Isogeometric topology optimization method, device and equipment based on body spatial domain mapping model and medium

Abstract

The application provides an isogeometric topology optimization method and device based on a body space domain mapping model, equipment and medium, relating to the isogeometric topology optimization technical field, and the method comprises the following steps: generating a reconstructed mapping body model according to a mapping point set obtained according to triangle facet information of a to-be-optimized geometric model and an initial mapping body model generated based on the mapping point set and a three-dimensional NURBS body; marking a design domain based on the reconstructed mapping body model and assembling a preset target structure parameter matrix; taking model construction parameters of the design domain as design variables, taking minimization of preset target structure parameters as an optimization target, constructing a preset isogeometric topology optimization model, updating the design variables of the preset isogeometric topology optimization model based on sensitivity by using an optimization criterion method, until a preset convergence condition is met, obtaining a target geometric model corresponding to the to-be-optimized geometric model, and solving the problem that the existing isogeometric topology optimization method is difficult to be used in topology optimization engineering application of a complex topology structure model.

Description

Technical Field

[0001] The present application relates to the technical field of isogeometric topology optimization, and in particular to an isogeometric topology optimization method, apparatus, device and medium based on a volume space domain mapping model. Background Art

[0002] Computer-aided design (CAD) and computer-aided engineering (CAE) in engineering design are indispensable in existing digital manufacturing. During the product design process, continuous optimization is required to meet the design performance requirements. That is, the product geometric model structure design is generated in CAD software, and then imported into CAE software to build the corresponding physical model for simulation analysis. If the result meets the product performance requirements, the design is completed. Otherwise, it is necessary to return to the CAD software for structural adjustment and simulation analysis again. The conversion cycle of geometric model design and physical model analysis is continuously carried out until the requirements are met.

[0003] Isogeometric analysis (IGA) integrates the fields of CAD and CAE by using the same basis functions to represent approximate solutions for both geometric models (CAD) and physical models (CAE). Topology optimization is a numerical iterative procedure that finds the optimal material distribution by following a specified objective function and constraints within a predefined design domain. Its advantages include significantly saving material and improving structural performance. However, topology optimization methods based on the finite element method (FEM) also struggle to ensure the smoothness of discrete models on surface boundaries. Isogeometric analysis, with its advantages of high precision and continuity, has been applied to the field of topology optimization and has replaced finite elements in topology optimization, becoming known as isogeometric topology optimization. Although IGA offers advantages in mesh refinement, computational accuracy, and stability, the tensor product structure of NURBS and the non-interpolation nature of its basis functions make the construction of isogeometric models, especially those of complex structures, a significant challenge for the application of IGA and its topology optimization.

[0004] Therefore, although isogeometric topology optimization is very successful for engineering applications of simple structural geometric models, it is rarely successfully applied to most engineering analysis models with complex topological structures. To solve the problems of isogeometric topology optimization of complex models, it is necessary to propose a method to construct a volume space domain mapping model and implement isogeometric topology optimization based on this mapping model. Summary of the Invention

[0005] The purpose of this application is to address the above problems and provide an isogeometric topology optimization method, device, equipment and medium based on a volume space domain mapping model to solve the problem that existing isogeometric topology optimization methods are difficult to use in topology optimization engineering applications of complex topological structure models.

[0006] In a first aspect, the present application provides an isogeometric topology optimization method based on a volume space domain mapping model, comprising:

[0007] Acquire a mapping point set according to the triangular facet information of the geometric model to be optimized, and generate an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume;

[0008] generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model;

[0009] Marking the design domain based on the reconstructed mapping model and assembling a preset target structural parameter matrix, using the model construction parameters of the design domain as design variables and minimizing the preset target structural parameters as the optimization goal, to construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0010] The sensitivity of the preset isogeometric topology optimization model is calculated, and the design variables of the preset isogeometric topology optimization model are updated using an optimization criterion method based on the sensitivity until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized.

[0011] According to the technical solution provided by the present application, the step of obtaining a mapping point set based on the triangular facet information of the geometric model to be optimized and generating an initial mapping body model based on the mapping point set and the three-dimensional NURBS body includes:

[0012] Acquire triangular facet information of the geometric model to be optimized, and acquire a mapping point set corresponding to the geometric model to be optimized based on the triangular facet information;

[0013] A three-dimensional NURBS body is constructed, and the mapping point set is mapped to corresponding positions of the three-dimensional NURBS body to form an initial mapping body model.

