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

Abstract

The invention provides an isogeometric topology optimization method and device based on a volume space domain mapping model, equipment and a medium, and relates to the technical field of isogeometric topology optimizing.The method comprises the steps that a mapping point set is obtained according to triangular patch information of a geometric model to be optimized, and an initial mapping volume model is generated based on the mapping point set and a three-dimensional NURBS volume; generating a reconstruction mapping body model; marking a design domain based on the reconstructed mapping body model, assembling a preset target structure parameter matrix, and constructing a preset isogeometric topology optimization model by taking a model construction parameter of the design domain as a design variable and taking a minimum preset target structure parameter as an optimization target; and updating design variables of a preset isogeometric topological optimization model by adopting an optimization criterion method based on the sensitivity until a preset convergence condition is met, and obtaining a target geometric model corresponding to the geometric model to be optimized, so as to solve the problem that an existing isogeometric topological optimization method is difficult to be applied to topological optimization engineering of a complex topological 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, device, equipment 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 the CAD software, and then imported into the 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, and the conversion cycle of geometric model design and physical model analysis is continuously performed until the requirements are met.

[0003] Isogeometric analysis (IGA) combines the two fields of CAD and CAE by using the same basis functions to represent the approximate solutions of geometric models (CAD) and physical models (CAE). Topology optimization is a numerical iterative procedure that finds the best material distribution by following the specified objective function and constraints in a predefined design domain. Its advantage is that it can save materials more significantly and improve structural performance. However, topology optimization methods based on the finite element method also have difficulties in ensuring the smoothness of discrete models on surface boundaries. Isogeometric analysis has the advantages of high precision and continuity and has been applied to the field of topology optimization. It has replaced finite elements in topology optimization and is called isogeometric topology optimization. Although isogeometric topology optimization has advantages in mesh refinement, computational accuracy and stability, the tensor product structure of NURBS and the non-interpolation of its basis functions make it difficult to construct isogeometric models, especially complex structural models, for the application of isogeometric analysis and its topology optimization.

[0004] Therefore, although isogeometric topology optimization is very successful for engineering application problems of simple structural geometric models, it is rarely successfully applied to most engineering analysis models with complex topological structures. In order 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 the 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] Based on the reconstructed mapping body model, the design domain is marked and a preset target structure parameter matrix is ​​assembled, the model construction parameters of the design domain are used as design variables, and the preset target structure parameter minimum is used as the optimization target 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 by using an optimization criterion method based on the sensitivity until a preset convergence condition is met, so as to obtain 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 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:

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

[0013] A three-dimensional NURBS body is constructed, and a 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 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:

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

[0016] Based on the triangle patch vertex information and a preset interpolation density, the triangle patch vertices are interpolated 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, the generating of the 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] Based on the ray method, the non-mapped cells are divided into imaginary cells and real cells;

[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, the identifying of mapping units and non-mapping units according to 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 volume 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 by the present application, the 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 as a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined as 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 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 minimum is used as the optimization target, 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 marked 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 ,K,ρ i ,K,ρ N ],

