JP2011204157A - Method of producing tire model, and tire model producing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a tire model providing an analytical result which is close to a measured value, when evaluating tire performance, and shortening the computation time.SOLUTION: The tire model is produced by setting a pseudo-model, in which a pseudo-elastomer that does not actually exist in a pneumatic tire is divided into a finite number of elements among microgroove 141-147 wall faces formed in a tread part, and by setting an elastic modulus lower than that of the tread part of the pseudo-model.

Description

  The present invention relates to a tire model creation method and a tire model creation device for creating a tire model in which a pneumatic tire is divided into a finite number of elements.

  In the development of pneumatic tires, with the development of numerical analysis methods such as the finite element method and the computer environment, newly designed pneumatic tires can be manufactured without actually manufacturing pneumatic tires and mounting them in automobiles for running tests. It has become possible to predict and evaluate tire performance such as tire running performance and characteristics (see, for example, Patent Document 1). By using the tire performance prediction method and replacing part of the development cycle, such as the design, manufacture, and evaluation of pneumatic tires, with numerical analysis, the development period of pneumatic tires has been shortened.

  In recent years, with the improvement in performance of pneumatic tires, there is an increasing demand to create a structural model that accurately represents a complex structure and perform a more accurate analysis using the structural model. Therefore, in the conventional tire performance prediction method, element division is set in a two-dimensional pattern formed on a plane, and then a three-dimensional model is created by subdividing in the height direction (that is, the tire radial direction). ing.

Japanese Patent Laid-Open No. 2006-168505 FIG. 4

  In the finite element method, if the size of an element is finely defined, a model having a complicated structure can be accurately created, but the number of elements increases. In addition, for example, where the model contacts between the tire model and the road surface model, such as the wall surfaces of the grooves set in the tire model, it is necessary to define boundary conditions for contact.

  For this reason, when a highly accurate model is created, not only the number of elements increases, but also the boundary conditions become complicated, so that the amount of calculation increases extremely. In addition, there is a high possibility that the calculation will not converge. For this reason, there is a problem that the calculation time that cannot be used in actual use is required and the advantage of substituting a part of the tire development cycle with numerical analysis is diminished.

  Therefore, the present invention provides a tire model creation method and a tire model creation device for creating a tire model that can obtain an analysis result close to an actual measurement value and reduce the calculation time when evaluating tire performance. Objective.

  In order to solve the above-described problems, the present invention has the following features. That is, the first feature of the present invention is that a pneumatic tire having a plurality of grooves formed in the tread portion and narrow grooves with which the wall surfaces of the grooves abut each other when the tread portion contacts the road surface is a finite number of elements. A tire model creation method for creating a tire model divided into a step, wherein a pseudo model in which a pseudo elastic body that does not exist in the pneumatic tire is divided into a finite number of elements is set between wall surfaces of the narrow grooves And a step of setting an elastic modulus lower than the elastic modulus of the tread portion in the pseudo model.

  According to the first feature of the present invention, instead of setting the boundary condition that abuts each other on the models of the opposing wall surfaces of the narrow groove, the fine groove is set so that the pseudo elastic body is disposed in the narrow groove. Compared with the case where boundary conditions for contact are set between the wall portions of the groove, the amount of calculation can be reduced. In addition, when analyzing tire performance using the created tire model, the models of the wall surfaces facing each other in the narrow groove do not lead to overlapping or penetrating results, and the convergence of computation Sexuality is enhanced.

  Accordingly, it is possible to provide a tire model creation method and a tire model creation device for creating a tire model that can obtain an analysis result close to an actual measurement value and that can reduce the calculation time.

  A second feature of the present invention relates to the first feature of the present invention, and is characterized in that the elastic modulus of the pseudo model is set to 1 / 10,000 or more and 1/100 or less of the elastic modulus of the tread portion. To do.

  A third feature of the present invention relates to any one of the first feature or the second feature of the present invention, and the Poisson's ratio of the pseudo model is set to 0.001 or more and 0.1 or less. To do.

  A fourth feature of the present invention relates to any one of the first to third features of the present invention, and the pseudo model exists in a central region including a tire equator line of the pneumatic tire in the tread portion. The gist is that it is set in a narrow groove extending in the tire width direction.

  A fifth feature of the present invention relates to any one of the first to third features of the present invention, wherein the pseudo model is provided in a shoulder region including an outer side in a front tire width direction than a tire equator line in the tread portion. It is set as the gist that it is set in a narrow groove extending in the tire circumferential direction.

