JP2005263070A - Forming method of abraded tire model, computer program for formation of abraded tire model, performance prediction method of abraded tire and abraded tire model - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To predict an abraded form of a tire and the performance of the abraded tire efficiently with high precision. <P>SOLUTION: An initial tire model is firstly formed (step S101), and a representative service condition under which the abraded tire model to be formed is estimated to be experienced is set (step S102). Thereafter, the initial tire model is rolled and analyzed under this service condition (step S103), and frictional energy per unit area in a tread grounding area of the initial tire model is found (step S104). Then, an abraded quantity at an optional position on the tread surface of the initial tire model is set and an abraded quantity at the other position is decided from a percentage of frictional energy at an optional position and frictional energy at the other position on the tread surface. Thereafter, the abraded tire model is formed (step S109) by changing a tread shape by moving the tread surface by the decided abraded quantity (step S108). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to tire wear, and more specifically, a method for creating a worn tire model that can more appropriately predict the performance of a worn tire, a computer program for creating a worn tire model, and a performance prediction method for a worn tire, And a worn tire model.

  As a method for predicting tire wear, for example, methods disclosed in Patent Documents 1 and 2 are known. The prediction methods disclosed in these are composed of the following procedures. That is, (1) a procedure for measuring the rubber wear index of the tire surface, (2) a procedure for measuring the friction energy of the tire under various operating conditions, and (3) each operating condition according to the frequency of each operating condition. Tire wear is predicted through a weighting procedure.

JP-A-11-326143 JP 2001-1723 A

  By the way, the methods for predicting tire wear disclosed in Patent Documents 1 and 2 are required to measure the friction energy because the tire wear is predicted by measuring the friction energy. Further, the methods for predicting tire wear disclosed in Patent Documents 1 and 2 predict tire wear amount and life, and distribution of tire wear forms (for example, portions that are easily worn and portions that are difficult to wear). Etc.) and tire performance when the tire was worn could not be predicted.

  Therefore, the present invention has been made in view of the above, and a method for creating a worn tire model and a computer program for creating a worn tire model capable of efficiently and accurately predicting the wear form of the tire and the performance of the worn tire And a method for predicting the performance of a worn tire, and a worn tire model.

  In order to solve the above-described problems and achieve the object, the method for creating a worn tire model according to the present invention is to divide a new tire into a finite number of minute elements when creating a worn tire model. A procedure for creating an initial tire model, a procedure for setting typical use conditions assumed to be experienced by the worn tire model to be created, and the set typical use conditions, A procedure for rolling analysis, a procedure for obtaining frictional energy per unit area in the tread area of the initial tire model by the rolling analysis, and setting a wear amount at an arbitrary position on the tread surface of the initial tire model The ratio of the frictional energy at the arbitrary position to the frictional energy at other positions on the tread surface More, a procedure for determining the amount of wear in the other position, determined abrasion amount, characterized in that it comprises a, a procedure for creating a wear tire model by moving the tread surface.

  In this method of creating a worn tire model, the frictional energy per unit area in the contact area of the initial tire model is obtained in consideration of typical use conditions of the tire, and the worn tire model is created based on this. In this worn tire model, since the use condition of the tire is taken into consideration, the wear form of the tire can be reflected. If this worn tire model is used, the performance of the worn tire can be accurately predicted. Moreover, since this method for creating a worn tire model can be realized by computer simulation, it is not necessary to actually measure the friction energy. For this reason, the wear form of the tire and the performance of the worn tire can be predicted efficiently and accurately. Furthermore, since the tread surface is moved in the wear direction by the ratio of the friction energy at an arbitrary position on the tread surface and the friction energy at other positions, even if there is no wear information on the rubber material, the wear amount of the coordinate change target node can be reduced. Can be determined. Here, the wear direction is, for example, the direction in which the thickness of the block or rib decreases, and is the central axis direction of the tire.

  The following method for creating a worn tire model according to the present invention includes: an initial tire model creating procedure for creating an initial tire model by dividing a tire into a finite number of microelements when creating a worn tire model; A worn tire model creating procedure for creating a worn tire model from a model, and the worn tire model creating procedure is a procedure for setting typical use conditions assumed to be experienced by the worn tire model to be created. And a procedure for rolling analysis of the initial tire model under the set typical use conditions, and a procedure for obtaining friction energy per unit area in a tread contact region of the initial tire model by the rolling analysis, While setting the amount of wear at an arbitrary position on the tread surface of the initial tire model, A procedure for determining a wear amount at the other position based on a ratio between the friction energy and the friction energy at the other position of the tread surface, and an intermediate wear tire by moving the tread surface by the determined wear amount And the wear tire model creation procedure is executed a plurality of times. In the second and subsequent wear tire model creation procedures, the latest intermediate wear tire model is used instead of the initial tire model. It is characterized by using.

  Since the wear tire model created by this wear tire model creation method takes into account the use conditions of the tire, the wear mode of the tire can be reflected. If this worn tire model is used, the performance of the worn tire can be accurately predicted. Moreover, since this method for creating a worn tire model can be realized by computer simulation, it is not necessary to actually measure the friction energy. For this reason, the wear form of the tire and the performance of the worn tire can be predicted efficiently and accurately. Further, the tread surface is moved in the wear direction in a plurality of steps up to the set final wear amount. In an actual tire, the form of wear changes depending on the progress of wear, but in this way, a tire model can be created in consideration of the progress of wear. This makes it possible to create a tire model that reproduces more actual wear.

  In the method for creating a worn tire model according to the present invention, in the method for creating a worn tire model, when there are a plurality of typical use conditions, the friction energy is calculated per unit area obtained under each use condition. It is the accumulated frictional energy obtained by multiplying the frictional energy by the weighting coefficient of the use condition.