[0033] min:J(ρ)=T T K h (ρ)T

[0034] ikB h (ρ)T=P

[0035] ∫ Ω ρdΩ≤V

[0036] 0<ρ min <ρ i ≤1

[0037] Where ρ is the design variable, i.e., the control point density of 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 units, 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, used for acquiring a mapping point set according to the triangular facet information of the geometric model to be optimized, and generating 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 body model and assemble a preset target structure parameter matrix, take the model construction parameters of the design domain as design variables, take the minimum preset target structure parameters as the optimization goal, and construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0042] The updating module is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, the design variables of the preset isogeometric topology optimization model are updated by using the optimization criterion method until the preset convergence conditions are met, so as to obtain the 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 present application has the following beneficial effects: 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 volume model based on the mapping point set and the three-dimensional NURBS volume; based on the mapping point set and the initial mapping volume model, obtains a reconstructed mapping volume model based on the generation; based on the reconstructed mapping volume model, the design domain is marked and a preset target structure parameter matrix is ​​assembled, and a preset isogeometric topology optimization model of the geometric model to be optimized is constructed with the model construction parameters of the design domain as the design variables and the minimum preset target structure parameters as the optimization target; the sensitivity of the preset isogeometric topology optimization model is calculated, and the design variables of the preset isogeometric topology optimization model are updated by using the optimization criterion method based on the sensitivity until the preset convergence conditions are met, so as to obtain the target geometric model corresponding to the geometric model to be optimized. By accurately mapping the CAD model to the 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 reconstructing the model; the reconstructed mapping volume model is divided into design domain and non-design domain, which are initialized as design variables participating in the optimization and non-design variables not participating in the optimization, so as 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 features or beneficial effects means that specific technical features, technical solutions or beneficial effects are included in at least one embodiment. Therefore, the description of technical features, technical solutions or beneficial effects 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 realized 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 a specific embodiment that does not embody all embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solution in this embodiment, the drawings required for use in the description of the embodiment will be briefly introduced below. 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 paying 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 A schematic diagram of a NURBS unit provided in an 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 of the mapping point interpolation provided in the embodiment of the present application;

[0056] Fig. 9A schematic diagram of converting the NURBS unit number provided in the embodiment of the present application into an index in different directions;

[0057] Fig.10 A schematic diagram of the classification of NURBS unit types provided in an embodiment of the present application;

[0058] Fig.11 A schematic diagram of the design domain and non-design domain of the reconstructed mapping body model provided in an embodiment of the present application;

[0059] Fig.12 A schematic diagram of an isogeometric topology optimization device based on a volume space domain mapping model provided in an embodiment of the present application;

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

[0061] In order to enable those skilled in the art to better understand the technical solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings. The description in this section 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 embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present application.

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

[0063] In order to make the technical solution of the present application clearer and easier to understand, the isogeometric topology optimization method based on the volume space domain mapping model provided in the embodiment of the present application is introduced below.

[0064] like Figure 1 As shown in FIG. 1 , the figure is a flow chart of an isogeometric topology optimization method based on a volume space domain mapping model provided in this embodiment, and the method comprises the following steps:

[0065] S101, acquiring a mapping point set according to the triangular facet information of the geometric model to be optimized, and generating an initial mapping volume model based on the mapping point set and the 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 method based on the triangular patch information; a three-dimensional NURBS body is constructed, and the mapping point set is mapped to the corresponding position 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 at least includes the vertex information of the triangular patch, and may also include other information, which may 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 may be set and adjusted according to actual conditions, and is not specifically limited here.

[0067] S102, based on the mapping point set and the initial mapping volume model, generate a reconstructed mapping volume model; specifically, the mapping point set includes multiple mapping points, and the initial mapping volume model includes multiple NURBS units; according to the mapping point set and the initial mapping volume model, for each NURBS unit of the initial mapping volume model, identify the NURBS unit containing the mapping point as a mapping unit, and identify the NURBS unit not containing the mapping point as a non-mapping unit; divide the non-mapping unit into imaginary units and real units based on a ray method; generate a reconstructed mapping volume model based on the mapping units and the real units.

[0068] S103, marking the design domain based on the reconstructed mapping body model and assembling a preset target structure parameter matrix, taking the model construction parameters of the design domain as design variables and taking the minimum preset target structure parameters as the optimization target, to construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0069] 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 unit and the real unit are assembled to form the preset target structural parameter matrix, and the model construction parameters of the design domain are used as design variables, and the preset target structural parameters are minimized as the optimization target to construct the preset equal geometric topology optimization model of the geometric model to be optimized. Among them, 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 can be understood that the virtual unit does not participate in the assembly of the preset target structural parameter matrix; in order to avoid the disappearance of materials at the assembly features due to subsequent optimization, the model construction parameters of the non-design domain are used as non-design variables and do not participate in the subsequent model optimization.

[0070] S104, 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.

[0071] 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 implement iterative updates of the design variables of the preset isogeometric topology optimization model until the 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. Among them, the preset convergence condition package can be that the change amount of the design variable (that is, the relative density of the control point) 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 the actual situation, and are not specifically limited here.

