JP2021041792A - Tire model creation method, tire shape optimization method, tire model creation device, tire shape optimization device, and program - Google Patents

Abstract

To provide a tire model creation method which allows a shape factor to be efficiently selected by taking into account an influence of effects on a target property, and to provide a tire model creation device, and a program for executing the tire model creation method.SOLUTION: A tire model creation method includes the steps of: obtaining node information of a tire model representing a tire and constituted by factors capable of being numerically analyzed by a computer; setting a plurality of displacement vectors for the respective nodes of the tire model: obtaining a plurality of deformed tire models by deforming tire models according to the displacement vectors, for the plurality of set displacement vectors respectively; obtaining a target property representing a preset tire physical amount, for the plurality of deformed tire models respectively; evaluating an influence degree of a displacement vector on a target property, on the basis of the respective target properties of the plurality of deformed tire models; selecting a displacement vector on the basis of the influence degree; and creating a tire model according to the displacement vector that has been selected.SELECTED DRAWING: Figure 2

Description

The present invention relates to a tire model creation method and a tire shape optimization method using a tire modeled by elements that can be numerically analyzed by a computer, a tire model creation device and a tire shape optimization device, and a program. The present invention relates to a tire model creation method for efficiently selecting a displacement vector considering the influence of an effect on characteristics, a tire model creation device, a tire shape optimization method and a tire shape optimization device based on the acquired tire cross-sectional shape, and a program.

Currently, a method of creating a tire model or the like that can be analyzed by a computer and simulating the performance of the tire or the like has been proposed. In the performance simulation, a tire model obtained by dividing a tire into a finite number of elements is created. The optimum shape of a tire is obtained by performing an optimization calculation using a tire model composed of finite elements.

For example, Patent Document 1 describes a method for designing a tire cross-sectional shape in which a wide design range is defined with a small number of design variables and the optimum design according to the tire performance is efficiently performed. In Patent Document 1, the shape of the tire is optimized by using a plurality of deformed shapes of the unique modes in the cross-sectional direction of the tire as the base shape.

Japanese Patent No. 4723057

In Patent Document 1, as described above, the shape of the tire is optimized by using the deformed shapes of a plurality of unique modes in the cross-sectional direction of the tire as the base shape. The deformed shape of the eigenmode includes various variables such as changes in shape and thickness in each part of the tire. However, since Patent Document 1 uses the eigenmode shape in the eigenvalue analysis result, it is possible to evaluate how much the change in the variable in the base shape affects the obtained characteristic value, but which part of the shape change It is not possible to geometrically evaluate how much affects the characteristic value. From this, in tire shape optimization, it is difficult to identify which target characteristic is affected by how the tire cross-sectional shape is changed, and it takes time to identify the shape factor that affects the target characteristic. It takes.

An object of the present invention is a tire model creation method, a tire model creation device, and a tire model capable of solving the above-mentioned problems based on the prior art and efficiently selecting a shape factor in consideration of the influence of an effect on a target characteristic. The purpose is to provide a program that executes the creation method.

In order to achieve the above object, the first aspect of the present invention is to obtain node information of a tire model composed of elements that represent tires and can be numerically analyzed by a computer, and to each of the nodes of the tire model. , The process of setting a plurality of displacement vectors, the process of obtaining a plurality of deformed tire models by deforming the tire model according to the displacement vector for each of the set plurality of displacement vectors, and each of the plurality of deformed tire models in advance. The process of obtaining the objective characteristics representing the set tire physical quantity, the process of evaluating the degree of influence of the objective characteristics of the displacement vector based on the objective characteristics of each of the plurality of deformed tire models, and the process of selecting the displacement vector based on the degree of influence. Provided is a method for creating a tire model, which comprises a process and a process of creating a tire model based on a selected displacement vector.

A second aspect of the present invention includes a step of acquiring a tire model composed of elements that can be numerically analyzed by a computer, a step of obtaining node information on the outer line of the tire model, and a step of obtaining node information on the outer line of the tire model. The process of setting a plurality of displacement vectors that give a shape change to the tire model for each of the nodes, and for each of the set plurality of displacement vectors, a displacement vector is given as a forced displacement to the nodes on the outline to deform the tire model. Based on the process of obtaining a plurality of deformed tire models, the process of obtaining the target characteristics representing the preset tire physical quantities for each of the plurality of deformed tire models, and the target characteristics of each of the plurality of deformed tire models. A tire model characterized by having a step of evaluating the degree of influence of the displacement vector on a target characteristic, a step of selecting a displacement vector based on the degree of influence, and a step of creating a tire model based on the selected displacement vector. It provides a method of creation.

After the step of obtaining the node information of the outline of the tire model, the step of dividing the outline of the tire model into a plurality of regions and setting a plurality of displacement vectors is at least one of the plurality of regions. It is preferable to set a plurality of displacement vectors in the region, and there may be a region in which the displacement vector is not set.
Further, in the step of evaluating the degree of influence of the displacement vector on the objective characteristic, the degree of influence of the displacement vector on the objective characteristic is evaluated in the region in which a plurality of displacement vectors are set among the plurality of regions, and the displacement vector is selected. In the step to be performed, it is preferable to select the displacement vector in the set region based on the degree of influence.

The step of dividing the outline of the tire model into a plurality of regions is preferably divided into at least a tread portion and a sidewall portion of the tire model.
In the step of selecting the displacement vector, it is preferable to select the displacement vector having a large contribution to the target characteristic.
The third aspect of the present invention is the displacement selected in the step of selecting the displacement vector after the step of selecting the displacement vector in the method of creating the tire model of the first aspect of the present invention and the second aspect of the present invention. It provides a tire shape optimization method characterized by having a step of performing an optimization calculation using a vector as a design variable and a weighting coefficient of a setting variable as a parameter and a tire physical quantity as an objective function.

A fourth aspect of the present invention is a condition setting unit for acquiring a tire model composed of elements that can be numerically analyzed by a computer, and a node information of the outer line of the tire model, which is on the outer line of the tire model. For each of the model setting unit that sets a plurality of displacement vectors that give a shape change to the tire model and each of the set plurality of displacement vectors at each of the nodes in the above, as a forced displacement at the node on the outline. A model creation unit that obtains a plurality of deformed tire models by deforming the tire model by giving a displacement vector, and a calculation unit that obtains a target characteristic representing a preset tire physical quantity for each of the plurality of deformed tire models. Based on each objective characteristic of the deformed tire model, it has an evaluation unit that evaluates the degree of influence of the displacement vector on the objective characteristic and selects the displacement vector based on the degree of influence, and the model creation unit has the selected displacement vector. Based on the above, the present invention provides a tire model creating apparatus characterized in that a tire model is created.

It is preferable that the model setting unit divides the outline of the tire model into a plurality of regions and sets a plurality of displacement vectors in at least one region among the plurality of regions.
It is preferable that the evaluation unit evaluates the degree of influence of the displacement vector on the target characteristic in the region in which a plurality of displacement vectors are set by the model setting unit among the plurality of regions, and selects the displacement vector based on the degree of influence. ..

The model setting unit preferably divides the outline of the tire model into at least a tread portion and a sidewall portion of the tire model.
The evaluation unit preferably selects a displacement vector having a large contribution to the target characteristics.
A fifth aspect of the present invention is a tire shape optimization device having the tire creation device of the fourth aspect of the present invention, and a combination of a plurality of base shapes that change the shape of the tire model in a model setting unit is used. It is expressed, and the domain is set to include at least as a design variable, at least two or more objective functions related to the physical quantity of the tire model are set, and the calculation unit uses the weighting coefficient of the setting variable as a parameter and sets the tire physical quantity as the objective function. Provided is a tire shape optimizing device characterized by carrying out an optimization calculation.