  Since the method for creating a worn tire model has the same configuration as the method for creating the worn tire model, the same operation and effect as the method for creating the worn tire model are achieved. Further, in the method of creating a worn tire model, when there are a plurality of typical use conditions, each use condition is weighted, so that the contribution of each use condition to tire wear can be considered. This makes it possible to create a worn tire model that is more suited to actual use conditions.

  The following method for creating a worn tire model according to the present invention is the method for creating a worn tire model, wherein the movement amount of the tread surface is the largest movement amount on the tread surface, the maximum groove of the initial tire model. It is characterized by being 20% or less of the depth.

  Since the method for creating a worn tire model has the same configuration as the method for creating the worn tire model, the same operation and effect as the method for creating the worn tire model are achieved. Furthermore, in this method for creating a worn tire model, the maximum amount of movement on the tread surface is 20% or less of the maximum groove depth of the initial tire model, so the amount of movement per tread surface is extremely small. Does not grow. Thus, a worn tire model can be created by reproducing a state closer to the progress of wear in an actual tire.

  The method for creating a worn tire model according to the next aspect of the present invention is the method for creating a worn tire model, wherein the friction energy is a node of the microelement and is calculated at a node located on the tread surface, The movement of the tread surface is realized by changing the coordinates of the nodes located on the tread surface.

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. Furthermore, this method for creating a worn tire model moves the tread surface in the wear direction by changing the coordinates of the node based on the frictional energy calculated at the node located on the tread surface. In this way, by calculating the friction energy and moving the tread surface with respect to the nodes of the minute elements, a worn tire model can be created accurately and simply.

  The method for creating a worn tire model according to the present invention is a method on all tread surfaces of the microelements including the nodes with respect to the nodes on the tread surface and located at the non-end portion of the land portion of the tread pattern. For the nodes located at the end of the tread pattern land portion, the line direction is moved in the average direction, and the method on all tread surfaces except for the groove wall surface of the minute elements including the nodes. The direction in which the linear direction is averaged is moved in the direction projected along the groove wall surface, and the amount of movement determined based on the frictional energy of the nodes located at the ends of the tread pattern land is not more than The movement amount of the node located at the end portion of the tread pattern land portion is corrected.

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. In addition, this method of creating a worn tire model is used to determine the movement direction and amount of the nodes, so that the nodes located at the ends of the tread pattern land such as blocks and ribs are positioned at the non-ends. A process different from the node to be executed is executed. This makes it possible to create a worn tire model with improved reproduction accuracy of actual tire wear.

  Further, regarding the amount of movement of the node existing at the end portion of the tread pattern land portion, the movement of the node located at the end portion of the tread pattern land portion is further performed as in the method for creating a worn tire model according to the present invention described below. The amount is preferably corrected using an angle formed by a direction obtained by averaging normal directions on all tread surfaces except the groove wall surface and a direction in which the direction is projected along the groove wall surface. Thus, when the groove wall surface is not perpendicular to the tread surface, this can be taken into consideration, so that a worn tire model with improved reproduction accuracy of actual tire wear can be created.

  The following method for creating a worn tire model according to the present invention is the method for creating a worn tire model, wherein when moving the tread surface, the amount of movement of a node located on the tread surface is a minute element including the node. If it is larger than the dimension, the microelement is deleted.

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. Furthermore, according to this method for creating a worn tire model, since the process for when the amount of movement of the node exceeds the dimension of the microelement (the dimension of the microelement in the wear direction and the thickness of the microelement) is specified, A worn tire model can be created even if it has advanced significantly.

  The following method for creating a worn tire model according to the present invention is characterized in that, in the method for creating a worn tire model, when the tread surface is moved, the microelements of the tread portion including the tread surface are subdivided. .

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. Furthermore, according to this method for creating a worn tire model, a worn tire model can be created by re-dividing the minute elements even in a state in which wear has greatly progressed. At the same time, the tread shape can be prevented from becoming an inappropriate shape. Thereby, it can suppress that the reproduction precision of wear of a real tire falls.

  In the method for creating a worn tire model according to the present invention, in the method for creating a worn tire model, when the tread surface is moved, a forced displacement corresponding to the wear amount is applied to a node located on the tread surface. In addition, the node located at the bottom of the groove and the node located at the bottom of the tread are restrained, and the Poisson's ratio is set to 0.

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. Furthermore, according to this method for creating a worn tire model, a forcible displacement corresponding to the amount of wear is applied to the nodes located on the tread surface, so that it is not necessary to subdivide the microelements. Thus, a worn tire model can be easily created while suppressing the tread shape from becoming an inappropriate shape.

  The method for creating a worn tire model according to the present invention is the method for creating a worn tire model, wherein the created worn tire model has a physical property value of at least a rubber material among the materials constituting the worn tire model. It is characterized by being different from the model.

  Since the tire model creation method has the same configuration as the worn tire model creation method, the same effects and advantages as the worn tire model creation method are achieved. Furthermore, according to this method for creating a worn tire model, at least the physical property values of the rubber material among the materials constituting the worn tire model are different from those of the initial tire model. As a result, the change with time of the material constituting the tire can be taken into consideration, so that the prediction accuracy of the wear form can be improved and a wear tire model adapted to actual wear can be created.

  A computer program for creating a worn tire model according to the present invention is characterized in that the method for creating a worn tire model is realized on a computer. Thus, the method for creating the worn tire model can be realized using a computer.

  A wear tire performance prediction method according to the present invention is characterized in that the performance of a worn tire is predicted using a wear tire model created by the method for creating a wear tire model. Thereby, it is possible to efficiently and accurately predict the wear form of the tire and the performance of the worn tire.