[0072] On the basis of the above embodiment, further, acquiring a mapping point set according to the triangular facet information of the geometric model to be optimized, and generating an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume, comprises:

[0073] Acquire triangular patch information of the geometric model to be optimized, and acquire a mapping point set corresponding to the geometric model to be optimized according to the triangular patch information;

[0074] Specifically, the geometric model to be optimized is as follows: Figure 2 As shown, the triangular face information of the geometric model to be optimized is read, and the vertex information of the triangular face of the geometric model to be optimized is extracted (such as Figure 3 As shown), based on the triangle patch vertex information and the preset interpolation density, the triangle patch vertices are interpolated to obtain mapping points that are not less than the preset density threshold (such as Figure 4 As shown), a mapping point set corresponding to the geometric model to be optimized is formed.

[0075] A three-dimensional NURBS body is constructed, and a mapping point set is mapped to corresponding positions of the three-dimensional NURBS body to form an initial mapping body model.

[0076] Specifically, a regular three-dimensional NURBS body is constructed. The specific construction method is: obtain 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 9x max ,ymax ,z max )、(x max ,y max ,z min ), 9x 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), thereby creating an out-of-body space domain mapping model, that is, the initial mapping volume model.

[0077] On the basis of the above embodiment, further, the obtaining of 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:

[0078] Read the triangular face information of the geometric model to be optimized, and extract the vertex information of the triangular face of the geometric model to be optimized;

[0079] For example, a CAD model based on an IGES file reads triangular face information. After reading the IGES file at a specified address, various entities in the IGES file are distinguished by type to obtain structural information of all entities, among which clipping surfaces is a necessary condition for extracting vertex information. Figure 7 This is a schematic diagram of the triangulation of the clipped surface, such as Figure 7 As shown, all clipping surfaces are gradually converted into triangular patches and the corresponding vertex information is read out.

[0080] Based on the triangle patch vertex information and a preset interpolation density, the triangle patch vertices are interpolated 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.

[0081] Specifically, Figure 8 The diagram of the mapping relationship between the rule parameter domain and the physical domain for mapping point interpolation is as follows: Figure 8 As shown, the specific interpolation processing method is: the spatial triangles constituting the triangular face are parameterized by vertex information. An arbitrary spatial triangle △ACE (vertices A, C, and E) can be parameterized as follows:

[0082] T(s,t)=A+sl1+tl2,(s,t)∈S={(s,t):s≥0,t≥0,s+t≤1}

[0083] Establish a mapping relationship from the rule parameter domain to the physical domain; where l1 and l2 represent vectors and In this way, we only need to generate several points uniformly in the parameter domain S with a preset interpolation density and set their coordinates Substituting into the above mapping relationship and mapping to the physical domain, a mapping point less than the preset density threshold can be generated. That is, the interpolation points of the triangular facets, and the interpolation points of all triangular facets constitute the mapping point set corresponding to the geometric model to be optimized. The preset density threshold can be set and adjusted according to actual conditions, and is not specifically limited here.

[0084] On the basis of the above embodiment, further, generating a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model includes:

[0085] identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume model;

[0086] 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 volume 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. In other words, 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.

[0087] Based on the ray method, the non-mapped cells are divided into imaginary cells and real cells;

[0088] 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 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.

[0089] A reconstructed mapping volume model is generated based on the mapping unit and the real unit.

[0090] 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.

[0091] On the basis of the above embodiment, further, the identifying the mapping unit and the non-mapping unit according to the mapping point set and the initial mapping volume model includes:

[0092] Obtain the three-dimensional coordinates of each mapping point in the mapping point set in the physical space;

[0093] For each NURBS unit of the initial mapping volume 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.