[0014] According to the technical solution provided by the present application, the step of obtaining triangular facet information of the geometric model to be optimized and obtaining a mapping point set corresponding to the geometric model to be optimized based on the triangular facet information includes:

[0015] Read the triangular facet information of the geometric model to be optimized, and extract the vertex information of the triangular facet of the geometric model to be optimized;

[0016] Based on the triangle patch vertex information and a preset interpolation density, interpolation processing is performed on the triangle patch vertices to obtain mapping points that are not less than a preset density threshold, thereby forming a mapping point set corresponding to the geometric model to be optimized.

[0017] According to the technical solution provided by the present application, generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model includes:

[0018] identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume model;

[0019] The non-mapped cells are divided into imaginary cells and real cells based on the ray method;

[0020] A reconstructed mapping volume model is generated based on the mapping unit and the real unit.

[0021] According to the technical solution provided by the present application, identifying mapping units and non-mapping units based on the mapping point set and the initial mapping volume model includes:

[0022] Obtain the three-dimensional coordinates of each mapping point in the mapping point set in the physical space;

[0023] For each NURBS unit of the initial mapping body model, it is determined whether there is a mapping point falling within its boundary coordinate range according to the three-dimensional coordinates; if so, the NURBS unit is determined to be a mapping unit, otherwise the NURBS unit is determined to be a non-mapping unit.

[0024] According to the technical solution provided in this application, non-mapped units are divided into imaginary units and real units based on the ray method, including:

[0025] For each non-mapping unit, emitting a ray from the non-mapping unit to a preset direction;

[0026] Calculate the number of intersections between the ray and all triangles;

[0027] If it is determined that the number of intersections is an odd number, the non-mapping unit is determined to be a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined to be an imaginary unit.

[0028] According to the technical solution provided by the present application, the target structural parameter is thermal conductivity compliance, and the model construction parameter of the design domain is control point density; accordingly, the design domain is marked based on the reconstructed mapping model and a preset target structural parameter matrix is ​​assembled, the model construction parameters of the design domain are used as design variables, and the preset target structural parameter is minimized as the optimization goal, to construct a preset isogeometric topology optimization model of the geometric model to be optimized, including:

[0029] Marking the area with assembly features in the reconstructed mapping body model as a non-design domain, and marking the remaining areas as a design domain;

[0030] Assembling the thermal conductivity matrices of the mapping unit and the real unit to form a thermal compliance matrix;

[0031] The preset geometric topology optimization model for constructing the geometric model to be optimized is:

[0032] Find:ρ=[ρ 1 ,ρ 2 ,…,ρ i ,…,ρ N ]

[0033] min:J(ρ)=T T K h (ρ) T

[0034] sqFt h (ρ)T=P

[0035] ∫ Ω ρdΩ≤V

[0036] 0<ρ mm <ρ i ≤1

[0037] Where ρ is the design variable, i.e., the density of control points in the design domain, J(ρ) is the target value of thermal conductivity compliance, and K h (ρ) is the thermal conductivity matrix, P and T are the control point heat load and control point temperature respectively, N is the number of control points, V is the maximum volume fraction of the reconstructed mapping model, Ω is the design domain of the model, ρ min is the minimum value of the design variable.

[0038] In a second aspect, the present application provides an isogeometric topology optimization device based on a volume space domain mapping model, comprising:

[0039] A processing module, configured to obtain a mapping point set according to triangular facet information of the geometric model to be optimized, and generate an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume;

[0040] A generating module, configured to generate a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model;

[0041] A construction module is used to mark the design domain based on the reconstructed mapping model and assemble a preset target structural parameter matrix, use the model construction parameters of the design domain as design variables, and take the minimization of the preset target structural parameters as the optimization goal to construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0042] An updating module is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, update the design variables of the preset isogeometric topology optimization model using an optimization criterion method until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized.

[0043] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described above when executing the computer program.

[0044] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, and the computer program implements the method described above when executed by a processor.

