Non-pneumatic tire topological optimization method based on isogeometric analysis

Abstract

The invention discloses a non-pneumatic tire topological optimization method based on isogeometric analysis in the technical field of wheel design, and aims to solve the problems of low analysis precision and low solving speed due to the fact that finite element analysis is generally adopted for optimization work in the prior art. The method comprises the following steps: performing parametric modeling on a non-pneumatic tire based on an NURBS curve to obtain a parametric model, performing grid division on the parametric model, obtaining units, a design domain and a structure model, dividing the units into multiple types of units under a fixed equidistant geometric background grid, and introducing boundary conditions under different working conditions based on the parametric model and the multiple types of units to obtain a design domain of the non-pneumatic tire. Analyzing the stress distribution and the displacement vector of the non-pneumatic tire to obtain a stress distribution matrix; according to the method, the situation that a straight line segment and an arc are discontinuous in traditional finite element analysis is overcome, the topological optimization precision is improved, the calculation time is shortened, the service life of the non-pneumatic tire is prolonged, the performance of the non-pneumatic tire is improved, and meanwhile the working efficiency of structural design optimization is guaranteed.

Description

Technical Field

[0001] The invention relates to a non-pneumatic tire topology optimization method based on isogeometric analysis, belonging to the technical field of wheel design. Background Art

[0002] Compressed air is an important component of pneumatic tires, while non-pneumatic tires abandon compressed air, and the tire and rim are integrated. Its rim and elastic spokes can deform to reduce vibration and rebound easily to absorb the energy of bumps on the ground. Since there is no need for inflation and no rims like traditional tires, non-pneumatic tires are maintenance-free, blow-free, and leak-free compared to ordinary tires. In addition, when non-pneumatic tires are subjected to impact loads longitudinally, their internal support structure can have much larger type variables than ordinary pneumatic tires, thereby reducing the impact of rough roads on the suspension and body through the tires, and improving the comfort performance of the vehicle. The topological optimization of non-pneumatic tires is the basic path for their structural optimization, so it is extremely important to adopt more precise optimization methods.

[0003] The finite element analysis method usually only has 0th-order function continuity, and often requires a simplified model. The time cost of solving complex models is high and the accuracy is insufficient. In addition, improper meshing will lead to problems such as stress singularity and displacement singularity, affecting the reliability of the calculation results. The accuracy of finite element analysis is more limited by the number of units. When the number of units increases to a certain level, the accuracy of the solution is no longer significantly improved, but the calculation time will continue to increase. It can be seen that the existing technology usually uses finite element analysis for topology optimization of non-pneumatic tires. It has the defects of low analysis accuracy and slow solution speed, resulting in poor use effect and affecting the work efficiency of structural design optimization. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a non-pneumatic tire topology optimization method based on isogeometric analysis to solve the problem that in the prior art, finite element analysis is usually used for optimization when performing topology optimization on non-pneumatic tires, resulting in low analysis accuracy and slow solution speed.

[0005] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a non-pneumatic tire topology optimization method based on isogeometric analysis, comprising the following steps:

[0007] Step a: parametric modeling is performed on the non-pneumatic tire based on the NURBS curve to obtain a parametric model, the parametric model is divided into multiple types of models, the parametric model is meshed to obtain units, design domains and structural models, and the units are divided into multiple types of units under a fixed equidistant geometric background grid;

[0008] Step b: Based on the parameterized model and multiple types of units, boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire to obtain the stress distribution matrix;

[0009] Step c: In response to the received unit density of the multi-class model, the unit sensitivity value is calculated respectively, and the multiple unit sensitivity values ​​are respectively used as sample points to fit the NURBS sensitivity field, and the sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value. The corresponding NURBS sensitivity field is intercepted by the sensitivity threshold, and the intercepted NURBS sensitivity fields of the multi-class model are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain. Based on the stress distribution matrix, the structural model is optimized and designed, and it is determined whether the objective function corresponding to the structural optimization design converges. If it converges, the optimization model is output and the optimization ends; if it does not converge, jump to step a and reclassify the unit.