[0094] 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 volume model, the mapping unit containing the mapping point and the non-mapping unit not containing the mapping point are identified by analyzing the relationship between the three-dimensional coordinates of each mapping point in the physical space and the boundary coordinates of the NURBS unit. Specifically, it is determined based on the three-dimensional coordinates whether there is a mapping point falling within the boundary coordinate range; if so, the NURBS unit is determined to be a mapping unit, otherwise, the NURBS unit is determined to be a non-mapping unit, that is, if any mapping point is inside the NURBS unit, the NURBS unit is defined as a mapping unit, otherwise it is a non-mapping unit. Fig. 9 Convert NURBS unit numbers into index diagrams in different directions to improve efficiency, such as Fig. 9 As shown, the mapping unit is judged in two directions (three directions for a three-dimensional model) respectively. 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.

[0095] On the basis of the above embodiment, further, the non-mapped unit is divided into imaginary unit and real unit based on the ray method, including:

[0096] For each non-mapping unit, emitting a ray from the non-mapping unit to a preset direction;

[0097] Calculate the number of intersections between the ray and all triangles;

[0098] If it is determined that the number of intersections is an odd number, the non-mapping unit is determined as a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined as an imaginary unit.

[0099] Specifically, Fig.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 positions 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 normal line of the triangle 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 side, the number of intersections is increased by 1, and if the ray intersects with the triangle from the back side, 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.

[0100] 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, 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 target, to construct a preset isogeometric topology optimization model of the geometric model to be optimized, including:

[0101] Marking the area with assembly features in the reconstructed mapping body model as a non-design domain, and marking the remaining areas as a marked design domain;

[0102] Specifically, the design domain and non-design domain of the mapping body model are reconstructed according to the assembly feature marks, wherein 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. Fig.11 Schematic diagram of design domain and non-design domain for reconstructing mapping body model, as shown in Fig.11 As shown in the figure, in order to avoid the disappearance of materials at the 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.

[0103] Assembling the thermal conductivity matrices of the mapping unit and the real unit to form a thermal compliance matrix;

[0104] Specifically, the target structural parameter is thermal conductivity flexibility, 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 conductivity flexibility matrix. The target structural parameter may also be stiffness, which may be set and adjusted according to actual conditions, and is not specifically limited here.

[0105] The preset geometric topology optimization model for constructing the geometric model to be optimized is:

[0106] Find:ρ=[ρ 1 ,ρ 2 ,K,ρ i ,K,ρ N ],

[0107] min:J(ρ)=T T K h (ρ)T

[0108] ikB h (ρ)T=P

[0109] ∫ Ω ρdΩ≤V

[0110] 0<ρ min <ρ i ≤1

[0111] Where ρ is the design variable, i.e., the control point density of 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 units, 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.

[0112] 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 volume model based on the mapping point set and the three-dimensional NURBS volume; obtains a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model; marks the design domain based on the reconstructed mapping volume 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 the 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 reconstructing the model; the reconstructed mapping volume model is divided into design domain and non-design domain, which are initialized as design variables participating in the optimization and non-design variables not participating in the optimization, so as 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.

[0113] Combination of the above Figure 1-Figure 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. Hereinafter, 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.

[0114] like Fig.12 As shown, the figure is a schematic diagram of an isogeometric topology optimization device based on a volume space domain mapping model provided by the present application, and the device includes:

[0115] 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;

[0116] A generating module 202, configured to generate a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model;

[0117] A construction module 203 is used to mark the design domain based on the reconstructed mapping body model and assemble a preset target structure parameter matrix, take the model construction parameters of the design domain as design variables, take the minimum preset target structure parameters as the optimization target, and construct a preset isogeometric topology optimization model of the geometric model to be optimized;

[0118] The updating module 204 is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, the design variables of the preset isogeometric topology optimization model are updated by 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.

[0119] 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.

[0120] An embodiment of the present application also provides an electronic device, including 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 isogeometric topology optimization method based on the volume space domain mapping model as described in the above embodiment is implemented.

[0121] like Fig.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 program stored in the ROM 302 or the program loaded from the storage part 308 to the RAM 303. In the RAM 303, various programs and data required for system operation are also stored. The CPU 301, the ROM 302 and the RAM 403 are connected to each other through the bus 304. The I / O interface 305 is also connected to the bus 304. Among them, 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.