  In the wear tire model according to the present invention, typical use conditions assumed to be experienced by the wear tire model to be created are set, and a tire in a new state is prepared under the set typical use conditions. Rolling analysis of the initial tire model created by dividing into a finite number of microelements, and by the rolling analysis, the friction energy per unit area in the tread area of the initial tire model is obtained, and the tread of the initial tire model The amount of wear at an arbitrary position on the surface is set, and the amount of wear at the other position is determined by the ratio between the friction energy at the arbitrary position and the friction energy at another position on the tread surface, and the determined wear It is created by moving the tread surface by an amount.

  The wear tire model is determined based on the friction energy per unit area in the contact area of the initial tire model in consideration of typical use conditions of the tire, and the wear tire model is created based on this. As a result, the use conditions of the tire are taken into consideration, so that the wear form of the tire can be reflected. If this worn tire model is used, the performance of the worn tire can be accurately predicted. Moreover, since this method for creating a worn tire model can be realized by computer simulation, it is not necessary to actually measure the friction energy. For this reason, the wear form of the tire and the performance of the worn tire can be predicted efficiently and accurately.

  The wear tire model according to the present invention is characterized in that, in the wear tire model, the created wear tire model is different from the initial tire model in at least physical property values of a rubber material constituting the wear tire model. To do.

  Since this worn tire model has the same configuration as the method for creating the worn tire model, the same effects and advantages as the worn tire model are achieved. Furthermore, according to this worn tire model, at least the physical property values of the rubber material are different from those of the initial tire model. As a result, the change with time of the material constituting the tire can be taken into consideration, so that the prediction accuracy of the wear form can be improved and a wear tire model adapted to actual wear can be created.

  A method for creating a worn tire model, a computer program for creating a worn tire model, a performance prediction method for a worn tire, and a worn tire model according to the present invention efficiently and accurately predict the wear form of a tire and the performance of a worn tire. There is an effect that can be done.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same. The present invention can be applied to all tires and is not limited to pneumatic tires.

  The method for creating a worn tire model according to the present embodiment is characterized by the following points. That is, the tire is subjected to rolling analysis based on typical use conditions of the tire, and the frictional energy per unit area in the tread contact area is obtained. Then, the wear amount at other points is determined based on the wear amount and frictional energy at an arbitrary point on the tread surface. Before describing a method for creating a worn tire model according to the present embodiment, a tire that is an evaluation target will be described.

  FIG. 1 is a partial cross-sectional view showing a cross section of a tire cut along a meridian plane including a rotation axis of the tire. The structure of the tire 10 that is the object of vibration characteristic evaluation will be briefly described with reference to FIG. The cap tread 11 is a rubber layer that is disposed on the road surface grounding portion of the tire 10 and covers the outside of the carcass 15, the belt 14, or the breaker. The cap tread 11 serves to protect the carcass 15 and the belt 14 against cut impact. Here, the surface where the cap tread 11 is in contact with the road surface is referred to as a tread surface 11p. The tread surface 11p is partitioned by a plurality of grooves 18 to form a plurality of blocks 11B. A pattern formed by the groove 18 or the block 11B formed on the tread surface 11p is referred to as a tread pattern or a block pattern.

  The undertread 12 is a rubber layer disposed between the cap tread 11 and the belt 14 and is used for the purpose of improving heat generation, adhesion, and the like. The side tread 13 is disposed on the outermost side of the sidewall portion to prevent external scratches from reaching the carcass 15 and, in the case of a radial tire, has an auxiliary role of transmitting driving force from the axle to the road surface. I'm in charge. The belt 14 is a rubberized cord layer disposed between the cap tread 11 and the carcass 15. In the case of a bias tire, it is called a breaker. In the radial tire, the belt 14 plays an important role as a shape maintaining and strength member. The carcass 15 is a rubberized cord layer that forms the skeleton of the tire 10. The carcass 15 is a strength member that serves as a pressure vessel when the tire 10 is filled with air, and is configured to support a load by the internal pressure of the air and withstand a dynamic load during traveling.

  The cord tension of the carcass 15 generated by the internal pressure of air is supported by a bundle of steel wires. A ring in which the bundle of steel wires is hardened with hard rubber is called a bead 16. The bead 16 serves as a strength member of the tire 10 together with the carcass 15, the belt 14, and the tread in addition to the role of fixing the tire 10 to the rim of the wheel. The bead filler 17 is a rubber that fills a space generated when the carcass 15 is wound around the bead wire. While fixing the carcass 15 to the bead 16, the shape of the part is adjusted and the rigidity of the whole bead part is improved.

  Next, the worn tire model creation apparatus according to the present embodiment will be described. FIG. 2 is an explanatory diagram illustrating the configuration of the tire vibration characteristic evaluation apparatus according to this embodiment. With this worn tire model creation device 50, the worn tire model creation method according to the present embodiment can be realized, and the worn tire model according to the present embodiment can be created. The worn tire model creation device 50 includes a processing unit 50p and a storage unit 50m. The processing unit 50p and the storage unit 50m are connected via an input / output port (I / O) 59.

  The processing unit 50p includes a model creation unit 51, a rolling analysis unit 52, a friction energy calculation unit 53, and a tread shape change unit 54. These execute the method of creating a worn tire model according to this embodiment. The model creation unit 51, the rolling analysis unit 52, the friction energy calculation unit 53, and the tread shape change unit 54 are connected to an input / output port (I / O) 59 so that data can be exchanged between them. It is configured.

Further, a terminal device 60 is connected to the input / output port (I / O) 59, and data necessary for executing the method for creating a worn tire model according to this embodiment, for example, the tire 10 is configured. The physical property value of the rubber, the physical property value of the wheel, the boundary condition in the rolling analysis, the traveling condition, and the like are given to the worn tire model creation device 50 by the input device 61 connected to the terminal device 60. Also, the wear tire model creation data is received from the wear tire model creation device 50, and the wear tire model is displayed on the display device 62 connected to the terminal device 60. Further, various data servers 64 ₁ , 64 _{2 and the} like are connected to the input / output port (I / O) 59. In executing the method for creating a worn tire model according to this embodiment, the processing unit 50p is configured to be able to use various databases stored in the various data servers 64 ₁ , 64 ₂ and the like.

