Tire model and how to create a tire model

Abstract

To provide a tire model enabling a tire performance evaluation considering the influence of a design of a tire side surface.SOLUTION: A tire model 1 is a model to be used for computer simulation of a tire. The tire model 1 has a first model part 10 for reproducing a tire body, a second model part 20 for reproducing a tire surface shape including a tread pattern, and a joint line 30 for combining the first model part 10 and the second model part 20. The second model part 20 includes a side design region 23 in which the design of a tire side surface is reproduced. The joint line 30 extends to a position corresponding to the side design region 23 of the second model part 20.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a tire model and a method for creating a tire model, and more particularly, to a tire model used for computer simulation of a tire. 【Background Art】 【0002】 Conventionally, a model that reproduces the surface shape and internal structure of a tire and is used for computer simulation of a tire is widely known. For example, Patent Documents 1 and 2 disclose a method of creating a FEM model of a tire in which the tire is divided into finite elements and predicting tire performance by computer simulation using the FEM model. Patent Documents 1 and 2 disclose a tire model configured by combining a tread model in which the tread is modeled and a casing model in which the portion excluding the tread is modeled. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2002-306838 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2004-317832 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In recent years, when evaluating the aerodynamic performance of a tire, etc., the uneven shape on the side surface of the tire may be emphasized. For this reason, it is required to perform a simulation considering the influence of the design on the side surface of the tire, but conventional tire models generally omit the design on the side surface of the tire (see FIG. 4 described later). 【0005】 An object of the present invention is to provide a tire model that enables evaluation of tire performance considering the influence of the design on the side surface of the tire. [Means for solving the problem] 【0006】 The tire model according to the present invention is a model used for computer simulation of a tire, and comprises a first model section that reproduces the tire body, a second model section that reproduces the tire surface shape including the tread pattern, and a joining line for combining the first model section and the second model section, wherein the second model section includes a side design region that reproduces the design of the tire side surface, and the joining line extends to a position corresponding to the side design region. 【0007】 The method for creating a tire model according to the present invention is a method for creating a tire model used in computer simulation of a tire, and includes the steps of: creating a first model part that reproduces the tire body; creating a second model part that includes a region that reproduces the tread pattern and a side design region that reproduces the design of the tire side; and combining the first model part and the second model part, wherein the joining line for combining the first model part and the second model part extends to a position corresponding to the side design region. [Effects of the Invention] 【0008】 According to the tire model of the present invention, tire performance evaluation can be efficiently performed while taking into account the influence of the tire sidewall design. [Brief explanation of the drawing] 【0009】 [Figure 1] This figure shows a portion of the cross-section in the width direction of a tire model, which is an example of an embodiment. [Figure 2] This is a plan view showing a part of the second model section, which is an example of an embodiment. [Figure 3] This figure shows a tire model, which is another example of an embodiment. [Figure 4] This figure shows an example of a conventional tire model. [Modes for carrying out the invention] 【0010】 Hereinafter, with reference to the drawings, an example of an embodiment of the tire model and the method for creating the tire model according to the present invention will be described in detail. The embodiments described below are merely examples, and the present invention is not limited to these embodiments. Furthermore, configurations obtained by selectively combining the various components of the multiple embodiments and modifications described below are included in the present invention. 【0011】 Figure 1 shows a tire model 1, which is an example of an embodiment. Figure 1 shows a portion of a two-dimensional cross-section of tire model 1. 【0012】 As shown in Figure 1, the tire model 1 has a first model part 10 that reproduces the tire body, a second model part 20 that reproduces the tire surface shape including the tread pattern, and a joining line 30 for combining the first model part 10 and the second model part 20. The tire body is the part that constitutes the frame of the tire and does not include the design of the tire surface. With the tire model 1, the first model part 10 and the second model part 20 can be handled separately. For example, one type of first model part 10 and multiple types of second model parts 20 can be prepared, and multiple types of tire models 1 can be created by combining each of the second model parts 20 with the first model part 10. 【0013】 Tire Model 1 is a model for computer simulation of a tire. As will be described in more detail later, the second model section 20 includes a first region 21 that reproduces the tread pattern and a second region 22 that reproduces the shape of the upper part of the tire sidewall. The second region 22 then includes a side design region 23 that reproduces the design of the tire sidewall. The joining line 30, defined as the joining position of the first model section 10 and the second model section 20, extends to a position corresponding to the side design region 23. 