[0045] Compared with the prior art, the beneficial effects of the present application are as follows: the isogeometric topology optimization method based on the volume space domain mapping model provided by the present application obtains a mapping point set according to the triangular facet information of the geometric model to be optimized, and generates an initial mapping body model based on the mapping point set and the three-dimensional NURBS body; based on the mapping point set and the initial mapping body model, obtains a reconstructed mapping body model based on the generation; based on the reconstructed mapping body model, the design domain is marked and a preset target structure parameter matrix is ​​assembled, and the model construction parameters of the design domain are used as design variables, and the preset target structure parameters are minimized as the optimization target to construct a preset isogeometric topology optimization model of the geometric model to be optimized; the sensitivity of the preset isogeometric topology optimization model is calculated, and the design variables of the preset isogeometric topology optimization model are updated using the optimization criterion method based on the sensitivity until the preset convergence conditions are met, thereby obtaining the target geometric model corresponding to the geometric model to be optimized. By accurately mapping the CAD model to a refined NURBS regular body, a volume space domain mapping model for isogeometric topology optimization is constructed, which solves the bottleneck that the existing isogeometric topology optimization is difficult to optimize complex models; the ray method is introduced into the construction of the volume space domain mapping model. Compared with the traditional complex analysis model reconstruction method, it fully utilizes the surface information of the CAD model to quickly determine the mapping unit category, with accurate judgment and stable effect, which improves the efficiency of the reconstructed model; the reconstructed mapping volume model is divided into design domain and non-design domain, which are initialized to design variables participating in the optimization and non-design variables not participating in the optimization, to avoid the disappearance of materials with assembly features due to subsequent optimization, laying a solid foundation for the engineering application development of isogeometric topology optimization of complex models.

[0046] It should be understood that the description of technical features, technical solutions, beneficial effects or similar language in this application does not imply that all features and advantages can be realized in any single embodiment. On the contrary, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution or beneficial effect is included in at least one embodiment. Therefore, the description of a technical feature, technical solution or beneficial effect in this specification does not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions and beneficial effects described in the present embodiment can also be combined in any appropriate manner. Those skilled in the art will understand that the embodiment can be implemented without one or more specific technical features, technical solutions or beneficial effects of a specific embodiment. In other embodiments, additional technical features and beneficial effects can also be identified in specific embodiments that do not embody all embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solution in this embodiment, the following is a brief introduction to the drawings required for the description of the embodiment. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0048] Figure 1 A flowchart of an isogeometric topology optimization method based on a volume space domain mapping model provided in an embodiment of the present application;

[0049] Figure 2 A schematic diagram of a geometric model to be optimized provided in an embodiment of the present application;

[0050] Figure 3 A schematic diagram of extracting triangular facet information provided in an embodiment of the present application;

[0051] Figure 4 A schematic diagram of the distribution of mapping points provided in an embodiment of the present application;

[0052] Figure 5 Schematic diagram of NURBS unit provided in the embodiment of the present application;

[0053] Figure 6 A schematic diagram of an initial mapping body model provided in an embodiment of the present application;

[0054] Figure 7 A schematic diagram of triangulating a trimmed surface provided in an embodiment of the present application;

[0055] Figure 8 A schematic diagram of the mapping relationship between the rule parameter domain and the physical domain for mapping point interpolation provided in an embodiment of the present application;

[0056] Figure 9A NURBS unit number conversion into different direction index schematic diagram provided by the embodiment of the present application;

[0057] Figure 10 A NURBS unit type division schematic diagram provided by the embodiment of the present application;

[0058] Figure 11 A reconstruction mapping body model design domain and non-design domain schematic diagram provided by the embodiment of the present application;

[0059] Figure 12 A body space domain mapping model based isometric topology optimization device schematic diagram provided by the embodiment of the present application;

[0060] Figure 13 A schematic diagram of a computer system of an electronic device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0061] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings, and the description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present application. Specifically, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0062] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0063] In order to make the technical solutions of the present application more clear and easy to understand, the body space domain mapping model based isometric topology optimization method provided by the embodiment of the present application is introduced below.

[0064] As shown in Figure 1 , the figure is a flowchart of a body space domain mapping model based isometric topology optimization method provided by the embodiment of the present application, and the method includes the following steps:

[0065] S101, obtaining a mapping point set according to triangular facet information of a geometric model to be optimized, and generating an initial mapping volume model based on the mapping point set and a three-dimensional NURBS volume;

[0066] Specifically, the triangular patch information of the geometric model to be optimized is obtained, and the mapping point set corresponding to the geometric model to be optimized is obtained by interpolation based on the triangular patch information; a three-dimensional NURBS body is constructed, and the mapping point set is mapped to the corresponding positions of the three-dimensional NURBS body to form an initial mapping body model. The geometric model to be optimized is a CAD model; the triangular patch information includes at least the vertex information of the triangular patch, and may also include other information, which can be set and adjusted according to actual conditions and is not specifically limited here. The density of the mapping point set is greater than a preset density threshold, and the preset density threshold can be set and adjusted according to actual conditions and is not specifically limited here.

[0067] S102, generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model;

[0068] Specifically, the mapping point set includes multiple mapping points, and the initial mapping body model includes multiple NURBS units; according to the mapping point set and the initial mapping body model, for each NURBS unit of the initial mapping body model, the NURBS unit containing the mapping point is identified as a mapping unit, and the NURBS unit not containing the mapping point is identified as a non-mapping unit; based on the ray method, the non-mapping unit is divided into imaginary units and real units; and a reconstructed mapping body model is generated based on the mapping units and the real units.