The storage unit 50m stores a computer program including a processing procedure of a method for creating a worn tire model according to this embodiment, and data such as material properties acquired from various data servers 64 ₁ and 64 _{2 and the} like. The data such as material properties are used when executing the method for creating a worn tire model according to this embodiment. Here, the storage unit 50m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof. The processing unit 50p can be configured by a memory and a CPU. The storage unit 50m may be built in the processing unit 50p or may be in another device (for example, a database server). As described above, the worn tire model creation device 50 may access the processing unit 50p and the storage unit 50m from the terminal device 60 by communication.

  The computer program realizes the processing procedure of the method for creating a worn tire model according to this embodiment by combining with the computer program already recorded in the model creation unit 51, the tread shape changing unit 54, and the like provided in the processing unit 50p. It may be possible. Further, the wear tire model creation device 50 uses a dedicated hardware instead of the computer program, and uses a model creation unit 51, a rolling analysis unit 52, a friction energy calculation unit 53, and a tread shape change included in the processing unit 50p. The function of the unit 54 may be realized. Next, a procedure for realizing a method for creating a worn tire model according to this embodiment using the worn tire model creating device 50 will be described.

  FIG. 3 is a flowchart showing a procedure of a method for creating a worn tire model according to the present embodiment. In the method for creating a worn tire model according to this embodiment, a finite element method (FEM) is used as an analysis method used for rolling simulation or the like when creating a worn tire model. Note that the analysis method applicable to the method for creating a worn tire model according to this embodiment is not limited to the finite element method, and a boundary element method (BEM), a finite difference method (FDM), and the like are also used. it can. Further, the most appropriate analysis method can be selected according to the boundary condition or the like, or a plurality of analysis methods can be used in combination. Note that the finite element method is an analysis method suitable for structural analysis, and therefore can be suitably applied particularly to structures such as tires and wheels.

  FIG. 4 is a perspective view showing an example of a tire model. In executing the method for creating a worn tire model according to this embodiment, the model creating unit 51 included in the processing unit 50p of the worn tire model creating device 50 is a tire model (initial tire) that reproduces a new state shown in FIG. 10M (corresponding to the model) is created (step S101). The tire model 10M is a reproduction of a tire shape including a tire internal structure and a tread pattern. In creating the tire model 10M, the tire model 10M suitable for each analysis method is created so that it can be analyzed by an analysis method such as a finite element method.

For example, when the finite element method is used, as shown in FIG. 4, the tire 10 is divided into a finite number of microelements 10M ₁ , 10M ₂ ,... 10M _n based on the finite element method. Thereby, the tire model 10M can be created based on the finite element method. The microelements based on the finite element method are, for example, a quadrilateral element in a two-dimensional plane, a solid element such as a tetrahedral solid element, a pentahedral solid element, a hexahedral solid element as a three-dimensional body, a triangular shell element, and a rectangular shell. It is desirable to use an element that can be used by a computer, such as a shell element. The microelements divided in this way are identified one by one using the three-dimensional coordinates in the process of analysis.

  When the tire tread pattern on which the tire model 10M is based employs a pitch arrangement composed of a plurality of pitches, this pitch arrangement may also be modeled. In this case, the tread pattern is preferably modeled over the entire circumference in the tire circumferential direction. Further, for example, the tire model 10M may be created as an equal pitch model using a representative pitch length such as an average pitch length (= tire outer circumference length / number of pitches). In this case, the tread pattern may be modeled over the entire circumference in the tire circumferential direction, but only a part in the circumferential direction may be modeled in detail, and the remaining part may be simplified. In this way, the calculation load can be reduced, so that the calculation speed can be improved and hardware resources can be used effectively.

  After the tire model 10M is created, typical use conditions for the tire are set in order to create a worn tire model (step S102). Here, the use condition of the tire means a vehicle on which the tire is mounted, a loading condition, a mounting position, a traveling mode, and the like. This typical use condition is a use condition assumed to be experienced by the worn tire model to be created. Considering the actual wear situation, it is preferable to set at least four typical use conditions. If representative use conditions are set in this way, a worn tire model reflecting actual use conditions can be created. For example, when it is assumed that the worn tire model to be created is attached to the driving wheel, the driving condition, the braking condition, the left turning condition, and the right turning condition are set. If it is assumed that the worn tire model to be created is mounted on a driven wheel, free rolling conditions, braking conditions, left turn conditions, and right turn conditions are set.

  The driving force that defines the driving condition, the braking force that defines the braking condition, and the turning force that defines the turning condition are set to at least one condition, and two or more conditions are set as necessary. Further, the camber angle of the tire model 10M and the rolling speed of the tire model 10M are set to at least one condition, and are set to two conditions or more as necessary. In this way, conditions that require high analysis accuracy can be set in detail, and conditions that have a low contribution to analysis accuracy can be set roughly, thus improving the speed of rolling analysis while maintaining the accuracy of rolling analysis. Can be made. Furthermore, the load applied to the tire model 10M may be constant under all typical use conditions. Moreover, it is preferable to add correction corresponding to the load fluctuation amount of the vehicle according to the driving acceleration, the braking acceleration, and the turning acceleration with respect to the load applied to the tire model 10M. By doing so, the actual rolling situation can be more accurately reproduced, so that the reproduction accuracy of the wear situation is improved.

  When typical use conditions of the tire are set (step S102), the set use conditions are input from the terminal device 60 to the worn tire model creation device 50. And under this use condition, the rolling analysis part 52 performs a rolling analysis of a tire (step S103). FIG. 5 is a schematic diagram showing a state of rolling analysis. In executing the rolling analysis, the created tire model 10M is mounted on the rim of the wheel model 3M created separately by the model creating unit 51 or the rim model. Alternatively, the boundary condition of the rim portion of the tire model 10M is set to a boundary condition corresponding to rim mounting.