  A sixth feature of the present invention relates to any one of the first to fifth features of the present invention. In the pseudo model, the wall surfaces of the grooves do not come into contact with each other due to ground pressure even when the tread portion is grounded. The gist is that it is not set to a groove having a groove width.

  The gist of a seventh feature of the present invention is a tire model creation device for executing the tire model creation method according to any one of the first to sixth features of the present invention.

  According to the present invention, when evaluating tire performance, it is possible to provide a tire model creation method and a tire model creation device for creating a tire model that can obtain an analysis result close to an actual measurement value and that can reduce the calculation time. .

FIG. 1 is a flowchart illustrating a process for evaluating tire performance using a tire model created using the tire model creation method according to the present embodiment. FIG. 2 is a flowchart illustrating a tire model creation method according to the present embodiment. FIG. 3 is a schematic diagram illustrating a unit block model. FIG. 4 is an enlarged side view of a unit block model for explaining a pseudo model set in a narrow groove (sipe). FIG. 5 is a diagram illustrating an example of a partial block model formed from a unit block model. FIG. 6 is an enlarged view of a side surface of the unit block model for explaining a modification of the pseudo model set in the narrow groove. FIG. 7 is an enlarged view of a side surface of the unit block model for explaining a modified example of the pseudo model set in the narrow groove. FIG. 8 is a plan view of a tread portion for explaining a groove in which a pseudo element can be set. FIG. 9 is a configuration diagram of a tire performance prediction apparatus that executes the tire performance prediction method according to the embodiment of the present invention.

  An embodiment of a tire performance prediction method according to the present invention will be described with reference to the drawings. Specifically, (1) tire performance evaluation method, (2) tire model creation method, (3) tire model creation device, (4) action and effect, (5) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(1) Tire Performance Evaluation Method FIG. 1 is a flowchart illustrating a process for evaluating the behavior of a pneumatic tire using a tire model created using the tire model creation method according to the present embodiment. As an example of a tire model analysis method for evaluating tire performance, a GL analysis (global analysis (hereinafter referred to as G analysis)) and a local analysis (local analysis (hereinafter referred to as L analysis)) combined with a global analysis (global analysis). (Global-Local Analysis) will be described.

  The present applicant has already proposed a technique (Japanese Patent No. 313338) related to a tire performance prediction method. Since details of the GL analysis are disclosed in the above publication, an outline will be described below.

  In step S1, a pneumatic tire to be evaluated by the tire performance prediction method is designed. Specifically, the tire size, shape, structure, material, tread pattern and the like of the pneumatic tire are determined.

  In step S2, G analysis is performed. In this embodiment, a finite element method (FEM) is applied as a numerical analysis method for creating a tire model. In the G analysis, a tire model in which the internal structure of a pneumatic tire such as a reinforcement cord made of rubber, belt, ply, iron / organic fiber, etc., or a reinforcement material in which the reinforcement cord is bundled in a sheet shape, is created according to the finite element method, A road surface model obtained by dividing the road surface into a finite number of elements is set. For example, by setting a different friction coefficient μ depending on the road surface state, it is possible to reproduce the road surface state corresponding to dry (DRY), wet (WET), on ice, on snow, unpaved, and the like.

  In G analysis, rolling analysis and deformation calculation are performed when rolling a tire model (smooth tire model) with no tread pattern and only internal structure set on the road surface model. From the calculation result, the trajectory of deformation of the tread pattern model in which the basic groove and land structure is set is calculated.

  In step S3, L analysis is performed based on the deformation trajectory of the tread pattern model calculated in step S2. In the L analysis, a physical quantity change of a tread pattern model in which a detailed structure is set in at least a part of the tread pattern model is calculated.

  In the L analysis, a unit block model in which a narrow groove is formed in one of land blocks (referred to as a unit block) constituting the tread pattern model is set. A partial block model in which a plurality of unit block models are collected is set.

  A boundary condition between the partial block model and the road surface model is set based on the deformation trajectory of the tread pattern model calculated in the G analysis. A physical quantity generated in the partial block model is calculated from the result of the rolling calculation for rolling the partial block model on the road surface model in which the boundary condition is set and the result of the deformation calculation.

  Based on the calculated physical quantity, the tire performance of the complete tire model corresponding to the entire pneumatic tire in which the partial block model is formed over the entire circumference of the tread portion can be predicted.