A sixth aspect of the present invention provides a program for causing a computer to execute each step of the tire forming method of the first aspect of the present invention as a procedure.
A seventh aspect of the present invention provides a program for causing a computer to execute each step of the tire shape optimization method of the third aspect of the present invention as a procedure.

According to the present invention, it is possible to efficiently select a displacement vector in consideration of the influence of the effect on the target characteristics, and it is possible to create a tire model that satisfies the target characteristics.

It is a schematic diagram which shows the tire model making apparatus used in the tire model making method of embodiment of this invention. It is a flowchart which shows the 1st example of the tire model making method of embodiment of this invention in process order. It is a schematic diagram which shows an example of the tire model used in the tire model making method of embodiment of this invention. (A) is a schematic view showing a first example of a displacement vector in a sidewall portion of a tire model used in the method for creating a tire model of the embodiment of the present invention, and (b) is a schematic diagram showing a first example of a displacement vector, and (b) is a tire model of the embodiment of the present invention. It is a schematic diagram which shows the 2nd example of the displacement vector in the sidewall part of the tire model used in the manufacturing method, (c) is the sidewall part of the tire model used in the tire model manufacturing method of the embodiment of this invention. It is a schematic diagram which shows the 3rd example of the displacement vector, and (d) is the schematic diagram which shows the 4th example of the displacement vector in the sidewall part of the tire model used in the tire model making method of the embodiment of this invention. is there. It is a flowchart which shows the 2nd example of the tire model making method of embodiment of this invention in process order. It is a schematic diagram for demonstrating the acquisition method of the new tire model of the tire model creation method of embodiment of this invention.

Hereinafter, based on the preferred embodiment shown in the attached drawings, the tire model creating method, the tire shape optimizing method, the tire model creating device, the tire shape optimizing device, and the tire forming method or the tire shape optimizing method of the present invention. A program for executing each step of the above as a procedure on a computer or the like will be described in detail.
FIG. 1 is a schematic view showing a tire model creating device used in the tire model creating method of the embodiment of the present invention.

The tire model creating device 10 shown in FIG. 1 is used to execute the tire model creating method of the present embodiment. Hereinafter, the tire model creating device 10 is also simply referred to as a creating device 10.
The creation device 10 is configured by using hardware such as a computer. As described above, the creating device 10 shown in FIG. 1 is used for the tire model creating method of the present invention. However, if the tire model creating method can be executed by using hardware and software such as a computer, the creating device 10 can be used. The program is not limited, and a program for causing a computer or the like to execute each step of the tire model creation method as a procedure may be used. Further, the creating device 10 is not limited to the configuration shown in FIG.

The creating device 10 has a processing unit 12, an input unit 14, and a display unit 16. The processing unit 12 includes a condition setting unit 20, a model setting unit 22, a model creation unit 24, a calculation unit 26, an evaluation unit 27, a memory 28, a display control unit 30, and a control unit 32. In addition to this, although not shown, it has a ROM and the like.
The processing unit 12 is controlled by the control unit 32. Further, in the processing unit 12, the condition setting unit 20, the model setting unit 22, the model creation unit 24, the calculation unit 26, and the evaluation unit 27 are connected to the memory 28, and the condition setting unit 20, the model setting unit 22, and the model creation unit are connected. The data of 24, the calculation unit 26, and the evaluation unit 27 are stored in the memory 28.
In the tire model creating method described below, various processes are performed in each part of the processing unit 12. In the following description, the description that various processes are performed by each unit of the processing unit 12 by the control unit 32 is omitted, but a series of processes of each unit is controlled by the control unit 32. The memory 28 also stores various evaluation conditions for the degree of influence by the evaluation unit 27, which will be described later.

The input unit 14 is various input devices for inputting various information such as a mouse and a keyboard according to an operator's instruction. The display unit 16 displays, for example, the results obtained by the tire model creation method, and various known displays are used. The display unit 16 also includes a device such as a printer for displaying various information on an output medium.

By executing the program (computer software) stored in the ROM or the like in the control unit 32, the creation device 10 causes the condition setting unit 20, the model setting unit 22, the model creation unit 24, the calculation unit 26, and the evaluation unit 27. Functionally form each part of. As described above, the creating device 10 may be configured by a computer in which each part functions by executing a program, or may be a dedicated device in which each part is composed of a dedicated circuit.

The purpose of the tire model creation method and the tire model creation device of the present embodiment is to efficiently select a displacement vector in consideration of the influence of the effect on the target characteristics, and the tire model creation method using a computer and the tire model creation device. Regarding the tire model making device.
In the tire model creation method and the tire model creation device, a plurality of displacement vectors are set for a tire model composed of elements that can be numerically analyzed by a computer, a deformed tire model is obtained for each displacement vector, and each deformation is obtained. Obtain the target characteristics of the tire model, evaluate the degree of influence of the displacement vector on the target characteristics, and select the displacement vector. This makes it possible to efficiently select a displacement vector that takes into consideration the degree of influence such as the magnitude of the effect on the target characteristics regardless of the tire size and the structure of the tire, and a shape that improves the characteristic values of the tire. It can be searched efficiently using a computer.

The condition setting unit 20 of the creating device 10 creates a tire model that represents a tire and is modeled by elements that can be numerically analyzed by a computer. The tire model is the standard for deformation. The shape of the reference tire is not particularly limited, and may be graphic data represented by a line, or may be a finite element model divided into a finite number of elements by a mesh.
A known production method can be used to produce the tire model. For example, a tire model is created by dividing a tire into a finite number of elements composed of a plurality of nodes. In the case of graphic data, it is converted into data modeled by elements that can be numerically analyzed by a computer. The tire model modeled with elements that can be numerically analyzed by a computer may be a discretized model that can be numerically calculated. For example, mesh data used for numerical simulation such as FEM, and design data such as CAD data. But it may be.
The elements that make up the tire model are, for example, a quadrilateral element in a two-dimensional plane, a tetrahedral solid element in a three-dimensional body, a pentahedral solid element, a solid element such as a hexahedral solid element, and a shell such as a triangular shell element and a quadrilateral shell element. Elements such as elements and surface elements that can be analyzed by a computer. In the process of analysis, the elements divided in this way are identified one by one using the three-dimensional coordinates in the three-dimensional model and the two-dimensional coordinates in the two-dimensional model.

The tire model also generates at least a road surface model to which the tire model is rolled. Further, a tire model that reproduces the rim, the wheel, and the tire rotation axis on which the tire is mounted may be used. Further, if necessary, a model that reproduces the vehicle on which the tire is mounted may be incorporated into the tire model. At this time, it is also possible to create a model in which the tire model, the rim model (wheel model), and the tire rotation axis model are integrated based on preset boundary conditions.
The form of the tire model used for the analysis is not particularly limited, and may be a smooth tire without a groove, a tire with only a main groove, or a pattern.
Using a tire model, for example, when seeking a tire design plan that optimizes tire performance such as tire wet performance, in addition to the road surface model and tire model, a model that reproduces inclusions existing on the road surface is available. You just have to generate it. For example, as an inclusion model, various models that reproduce water, snow, mud, sand, gravel, ice, etc. on the road surface may be generated by a discretized model that can be numerically calculated. The road surface model is not limited to a model that reproduces a road surface having a flat surface, and may be a model that reproduces a road surface shape having irregularities on the surface, if necessary.