[0010] Furthermore, the different working conditions include: the tire rolling in a straight line, the tire bouncing up and down, and the tire turning left and right.

[0011] Furthermore, the expression of the NURBS curve is as follows:

[0012]

[0013] Where: ( =1, 2, …, ; =1, 2, …, ) is the control vertex; is the corresponding weight factor of the control vertex; and They are defined as the node vector U={ , ,…, }, and V = { , ,…, }, Represents a NURBS curve; and is a vector; for The total number of control points on the vector; for The total number of control points on the vector.

[0014] Furthermore, the multiple types of models include a hub model, a spoke model and a tread model.

[0015] Furthermore, the multiple types of cells include solid cells, empty cells and boundary cells.

[0016] Furthermore, the obtaining of the stress distribution matrix specifically includes:

[0017] The solid unit stiffness matrix and the empty unit stiffness matrix are assembled to obtain the assembled unit stiffness matrix, and the boundary conditions under different working conditions are introduced to solve the stress distribution matrix.

[0018] Among them, the expression of the entity element stiffness matrix is ​​as follows:

[0019]

[0020] Where: is the entity element stiffness matrix; is the strain matrix of the element; is the elastic matrix of the solid element; is the overall displacement vector; is a unit; T is the mathematical symbol for matrix transposition;

[0021] The expression of the stiffness matrix of the empty element is as follows:

[0022]

[0023] Where: is the stiffness matrix of the empty element; is the elasticity matrix of the empty cell.

[0024] Furthermore, the model expression of the structural optimization design is:

[0025] Find: ,

[0026] Min:

[0027]

[0028] Where: K is the assembly unit stiffness matrix; is the overall displacement vector; F is the boundary condition under different working conditions, that is, the external load vector; and is the node coordinate of the wheel hub, and its distance from the center point of the tire is r; and is the node coordinate on the tread, and its distance from the center point of the tire is R; O is the center point of the tire; , , , , All are spoke control points, satisfying , , , , The distance from the center point of the tire increases successively; is the design variable; is the assembly stress matrix; is the stress matrix of the solid element; is the empty element stress matrix; is the elastic matrix; is the design domain unit; x is the number of each unit in the design domain.

[0029] In a second aspect, the present invention provides a non-pneumatic tire topology optimization device based on isogeometric analysis, comprising:

[0030] Classification module: parametric modeling of non-pneumatic tires based on NURBS curves to obtain parametric models, classify the parametric models into multiple types of models, mesh the parametric models, obtain units, design domains and structural models, and classify the units into multiple types of units under a fixed equidistant geometric background grid;

[0031] Analysis module: Based on the parametric model and multiple types of units, the boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire and obtain the stress distribution matrix;

[0032] Processing module: In response to the received unit density of multiple types of models, the unit sensitivity values ​​are calculated respectively, and the unit sensitivity values ​​are used as sample points to fit the NURBS sensitivity field. The sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value. The NURBS sensitivity field is intercepted by the sensitivity threshold, and the NURBS sensitivity fields intercepted by multiple types of models are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain. Based on the stress distribution matrix, the structural model is optimized and designed, and it is determined whether the objective function corresponding to the structural optimization design converges. If it converges, the optimization model is output and the optimization ends; if it does not converge, it jumps to the classification module and reclassifies the units.

[0033] In a third aspect, the present invention provides a server, including a processor and a storage medium;

[0034] The storage medium is used to store instructions;

[0035] The processor is used to operate according to the instructions to execute the steps of the method according to the first aspect.