  In step S4, the tire behavior is evaluated. If the target performance is not satisfied, the result is negative in step S4, and in step S5, the design plan is changed or modified, and only the L analysis is repeated. If the performance is sufficient, the result is affirmative in step S4, and in step S6, the tire of the design plan set in step S1 or the design plan modified in step S5 is adopted, and this routine is terminated.

(2) Tire Model Creation Method (2-1) Creation of Pseudo Model The tire model creation method according to the embodiment of the present invention is detailed in at least a part of the tread pattern model to be analyzed by the L analysis in step S3. The present invention can be applied to creation of a tread pattern model in which a structure (for example, a narrow groove) is set. Hereinafter, a tire model creation method according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a flowchart illustrating a tire model creation method according to the present embodiment.

  In step S31, a unit block model 140 is created. The unit block model is obtained by dividing one block of land blocks of a pneumatic tire by a finite number of elements.

  FIG. 3 is a perspective view illustrating the unit block model. 4 is an enlarged side view of the narrow groove of the unit block model as seen from the direction of the arrow F3 shown in FIG. In step S31, a pseudo model 201 in which a pseudo elastic body that does not exist between the walls of the narrow grooves of the actual pneumatic tire is divided by a finite number of elements between the walls of the narrow grooves 141 to 147 of the unit block model 140. ~ 207 are set. In the present embodiment, the narrow groove refers to a groove having a groove width of about 0.3 mm to 4 mm, for example.

  In step S32, an elastic modulus lower than that of the tread portion is set in the pseudo model. As an example, the elastic modulus of the pseudo models 201 to 207 is set to 1 / 10,000 or more and 1/100 or less of the elastic modulus set in the tread portion, that is, the unit block model 140. Further, the Poisson's ratio of the pseudo models 201 to 207 is set to 0.001 or more and 0.1 or less.

  FIG. 5 is a diagram for explaining the partial block model 150. In step S33, a partial block model 150 formed by collecting a plurality of unit block models 140 is set. The partial block model 150 is formed by arranging a plurality of unit block models 140 in the tire tread width direction TW and the circumferential direction TR.

  In step S33, a road surface model is set.

  In step S34, a boundary condition between the road surface model and the partial block model 150 is set. That is, the boundary condition is set for the road surface model based on the deformation trajectory of the tread pattern model calculated in the G analysis.

  In step S35, rolling calculation for rolling the partial block model 150 on the road surface model for which boundary conditions are set is executed.

  In step S36, the deformation locus of the partial block model 150 is calculated from the result of the rolling calculation. Further, the fluctuation of the physical quantity generated in the partial block model 150 is calculated. The tire performance is predicted based on the calculated physical quantity.

  With the above processing, the tire performance is predicted using the partial block model 150 formed by the pseudo model.

(2-2) Modified Example of Pseudo Model In the tire model creation method described above, the case where the pseudo elastic body satisfies the narrow grooves 141 to 147 has been described. However, a pseudo model in which the pseudo elastic body is partially present in the grooves of the narrow grooves 141 to 147 can be set. 6 and 7 are enlarged views of the side surface of the unit block model 140 for explaining a modification of the pseudo model set in the narrow groove.

  In FIG. 6, the pseudo models 213 and 214 exist from the groove bottoms of the narrow grooves 143 and 144 to a predetermined height h1 and h2. The pseudo models 224 and 224 shown in FIG. 7 exist from the groove openings of the narrow grooves 143 and 144 to the middle of the grooves.

(2-3) Groove for Setting a Pseudo Model In the tire model creation method described above, a pseudo model is created between the wall surfaces of the narrow grooves 141 to 147 formed in the land block. However, the pseudo model may be set in a groove other than the narrow grooves 141 to 147 formed in the land block. FIG. 8 is a plan view of a tread portion for explaining a groove in which a pseudo model can be set.

  In the tread portion 250 shown in FIG. 8, a center land portion 260 is formed in a central region including the tire equator line CL. In the center land portion 260, narrow grooves 261, 262, 263, and 264 are formed along the tread width direction. A pseudo model can be set in the narrow grooves 261, 262, 263, 264.

  Further, block-shaped shoulder land portions 270, 271, 272, and 273 are formed in the shoulder region including the outer side in the width direction of the tread portion 250. In the shoulder land portions 270, 271, 272, and 273, narrow grooves 281, 282, 283, and 284 are formed along the circumferential direction. A pseudo model can be set in the narrow grooves 281, 282, 283, 284. Here, the narrow grooves 281, 282, 283, and 284 in which the pseudo model is set are grooves having groove widths in which the wall surfaces of the grooves come into contact with each other by the contact pressure when the tread portion 250 is grounded.