The tire model is, for example, input to the condition setting unit 20 via the input unit 14 and stored in the memory 28. Further, the condition setting unit 20 may store the data of the tire cross-sectional shape to be the tire model in the memory 28 in advance, call the data of the tire cross-sectional shape from the memory 28, and set the tire model.

Further, the condition setting unit 20 sets the objective characteristic, the design variable necessary for the optimization calculation of the tire model, the objective function, and the constraint condition. In addition, various conditions and information necessary for the target characteristics and the optimization calculation of the tire model are input and set. Objective characteristics, design variables, objective functions and constraints, various conditions, and information are input via the input unit 14. Objective characteristics, design variables, objective characteristics, objective functions and constraint conditions, various conditions, and information set by the condition setting unit 20 are stored in the memory 28.

A plurality of parameters defined as design variables among the parameters defining the tire and the materials constituting the tire are set in the condition setting unit 20. In the parameters of the design variables, variation factors such as load and boundary conditions, and in the case of products, constraint conditions such as size and mass may be set.
Further, in addition to the physical quantity of the tire, a plurality of parameters defined as characteristic values (objective characteristics, objective function) among the parameters defining the tire and the material constituting the tire are set. For the characteristic value, an index for evaluating the tire and the material constituting the tire other than the physical and chemical characteristic value such as cost may be used.
The tire and the material constituting the tire may be not a single tire but the entire system including the tire such as the parts constituting the tire and the assembly form of the tire, or a part thereof.

The plurality of types of characteristic values (objective characteristics, objective functions) set in the condition setting unit 20 are physical quantities to be evaluated, that is, objective characteristics or objective functions. The objective characteristic and the objective function have a favorable direction in terms of performance, and the value may increase, decrease, or approach a predetermined value. Further, regarding the objective characteristic and the objective function, in addition to the above-mentioned preferable direction, there is also an unfavorable direction opposite to the preferable direction.
The objective characteristic and the objective function may be one, that is, may be a single purpose. Of course, there may be a plurality of objective functions.

The objective characteristic and the objective function are tire characteristic values (tire physical quantities). In this case, the characteristic value is a physical quantity to be evaluated as tire performance, for example, CP (cornering power) which is a lateral force near zero slip angle which is an index of steering stability, and an index of riding comfort. Examples include the primary natural frequency of the tire, rolling resistance as an index of rolling resistance, lateral spring constant as an index of steering stability, wear energy of a tire tread member as an index of wear resistance, fuel efficiency, and the like. In addition to this, there are shape and dimensional values as examples of physical quantities of tires. The shape is, for example, a cross-sectional shape. The dimensional values include, for example, the width of the tire, the outer diameter of the tire, and the like. Other examples of physical quantities of tires include, in addition to shape or dimensional values, the amount of deflection, ground pressure distribution, rolling resistance, cornering characteristics, and the like.

Design variables (design parameters) define the shape of the tire, the internal structure of the tire, the material properties, and the like. The design variables are a plurality of parameters among the material behavior of the tire, the shape of the tire, the cross-sectional shape of the tire, the natural vibration mode of the tire, and the structure of the tire. Examples of the design variables include a radius of curvature that defines the crown shape in the tread portion of the tire, a tire belt width dimension that defines the tire internal structure, and the like. In addition to this, for example, a filler dispersion shape that defines material properties in the tread portion, a filler volume fraction, and the like can be mentioned. When obtaining mold shape data, the design variables preferably relate to the shape of the tire.
The constraint condition is a condition for constraining the value of the objective function to a predetermined range or constraining the value of the design variable to a predetermined range.
In addition, information such as tire load, running conditions such as tire rolling speed, road surface conditions on which tires run, such as uneven shape, friction coefficient, and vehicle specifications for use in vehicle running simulation, etc. Set.

Further, information for determining a non-linear response relationship between a plurality of types of design variables and a plurality of types of characteristic values is set in the condition setting unit 20. This nonlinear response relationship includes, for example, numerical simulations such as FEM (finite element method), theoretical formulas, and the like.
The condition setting unit 20 sets the model generated by the non-linear response relationship, the boundary conditions of the model, the simulation conditions in the case of numerical simulation such as FEM, and the constraint conditions in the simulation.
Further, in the condition setting unit 20, in addition to the FEM and the theoretical formula, a calculation formula in which the input / output relationship is defined may be set. As a calculation formula that defines the input / output relationship, for example, use a metamodel such as a response curved surface, expand the cross-sectional area after the shape change in the circumferential direction to calculate the volume, and use an empirical formula after the shape change. It is to calculate the target characteristic by using the information of.

Further, optimization conditions for obtaining a Pareto solution, for example, conditions for searching for a Pareto solution may be set. The conditions for the Pareto solution search are a method for searching for the Pareto solution and various conditions in the Pareto solution search. In this embodiment, for example, a genetic algorithm (GA), which is one of evolutionary computation methods, can be used as a method for searching for a Pareto solution.
In addition to this, the domain of the design variable is set in the condition setting unit 20. The domain of the design variable may be a discrete level value or a constant. Since there are multiple types of design variables, discrete level values are set for all design variables, and the domain is set as a constant for the remaining design variables, and the computer changes the combination of design variables. While calculating the characteristic value, the Pareto solution described later may be extracted.

For the optimization calculation, either a sequential search method such as the Monte Carlo method or a method of calculating and searching the output value while changing the input variable according to the optimization algorithm such as the evolutionary computation method may be used. ..

The model setting unit 22 acquires node information of the outer line of the tire model, and sets a plurality of displacement vectors that give a shape change to the tire model at each of the nodes on the outer line of the tire model. The tire model for obtaining node information on the outline is a tire model modeled by elements that can be numerically analyzed by a computer in the condition setting unit 20 as described above. The tire model has a reference tire cross-sectional shape, and is, for example, the tire model 40 shown in FIG. The tire model 40 is a finite element model having a tread portion 41. In the cross-sectional shape of the tire model 40, a plurality of nodes of the outer line 42 constituting the outer contour of the tire model 40 are extracted, and node information on the outer line of the tire model is obtained.
Here, the outline is an outer line from one bead toe through the tread portion to the opposite bead toe in the tire cross section orthogonal to the equatorial plane of the tire.

A plurality of displacement vectors are set for each of the plurality of nodes constituting the outline 42. That is, a plurality of displacement vectors are set for each node for all nodes.
The displacement vector is a shape change vector that changes the shape of the tire model. Therefore, it is preferable that the displacement vector at each node is determined so that they are combined to give one shape change. That is, by setting a plurality of displacement vectors for each node, it is possible to give a plurality of shape changes in the model.
The plurality of displacement vectors are different vectors from each other. Different vectors need only be different in magnitude and orientation at least one of them. For example, as shown in FIG. 3, a first displacement vector 43a and a second displacement vector 43b are set at the node 43. The first displacement vector 43a and the second displacement vector 43b are displacement vectors that deform the tire model so as to have a wider width. The displacement vector is not limited to this, and may be a third displacement vector 43c that narrows the width of the tire model.
The displacement vector may be set to the nodes in a part of the target area without being set to all the nodes, or the area where the displacement vector is not set or apparently there is no displacement, but the setting is There may be a region where a zero vector is given.