【0014】 According to tire model 1, in evaluating tire performance using computer simulation, it is possible to consider the influence of not only the tread pattern but also the design formed on the tire sidewall (hereinafter sometimes referred to as "side design"). Preferably, the joint line 30 extends radially inward in the tire to a position beyond the radially inward end (side design end) of the side design region 23. In this case, the entire side design region 23 is included in the second model part 20, making it possible to evaluate performance considering the entire side design. 【0015】 Computer simulations using tire model 1 are performed, for example, based on the finite element method (FEM). FEM analyzes the structure under analysis by dividing it into finite elements and calculating the equations of motion for each element. Tire model 1, illustrated in Figure 1, is an FEM model meshed into multiple elements. Figure 1 shows a portion of a two-dimensional cross-section divided into multiple elements in the tire width direction and radial direction, but it is preferable that tire model 1 is a three-dimensional model divided into multiple elements in the tire circumferential direction as well. 【0016】 The simulation using tire model 1 is performed using a computer equipped with a processor and memory. Tire model 1 may be created on the computer used for the simulation, or on a separate computer. In this embodiment, the creation of tire model 1 and the simulation using the model are performed on the same computer. Since tire model 1 allows for performance evaluation that takes into account the uneven shape of the tire sidewall, simulations using tire model 1 are useful for evaluating, for example, the aerodynamic performance, air cooling performance, rigidity of the tire sidewall, and cut resistance of the tire. 【0017】 The above-mentioned processor executes each step for creating the tire model 1 described below and each step of the simulation using the tire model 1 by, for example, reading and executing a program stored in a memory. The memory is composed of a RAM, a ROM, a hard disk, etc., and stores various setting information including a simulation program, creation conditions of the tire model 1, material physical property values, boundary conditions, etc. Note that the computer may be composed of one computer or may be composed of a plurality of computers. 【0018】 The first model part 10 and the second model part 20 constituting the tire model 1 are divided into a plurality of elements by a mesh. The first model part 10 and the second model part 20 are models created independently of each other. For example, the number of mesh divisions, the shape and size of the elements, etc. are different in each model part. Also, there are a plurality of types of element shapes and sizes within each model part. The tire model 1 is data obtained by digitizing a tire into an input data format for a computer program so as to be analyzable based on a mathematical method, and has data regarding the surface shape and internal structure of the tire. 【0019】 The tire model 1 is created by using the tire shape in the natural equilibrium state as a reference shape and modeling this reference shape by FEM. Each node of the finite elements of the tire model 1 is specified by three-dimensional coordinates. The tire model 1 is created by, for example, performing mesh generation on the shape of a tire body created by two-dimensional CAD software using mesh generation software, and then expanding it in the tire circumferential direction to obtain a first model part, and using three-dimensional data indicating the shape of a tread pattern and a side design area created by three-dimensional CAD software or three-dimensional modeling software, and performing mesh generation on the three-dimensional data using mesh generation software to create a second model part, and then combining them. The mesh shape is preferably a polygon, and generally, it is a quadrilateral or a triangle (in the three-dimensional case, a hexahedron mesh or a tetrahedron mesh), and they may be mixed. 【0020】 The first model part 10 and the second model part 20 are independent models of each other, and are joined by a joint line 30 to form one tire model 1. In the present embodiment, the cross-section in the width direction of the tire model 1 has a shape symmetric about the tire equator passing through the center in the width direction. By preparing one type of first model part 10 and a plurality of types of second model parts 20 and changing only the second model part 20, a plurality of types of tire models 1 can be created. Even when a plurality of types of second model parts 20 are prepared, for example, the joint lines 30 of each model are set to have the same shape and the same length as each other. 【0021】 As described above, the first model part 10 is a FEM model that reproduces the tire body, and is created by developing a model of the cross-section along the width direction and the radial direction of the tire in the circumferential direction. The tire body is a part that constitutes the skeleton of the tire, and includes a carcass, a belt, beads (bead cores and bead fillers), sidewall rubber, an inner liner, and the like. The first model part 10 includes a carcass region 11 that reproduces the carcass, a belt region 12 that reproduces the belt, a bead region 13 that reproduces the beads, and a rubber region 14 that reproduces rubber parts such as sidewall rubber. 【0022】 In the region of the first model part 10 corresponding to the buttless region of the tire, the thickness is substantially constant. In other words, the joint line 30 is defined so that the thickness of the first model part 10 is substantially constant. In this case, the variation in the size of each element generated by mesh division can be suppressed, and the analysis accuracy can be improved. In this specification, the buttless region is defined as a region located in the upper part of the tire side surface portion, and more specifically, as a region located in the range from the ground contact end of the tire to the portion where the width of the tire is maximum. 