(3) Tire Performance Prediction Device FIG. 9 shows an outline of a computer 300 as a tire performance prediction device that executes a tire performance prediction method according to an embodiment of the present invention. As shown in FIG. 9, the computer 300 includes a main body 310 including a storage unit (not shown) such as a semiconductor memory and a hard disk, a processing unit (not shown), an input unit 320, and a display unit 330. . The processing unit executes the tire performance prediction method described using FIG. 1 and the tire model creation method described using FIG.

  The computer 300 may be provided with a removable storage medium (not shown) and a driver capable of writing / reading the storage medium. A program for executing the tire performance prediction method and the tire model creation method described with reference to FIGS. 1 and 2 may be recorded in advance on a storage medium, and the program read from the storage medium may be executed. The program may be stored (installed) in the storage unit of the computer 300 and executed. Although not shown, the computer 300 may be connectable to a network, for example. You may acquire the program which performs a tire performance prediction method and a tire model creation method via a network.

(4) Actions / Effects According to the tire model creation method of the present embodiment, instead of setting boundary conditions for contacting the mutually facing wall surface models of the narrow grooves 141 to 147, pseudo-elasticity is applied to the narrow grooves 141 to 147. Since the body is set so as to be arranged, the amount of calculation can be reduced as compared with the case where the boundary condition for contact is set between the walls of the narrow grooves 141 to 147. Further, when analyzing the tire performance using the created tire model, an analysis result in which the models of the wall surfaces facing each other of the narrow grooves 141 to 147 overlap or penetrate is not derived. , The convergence of the operation is improved.

  Thereby, an analysis result close to the actual measurement value can be obtained, and a tire model that can shorten the calculation time can be created.

  In the present embodiment, the elastic modulus of the pseudo model is preferably set to 1 / 10,000 or more and 1/100 or less of the elastic modulus of the tread portion. The Poisson's ratio of the pseudo model is preferably set to 0.001 or more and 0.1 or less. By setting the elastic modulus and Poisson's ratio of the pseudo model within the above ranges, it is possible to analyze a behavior close to the behavior of an actual pneumatic tire with which the wall surface of the groove abuts.

  The pseudo model can be set in the narrow grooves 261, 262, 263, and 264 formed in the central region including the tire equator line CL of the tread portion 300. The wall surfaces of the narrow grooves 261, 262, 263, 264 formed in the central region are likely to come into contact with each other by a circumferential shearing force applied when stepping and kicking. Therefore, by analyzing using a tire model in which a pseudo elastic body is arranged in the narrow grooves 261, 262, 263, and 264 formed in the central region including the tire equator line CL, it is close to actual measurement, that is, with high accuracy. Analysis becomes possible.

  The pseudo model can be set to narrow grooves 281, 282, 283, and 284 formed in the shoulder land portions 270, 271, 272, and 273 along the circumferential direction. The wall surfaces of the narrow grooves 281, 282, 283, and 284 formed along the circumferential direction in the shoulder land portions 270, 271, 272, and 273 are likely to come into contact with each other by a shearing force in the tread width direction at the time of ground contact. Therefore, analysis using a tire model in which pseudo elastic bodies are arranged in the narrow grooves 281, 282, 283, and 284 enables analysis close to actual measurement, that is, highly accurate analysis.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

  In the embodiment, the case where the tire model creation method according to the present invention is applied to creation of a model used in L analysis in GL analysis has been described. However, it is not limited to the creation of a tire model in GL analysis.

  In the tire model creation method of the embodiment, as shown in FIG. 5, a partial block model 150 is set as an aggregate of unit block models 140. However, the unit block model 140 may not be an aggregate. A partial block model 150 having a complicated asymmetric pattern may be set.

  In the tire model creation method described above, the pseudo elastic bodies assumed in the narrow grooves 141 to 147 are not limited to FIGS. For example, a model in which a pseudo elastic body is disposed near the center in the depth direction of the groove may be created.

  In the present embodiment, the case of contact between the wall surfaces of the groove in the tread portion is described, but the present invention is not necessarily limited to the groove. Further, the pseudo model may not be set to a groove having a groove width in which the wall surfaces of the grooves do not contact each other due to the contact pressure even when the tread portion 250 is grounded. By not setting a pseudo model in the groove where the wall surfaces of the grooves do not contact each other even if the tread portion is grounded, useless calculation can be omitted.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

A tire model in which a pseudo model was set under the conditions shown in Table 1 was created by the tire model creation method described in the present embodiment.