[0036] In a fourth aspect, a computer-readable storage medium stores a computer program thereon, wherein the program, when executed by a processor, implements the steps of the method described in the first aspect.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The non-pneumatic tire topology optimization method based on isogeometric analysis models the tire model based on NURBS curves. Under a fixed background grid, the units are divided into three types: solid units, empty units, and boundary units. The isogeometric analysis method is used to introduce boundary conditions under three working conditions, and the tire is subjected to stress analysis using the equilibrium equation. The unit sensitivity value is then used as a sample point, the corresponding sensitivity threshold is selected, and the structural topology configuration is updated. The minimum variance of the stress matrix is ​​taken as the optimization goal, and finally the convergence of the objective function is judged and corresponding processing is made. This method overcomes the discontinuity of straight line segments and circular arcs in traditional finite element analysis and improves the accuracy of topological optimization. The geometric models of this isogeometric analysis method are all represented by parameters. The division and refinement of the grid are different from those of the classical finite element. Only natural division or insertion point subdivision is required on the parameter domain, which avoids direct operation of the analysis grid model and saves the process of special grid division in the classical finite element, speeds up the analysis cycle, and reduces the calculation time. Moreover, the isogeometric analysis uses the basis function of the constructed model as the shape function for calculation, and its unit node accuracy is much higher than that of the classical finite element. Therefore, this method improves the simulation efficiency and accuracy of non-pneumatic tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic flow chart of a non-pneumatic tire topology optimization method based on isogeometric analysis provided according to an embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of tire and spoke control points provided according to an embodiment of the present invention;

[0041] Figure 3 is a schematic diagram of a hub and tread control points provided according to an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of external load distribution of a tire under three working conditions provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0044] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0045] Embodiment 1:

[0046] like Figure 1 As shown, the present invention provides a non-pneumatic tire topology optimization method based on isogeometric analysis, comprising the following steps:

[0047] Step a: parametric modeling is performed on the non-pneumatic tire based on the NURBS curve to obtain a parametric model, the parametric model is divided into multiple types of models, the parametric model is meshed to obtain units, design domains and structural models, and the units are divided into multiple types of units under a fixed equidistant geometric background grid;

[0048] Step b: Based on the parameterized model and multiple types of units, boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire to obtain the stress distribution matrix;

[0049] Step c: In response to the received unit density of the multi-class model, the unit sensitivity value is calculated respectively, and the multiple unit sensitivity values ​​are respectively used as sample points to fit the NURBS sensitivity field, and the sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value. The corresponding NURBS sensitivity field is intercepted by the sensitivity threshold, and the intercepted NURBS sensitivity fields of the multi-class model are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain. Based on the stress distribution matrix, the structural model is optimized and designed, and it is determined whether the objective function corresponding to the structural optimization design converges. If it converges, the optimization model is output and the optimization ends; if it does not converge, jump to step a and reclassify the unit.

[0050] Specifically, the NURBS curve is described by a control point vector, a node vector, and a weight; the symmetrical non-pneumatic tire geometric model is divided into three parts: a hub, a spoke, and a tread, and the hub and the tread are both perfect circles; the non-pneumatic tire is parametrically modeled based on the NURBS curve to obtain a parametric model, and the geometric model is divided into three parts, namely, a hub model, a spoke model, and a tread model; the parametric model is meshed, and under a fixed geometric background mesh, the divided units are classified into solid units, empty units, and boundary units; the non-pneumatic tire is subjected to stress analysis, and under three working conditions, the geometric model established based on the NURBS curve is introduced to introduce boundary conditions, and the stress distribution and displacement vector of the non-pneumatic tire are analyzed to obtain a stress distribution matrix; the unit density of the three types of models is set, and the unit sensitivity value is calculated in combination with the unit density and the overall displacement vector, and the unit sensitivity value is used as the unit center point sensitivity, and it is used as a sample point to fit the NURBS sensitivity field; a density threshold is selected according to the current sensitivity field and the corresponding volume constraint value to fit the current NURBS The NURBS sensitivity field is intercepted, and the NURBS sensitivity fields intercepted by the three types of models are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain, and then update the structural topology configuration; it is determined whether the objective function corresponding to the structural optimization model converges. If it converges, the topology optimization is terminated and the optimal structural topology configuration is obtained; if it does not converge, the units are reclassified and the above steps are repeated.