  Then, as shown in FIG. 5, the rolling analysis unit 52 applies a predetermined load FR to the tire model 10M and presses it against the road surface model 40M based on the set typical use conditions. In addition, the road surface model 40M models the road surface 40 based on the typical use conditions set by the model creating unit 51. For example, modeling is performed in consideration of a case where the road surface 40 is an asphalt paved road, a wet condition, or a non-paved road surface.

  FIG. 6A is a perspective view illustrating an axis of a tire model. FIG. 6B is a side view of the relationship between the tire model and the road surface model. FIG. 6-3 is a front view showing the relationship between the tire model and the road surface model. As illustrated in FIGS. 6-1 to 6-3, the rotation axis of the tire model 10M is the Y axis, and is orthogonal to the rotation axis, and the rolling direction of the tire model 10M is the X axis. The Z axis is an axis orthogonal to the Y axis and the X axis, and is an axis parallel to the vertical axis of the road surface model 40M.

  The degree of freedom in the vertical direction of the road surface model 40M (the Z-axis direction of the tire model 10M) may be constrained, and the load FR may be applied to the tire model 10M and pressed against the road surface model 40M. Alternatively, the load FR may be applied to the tire model 10M by restraining the degree of freedom of the rotation axis Y of the tire model 10M or the rim model (the Z-axis direction of the tire model 10M) and may be pressed against the road surface model 40M. The boundary condition when the tire model 10M is pressed against the road surface model 40M may be a forced displacement applied to at least one of the tire model 10M or the road surface model 40M, or a load is applied to at least one of the tire model 10M or the road surface model 40M. May be. However, since the displacement when a predetermined load is applied to the tire model 10M or the like is generally unknown, it is preferable to apply a load to at least one of the tire model 10M or the road surface model 40M.

  When the rolling analysis is completed (step S104), the friction energy calculating unit 53 acquires or calculates the friction energy per unit area from the result of the rolling analysis. In this procedure, the frictional energy calculation unit 53 acquires the frictional energy per unit area from the rolling analysis result after the tire model 10M starts rolling and the cornering force and the longitudinal force are almost in a steady state. Start processing. If the frictional energy per unit area cannot be obtained directly from the result of the rolling analysis, the slip amount and the contact shear stress are obtained or calculated, and the frictional energy per unit area is calculated from the product of the slip amount and the shear stress. Next, an example of this procedure will be described.

  The reason for using the friction energy per unit area is to correctly evaluate the distribution of the friction energy on the contact surface 11pmm of the tread surface 11p (see FIG. 1) of the tire 10 (tire model 10M). Next, the reason will be described. FIGS. 7-1 and FIGS. 7-2 are explanatory drawings showing an example in which the ground surface on which the cap tread contacts the ground is divided into minute elements. As shown in FIG. 7A, when the ground contact surface 11pm is divided into one, the vertical contact force F acts equally on the nodes N1 to N4, so that each of the nodes N1 to N4 has F / 4. The vertical contact force acts.

  In general, in an analysis technique such as FEM or BEM, the calculation time increases but the calculation accuracy increases as the number of divisions of elements regarded as constant increases. Therefore, the number of element divisions is increased as much as possible in consideration of a balance with calculation time. In addition, since the friction energy becomes high at the end of the block 11B, the evaluation accuracy inside the block 11B decreases if the number of element divisions is small. For this reason, when predicting the frictional energy of the ground contact surface 11pm, the number of divisions of the ground contact surface 11pm is increased as shown in FIG. In the example shown in FIG. 7B, since the ground plane 11pm is divided into four, the ground plane 11pm includes a total of nine nodes from N1 to N9.

  Here, the vertical contact force of F / 16 acts on the nodes N1, N3, N7, and N9 at the corners of the ground contact surface 11pm from the relationship between the number of nodes and the location of the nodes. Similarly, a vertical contact force of F / 8 acts on each of the nodes N2, N4, N6, and N8 on the side of the ground plane 11pm, and a vertical contact force of F / 4 is applied to the node N1 in the center portion of the ground plane 11pm. Works. Here, when the friction coefficient is μ and the slip amount is L, the shear contact force can be obtained by μ × vertical contact force, and the friction energy can be obtained by μ × vertical contact force × L. Therefore, the friction energy at the nodes N1, N3, N7, and N9 is L × μ × F / 16, the friction energy at the nodes N2, N4, N6, and N8 is L × μ × F / 8, and the node N1 The frictional energy at is L × μ × F / 4.

  Originally, friction energy is uniformly distributed on the ground contact surface 11pm in this example. However, if the friction energy is calculated from the shear contact force and slip amount of each of the nodes N1 to N9, the value of the friction energy differs depending on the number of element divisions, the number of nodes, or the node position, and the wear of the ground contact surface 11pm should be evaluated correctly. I can't. Therefore, in the present invention, the wear of the ground contact surface 11pm is evaluated based on the friction energy per unit area. At the same time, the vertical contact force and the shear contact force were evaluated as a vertical contact force per unit area (that is, a vertical ground pressure Pn) and a shear contact force per unit area (Ps = μ × Pn). In this way, since the distribution of friction energy on the surface of the ground contact surface 11pm can be obtained correctly, the wear of the ground contact surface 11pm can be correctly evaluated.