[0069] S103, marking a design domain based on the reconstructed mapping body model and assembling a preset target structural parameter matrix, using the model construction parameters of the design domain as design variables and minimizing the preset target structural parameters as the optimization goal, to construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0070] Specifically, the reconstructed mapping body model is divided into a design domain and a non-design domain according to the assembly features, and the matrices of the preset target structural parameters of the mapping units and the real units are assembled to form the preset target structural parameter matrix. The model construction parameters of the design domain are used as design variables, and the minimum preset target structural parameters are used as the optimization target to construct the preset iso-geometric topology optimization model of the geometric model to be optimized. The preset target structural parameters can be thermal conductivity flexibility or stiffness, or other parameters, which can be set and adjusted according to actual conditions and are not specifically limited here. It is understandable that the virtual units do not participate in the assembly of the preset target structural parameter matrix; in order to avoid the disappearance of materials at locations with assembly features due to subsequent optimization, the model construction parameters of the non-design domain are treated as non-design variables and do not participate in subsequent model optimization.

[0071] S104. Calculate the sensitivity of the preset isogeometric topology optimization model, and update the design variables of the preset isogeometric topology optimization model using an optimization criterion method based on the sensitivity until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized.

[0072] Specifically, the sensitivity of the preset isogeometric topology optimization model is calculated, and based on the sensitivity, the optimization criterion method (OC method) is used to iteratively update the design variables of the preset isogeometric topology optimization model until a preset convergence condition is met, that is, the optimization design result of the preset isogeometric topology optimization model converges, and the optimized target geometric model corresponding to the geometric model to be optimized is obtained. The preset convergence condition can be that the change in the design variable (i.e., the relative density of the control points) is less than a preset threshold or the number of iterations reaches a preset number. For example, the preset threshold can be set to 0.002, and the preset number can be set to 100 times. The specific values ​​can be set and adjusted according to actual conditions and are not specifically limited here.

[0073] On the basis of the above embodiment, further, obtaining a mapping point set according to the triangular facet information of the geometric model to be optimized, and generating an initial mapping body model based on the mapping point set and the three-dimensional NURBS body, includes:

[0074] Acquire triangular facet information of the geometric model to be optimized, and acquire a mapping point set corresponding to the geometric model to be optimized based on the triangular facet information;

[0075] Specifically, the geometric model to be optimized is as follows: Figure 2 As shown, read the triangle facet information of the geometric model to be optimized, extract the vertex information of the triangle facet of the geometric model to be optimized (such as Figure 3 As shown), based on the triangle face vertex information and the preset interpolation density, the triangle face vertices are interpolated to obtain a mapping point that is not less than a preset density threshold (as shown Figure 4 As shown), a mapping point set corresponding to the geometric model to be optimized is formed.

[0076] A three-dimensional NURBS body is constructed, and the mapping point set is mapped to corresponding positions of the three-dimensional NURBS body to form an initial mapping body model.

[0077] Specifically, a regular three-dimensional NURBS body is constructed by obtaining the maximum and minimum coordinate values ​​of the xyz coordinates of all mapping points, that is, x max 、x min 、y max 、y min 、z max 、z min, based on these coordinate values, the vertex coordinates are generated as (x max ,y max , z max )、(x max ,y max , z min )、(x max ,y min , z max )、(x max ,y min , z min )、(x min ,y max , z max )、(x min ,y max , z min )、(x min ,y min , z max )、(x min ,y min , z min ) is refined into several regular NURBS units. The refined NURBS units are as follows: Figure 5 It should be noted that the refined NURBS unit should satisfy the following requirements: the NURBS unit size should be larger than the distance between the two mapping points with the smallest distance. According to the three-dimensional coordinates of each mapping point in the mapping point set in the physical space, all mapping points are mapped to the corresponding positions of the three-dimensional NURBS body (such as Figure 6 As shown), an out-of-body space domain mapping model is created, namely, the initial mapping body model.

[0078] On the basis of the above embodiment, further, obtaining triangular facet information of the geometric model to be optimized, and obtaining a mapping point set corresponding to the geometric model to be optimized according to the triangular facet information, includes:

[0079] Read the triangular facet information of the geometric model to be optimized, and extract the vertex information of the triangular facet of the geometric model to be optimized;

[0080] For example, a CAD model based on an IGES file reads triangular face information. After reading the IGES file at a specified address, the various entities in the IGES file are distinguished by type to obtain the structural information of all entities. Clipping the surface is a necessary condition for extracting vertex information. Figure 7 This is a schematic diagram of the triangulation of the clipping surface, such as Figure 7 As shown, all clipping surfaces are gradually converted into triangular patches and the corresponding vertex information is read out.