【0023】 Figure 2 is a plan view of the second model section 20. Figure 2 shows the model for one pitch, which is the smallest repeating unit. The second model section 20 is created by repeating a detailed shape model that reproduces the tire surface shape the required number of times in the circumferential direction. The second model section 20 is meshed more finely than the first model section 10. The first region 21 of the second model section 20 is the region that reproduces the tread pattern that contacts the road surface. The first region 21 reproduces, for example, circumferential grooves, widthwise grooves, and land areas partitioned by each groove. The second region 22 is the region that reproduces the shape of the upper part of the tire sidewall located widthwise outward from the contact edge. 【0024】 The second region 22 includes a side design region 23 that reproduces the side design. Examples of side design elements include side blocks, the uneven shape of the shoulder block sides of the tread, and side ribs formed along the circumferential direction of the tire. The uneven shapes of the side blocks and shoulder block sides are generally arranged in predetermined repeating units in the circumferential direction of the tire, contributing to improved cut resistance and other performance improvements. The side design also affects the aerodynamic performance of the tire. One pitch shown in Figure 2 corresponds to the smallest repeating unit of the tread pattern and side design. 【0025】 The joint line 30 is defined as the joining position of the first model portion 10 and the second model portion 20 in the widthwise cross-section of the tire model 1. The central part of the joint line 30 is formed in a substantially straight line, while both ends of the joint line 30 and their vicinity are greatly curved. The joint line 30 extends from a position corresponding to the tread pattern to a position corresponding to the side design. Preferably, the end of the joint line 30E coincides with the inner end in the tire radial direction of the side design area 23 (side design end), or is set to be radially inward of the side design end. In this case, the entire side design can be modeled in the second model portion 20. 【0026】 The joint line 30 is greatly curved, convex toward the outside of the tire, from a predetermined position outside the tire width direction relative to the contact edge to the joint line end 30E. The predetermined position where the joint line 30 begins to curve is set such that the thickness of the first model portion 10, which is located inside the joint line 30, remains substantially constant without significant local changes. That is, the joint line 30 is curved such that the thickness of the first model portion 10 remains substantially constant, at least in the region corresponding to the buttress region of the tire. The first model portion 10 may be formed such that the thickness of the portion excluding the bead region 13 is substantially constant. 【0027】 The joint line end 30E can be set according to the shape and size of the side design to be evaluated. The joint line end 30E is usually set at a position corresponding to the buttress area of ​​the tire. Preferably, the position of the joint line end 30E is constant along the circumferential direction of the tire and is set beyond the side design end located furthest inward in the radial direction of the tire. 【0028】 Outside the curved portion of the joint line 30, the second region 22 of the second model section 20 is located. The second region 22, excluding the side design region 23, gradually decreases in thickness from the first region 21 towards the joint line end 30E. In this embodiment, the second model section 20 is mainly divided into multiple elements by hexa mesh, but in this case, it is preferable to have the same number of hexa mesh layers in the first region 21 and the second region 22. That is, the second model section 20 is meshed such that the number of hexa mesh layers in the thickness direction of each region is the same. 【0029】 In this embodiment, in the second region 22 of the second model section 20, the side design region 23 exists outside the profile line along the surface (tread surface) of the first region 21. In this case, it is preferable that the side design region 23 is meshed such that the thickness of the elements constituting the region and the thickness of the elements located inside the side design region 23 are the same or approximately the same. 【0030】 Furthermore, if there are two or more layers of hexa mesh in the side design region 23, it is preferable that the thickness of each hexa mesh layer be approximately the same. That is, the thickness of the hexa mesh layers in the side design region 23 is set to be approximately the same, while also being set to be as close as possible to the thickness of the hexa mesh layers in the portion of the second region 22 located inside the side design region 23. By dividing the mesh in this way, the accuracy of the FEM analysis is improved. 【0031】 Figure 3 shows a modified example of the mesh division configuration of the side design area 23. The configuration illustrated in Figure 3 differs from the configuration illustrated in Figure 4 in that the side design area 23 is divided into multiple elements by a tetrahedron mesh. For example, if the shape of the side design area 23 is complex, the side design area 23 is divided using a tetrahedron mesh, or by using a combination of a hexahedron mesh and a tetrahedron mesh. In this case, it is preferable to divide the side design area 23 with a mesh such that the length of one side of the tetrahedron mesh and the thickness of the tetrahedron mesh layer are approximately equal. 【0032】 A tire model 1 with the above configuration can be created, for example, by the following procedure. (1) Step of creating the first model part 10 which reproduces the tire body. (2) Step of creating a second model section 20 which includes a first area 21 that reproduces the tread pattern and a side design area 23 (second area 22) that reproduces the design of the tire sidewall. (3) Step of combining the first model part 10 and the second model part 20. The order in which the first model section 10 and the second model section 20 are created is not particularly limited. The tire surface shape of the second model section 20 is created using 3D CAD software or the like, and then meshed into finite elements. Material properties are then set for each element according to the rubber compound. 