radius, directly setting the radius value of the curved rod's cross-section, i.e., R(t) = A; when the radius is a variable radius, first setting the fixed radius values ​​of the cross-sections at both ends of the curved rod, and then adjusting the radius between the two ends of the curved rod by... Function control, Let be the radius of the cross section at the starting point of the curved rod. Let B be the radius of the cross-section at the end of the curved rod; when the radius is variable, set one end of the curved rod cross-section to a fixed radius value B, and the radius of the curved rod cross-section changes from one end to the other in the direction of extension. Function control.

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