Further, the model setting unit 22 has a function of acquiring all node information of the tire model and setting a plurality of displacement vectors that give a shape change to the tire model at each of all the nodes of the tire model. May be good.
In addition, in order to unify the amount of change with respect to the shape change of the tire model due to the plurality of displacement vectors to be set, the displacement amount (the magnitude of the displacement vector) normalized in advance with respect to the tire model (reference shape) is used as the displacement vector. Is desirable.

Even if the model creation unit 24 has a function of obtaining a plurality of deformed tire models in which the tire model is deformed by giving a displacement vector as a forced displacement to all the nodes for each displacement vector among the plurality of displacement vectors. Good. In this case, for example, the first displacement vector 43a of FIG. 3 is given to all the nodes to forcibly displace them. At this time, the shape of the tire model after displacement is calculated using FEM (finite element method). As a result, a deformed tire model based on the first displacement vector 43a is obtained. In this way, a deformed tire model obtained by deforming the tire model according to the displacement vector is obtained.

Further, among the plurality of displacement vectors, the model creation unit 24 deforms the tire model by giving a displacement vector as a forced displacement to the nodes on the outer line in the region to be the target of the shape change for each displacement vector. It may have a function of obtaining a deformed tire model. In this case, for example, when the first displacement vector 43a of FIG. 3 is given as the entire cross section of the region to be the target of the shape change, it is given to all the nodes on the outline to be forcibly displaced. As described above, the shape of the tire model after displacement is calculated using FEM (finite element method). As a result, a deformed tire model based on the first displacement vector 43a is obtained. In this way, a deformed tire model obtained by deforming the tire model according to the displacement vector is obtained.
Further, the model creation unit 24 obtains the tire outline obtained by the shape optimization calculation from the information on the cross-sectional shape of the tire model, and obtains the tire outline obtained by the shape optimization calculation as mold shape data. It can also be output as.

In the tire model 40 (see FIG. 3), the bead ring portion 40c (see FIG. 3) in contact with the rim flange (not shown) has a broken mesh or a broken contact with the rim flange when the shape is changed. Is likely to occur. Therefore, by providing a node (not shown) for restraining the bead ring portion 40c so as not to change the shape of the bead ring portion 40c, the above-mentioned mesh breakage and calculation failure due to poor contact Can be solved.
The constrained node is, for example, a point at which the coordinate points do not change even when an external force is applied. However, the constraint here is when the shape is changed, and this constraint condition is used when acquiring the changed shape and calculating the characteristic value, for example, the contact calculation with the rim flange. May be calculated excluding.

Further, when it is desired to give a shape change that changes the distance between paired beads in the tire cross section, the distance between the beads is designed while maintaining the shape of the bead ring portion 40c by removing the constraint only in the cross-sectional width direction. Can be included as a variable. Similarly, when changing the rim diameter of the tire model, it is possible to search for a tire shape having a different applicable rim diameter while maintaining the shape of the bead ring portion 40c by removing the constraint in the cross-sectional height direction. For example, by setting the radial displacement as a plurality of discrete level values using the above method and performing the same shape search for each level value, the tire product shape search assuming size development is efficiently performed. can do.

The calculation unit 26 obtains a target characteristic representing a preset tire physical quantity for each of the plurality of deformed tire models.
The target characteristics are tire physical quantities such as tire mass, rolling resistance, lateral rigidity, and vertical rigidity exemplified above, and are not particularly limited.
The calculation unit 26 uses the displacement vectors of the plurality of deformed tire models created by the model creation unit 24 as design variables as design variables, and obtains the target characteristics by numerical simulation such as FEM. As a result, the desired characteristics can be obtained for each of the plurality of deformed tire models. The obtained target characteristic (output value) is stored in the memory 28. The arithmetic unit 26 functions, for example, by executing a subroutine by a known finite element solver.

The calculation unit 26 uses a non-linear response relationship to perform sampling calculation for obtaining an input / output relationship composed of values of a plurality of types of design variables (design parameters) and characteristic values (objective characteristics). Further, the calculation unit 26 creates an approximate model (metamodel) using the sampling calculation result and the characteristic value which is the output value as the objective function.
The above-mentioned approximation model (metamodel) is a mathematical model that approximates the input / output relationships, and various input / output relationships can be approximated by adjusting the parameters. For the above-mentioned approximate model, for example, a polynomial model, kriging, a neural network, a radial basis function, or the like can be used.

The calculation unit 26 also executes the optimization calculation using the approximate model. In this case, the tire model creating device 10 also serves as a tire shape optimization device.
Using the solution (which may include the Pareto solution) extracted by the evaluation unit 27 from the optimization calculation result, the actual calculation is executed using the defined nonlinear relationship. In addition to this, the calculation unit 26 uses the finite element method without using an approximate model to give boundary conditions to the tire model expressed from the combination of design variables set by the optimization calculation method, and directly characteristics the tire model. It also calculates the value. As the optimization calculation method, for example, a genetic algorithm (GA), which is one of the evolutionary calculation methods, is used. As a genetic algorithm, for example, DRMOGA (Divided Range Multi-Objective GA), NCGA (Neighborhood Cultivation GA), which divides a solution set into a plurality of regions along an objective function and performs a multi-objective GA for each divided solution set. , DCMOGA (Distributed Cooperation model of MOGA and SOGA), NSGA (Non-dominated Sorting GA), NSGA2 (Non-dominated Sorting GA-II), SPEAII (Strength Pareto Evolutionary Algorithm-II) method, etc. Can be done.

The calculation unit 26 searches for a Pareto solution from the optimization calculation result using the approximate model obtained by the calculation unit 26 according to the Pareto solution search condition set by the condition setting unit 20, and extracts the Pareto solution. It is also something to do. The obtained Pareto solution is stored in the memory 28.
Here, the Pareto solution cannot be said to be superior to any other solution in a plurality of characteristic values (objective functions) having a trade-off relationship, but a solution in which no other better solution exists. Say. Generally, there are a plurality of Pareto solutions as a set. For the search of the Pareto solution, for example, the Pareto ranking method is used.

The calculation unit 26 makes a selection using, for example, a Vector Evaluated Generic Algorithms (VEGA), a Pareto ranking method, or a tournament method. In addition to the genetic algorithm (GA), for example, Simulated Annealing (SA) or Particle Swarm Optimization (PSO) may be used as the same evolutionary computation method.

The calculation unit 26 can also set design variables for the objective function and obtain them in the same manner as the objective characteristics.
The calculation unit 26 uses a non-linear response relationship defined between a design variable (design parameter) and a characteristic value (objective characteristic, objective function), that is, a design variable (design parameter) to provide a characteristic value (objective characteristic, objective). The function) is not limited to the simulation of FEM or the like, and a theoretical formula or the like can be used in addition to the numerical simulation of FEM or the like. In the case of a theoretical formula or the like, a plurality of deformed tire models (design parameters) and a theoretical formula or the like corresponding to the objective characteristic (objective function) are created.

The evaluation unit 27 evaluates the degree of influence of the displacement vector on the target characteristic based on the target characteristics of each of the plurality of deformed tire models, and selects the displacement vector based on the degree of influence.
The evaluation unit 27 reads the evaluation conditions from the memory 28, compares the target characteristics of the plurality of deformed tire models obtained by the calculation unit 26, evaluates the degree of influence, and selects a displacement vector based on the degree of influence.
The method for evaluating the degree of influence of the displacement vector on the target characteristic is not particularly limited, and examples thereof include the following methods. The evaluation conditions according to the influence degree evaluation method shown below are stored in the memory 28.
The characteristic value at each level value in the domain is obtained, a predetermined threshold value is set, and the presence or absence of a significant difference is determined.
An analysis of variance is used to extract significant factors with the error variance as the threshold.
ANOVA is performed and the characteristic values are evaluated based on the obtained interactions and main effects.
If it is known in advance that there is no interaction between the design variables, or if the interaction is not considered, a single factor experiment or an orthogonal experiment is used, and the judgment is made from the amount of change in the characteristic value when the displacement vector is changed as a factor. To do.
If, for example, tire mass, rolling resistance, lateral rigidity, vertical rigidity, etc. are set as the target characteristics, the evaluation unit 27 evaluates the degree of influence on these set target characteristics as described above. And select the displacement vector.