  When evaluating by a physical quantity such as friction energy per unit area, it is necessary to obtain the area of the surface of the dividing element (hereinafter referred to as the dividing element surface) shared by each node. Next, an example of this procedure will be described. FIGS. 8-1 and FIGS. 8-2 are plan views showing a ground plane divided into nine by quadrangular elements. Since the ground plane 11pm is divided into nine, the nodes are 16 nodes N1 to N16. Here, a case where the area of the node N6 is calculated will be described. First, information on the surface of the dividing element including the node N6 is acquired. In this example, the division element surfaces including N6 are S1, S2, S4, and S5. Further, the information on the surface of the dividing element is information such as the nodes constituting the surface of the dividing element and the coordinates of the nodes.

  Next, the respective areas of the respective divided element surfaces S1, S2, S4, and S5 are calculated. This can be calculated from the acquired coordinates of the nodes constituting each surface of the divided elements and the shape of each surface of the divided elements. When the area of each division element surface is calculated, the area shared by the node N6 is calculated according to the shape of each division element surface. In the example shown in FIG. 8A, since the ground contact surface 11pm is divided by quadrangular elements, the shapes of the divided element surfaces S1, S2, S4, and S5 are quadrangular. In this case, that is, when the shape of the surface of the divided element divided by the divided elements is a quadrangle, the node N6 shares ¼ of the area of the divided element surface S1.

  Thus, when the shape of the surface of the split element on the ground contact surface 11pm is a quadrangle, the target nodes share the size of 1/4 of the area occupied by the shape. Further, as shown in FIG. 8B, when the shape of the surface of the dividing element on the ground contact surface is a triangle, the target node shares the size of 1/3 of the area occupied by the shape. . Next, all areas of the respective divided element surfaces S1, S2, S4, and S5 shared by the node N6 are added. This area is an area shared by the node N6. A similar procedure is applied to the remaining nodes N1, N2, etc. to calculate the area shared by each node on the ground plane 11pm.

  9A to 9C are perspective views illustrating one of the dividing elements including the ground contact surface of the tire model. When the area shared by each node is calculated by the above procedure, the area of the surface of the dividing element that is not actually grounded (the hatched portion in FIG. 9-1) such as the groove wall 11s shown in FIG. It will be included in the shared area. In this case, the friction energy per unit area is obtained by an area that is larger than the actual ground contact area. Therefore, the wear of the ground contact surface 11pm is evaluated by the friction energy per unit area that is smaller than the actual area. . In order to avoid this inconvenience, when calculating the area of the node (for example, N1) including the surface of the split element that is not grounded, the split element surface 20 that is grounded and the split element surface 21 that is not grounded are determined and grounded. It is necessary to obtain the area shared by each node, excluding the area of the dividing element surface 21 that is not (FIG. 9-2). Next, this determination method will be described.

  10A and 10B are explanatory diagrams illustrating an example of a method for determining the contact of the surface of the dividing element. FIGS. 11A, 11B, and 11C are explanatory diagrams illustrating another example of the method for determining the grounding of the surface of the dividing element. The method of determining the contact of the surface of the dividing element is based on the initial shape of the tire model 10M. There is a method of determining an element surface before calculating an area shared by nodes.

  In this determination method, for example, a vector heading from the center 10c of the tire model 10M toward the center of the surface of the splitting element to be determined is used as a reference vector, and the presence / absence of ground contact is determined from the angle formed by the normal vector of the splitting element surface and the reference vector. There is something to judge. In this case, when the angle formed by both vectors is smaller than the ground contact angle, it is determined that the surface of the divided element is grounded. When the angle formed by both vectors is larger than a predetermined value, the surface of the divided element is not grounded. judge. If the angle formed by both vectors is 35 to 45 degrees as the ground contact reference angle, the presence or absence of ground contact can be determined with sufficient accuracy for practical use, so that the wear of the ground contact surface 11pm can be evaluated with high accuracy. Here, the ground contact reference angle refers to an angle at which the surface of the dividing element does not touch when the angle is larger than the angle.

  For example, in the example shown in FIG. 10, a vector from the center 10c of the tire 10 toward the center of the division element surface 20 to be determined is a reference vector V11, and the normal vector V12 of the division element surface 20 and the reference vector V11 are used. The angle θ1 is defined as When the ground contact reference angle is set to 35 degrees, for example, the angle θ1 at the split element surface 20 is smaller than the ground reference angle, so the split element surface 20 is determined to be the ground contact surface (11p). On the other hand, the dividing element surface 21 has a reference vector V22 and a normal vector V21. The angle formed by both vectors is θ2, but since θ2 is larger than the ground contact reference angle, it is determined that the split element surface 21 is not grounded. The dividing element surface 21 is a part of the groove wall 11s.

  According to this determination method, when the area shared by each node is obtained, it is possible to exclude the surface of the divided element that does not come into contact with the ground, so that it is possible to accurately predict the wear of the ground contact surface 11pm. Further, since the ground contact state of each split element surface is determined based on the initial shape of the tire, it is not necessary to determine the ground contact state of each split element surface for each time step. As a result, the amount of calculation can be reduced, so that the time required for calculation can be shortened in computer simulation, and effective evaluation can be performed even when hardware resources are limited.

  As another determination method, there is also a method of determining, for each time step, the surface of the divided element that contacts the ground and the surface of the divided element that does not contact based on the deformed shape at the time of rolling of the tire model 10M. In this determination method, since the contact surface is determined according to the deformation shape at the time of rolling of the tire 10 model, the wear of the contact surface 11pm can be predicted with higher accuracy. In this determination method, V11 or V22 may be used as the reference vector, or the normal vectors Vn1 and Vn2 of the division element surfaces 20 and 21 and the normal vector Vbr of the road surface model 40M as shown in FIG. And may be used. When the normal vector Vbr of the road surface model 40M is used, the ground contact reference angle is preferably 160 ° to 179 °, and the normal vector of the surface of the dividing element and the normal vector of the road surface model 40M are more than the ground contact reference angle. It is determined that the grounding is made when the angle formed by is large.