[0051] Specifically, the sensitivity value of any point in the design domain can be determined based on the NURBS sensitivity field. , select a sensitivity threshold according to the corresponding volume constraint value The NURBS sensitivity field is intercepted to update the design variables in the design domain (density value at any point in the design domain), thereby updating the structural topology. When the sensitivity value on the NURBS sensitivity surface is higher than the sensitivity threshold, that is, , this area is the structural entity area, and the design variables of this area are =1; when the sensitivity value on the NURBS sensitivity surface is lower than the sensitivity threshold, , this area is the structural hole area, and the design variables of this area are = 0; the sensitivity value on the NURBS sensitivity surface corresponding to the structure boundary is exactly equal to the sensitivity threshold, that is, , the design variables for this region =1.

[0052] In one embodiment, the different operating conditions include: the tire rolling in a straight line, the tire bouncing up and down, and the tire turning left and right.

[0053] Specifically, if Figure 4 As shown, for the tire rolling in a straight line, the external load it receives is , ; For the up and down movement of the tire, the external load it receives is , ; For the tire turning left or right, the external load it receives is , , .

[0054] In one embodiment, the expression of the NURBS curve is as follows:

[0055]

[0056] Where: ( =1, 2, …, ; =1, 2, …, ) is the control vertex; is the corresponding weight factor of the control vertex; and They are defined as the node vector U={ , ,…, }, and V = { , ,…, }, Represents a NURBS curve; and is a vector; for The total number of control points on the vector; for The total number of control points on the vector.

[0057] In one embodiment, the multi-type models include a hub model, a spoke model and a tread model, and the multi-type units include solid units, void units and boundary units.

[0058] In one embodiment, obtaining the stress distribution matrix specifically includes:

[0059] The solid unit stiffness matrix and the empty unit stiffness matrix are assembled to obtain the assembled unit stiffness matrix, and the boundary conditions under different working conditions are introduced to solve the stress distribution matrix.

[0060] Among them, the expression of the entity element stiffness matrix is ​​as follows:

[0061]

[0062] Where: is the entity element stiffness matrix; is the strain matrix of the element; is the elastic matrix of the solid element; is the overall displacement vector; is a unit; T is the mathematical symbol for matrix transposition;

[0063] The expression of the stiffness matrix of the empty element is as follows:

[0064]

[0065] Where: is the stiffness matrix of the empty element; is the elasticity matrix of the empty cell.

[0066] Specifically, the strain matrix is ​​solved using the Jacobian determinant , and then assemble the entity unit stiffness matrix and the empty unit stiffness matrix to obtain the assembled unit stiffness matrix K, and then introduce the boundary condition F, using the equation relationship The stress distribution matrix and element offset matrix are obtained by solving.

[0067] like Figure 2-Figure 3 As shown in one embodiment, the model expression of the structural optimization design is:

[0068] Find: ,

[0069] Min:

[0070]

[0071] Where: K is the assembly unit stiffness matrix; is the overall displacement vector; F is the boundary condition under different working conditions, that is, the external load vector; and is the node coordinate of the wheel hub, and its distance from the center point of the tire is r; and is the node coordinate on the tread, and its distance from the center point of the tire is R; O is the center point of the tire; , , , , All are spoke control points, satisfying , , , , The distance from the center point of the tire increases successively; is the design variable; is the assembly stress matrix; is the stress matrix of the solid element; is the empty element stress matrix; is the elastic matrix; is the design domain unit; x is the number of each unit in the design domain.

[0072] Specifically, for the tread and wheel hub models, the control points are ~ , node vector U={0, 0, 0, 1 / 4, 1 / 4, 1 / 2, 1 / 2, 3 / 4, 3 / 4, 1, 1, 1} weight W={1, , 1, , 1, , 1, , 1}, the hub thickness is H1, and the tread thickness is H2; each spoke has 5 control points Q1~Q5, and its control point vector, node vector, weight and thickness are CF, V, WF, H3 respectively; specifically, the hub thickness H1, tread thickness H2 are initially set to 100mm, and the spoke thickness H3 is 50mm, and the control points, node vectors and weights of the spokes are the input quantities of each non-pneumatic tire; after the spoke centerline distribution and thickness distribution are determined, the complete spoke structure can be determined through the operation of symmetry and center rotation array.