The selection of the displacement vector in the evaluation unit 27 is not limited to the selection of one displacement vector, and a plurality of displacement vectors may be selected. For example, a threshold value may be set for the rank of the degree of influence, and a displacement vector having a degree of influence higher than the threshold value may be selected.
In the creation device 10 that also serves as a tire shape optimization device, after the evaluation unit 27 selects the displacement vector, the calculation unit 26 uses the displacement vector as a design variable, the weighting coefficient of the setting variable as a parameter, and the tire physical quantity as an objective function. Optimization calculations can be performed.

The model creation unit 24 also creates a tire model based on the selected displacement vector.
The display control unit 30 includes various parameters such as design variables and characteristic values set in the condition setting unit 20, a tire model obtained by the condition setting unit 20, displacement vector information set by the model setting unit 22, and model creation. The display unit 16 displays the deformed tire model created by the unit 24, the target characteristic obtained by the calculation unit 26, the degree of influence of the target characteristic obtained by the evaluation unit 27, and the tire model. For example, the deformed tire model, the target characteristic, the degree of influence of the target characteristic, and the result of the tire model are read from the memory 28 and displayed on the display unit 16.
In addition, the display control unit 30 can also display various information and the like input via the input unit 14 on the display unit 16.

As described above, the control unit 32 controls the processing unit 12, and the condition setting unit 20, the model setting unit 22, and the model creation of the processing unit 12 perform various processes performed by the tire model creation method shown below. This is to be performed by the unit 24, the calculation unit 26, and the evaluation unit 27.
In the creation device 10, in the input file when changing the shape or structure, the common part such as the boundary condition and the analysis step and the part different depending on the individual shape such as the node coordinate value, the arrangement angle of the reinforcing material and the initial tension are divided. However, by automating using a file format that incorporates into common parts, that is, by making individual information into an include file, it is easy to study tire shapes even when considering a large number of tire shapes. It is possible.

When evaluating a deformed tire model, it is preferable that the residual stress, residual strain, etc. generated in the deformation process from the reference tire model are reset. That is, in the deformed tire model, it is preferable that the initial shape has no residual stress and residual strain. Thereby, the influence of the residual stress and the residual strain on the target characteristic can be eliminated.

It is preferable that the method of giving the material physical properties is different between the time of acquiring the deformed tire model calculated by applying the forced displacement to the nodes on the outline and the time of evaluating the degree of influence on the target characteristics.
For example, it is preferable to set the Poisson's ratio of each element of the deformed tire model to a constant value of 0.1 or less, and to give a constant value to the elastic constant and the mass density. Generally, the Poisson's ratio of the element corresponding to rubber is, for example, 0.4999 in consideration of the incompressibility of rubber, but in the deformation calculation of the tire model 40, the deformation result can be appropriately obtained. Each element (all elements) of the tire model 40 is a compression element, and Poisson's ratio is, for example, 0.01. Further, the elastic modulus including the Young's modulus of each element (all elements) and the shear rigidity is set to, for example, 1/10 or less, preferably 1/100 or less of the value used in the simulation calculation of the tire performance. Similarly, the mass density is also set to, for example, 1/100 or less, preferably 1/1000 or less. In this way, the deformed tire model is deformed by performing the deformation calculation using a virtual physical property value having a compressibility and using a soft elastic constant as compared with the elastic constant when the deformed tire model is used for the simulation calculation of the tire performance. The tire cross-sectional shape of the tire outer peripheral surface has the shape of the tire outer peripheral surface in which the distribution of the modified shape difference is added to the tire cross-sectional shape of the deformed tire model without adversely affecting the mesh division inside the model. Here, the adverse effect on the mesh division indicates that the aspect ratio or distortion of the elements becomes large, the calculation tends to break down, or the calculation accuracy decreases.

Unify each element (all elements) of the deformed tire model to the same physical property value. Specifically, the Poisson's ratio is set to 0.01 as a virtual physical property value that has compressibility, is very soft, and has a very small mass density, and the elastic constants including Young's modulus and shear rigidity are set at the time of simulation calculation of tire performance. Set the value to 1/100 of the value used (actual rubber member value), and set the mass density to 100,000 minutes of the value used in the simulation calculation of tire performance (actual rubber, steel, etc. tire component value). Set to a value of 1. In this case, in the result after the deformation calculation of the deformed tire model, the nodes inside the deformed tire model are arranged in an orderly manner without being disturbed. In that the deformed tire model generated by the deformation calculation of the tire model can be obtained as an appropriate tire model, the Poisson's ratio of each element (all elements) of the deformed tire model is set to a constant value of 0.1 or less, and each element It is preferable to give constant values to the elastic constant and the mass density.

When selecting the displacement vector, the evaluation unit 27 preferably selects the displacement vector having a large contribution to the target characteristic. In this way, by selecting the displacement vector that contributes greatly to the determined characteristic value in each region, it is possible to increase the solution space (improvement width) at the time of optimization calculation.
The degree of contribution is the amount of influence on the output value over the entire domain, and is an index different from the sensitivity. It is known to acquire shape changes with high sensitivity, but in the case of tires, standard values of dimensions (for example, JATTA, TRA, ETRTO, etc.) are set for each size, and when searching for a product shape, The swing width (domain) is limited by the part that changes the shape. Therefore, in order to judge the degree of influence on the characteristic value while changing the shape while satisfying the above standard, it is evaluated using the contribution to judge how much the characteristic value changes in the given domain. It is preferable to do so.
Further, the number of displacement vectors selected by the evaluation unit 27 may be one or a plurality. Further, the displacement vector to be selected may be a composite vector in which a plurality of displacement vectors are combined. When the composite vector is selected, it means that a plurality of displacement vectors are substantially selected.

The model setting unit 22 may divide the outline 42 of the tire model 40 into a plurality of regions and set a plurality of displacement vectors in at least one region among the plurality of regions.
Specifically, as shown in FIGS. 4A to 4D, the model setting unit 22 divides the outer line 42 of the tire model 40 into at least the tread portion 45 and the sidewall portion 46 of the tire model 40. It is preferable to do so. This makes it possible to search for the shape by dividing the part that comes into contact with the road surface or inclusions (water, snow, mud, etc.). Therefore, even if there are a plurality of target characteristics and there is a trade-off relationship, it is possible to obtain a shape having higher-dimensional and balanced characteristics.
By dividing the outer line 42 of the tire model 40 into a plurality of regions, the shape can be searched for each region, and the shape can be searched efficiently.

The boundary 47 between the tread portion 45 and the sidewall portion 46 is not limited to the positions shown in FIGS. 4A to 4D, but is appropriately determined depending on the shape of the tire model 40 and the like. ..
FIG. 4A shows a first example of the displacement vector in the sidewall portion 46 of the tire model 40. The sidewall portion 46 is deformed by the displacement vector 48a, and the deformed sidewall portion 49a of the tire model 40 has a central portion in the radial direction of the tire model 40 protruding outward.
FIG. 4B shows a second example of the displacement vector in the sidewall portion 46 of the tire model. The sidewall portion 46 is deformed by the displacement vector 48b, and the deformed sidewall portion 49b of the tire model 40 has a region near the boundary 47 protruding outward.