  For example, when the ground contact reference angle is set to 160 degrees, the angle θ1 on the split element surface 20 is larger than the ground reference angle, and therefore it is determined that the split element surface 20 is grounded. On the other hand, since the angle θ2 at the dividing element surface 21 is smaller than the ground contact reference angle, it is determined that the dividing element surface 21 is not grounded. In this determination example, the angle (θ1, θ2 in FIG. 11A) formed by the normal vector of the surface of the dividing element and the normal vector of the road surface is 180 degrees at the maximum.

Further, the ground contact state of the dividing element surface 20 is determined from the difference between the coordinates R (Xr, Yr, Zr) of the road surface model 40M and the coordinates T ₁ (Xt1, Yt1, Zt1) of the dividing element surface 20 or the like to be determined. You may judge. In this case, the contact state of the dividing element surface 20 or the like is determined using the vertical coordinate (the direction indicated by the arrow Z in FIG. 11-2). For example, when the difference δ = (Zt1−Zr) between Zt1 and Zr is equal to or less than a reference value, it is determined that the dividing element surface 20 is grounded. Such a determination is made for the following reason. That is, in the case of numerical simulation using a computer, numerical errors are unavoidable, and δ cannot be perfectly matched. Therefore, it is necessary to determine whether to ground in consideration of this numerical error. Here, the reference value is preferably about 0.01 mm to 2.00 mm.

  Further, the coordinates Nc at the center of the division element surface 20 can be used as the coordinates of the division element surface 20. For example, the average value (Z1 + Z2 + Z3 + Z4) / 4 of the coordinates in the vertical direction of the nodes N1 to N4 included in the dividing element surface 20 can be set as the vertical coordinate value Zc at the center of the dividing element surface 20 (FIG. 11). -3). Then, the coordinate value Zr in the vertical direction of the road surface model 40M and the coordinate value Zc in the vertical direction of the dividing element surface 20 are compared, and if both are equal, it is determined that the dividing element surface is grounded. Furthermore, when the coordinates in the vertical direction of one node among the nodes N1 to N4 included in the dividing element surface 20 are not equal to the coordinates in the vertical direction of the road surface model 40M, it is determined that the dividing element surface 20 is not grounded. Also good.

  Next, a procedure for obtaining the friction energy per unit area will be described. FIG. 12 is a flowchart showing a procedure for calculating the friction energy per unit area. In this calculation procedure, based on the initial shape of the tire model 10M, the friction energy calculation unit 53 determines the surface of the divided element that contacts the ground and the surface of the divided element that does not contact before calculating the area shared by each node. . First, it is determined whether or not the surface of the split element to be grounded (step S201). Here, this determination procedure will be described. FIG. 13 is a flowchart showing a procedure for determining whether or not the surface of a split element to be grounded.

  In this contact determination, first, the friction energy calculation unit 53 acquires node coordinates and division element surface information (for example, nodes and division shapes constituting the division element surface) from the data of the tire model 10M (step S301). ). Next, the friction energy calculation unit 53 determines whether or not the surface of the division element is the surface of the division element of the tire surface (step S302). When the surface of the division element is a tire surface, the friction energy calculation unit 53 determines whether or not the surface of the division element is grounded, and the result is stored in, for example, the storage unit 50m (see FIG. 2) of the worn tire model creation device 50. (Refer to step S303). When this procedure is executed by a computer, the determination result is stored on a RAM or a predetermined storage area of a hard disk. For example, a method based on an angle formed by the above-described reference vector and a normal vector of the surface of the dividing element can be used to determine whether or not the surface of the dividing element is grounded. The frictional energy calculation unit 53 determines whether or not the process has been completed for all the divided element surfaces existing on the tire surface (step S304), and when the process is completed for all the divided element surfaces, the contact determination procedure ends.

  Next, referring back to FIG. When the ground contact determination procedure for the split element surface is completed, the frictional energy calculating unit 53 determines whether the node of the split element is touched (step S202). In this determination method, for example, when the vertical contact force between the node and the road surface exceeds 0, it is determined that the node is grounded. When it is determined that the determination target node is grounded, the friction energy calculation unit 53 calculates an area shared by the node (hereinafter referred to as a node area) (step S203). The procedure for calculating the nodal area will be described later.

Next, the friction energy calculation unit 53 calculates the shear contact force Fs from the contact force component parallel to the road surface (step S204), and the displacement Dn of the node between the time step and the immediately preceding time step. The slip amount L between the tread surface 11p that is in contact with the road surface is calculated from the displacement difference Dn−Dr between the road surface displacement Dr and the road surface displacement Dr (step S205). Here, the order of steps S203 to S205 does not matter. From the shear contact force Fs, the slip amount L, and the nodal area A, the friction energy calculation unit 53 calculates the friction energy E per unit area based on the equation (1) (step S206). This value is added to the total friction energy per unit area after the node starts grounding (step S207).
E = Fs × L / A (1)
Here, A is the nodal area.

  As described above, when the displacement difference Dn−Dr is used to calculate the slip amount L, it is effective when the slip amount L cannot be directly obtained. If the slip amount L can be directly obtained, the directly obtained slip amount L may be used. Further, the slip amount L may be obtained from the speed of the tire model 10M. In this case, the acquired relative speed (slip speed) is calculated from the speed at each contact portion of the tread surface 11p and the road surface speed, and the slip amount is calculated from the product of the unit time (for example, sampling time). The method of calculating the shear contact force Fs from the contact force component parallel to the road surface is effective when the shear contact force Fs cannot be directly obtained from the rolling analysis result. When the shear contact force Fs and the slip amount L are obtained as discrete information of the time history, the friction energy per unit area at each sampling time is acquired or calculated, and until the tread surface 11p starts the grounding until the grounding is finished. Integrate with time to obtain frictional energy per unit area. Further, it is preferable that the slip amount L, the shear contact force Fs, and the frictional energy per unit area are obtained separately in the tire front-rear direction and the tire lateral direction, and then the sum of the two is obtained.