[0081] Interpolate the vertex of the triangular facet based on the vertex information of the triangular facet and a preset interpolation density, to obtain a mapping point set corresponding to the to-be-optimized geometric model.

[0082] Specifically, Figure 8 A mapping relationship diagram for interpolating a regular parameter domain into a physical domain for a mapping point is shown in the figure, and a specific interpolation processing method is as follows: a spatial triangle constituting a triangular facet is parameterized by vertex information, and an arbitrary spatial triangle ACE (vertices A, C, and E) can be parameterized as follows: Figure 8

[0083] T(s,t)=A+sl1+tl2,(s,t)∈S={(s,t):s≥0,t≥0,s+t≤1}

[0084] A mapping relationship from a regular parameter domain to a physical domain is established, wherein l1 and l2 represent vectors In this way, only a plurality of points with a preset interpolation density need to be generated in the parameter domain S, and the coordinates of the points are substituted into the above mapping relationship to generate mapping points in the physical domain, which are smaller than a preset density threshold. That is, the interpolation points of the triangular facet, and all the interpolation points of the triangular facets constitute the mapping point set corresponding to the to-be-optimized geometric model. The preset density threshold can be set and adjusted according to actual conditions, and is not specifically limited here.

[0085] Further, based on the mapping point set and the initial mapping body model, a reconstructed mapping body model is generated, including:

[0086] According to the mapping point set and the initial mapping body model, a mapping unit and a non-mapping unit are identified.

[0087] Specifically, the three-dimensional coordinates of each mapping point in the mapping point set in the physical space are obtained, and for each NURBS unit of the initial mapping body model, it is determined whether there is a mapping point falling within the boundary coordinate range according to the three-dimensional coordinates; if yes, the NURBS unit is determined as a mapping unit, otherwise, the NURBS unit is determined as a non-mapping unit. That is, the NURBS unit containing the mapping point is identified as the mapping unit, and the NURBS unit not containing the mapping point is identified as the non-mapping unit.

[0088] Based on the ray method, the non-mapping unit is divided into a virtual unit and a real unit.

[0089] ​​​Specifically, for each non-mapping unit, a ray is emitted from the non-mapping unit in a preset direction; the number of intersections between the ray and all triangular facets is calculated; if the number of intersections is an odd number, the non-mapping unit is determined to be a real unit; if the number of intersections is an even number, the non-mapping unit is determined to be an imaginary unit.

[0090] A reconstructed mapping volume model is generated based on the mapping unit and the real unit.

[0091] Specifically, a reconstructed mapping volume model is generated according to the mapping unit and the real unit, and the reconstructed mapping volume model can be directly used for isogeometric analysis.

[0092] Based on the above embodiment, further, identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume model includes:

[0093] Obtain the three-dimensional coordinates of each mapping point in the mapping point set in the physical space;

[0094] For each NURBS unit of the initial mapping body model, it is determined whether there is a mapping point falling within its boundary coordinate range according to the three-dimensional coordinates; if so, the NURBS unit is determined to be a mapping unit, otherwise the NURBS unit is determined to be a non-mapping unit.

[0095] Specifically, the three-dimensional coordinates of each mapping point in the mapping point set in physical space are obtained. For each NURBS cell of the initial mapping volume model, the relationship between the three-dimensional coordinates of each mapping point in physical space and the boundary coordinates of the NURBS cell are analyzed to identify mapping cells that contain mapping points and non-mapping cells that do not contain mapping points. Specifically, based on the three-dimensional coordinates, it is determined whether there are mapping points that fall within the boundary coordinate range. If so, the NURBS cell is determined to be a mapping cell; otherwise, the NURBS cell is determined to be a non-mapping cell. That is, if any mapping point is within the NURBS cell, the NURBS cell is defined as a mapping cell; otherwise, it is defined as a non-mapping cell. Figure 9 Convert NURBS unit numbers into index diagrams in different directions to improve efficiency, such as Figure 9 As shown, the mapping unit is determined in two directions (three directions for a three-dimensional model). It is only necessary to determine the index of the NURBS unit where the mapping point is located in the two directions, and the number of the mapping unit is determined accordingly.

[0096] On the basis of the above embodiment, further, the non-mapped units are divided into imaginary units and real units based on the ray method, including:

[0097] For each non-mapping unit, emitting a ray from the non-mapping unit to a preset direction;

[0098] Calculate the number of intersections between the ray and all triangles;

[0099] If it is determined that the number of intersections is an odd number, the non-mapping unit is determined to be a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined to be an imaginary unit.