FIG. 4C shows a third example of the displacement vector in the sidewall portion 46 of the tire model. The sidewall portion 46 is deformed by the displacement vector 48c, and the deformed sidewall portion 49c of the tire model 40 has a region on the bead ring portion 40c side of the central portion projecting outward in the diameter direction of the tire model 40.
FIG. 4D shows a fourth example of the displacement vector in the sidewall portion 46 of the tire model. The sidewall portion 46 is deformed by the displacement vector 48d, and the sidewall portion 49d of the deformed tire model 40 moves inward as a whole, and the width of the tire model is narrowed.
In addition, in FIGS. 4A to 4D, the displacement vector is shown discretely in consideration of the visibility in the example.
Further, among the tread portion 45 and the sidewall portion 46 of the divided plurality of regions, a plurality of displacement vectors may be set only in the sidewall portion 46, and the tire to be finally obtained is subject to shape restrictions. In this case, the region for setting the displacement vector may be limited to, for example, the sidewall portion 46 or the like.

The evaluation unit 27 evaluates the degree of influence of the displacement vector on the target characteristic in the region in which the model setting unit 22 sets a plurality of displacement vectors among the plurality of regions, and selects the displacement vector based on the degree of influence. It may be.
As described above, when the outline 42 of the tire model 40 is divided into a plurality of regions, the selected displacement vectors may all be the same or may be different for each region. Further, a plurality of displacement vectors may be set in only one of the plurality of regions, and the displacement vector may be selected based on the degree of influence.

[First example of tire model creation method]
Next, a first example of the tire model creating method of the present embodiment will be described.
FIG. 2 is a flowchart showing a first example of the tire model creating method of the embodiment of the present invention in the order of processes.

For example, a tire model 40 composed of elements that can be numerically analyzed by a computer as shown in FIG. 3 is created (step S10). The tire model 40 represents a tire and serves as a reference shape for deformation. The tire model 40 can have any tire shape, and may be a commercially available tire or a tire under design, and is not particularly limited. The tire model composed of elements that can be numerically analyzed by a computer is, for example, design data such as mesh data and CAD data used for numerical simulation such as FEM.
The tire model 40 is, for example, input to the condition setting unit 20 via the input unit 14 and stored in the memory 28. Further, if the data of the tire cross-sectional shape to be the tire model is stored in the memory 28 in advance, the data of the tire cross-sectional shape is called from the memory 28. A tire model is prepared in advance, and calling this tire model is also included in the creation of the tire model in step S10.

Next, a plurality of displacement vectors are set at all the nodes of the tire model 40 (step S12). The plurality of displacement vectors are set by the model setting unit 22 for all the nodes of the tire model 40. The plurality of displacement vectors set in step S12 are set in the condition setting unit 20, and are stored in, for example, the memory 28.
Next, among the plurality of displacement vectors, for each displacement vector, the model creation unit 24 gives a displacement vector as a forced displacement to the node, calculates using FEM (finite element method), and deforms the tire model according to the displacement vector. Then, a deformed tire model is created (step S14).
For each of the set plurality of displacement vectors, the deformation tire model is created by repeating until a deformed tire model is obtained (step S16).

Next, for each of the plurality of deformed tire models, a target characteristic representing a preset tire physical quantity is obtained (step S18). As described above, the target characteristics are, for example, rolling resistance, lateral rigidity, vertical rigidity, and the like.
In step S18, the calculation unit 26 obtains the target characteristics for each deformed tire model, for example, as follows.
When the calculation unit 26 obtains the target characteristic, the displacement vector of the deformed tire model is set as a design parameter and set as the target characteristic representing the physical quantity of the tire such as vertical rigidity and rolling resistance. Then, for example, in the case of numerical simulation using FEM (finite element method), the simulation conditions and the constraint conditions in the simulation are set. A numerical simulation of FEM is performed on the deformed tire model. As a result, the desired characteristics such as vertical rigidity and rolling resistance are obtained for the deformed tire model.

The timing for setting the target characteristics is not particularly limited, and may be set when the tire model is created, or may be stored in the memory 28.
Next, the degree of influence of the displacement vector on the target characteristics is evaluated based on the target characteristics of each of the plurality of deformed tire models (step S20). In step S20, the evaluation unit 27 evaluates the degree of influence of the displacement vector on the target characteristic by using the above-exemplified method. As a result, the displacement vector can be selected in consideration of the influence of the effect on the target characteristic.

Next, a new tire model is created based on the selected displacement vector (step S22). In step S22, the model creation unit 24 combines the selected displacement vectors to deform the tire model that serves as the reference shape, and obtains a new tire model. In the first example of the tire model creation method, the displacement vector can be efficiently selected in consideration of the influence of the effect on the target characteristic.

From the information on the cross-sectional shape of the new tire model obtained in step S22, the tire outline obtained by the shape optimization calculation is obtained, and the tire outline obtained by the shape optimization calculation is used as the mold shape. It can also be output as data. It is possible to obtain a tire cross-sectional shape in consideration of the physical quantity affected by the contour line on the outer side of the tire, and it is also possible to efficiently calculate the tire cross-sectional shape as mold shape data.
The mold shape data is dimensional data indicating the length of a straight line constituting the outline, the curvature of the curve, the position coordinates of the straight line, and the position coordinates of the curve. Specifically, for example, it is dimensional data required when manufacturing a mold using an NC processing machine. The mold shape data may be shown by the shape of the tire model in addition to the dimensional data. In this case, the tire model may be modeled by, for example, numerically analyzable elements.

[Second example of tire model creation method]
Next, a second example of the tire model creating method of the present embodiment will be described.
FIG. 5 is a flowchart showing a second example of the tire model creating method of the embodiment of the present invention in the order of processes.
In the second example of the tire model creating method, the detailed description of the same steps as in the first example of the tire model creating method described above will be omitted. Hereinafter, the second example of the tire model creation method is simply referred to as the second example.

In the second example, for example, a tire model composed of elements that can be numerically analyzed by a computer as shown in FIG. 3 is created (step S30). As described above, the tire model has a reference shape, and the same tire model as in the first example of the tire model creation method can be used as the tire model. For the tire model created in step S30, for example, graphic data or a finite element model is used. Since step S30 is the same as step S10 of the first example of the tire model creating method, detailed description thereof will be omitted.
Next, the node information of the outline is obtained for the tire model (step S32). The node information of the outer line in step S32 is obtained by extracting a plurality of nodes on the outer line 42 forming the outer contour of the cross-sectional shape of the tire model 40 in the model setting unit 22.

Next, a plurality of displacement vectors are set for each of the nodes on the outline of the tire model (step S34). In step S34, the plurality of displacement vectors are set by the model setting unit 22 for all the nodes of the outline 42 of the tire model 40. The plurality of displacement vectors set in step S12 are set in the condition setting unit 20, and are stored in, for example, the memory 28.
Next, among the plurality of displacement vectors, for each displacement vector, the model creation unit 24 gives a displacement vector as a forced displacement to the node, then calculates using FEM (finite element method), and obtains a tire model according to the displacement vector. It is deformed (step S36). In step S36, a deformed tire model is obtained (step S38).
A deformed tire model is obtained for each of the set plurality of displacement vectors (step S40).