[0122] The following components are connected to the I / O interface 305: an input section 306 including a keyboard, a mouse, etc.; an output section 307 including a cathode ray tube, a liquid crystal display, etc., and a speaker, etc.; a storage section 308 including a hard disk, etc.; and a communication section 309 including a network interface card such as a LAN card, a modem, etc. 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. A removable medium 311, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 310 as needed, so that a computer program read therefrom is installed into the storage section 308 as needed.

[0123] In particular, the process of the isogeometric topology optimization method based on the volume space domain mapping model described in the above embodiment 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 a method for executing the isogeometric topology optimization method based on the volume space domain mapping model described in the above embodiment. 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.

[0124] An embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. 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.

[0125] Specifically, the computer-readable storage medium may be included in the electronic device described in the above embodiment; or it may exist independently without being assembled into the electronic device. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed by an electronic device, the electronic device implements the isogeometric topology optimization method based on the volume space domain mapping model as described in the above embodiment.

[0126] It should be noted that the computer-readable storage medium shown in the present application may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, in which a computer-readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above.

[0127] 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 its 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 and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, 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; Based on the reconstructed mapping body model, the design domain is marked and a preset target structure parameter matrix is ​​assembled, the model construction parameters of the design domain are used as design variables, and the preset target structure parameter minimum is used 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 by using an optimization criterion method based on the sensitivity until a preset convergence condition is met, so as to obtain a target geometric model corresponding to the geometric model to be optimized.

2. The method according to claim 1, characterized in that The step of acquiring 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, comprises: Acquire triangular patch information of the geometric model to be optimized, and acquire a mapping point set corresponding to the geometric model to be optimized according to the triangular patch information; A three-dimensional NURBS body is constructed, and a 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 face information of the geometric model to be optimized, and extract the vertex information of the triangular face of the geometric model to be optimized; Based on the triangle patch vertex information and a preset interpolation density, the triangle patch vertices are interpolated 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 1, characterized in that: 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; Based on the ray method, the non-mapped cells are divided into imaginary cells and real cells; A reconstructed mapping volume model is generated based on the mapping unit and the real unit.

5. The method according to claim 4, characterized in that The identifying mapping units and non-mapping units according to the mapping point set and the initial mapping volume 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 volume 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.

6. The method according to claim 5, 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 as a real unit; if it is determined that the number of intersections is an even number, the non-mapping unit is determined as an imaginary unit.

7. The method according to claim 6, characterized in that The target structural parameter is thermal conductivity compliance, and the model building 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 building parameters of the design domain are used as design variables, and the preset target structural parameter minimum is used as the optimization target, to build 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 marked 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,ρ2,K,ρ,K,μ min:J(ρ)=TiKh(ρ)T stKh(ρ)T=P Ω μdΩ≤V 0<ρ mim <ρi≤1 Where ρ is the design variable, i.e., the control point density of 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 units, V is the maximum volume fraction of the reconstructed mapping model, Ω is the design domain of the model, ρm i n is the minimum value of the design variable.

8. An isogeometric topology optimization device based on a volume space domain mapping model, characterized in that: include: A processing module, used for acquiring a mapping point set according to the triangular facet information of the geometric model to be optimized, and generating an initial mapping volume model based on the mapping point set and the three-dimensional NURBS volume; A generating module, configured to generate a reconstructed mapping volume model based on the mapping point set and the initial mapping volume model; A construction module is used to mark the design domain based on the reconstructed mapping body model and assemble a preset target structure parameter matrix, take the model construction parameters of the design domain as design variables, take the minimum preset target structure parameters as the optimization goal, and construct a preset isogeometric topology optimization model of the geometric model to be optimized; The updating module is used to calculate the sensitivity of the preset isogeometric topology optimization model, and based on the sensitivity, the design variables of the preset isogeometric topology optimization model are updated by using the optimization criterion method until the preset convergence conditions are met, so as to obtain the target geometric model corresponding to the geometric model to be optimized.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. 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 7 is implemented.

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