  In Example 1, the elastic modulus of the pseudo model was set to 1/1000 of the elastic modulus of the unit block model, and the Poisson ratio of the pseudo model was set to 0.001. A pseudo model was set for all narrow grooves.

  In Example 2, the elastic modulus of the pseudo model was set to 1/1000 of the elastic modulus of the unit block model, and the Poisson ratio of the pseudo model was set to 0.001. Moreover, the pseudo model was set with respect to the circumferential direction groove | channel of a shoulder part, and the width direction groove | channel of the center part.

  In Example 3, the elastic modulus of the pseudo model was set to 1/100 of the elastic modulus of the unit block model, and the Poisson ratio of the pseudo model was set to 0.01. Moreover, the pseudo model was set with respect to the circumferential direction groove | channel of a shoulder part, and the width direction groove | channel of the center part.

  In Example 4, the elastic modulus of the pseudo model was set to 1/50 of the elastic modulus of the unit block model, and the Poisson ratio of the pseudo model was set to 0.1. Moreover, the pseudo model was set with respect to the circumferential direction groove | channel of a shoulder part, and the width direction groove | channel of the center part.

  In Comparative Example 1, the elastic modulus of the pseudo model was set to 1/50 of the elastic modulus of the unit block model. The Poisson's ratio of the pseudo model was set to 0.1. A pseudo model was set for the circumferential groove at the shoulder and the width groove at the center.

Using the tire models in Table 1, the contact rectangle ratio, contact width, contact pressure deviation, and analysis time were compared. The case where the fine groove was not modeled and the case where the contact setting was made on the wall surface of the fine groove were used as comparative examples. The results are shown in Table 2. The results were expressed as an index where the actual measurement was 100.

  When the elastic modulus of the pseudo model was set to 1/1000 to 1/100 of the elastic modulus of the unit block model, results close to the actual measurement were obtained in the rectangular ratio at the time of contact, the contact width, and the contact pressure deviation. In any of Examples 1 to 3, the analysis time can be shortened as compared with Comparative Example 3 in which the boundary condition for contacting the wall surface of the narrow groove was set, and in addition, an analysis result close to actual measurement was obtained.

  140: Unit block model, 141-147 ... Narrow groove, 150 ... Partial block model, 201-207 ... Pseudo model, 213, 214 ... Pseudo model, 224, 224 ... Pseudo model, 250 ... Tread part, 260 ... Center land part 261, 262, 263, 264 ... narrow groove, 270, 271, 272, 273 ... shoulder land part, 281, 282, 283, 284 ... narrow groove, 300 ... computer, 310 ... main body part, 320 ... input part, 330 ... Display section

Claims (7)

Tire model creation that creates a tire model in which a pneumatic tire is divided into a finite number of elements, with a plurality of grooves formed in the tread portion, and a narrow groove in which the groove wall surfaces come into contact with each other when the tread portion contacts the road surface A method,
A step of setting a pseudo model in which a pseudo elastic body that does not exist in the pneumatic tire is divided into a finite number of elements between the wall surfaces of the narrow grooves;
Setting a modulus of elasticity lower than a modulus of elasticity of the tread portion in the pseudo model.   The tire model creation method according to claim 1, wherein an elastic modulus of the pseudo model is set to 1 / 10,000 or more and 1/100 or less of an elastic modulus of the tread portion.   The tire model creation method according to claim 1 or 2, wherein a Poisson's ratio of the pseudo model is set to 0.001 or more and 0.1 or less.   The said pseudo model is set in the narrow groove | channel extended in the said tire width direction which exists in the center area | region containing the tire equator line of the said pneumatic tire of the said tread part. Tire model creation method.   4. The pseudo model according to claim 1, wherein the pseudo model is set in a narrow groove extending in a tire circumferential direction in a shoulder region including an outer side in a front tire width direction than a tire equator line in the tread portion. How to create a tire model.   The tire model creation according to any one of claims 1 to 5, wherein the pseudo model is not set to a groove having a groove width in which the wall surfaces of the grooves do not contact each other due to contact pressure even when the tread portion contacts the ground. Method.   A tire model creation device that executes the tire model creation method according to any one of claims 1 to 6.

Images