For each of the set multiple displacement vectors, the displacement vector is given as a forced displacement to the node until a deformed tire model is obtained, and then the calculation is performed using FEM (finite element method) to obtain the tire model. Deformation (step S36) and obtaining a deformed tire model (step S38) are repeatedly executed.
After obtaining a deformed tire model for each displacement vector for all the displacement vectors, a target characteristic representing a preset tire physical quantity is obtained for each of the plurality of deformed tire models (step S42). Since step S42 is the same as step S18 of the first example of the tire model creating method, detailed description thereof will be omitted.

Next, the degree of influence of the displacement vector on the target characteristics is evaluated based on the target characteristics of each of the plurality of deformed tire models (step S44). Since step S44 is the same as step S20 of the first example of the tire model creating method, detailed description thereof will be omitted.
Next, a new tire model is created based on the displacement vector selected in consideration of the influence of the effect on the target characteristic (step S46). Since the step of creating a new tire model in step S46 is the same as step S22 of the first example of the tire model creating method, detailed description thereof will be omitted.
In the second example of the tire model creating method, a new tire model can be created based on the selected displacement vector as in the first example of the tire model creating method. Moreover, also in the second example of the tire model creating method, the displacement vector in consideration of the influence of the effect on the target characteristic can be efficiently selected.

In the step of selecting the displacement vector, it is preferable to select the displacement vector having a large contribution to the target characteristic. As a result, it is possible to increase the solution space (improvement width) at the time of optimization calculation by selecting a displacement vector that contributes greatly to the determined characteristic value in each region. The degree of contribution is as described above.

After the step of obtaining the node information of the outline of the tire model, the step of dividing the outline of the tire model into a plurality of regions and setting a plurality of displacement vectors is at least one of the plurality of regions. It is preferable to set a plurality of displacement vectors in the region.
The step of dividing the outer line of the tire model into a plurality of regions is preferably divided into at least a tread portion and a sidewall portion of the tire model as described above.

In both the first example of the tire model creation method and the second example of the tire model creation method, the displacement vector selected in the step of selecting the displacement vector is set as the design variable after the step of selecting the displacement vector. It may have a step of carrying out the optimization calculation using the weight coefficient of the variable as a parameter and the physical quantity of the tire as an objective function, that is, a search step for designing the initial shape of the tire. As a result, by selecting a shape mode that takes into consideration the effect on the target characteristics for any tire physical characteristics, it is possible to search for shapes with a large improvement in characteristic values and improve the efficiency of search by reducing the degree of freedom. It is possible to optimize the tire shape that is compatible with each other.
In this case, the target characteristic and the physical quantity of the tire may be the same or different.
In both the first example of the tire model creation method and the second example of the tire model creation method, the tire shape optimization method is further carried out by carrying out the step of carrying out the above-mentioned optimization calculation. ..
The trial shape of the tire model can be changed by changing the weight and linear addition.

FIG. 6 is a schematic diagram for explaining a method of acquiring a new tire model in the method of creating a tire model according to the embodiment of the present invention.
Specifically, the tire model 50 of the first shape change shown in FIG. 6 is multiplied by a weight 1 as a weight coefficient. Further, the tire model 52 of the second shape change is multiplied by the weight 2 as a weight coefficient. Multiply the tire model of shape change by the number of displacement vectors. Find the linear sum of these. As a result, the second tire model can be acquired.
Reference numeral 51 in FIG. 6 indicates a displacement vector, and reference numeral 53 indicates a displacement vector.

When creating the tire model, the value of the weighting factor is given to the displacement vector as described above.
The value of the weighting coefficient is set by the condition setting unit 20. The value of the weighting factor can be set using, for example, a known design of experiments method, specifically a design matrix such as a Latin hypercube or an orthogonal array.
The weighting factor values may be set according to the design matrix described above or may be changed sequentially within a defined range, and each time the weighting factor values are changed, a second tire model is created. .. In each case, the value of the weighting coefficient is changed so as to evenly cover the entire set range, and the second tire model is created. The value of the weighting coefficient is changed discretely so as to increase or decrease by a certain magnitude, for example, but the value of the weighting coefficient may be changed randomly.

In addition, in the first example of the tire model creating method described above, the computer executes each step of the above-mentioned first example of the tire model creating method by a program for executing the first example of the tire model creating method. Can be executed.
In the second example of the tire model creation method, a program that executes the second example of the tire model creation method can cause a computer to execute each step of the second example of the tire model creation method described above as a procedure. ..

As described above, the creating device 10 shown in FIG. 1 is also used in the tire shape optimization method of the present invention, but if the tire shape optimization method can be executed by using hardware and software such as a computer. The program is not limited to the creating device 10, and may be a program for causing a computer or the like to execute each step of the tire shape optimization method as a procedure.
The present invention is basically configured as described above. Although the tire model creation method and the tire shape optimization method, the tire model creation device, the tire shape optimization device, and the program of the present invention have been described in detail above, the present invention is not limited to the above-described embodiment, and the present invention is the present invention. Of course, various improvements or changes may be made without departing from the gist of.

Hereinafter, examples of the tire model creating method and the tire shape optimization method of the present invention will be specifically described.
In this example, the effect of the tire model making method of the present invention was confirmed by using Examples 1 and 2 and Comparative Examples 1 and 2 shown below.
In this embodiment, a displacement vector representing 20 preset shape changes is set with reference to a tire model having a tire size of 215 / 55R17. This displacement vector was used as a design parameter. The objective characteristics were reduction of rolling resistance and improvement of lateral rigidity. A displacement vector satisfying the above-mentioned target characteristics was selected.
The target characteristics were obtained by performing FEM optimization simulation of 500 cases (50 individuals, 10 generations) using evolutionary computation.
In Examples 1 and 2 and Comparative Examples 1 and 2, the rate at which the rolling resistance of the finally obtained new tire model was reduced and the rate at which the lateral rigidity was improved were determined with respect to the reference tire model. The results are shown in Table 1 below. The rolling resistance and lateral rigidity of the standard tire model were calculated.

Hereinafter, Examples 1 and 2 and Comparative Examples 1 and 2 will be described.
In Example 1, a deformed tire model was obtained by applying displacement vectors to all the nodes on the outline of the tire model. Further, out of the 20 displacement vectors, the displacement vectors with the highest contribution degree were selected.
In Example 2, a deformed tire model was obtained by applying displacement vectors to all the nodes on the outline of the tire model. Further, out of the 20 displacement vectors, the displacement vectors with the highest contribution degree were selected.
In Comparative Example 1, a deformed tire model was obtained by applying displacement vectors to all the nodes on the outline of the tire model. In addition, the displacement vector was not selected.
In Comparative Example 2, a deformed tire model was obtained by applying displacement vectors to all the nodes of the tire model. In addition, the displacement vector was not selected.

As shown in Table 1 above, in Example 1 and Example 2, the required time can be shortened while the improvement range of the target characteristic (characteristic value) is the same as that in Comparative Example 1 and Comparative Example 2. We were able to reduce the time cost and improve the efficiency of searching for the optimum tire shape. In this way, it was possible to efficiently select the displacement vector in consideration of the effect of the effect on the target characteristics.