[0073] The non-pneumatic tire topology optimization method based on isogeometric analysis models the tire model based on NURBS curves. Under a fixed background grid, the units are divided into three types: solid units, empty units, and boundary units. The isogeometric analysis method is used to introduce boundary conditions under three working conditions, and the tire is subjected to stress analysis using the equilibrium equation. The unit sensitivity value is then used as a sample point, the corresponding sensitivity threshold is selected, and the structural topology configuration is updated. The minimum variance of the stress matrix is ​​taken as the optimization goal, and finally the convergence of the objective function is judged and corresponding processing is made. This method overcomes the discontinuity of straight line segments and circular arcs in traditional finite element analysis and improves the accuracy of topological optimization. The geometric models of this isogeometric analysis method are all represented by parameters. The division and refinement of the grid are different from those of the classical finite element. Only natural division or insertion point subdivision is required on the parameter domain, which avoids direct operation of the analysis grid model and saves the process of special grid division in the classical finite element, speeds up the analysis cycle, and reduces the calculation time. Moreover, the isogeometric analysis uses the basis function of the constructed model as the shape function for calculation, and its unit node accuracy is much higher than that of the classical finite element. Therefore, this method improves the simulation efficiency and accuracy of non-pneumatic tires.

[0074] Embodiment 2:

[0075] The embodiment of the present invention further provides a non-pneumatic tire topology optimization device based on isogeometric analysis, comprising:

[0076] Classification module: parametric modeling of non-pneumatic tires based on NURBS curves to obtain parametric models, classify the parametric models into multiple types of models, mesh the parametric models, obtain units, design domains and structural models, and classify the units into multiple types of units under a fixed equidistant geometric background grid;

[0077] Analysis module: Based on the parametric model and multiple types of units, the boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire and obtain the stress distribution matrix;

[0078] Processing module: In response to the received unit density of multiple types of models, the unit sensitivity values ​​are calculated respectively, and the unit sensitivity values ​​are used as sample points to fit the NURBS sensitivity field. The sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value. The NURBS sensitivity field is intercepted by the sensitivity threshold, and the NURBS sensitivity fields intercepted by multiple types of models are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain. Based on the stress distribution matrix, the structural model is optimized and designed, and it is determined whether the objective function corresponding to the structural optimization design converges. If it converges, the optimization model is output and the optimization ends; if it does not converge, it jumps to the classification module and reclassifies the units.

[0079] Embodiment three:

[0080] An embodiment of the present invention further provides a terminal, including a processor and a storage medium;

[0081] The storage medium is used to store instructions;

[0082] The processor is used to operate according to the instructions to execute the steps of the method described in embodiment 1.

[0083] Embodiment 4:

[0084] The embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the method described in the first embodiment are implemented.

[0085] Since the storage medium provided in the embodiment of the present invention can execute the method provided in the first embodiment of the present invention, it has the corresponding functional modules and beneficial effects of the execution method.

[0086] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0087] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0088] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0089] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A non-pneumatic tire topology optimization method based on isogeometric analysis, characterized in that: The following steps are involved: Step a: parametric modeling is performed on the non-pneumatic tire based on the NURBS curve to obtain a parametric model, the parametric model is divided into multiple types of models, the parametric model is meshed to obtain units, design domains and structural models, and the units are divided into multiple types of units under a fixed equidistant geometric background grid; Step b: Based on the parameterized model and multiple types of units, boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire to obtain the stress distribution matrix; Step c: in response to the received unit densities of the multiple types of models, the unit sensitivity values ​​are calculated respectively, and the multiple unit sensitivity values ​​are respectively used as sample points to fit the NURBS sensitivity field, and the sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value, and the corresponding NURBS sensitivity field is intercepted by the sensitivity threshold, and the NURBS sensitivity fields intercepted by the multiple types of models are assembled to obtain the total NURBS sensitivity field to update the design variables in the design domain, and the structural model is optimized based on the stress distribution matrix to determine whether the objective function corresponding to the structural optimization design converges, and if converged, the optimization model is output and the optimization ends; If it does not converge, jump to step a and reclassify the unit.

2. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 1, characterized in that: The different working conditions include: the tire rolling in a straight line, the tire bouncing up and down, and the tire turning left and right.

3. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 1, characterized in that: The expression of the NURBS curve is as follows: Where: ( =1, 2, …, ; =1, 2, …, ) is the control vertex; is the corresponding weight factor of the control vertex; and They are defined as the node vector U={ , ,…, }, and V = { , ,…, }, Represents a NURBS curve; and is a vector; for The total number of control points on the vector; for The total number of control points on the vector.

4. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 1, characterized in that: The multiple types of models include a hub model, a spoke model and a tread model.

5. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 1, characterized in that: The multiple types of cells include solid cells, void cells and boundary cells.

6. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 5, characterized in that: The obtaining of the stress distribution matrix specifically includes: The solid unit stiffness matrix and the empty unit stiffness matrix are assembled to obtain the assembled unit stiffness matrix, and the boundary conditions under different working conditions are introduced to solve the stress distribution matrix. Among them, the expression of the entity element stiffness matrix is ​​as follows: Where: is the entity element stiffness matrix; is the strain matrix of the element; is the elastic matrix of the solid element; is the overall displacement vector; is a unit; T is the mathematical symbol for matrix transposition; The expression of the stiffness matrix of the empty element is as follows: Where: is the stiffness matrix of the empty element; is the elasticity matrix of the empty cell.

7. The non-pneumatic tire topology optimization method based on isogeometric analysis according to claim 1, characterized in that: The model expression of the structural optimization design is: Find: , Min: Where: K is the assembly unit stiffness matrix; is the overall displacement vector; F is the boundary condition under different working conditions, that is, the external load vector; and is the node coordinate of the wheel hub, and its distance from the center point of the tire is r; and is the node coordinate on the tread, and its distance from the center point of the tire is R; O is the center point of the tire; , , , , All are spoke control points, satisfying , , , , The distance from the center point of the tire increases successively; is the design variable; is the assembly stress matrix; is the stress matrix of the solid element; is the empty element stress matrix; is the elastic matrix; is the design domain unit; x is the number of each unit in the design domain.

8. A non-pneumatic tire topology optimization device based on isogeometric analysis, characterized in that: include: Classification module: parametric modeling of non-pneumatic tires based on NURBS curves to obtain parametric models, classify the parametric models into multiple types of models, mesh the parametric models, obtain units, design domains and structural models, and classify the units into multiple types of units under a fixed equidistant geometric background grid; Analysis module: Based on the parametric model and multiple types of units, the boundary conditions under different working conditions are introduced to analyze the stress distribution and displacement vector of the non-pneumatic tire and obtain the stress distribution matrix; Processing module: in response to the received unit density of multiple types of models, the unit sensitivity values ​​are calculated respectively, the unit sensitivity values ​​are used as sample points to fit the NURBS sensitivity field, the sensitivity threshold is obtained according to the NURBS sensitivity field and the corresponding volume constraint value, the NURBS sensitivity field is intercepted by the sensitivity threshold, the NURBS sensitivity fields intercepted by multiple types of models are assembled, and the total NURBS sensitivity field is obtained to update the design variables in the design domain, and the structural model is optimized based on the stress distribution matrix to determine whether the objective function corresponding to the structural optimization design converges. If converged, the optimization model is output and the optimization ends; If it does not converge, jump to the classification module and reclassify the unit.

9. A server, characterized in that: including processor and storage medium; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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