[0100] Specifically, if Figure 10 As shown, all non-mapping units are traversed, and for each non-mapping unit, a ray is emitted from the non-mapping unit in a preset direction. The preset direction can be set and adjusted according to the actual situation and is not specifically limited here. For each triangle, check whether the ray intersects with the triangle, find all the intersection points and calculate the position of the intersection points to obtain the normal vector at the intersection point; if the angle formed by the direction of the ray and the direction of the triangle normal is less than 90°, that is, the dot product of the ray direction vector and the normal vector at the intersection of the triangle is positive, then it is considered that the ray intersects with the front side of the triangle, otherwise it intersects with the back side; if the ray intersects with the triangle from the front, the number of intersections is increased by 1, and if the ray intersects with the triangle from the back, the number of intersections is reduced by 1, and the number of intersections between the ray and all triangles is calculated in this way. If the number of intersections is determined to be an odd number, the non-mapping unit is determined to be a real unit; if the number of intersections is determined to be an even number, the non-mapping unit is determined to be an imaginary unit.

[0101] On the basis of the above embodiment, further, the target structural parameter is thermal conductivity compliance, and the model construction parameter of the design domain is control point density; accordingly, marking the design domain based on the reconstructed mapping body model and assembling a preset target structural parameter matrix, using the model construction parameters of the design domain as design variables and minimizing the preset target structural parameters as the optimization goal, to construct a preset isogeometric topology optimization model of the geometric model to be optimized, including:

[0102] Marking the area with assembly features in the reconstructed mapping body model as a non-design domain, and marking the remaining areas as a design domain;

[0103] Specifically, the design domain and non-design domain of the mapping body model are reconstructed according to the assembly feature marks, where the assembly features include loading features, installation features, fixing features, limiting features, etc., and may also include other features, which can be set and adjusted according to actual conditions and are not specifically limited here. Figure 11 Schematic diagram of the design domain and non-design domain for the reconstructed mapping model, as shown in Figure 11 As shown in the figure, in order to avoid the disappearance of materials at locations with assembly features due to subsequent optimization, the reconstructed mapping model is marked as a non-design domain (blue area) and initialized to the corresponding non-design variables that do not participate in the optimization. The rest is the design domain (gray area) and is initialized to the design variables that participate in the optimization.

[0104] Assembling the thermal conductivity matrices of the mapping unit and the real unit to form a thermal compliance matrix;

[0105] Specifically, the target structural parameter is thermal compliance, and the thermal conductivity matrices of the mapping unit and the real unit are assembled into a preset target structural parameter matrix, namely the thermal compliance matrix. The target structural parameter may also be stiffness, which can be set and adjusted based on actual conditions and is not specifically limited here.

[0106] The preset geometric topology optimization model for constructing the geometric model to be optimized is:

[0107] Find:ρ=[ρ 1 ,ρ 2 ,…,ρ i ,…,ρ N ]

[0108] min:J(ρ)=T T K h (ρ)T

[0109] sqFt h (ρ)T=P

[0110] ∫ Ω ρdΩ≤V

[0111] 0<ρ min <ρ i ≤1

[0112] Where ρ is the design variable, i.e., the density of control points in the design domain, J(ρ) is the target value of thermal conductivity compliance, and K h (ρ) is the thermal conductivity matrix, P and T are the control point heat load and control point temperature respectively, N is the number of control points, V is the maximum volume fraction of the reconstructed mapping model, Ω is the design domain of the model, ρ min is the minimum value of the design variable.

[0113] The embodiment of the present application provides an isogeometric topology optimization method based on a volume space domain mapping model, which obtains a mapping point set according to the triangular facet information of the geometric model to be optimized, and generates an initial mapping body model based on the mapping point set and the three-dimensional NURBS body; obtains a reconstructed mapping body model based on the generation based on the mapping point set and the initial mapping body model; marks the design domain based on the reconstructed mapping body model and assembles a preset target structure parameter matrix, constructs a preset isogeometric topology optimization model of the geometric model to be optimized with the model construction parameters of the design domain as design variables and the minimum preset target structure parameters as the optimization target; calculates the sensitivity of the preset isogeometric topology optimization model, and updates the design variables of the preset isogeometric topology optimization model based on the sensitivity using an optimization criterion method until the preset convergence conditions are met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized. By accurately mapping the CAD model to a refined NURBS regular body, a volume space domain mapping model for isogeometric topology optimization is constructed, which solves the bottleneck that the existing isogeometric topology optimization is difficult to optimize complex models; the ray method is introduced into the construction of the volume space domain mapping model. Compared with the traditional complex analysis model reconstruction method, it fully utilizes the surface information of the CAD model to quickly determine the mapping unit category, with accurate judgment and stable effect, which improves the efficiency of the reconstructed model; the reconstructed mapping volume model is divided into design domain and non-design domain, which are initialized to design variables participating in the optimization and non-design variables not participating in the optimization, to avoid the disappearance of materials with assembly features due to subsequent optimization, laying a solid foundation for the engineering application development of isogeometric topology optimization of complex models.