Next, a second embodiment will be described.
In the second example, the effects of the tire model creating method of the present invention were confirmed using Examples 10 and 11 and Comparative Examples 10 and 11 shown below.
In the second embodiment, as compared with the first embodiment, the tire model is divided into a tread portion and a sidewall portion, and a displacement vector that changes only the tread portion and a displacement vector that changes only the sidewall portion are obtained. The point that a total of 20 was set for each of 10 was different, and the method of selecting the displacement vector, the desired direction of the target characteristic, and the like were the same as those of the first embodiment.
In Examples 10 and 11 and Comparative Examples 10 and 11, the rate at which the rolling resistance of the finally obtained new tire model was reduced and the rate at which the lateral rigidity was improved were determined with respect to the reference tire model. The results are shown in Table 2 below. The rolling resistance and lateral rigidity of the standard tire model were calculated.

Hereinafter, Examples 10 and 11 and Comparative Examples 10 and 11 will be described.
The tenth embodiment is different from the first embodiment in that the tire model is divided into a tread portion and a sidewall portion, and a displacement vector for changing only the tread portion and the sidewall portion is set. Was the same as in Example 1.
The eleventh embodiment is different from the second embodiment in that the tire model is divided into a tread portion and a sidewall portion, and a displacement vector for changing only the tread portion and the sidewall portion is set. Was the same as in Example 2.
Comparative Example 10 is different from Comparative Example 1 in that the tire model is divided into a tread portion and a sidewall portion, and a displacement vector that changes only the tread portion and only the sidewall portion is set. Was the same as in Comparative Example 1.
Comparative Example 11 is different from Comparative Example 2 in that the tire model is divided into a tread portion and a sidewall portion, and a displacement vector that changes only the tread portion and only the sidewall portion is set. Was the same as in Comparative Example 2.

As shown in Table 2 above, in Example 10 and Example 11, the required time can be shortened as compared with Comparative Example 10 and Comparative Example 11 while maintaining the improvement range of the target characteristic (characteristic value). We were able to reduce the time cost and improve the efficiency of searching for the optimum tire shape. As a result of searching by combining a displacement vector that changes only the tread portion and a displacement vector that changes only the sidewall portion in this way, a displacement vector that considers the influence of the effect on the target characteristics is more efficient than in the first embodiment. I was able to select.

10 Tire model creation device (creation device)
12 Processing unit 14 Input unit 16 Display unit 20 Condition setting unit 22 Model setting unit 24 Model creation unit 26 Calculation unit 27 Evaluation unit 28 Memory 30 Display control unit 32 Control unit 40 Tire model 40c Bead ring unit 41 Tread unit 42 Outline 43 Nodal 43a First displacement vector 43b Second displacement vector 43c Third displacement vector 45 Tread portion 46 Side wall portion 47 Boundary 50 First shape change tire model 52 Second shape change tire model

Claims (15)

The process of obtaining node information of a tire model composed of elements that can be numerically analyzed by a computer, representing the tire,
A process of setting a plurality of displacement vectors at each of the nodes of the tire model, and
A step of obtaining a plurality of deformed tire models in which the tire model is deformed according to the displacement vector for each of the set plurality of displacement vectors.
For each of the plurality of deformed tire models, a step of obtaining a target characteristic representing a preset tire physical quantity and a step of obtaining the target characteristic.
A step of evaluating the degree of influence of the target characteristic of the displacement vector based on the target characteristics of each of the plurality of deformed tire models, and a step of evaluating the degree of influence of the target characteristic.
The process of selecting the displacement vector based on the degree of influence and
A tire model creating method comprising a step of creating a tire model based on the selected displacement vector. For tires, the process of acquiring a tire model composed of elements that can be numerically analyzed by a computer,
The process of obtaining node information on the outline of the tire model and
A step of setting a plurality of displacement vectors that give a shape change to the tire model at each of the nodes on the outline of the tire model, and
A step of obtaining a plurality of deformed tire models in which the tire model is deformed by giving a displacement vector as a forced displacement to the node on the outline for each of the set plurality of displacement vectors.
For each of the plurality of deformed tire models, a step of obtaining a target characteristic representing a preset tire physical quantity and a step of obtaining the target characteristic.
A step of evaluating the degree of influence of the displacement vector on the target characteristics based on the target characteristics of each of the plurality of deformed tire models, and
The process of selecting the displacement vector based on the degree of influence and
A tire model creating method comprising a step of creating a tire model based on the selected displacement vector. After the step of obtaining the node information of the outer line of the tire model, there is a step of dividing the outer line of the tire model into a plurality of regions.
The tire model creation method according to claim 2, wherein the step of setting the plurality of displacement vectors is to set the plurality of displacement vectors in at least one of the plurality of the regions. In the step of evaluating the degree of influence of the displacement vector on the target characteristic, the degree of influence of the displacement vector on the target characteristic is evaluated in the region in which the plurality of displacement vectors are set among the plurality of the regions. And
The tire model creation method according to claim 3, wherein the step of selecting the displacement vector is to select the displacement vector in the set region based on the degree of influence. The method for creating a tire model according to claim 3 or 4, wherein the step of dividing the outline of the tire model into a plurality of regions is divided into at least a tread portion and a sidewall portion of the tire model. The tire model creation method according to any one of claims 1 to 5, wherein the step of selecting the displacement vector is a step of selecting a displacement vector having a large contribution to the target characteristic. In the tire model creating method according to any one of claims 1 to 6,
After the step of selecting the displacement vector, the step of performing the optimization calculation with the displacement vector selected in the step of selecting the displacement vector as the design variable, the weighting coefficient of the setting variable as the parameter, and the tire physical quantity as the objective function. A method for optimizing the shape of a tire, which comprises having. For tires, a condition setting unit that acquires a tire model composed of elements that can be numerically analyzed by a computer,
A model setting unit that acquires node information of the outer line of the tire model and sets a plurality of displacement vectors that give a shape change to the tire model at each of the nodes on the outer line of the tire model.
For each of the set plurality of displacement vectors, a model creation unit for obtaining a plurality of deformed tire models by giving a displacement vector as a forced displacement to the node on the outline for each displacement vector to deform the tire model.
For each of the plurality of deformed tire models, a calculation unit for obtaining a target characteristic representing a preset tire physical quantity, and a calculation unit.
It has an evaluation unit that evaluates the degree of influence of the displacement vector on the target characteristic based on each target characteristic of the plurality of deformed tire models and selects a displacement vector based on the degree of influence.
The model creating unit is a tire model creating device characterized in that a tire model is created based on the selected displacement vector. The tire model creating device according to claim 8, wherein the model setting unit divides the outline of the tire model into a plurality of regions and sets the plurality of displacement vectors in at least one region among the plurality of regions. .. The evaluation unit evaluates the degree of influence of the displacement vector on the target characteristic in the region in which the plurality of displacement vectors are set by the model setting unit among the plurality of the regions, and is based on the degree of influence. The tire model creating device according to claim 9, wherein the displacement vector is selected. The tire model creating device according to claim 9 or 10, wherein the model setting unit divides the outline of the tire model into at least a tread portion and a sidewall portion of the tire model. The tire model creating device according to any one of claims 8 to 11, wherein the evaluation unit selects a displacement vector having a large contribution to the target characteristic. A tire shape optimization device having the tire model creation device according to any one of claims 8 to 12.
After the displacement vector is selected by the evaluation unit, the calculation unit is characterized in that the optimization calculation is performed using the displacement vector as a design variable, the weighting coefficient of the setting variable as a parameter, and the tire physical quantity as an objective function. Tire shape optimization device. A program for causing a computer to execute each step of the tire model creating method according to any one of claims 1 to 7 as a procedure. A program for causing a computer to execute each step of the tire shape optimization method according to claim 8 as a procedure.

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