【0033】 In the process of creating the tire model 1, a joining line 30 is defined for combining the first model section 10 and the second model section 20. The joining line 30 is a line that extends from a position corresponding to the tread pattern, far beyond the position corresponding to the contact edge, to a position corresponding to the side design area 23. It is preferable that the end of the joining line 30E is set to coincide with the side design edge or to a position beyond the side design edge. Furthermore, it is preferable that the joining line 30 is set so that the thickness of the first model section 10 is substantially constant, at least in the area corresponding to the buttress area of ​​the tire. 【0034】 Furthermore, from the viewpoint of improving the accuracy of FEM analysis, it is preferable to divide the side design region 23 into a mesh such that the thickness of the elements constituting the region and the thickness of the elements located inside the side design region 23 are the same or approximately the same, as described above. The difference in thickness between each element in the side design region 23 and its inner portion is preferably 40% or less, and more preferably 20% or less. 【0035】 Figure 4 shows a portion of a two-dimensional cross-section of a conventional tire model 50. The tire model 50 is similar to the tire model 1 in that it has a first model section 51 that reproduces the tire body, a second model section 52 that reproduces the tire surface shape including the tread pattern, and a joining line 53 for combining the first model section 10 and the second model section 20. On the other hand, the joining line 53 is formed in a substantially straight line, and the second model section 52 does not include a region corresponding to the side of the tire. That is, the second model section 52 does not have a region that reproduces the design of the tire side. Furthermore, the design of the tire side is not modeled in the first model section 51 either. 【0036】 In contrast, in tire model 1, the joining line 30 extends to the area corresponding to the side design, and the second model section 20 includes a first region 21 that reproduces the tread pattern and a side design region 23 (second region 22) that reproduces the design of the tire sidewall. Therefore, by using tire model 1, tire performance evaluation can be efficiently performed by considering the influence of not only the tread pattern but also the design of the tire sidewall. 【0037】 Simulations using Tire Model 1 are suitable for evaluating performance where the design of the tire sidewall is likely to have an effect. An example of performance evaluation using Tire Model 1 is the evaluation of the aerodynamic performance of a tire. 【0038】 Furthermore, it is preferable that the joining line 30 is defined such that the thickness of the first model portion 10 is substantially constant, at least in the region corresponding to the buttress area of ​​the tire. In this case, variations in the size of each element of the first model portion 10 are suppressed, and the accuracy of the FEM analysis is improved. 【0039】 The embodiments described above can be modified as appropriate without impairing the objectives of the present invention. For example, the cross-section in the width direction of tire model 1 has a symmetrical shape with respect to the tire equator, but the tire model according to the present invention may have an asymmetrical shape with respect to the tire equator. [Explanation of symbols] 【0040】 1 Tire model, 10 First model section, 11 Carcass area, 12 Belt area, 13 Bead area, 14 Rubber area, 20 Second model section, 21 First area, 22 Second area, 23 Side design area, 30 Joint line, 30E Line end

Claims

[Claim 1] A method for simulating tire performance using a tire model, which is performed by a computer having a processor and memory, The processor executes a program stored in the memory to perform a simulation of tire performance using the tire model. The aforementioned tire model is The first model part reproduces the tire body, The second model part reproduces the tire surface shape, including the tread pattern, A joining line for combining the first model section and the second model section, It has, The second model section includes a side design area that reproduces the design of the tire sidewall. A tire simulation method wherein the joining line extends to the inner end of the tire radially in the side design area, or to a position beyond the inner end of the tire radially in the side design area. [Claim 2] The tire simulation method according to claim 1, wherein in the tire model, the joint line is curved such that the thickness of the first model portion is substantially constant in the region corresponding to the buttress region of the tire. [Claim 3] The tire simulation method according to claim 1 or 2, wherein in the tire model, the first and second model portions are meshed with finite elements, and the side design region is meshed such that the thickness of the elements constituting the design region and the thickness of the elements located inside the design region are the same or approximate. [Claim 4] A processor that performs tire performance simulations using a tire model, Memory and Equipped with, The aforementioned tire model is The first model part reproduces the tire body, The second model part reproduces the tire surface shape, including the tread pattern, A joining line for combining the first model section and the second model section, It has, The second model section includes a side design area that reproduces the design of the tire sidewall. A tire simulation device in which the joining line extends to the inner end of the tire radially in the side design area, or to a position beyond the inner end of the tire radially in the side design area.

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