[0114] Combined with the above Figures 1-11 The isogeometric topology optimization method based on the volume space domain mapping model provided in the embodiment of the present application is introduced in detail. The isogeometric topology optimization device, electronic device and computer-readable storage medium based on the volume space domain mapping model provided in the embodiment of the present application will be introduced in conjunction with the accompanying drawings.

[0115] like Figure 12 As shown in FIG, this figure is a schematic diagram of an isogeometric topology optimization device based on a volume space domain mapping model provided by the present application, the device comprising:

[0116] The processing module 201 is used to obtain a mapping point set according to the triangular facet information of the geometric model to be optimized, and generate an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume;

[0117] A generating module 202 is configured to generate a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model;

[0118] A construction module 203 is configured to mark a design domain based on the reconstructed mapping body model and assemble a preset target structural parameter matrix, using the model construction parameters of the design domain as design variables and minimizing the preset target structural parameters as the optimization goal to construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0119] The updating module 204 is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, update the design variables of the preset isogeometric topology optimization model using an optimization criterion method until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized.

[0120] The isogeometric topology optimization device provided in the embodiment of the present application can correspond to executing the isogeometric topology optimization method based on the volume space domain mapping model described in the embodiment of the present application, and the above functions of each module of the device correspond to realizing Figure 1 For the sake of brevity, the corresponding process of the method shown will not be repeated here.

[0121] An embodiment of the present application also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the isogeometric topology optimization method based on the volume space domain mapping model as described in the above embodiment is implemented.

[0122] like Figure 13 As shown, the computer system 300 of the electronic device includes a CPU 301, which can perform various appropriate actions and processes according to the programs stored in the ROM 302 or the programs loaded from the storage unit 308 into the RAM 303. The RAM 303 also stores various programs and data required for system operation. The CPU 301, ROM 302, and RAM 403 are connected to each other via a bus 304. An I / O interface 305 is also connected to the bus 304. Here, CPU 301 represents a central processing unit, ROM 302 represents a read-only memory, RAM 403 represents a random access memory, and I / O represents input / output.

[0123] The following components are connected to the I / O interface 305: an input section 306 including a keyboard, a mouse, and the like; an output section 307 including devices such as a cathode ray tube, a liquid crystal display, and a speaker; a storage section 308 including devices such as a hard disk; and a communication section 309 including a network interface card such as a LAN card or a modem. The communication section 309 performs communication processing via a network such as the Internet. A drive 310 is also connected to the I / O interface 305 as needed. Removable media 311, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 310 as needed, so that computer programs read from the media can be installed in the storage section 308 as needed.

[0124] In particular, the process of the isogeometric topology optimization method based on the volume space domain mapping model described in the above embodiments can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains instructions for executing the isogeometric topology optimization method based on the volume space domain mapping model described in the above embodiments. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 309, and / or installed from the removable medium 311. When the computer program is executed by the CPU 301, the above functions defined in the present computer system 300 are executed.

[0125] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the isogeometric topology optimization method based on the volume space domain mapping model as described in the above embodiment is implemented.

[0126] Specifically, the computer-readable storage medium may be included in the electronic device described in the above embodiments, or may exist independently and not be incorporated into the electronic device. The computer-readable storage medium carries one or more programs. When the one or more programs are executed by the electronic device, the electronic device implements the isogeometric topology optimization method based on the volume space domain mapping model described in the above embodiments.

[0127] It should be noted that the computer-readable storage medium described in this application may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. Computer-readable storage media may include, for example, but are not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or components, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to, an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device, or component. Furthermore, in this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. This propagated data signal may take a variety of forms, including, but not limited to, electromagnetic signals, optical signals, or any suitable combination thereof.

[0128] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. An isogeometric topology optimization method based on a volume space domain mapping model, characterized in that: include: Acquire a mapping point set according to the triangular facet information of the geometric model to be optimized, and generate an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume; generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model; Marking the design domain based on the reconstructed mapping model and assembling a preset target structural parameter matrix, using the model construction parameters of the design domain as design variables and minimizing the preset target structural parameters as the optimization goal, to construct a preset isogeometric topology optimization model of the geometric model to be optimized; Calculating the sensitivity of the preset isogeometric topology optimization model, and updating the design variables of the preset isogeometric topology optimization model using an optimization criterion method based on the sensitivity until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized; The step of generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model comprises: identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume model; The non-mapped cells are divided into imaginary cells and real cells based on the ray method; A reconstructed mapping volume model is generated based on the mapping unit and the real unit.

2. The method according to claim 1, characterized in that The step of obtaining a mapping point set according to triangular facet information of the geometric model to be optimized and generating an initial mapping body model based on the mapping point set and a three-dimensional NURBS body includes: Acquire triangular facet information of the geometric model to be optimized, and acquire a mapping point set corresponding to the geometric model to be optimized based on the triangular facet information; A three-dimensional NURBS body is constructed, and the mapping point set is mapped to corresponding positions of the three-dimensional NURBS body to form an initial mapping body model.

3. The method according to claim 2, characterized in that The step of obtaining triangular patch information of the geometric model to be optimized and obtaining a mapping point set corresponding to the geometric model to be optimized according to the triangular patch information includes: Read the triangular facet information of the geometric model to be optimized, and extract the vertex information of the triangular facet of the geometric model to be optimized; Based on the triangle patch vertex information and a preset interpolation density, interpolation processing is performed on the triangle patch vertices to obtain mapping points that are not less than a preset density threshold, thereby forming a mapping point set corresponding to the geometric model to be optimized.

4. The method according to claim 3, characterized in that The identifying of mapping units and non-mapping units according to the mapping point set and the initial mapping body model comprises: Obtain the three-dimensional coordinates of each mapping point in the mapping point set in the physical space; For each NURBS unit of the initial mapping body model, it is determined whether there is a mapping point falling within its boundary coordinate range according to the three-dimensional coordinates; if so, the NURBS unit is determined to be a mapping unit, otherwise the NURBS unit is determined to be a non-mapping unit.

5. The method according to claim 4, characterized in that The non-mapped cells are divided into imaginary cells and real cells based on the ray method, including: For each non-mapping unit, emitting a ray from the non-mapping unit to a preset direction; Calculate the number of intersections between the ray and all triangles; If it is determined that the number of intersections is an odd number, the non-mapping unit is determined to be a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined to be an imaginary unit.

6. The method according to claim 5, characterized in that The target structural parameter is thermal conductivity compliance, and the model construction parameter of the design domain is control point density. Accordingly, the design domain is marked based on the reconstructed mapping body model and a preset target structural parameter matrix is ​​assembled. The model construction parameters of the design domain are used as design variables, and the preset target structural parameter is minimized as the optimization goal to construct a preset isogeometric topology optimization model of the geometric model to be optimized, including: Marking the area with assembly features in the reconstructed mapping body model as a non-design domain, and marking the remaining areas as a design domain; Assembling the thermal conductivity matrices of the mapping unit and the real unit to form a thermal compliance matrix; The preset geometric topology optimization model for constructing the geometric model to be optimized is: Find:ρ=[ρ 1 ,r 2 ,…,r i ,…,r N ] min: J(ρ)=T T K h (p)T s.t.K h (ρ)T=P ∫ Ω ρdΩ≤V 0<ρ min <p i ≤1 Where ρ is the design variable, i.e., the density of control points in the design domain, J(ρ) is the target value of thermal conductivity compliance, and K h (ρ) is the thermal conductivity matrix, P and T are the control point heat load and control point temperature respectively, N is the number of control points, V is the maximum volume fraction of the reconstructed mapping model, Ω is the design domain of the model, ρ min is the minimum value of the design variable.

7. An isogeometric topology optimization device based on a volume space domain mapping model, characterized in that: include: A processing module, configured to obtain a mapping point set according to triangular facet information of the geometric model to be optimized, and generate an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume; A generating module is configured to generate a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model; the generating the reconstructed mapping volume model based on the mapping point set and the initial mapping volume model comprises: identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume model; The non-mapped cells are divided into imaginary cells and real cells based on the ray method; generating a reconstructed mapping volume model based on the mapping unit and the real unit; A construction module is used to mark the design domain based on the reconstructed mapping body model and assemble a preset target structural parameter matrix, use the model construction parameters of the design domain as design variables, and take the minimization of the preset target structural parameters as the optimization goal to construct a preset isogeometric topology optimization model of the geometric model to be optimized; An updating module is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, update the design variables of the preset isogeometric topology optimization model using an optimization criterion method until a preset convergence condition is met, thereby obtaining a target geometric model corresponding to the geometric model to be optimized.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

Images