  The friction energy calculation unit 53 determines whether or not the processing for all nodes has been completed (step S208), and repeats steps S202 to S207 if the processing for all nodes has not been completed. When all the nodes have been processed in this step, the frictional energy calculating unit 53 determines whether or not all the steps have been processed (step S209). If all the steps have not been completed, steps S202 to S208 are performed. All steps are repeated to complete the friction energy E prediction procedure.

  Next, the procedure for calculating the nodal area will be described. FIG. 14 is a flowchart showing the procedure for calculating the nodal area. First, in order to calculate the nodal area, the frictional energy calculating unit 53 obtains division element surface information (node coordinates constituting the division element surface, division shape of the division element surface, and the like) including the node whose area is to be calculated. (Step S401). In addition, since the node information inside a tread is unnecessary when calculating | requiring the friction energy E, only the node which exists in the tread surface will be the object of node area calculation. Next, the frictional energy calculation unit 53 obtains the determination result as to whether or not the surface of the split element to be grounded, which is stored in the storage unit in the above-described contact determination procedure for the surface of the split element (step S402). In addition, the order of step S401 and S402 is not ask | required.

  In the procedure for calculating the nodal area, the surface of the split element to be grounded is the target, so the frictional energy calculating unit 53 determines whether or not the split element surface including the node is grounded (step S403). This can be determined based on the determination result obtained in step S402 as to whether or not the surface of the split element is to be grounded.

  In the case of the surface of the divided element to be grounded, the friction energy calculating unit 53 calculates the node area of the node whose area is to be calculated from the area of the surface of the divided element and the divided shape, and adds it to the already obtained node area. (Step S404). The frictional energy calculating unit 53 calculates the node area of the area calculation target for all of the divided element surfaces including the node of the area calculation target that is in contact with the ground, and when it is added to the already obtained node area, the area calculation of the node is completed. To do. If the processing of all the divided element surfaces has not been completed, the frictional energy calculating unit 53 repeats steps S403 and S404 to process all the divided element surfaces (step S405), and the calculation of all the nodal areas is completed.

  In the above procedure, based on the initial shape of the tire model 10M, the contact of the surface of the dividing element is determined before calculating the nodal area, and the frictional energy per unit area is calculated. Thereby, since it is not necessary to determine the contact state of the surface of each divided element for each time step, the amount of calculation for calculating the friction energy per unit area can be reduced. As a result, in computer simulation, the time required for calculation can be shortened, and effective evaluation can be performed even when hardware resources are limited.

Here, it returns and demonstrates to FIG. When the friction energy per unit area is obtained by the above procedure or the like (step S104), the friction energy calculation unit 53 determines whether or not the typical use condition (representative condition) of the tire 10 is 2 or more (step S104). S105). When the typical use condition (representative condition) of the tire 10 is single (step S105; No), the procedure proceeds to a tread shape changing procedure (step S108). When there are two or more typical use conditions (representative conditions) of the tire 10 (step S105; Yes), a weighting coefficient for each use condition is determined (step S106). Then, the friction energy of each use condition is weighted and integrated according to equation (2) to obtain the integrated friction energy (step S107). The cumulative friction energy is a value per unit area.
E _F = ΣC _i × E _fi ; {i = 1 to n} (2)

E _F is the cumulative friction energy, C _i is a weighting coefficient for each use condition, E _fi is the friction energy per unit area in each use condition, i is a subscript representing the condition, and n is the number of use conditions. The weighting coefficient C _{i for} each use condition can be determined from, for example, the use condition of the tire 10, that is, the average acceleration in consideration of the travel mode. As described above, the weight of each use condition is considered in consideration of each use condition, whereby the contribution of each use condition to the wear of the tire 10 can be taken into consideration. This makes it possible to create a worn tire model that is more suited to actual use conditions.

After determining the accumulated frictional energy E _F (step S107), and proceeds to change procedure tread shape (step S108). FIG. 15 is a conceptual diagram showing the accumulated friction energy distribution on the surface of the block included in the tread contact area. In the figure was determined by the above procedure, the value of the accumulated frictional energy E _F per unit area in the block 11B surface are shown color-coded. Dark portion is large value of the integrated frictional energy E _F is color, the value of the accumulated frictional energy E _F according to the color becomes thinner becomes smaller. In this procedure, the tread shape changing unit 54 changes the node coordinates of each part of the tread ground contact region according to the accumulated friction energy value of the nodes in the tread ground contact region. Alternatively, instead of changing the node coordinates, a new tire model may be created. Next, a method for changing the node coordinates will be described.

FIGS. 16A and 16B are explanatory diagrams illustrating a method of changing the node coordinates when the node is inside the block or the like. First, the direction in which the node coordinates are changed will be described. In the following description, the blocks 11B and ribs constituting the tread pattern correspond to the tread pattern land portion. The end portions of the block 11B and the rib correspond to the end portion of the tread pattern land portion, and the inside of the block 11B and the rib, that is, the non-end portion corresponds to the non-end portion of the tread pattern land portion. Assuming the actual wear, the direction of changing the nodal coordinates, the normal direction at the position of the nodes N1, N2, etc. present in the cumulative frictional energy E _F a tread surface 11p of the calculated tire model 10M (the surface of the block 11B) It is preferable that 16-1 and FIG. 16-2, when a node whose coordinates are to be changed is included by the tread surface of the plurality of microelements 10Mi, that is, the node whose coordinates are to be changed is inside the block 11B. Or when it exists in the inside of a rib, the normal line Vs in the tread surface 11p of each microelement 10Mi is calculated | required. Then, it is preferable that the average direction Va is a direction in which the coordinates of the node N5 are changed, because the calculation can be simplified.

  FIGS. 17A and 17B are explanatory diagrams illustrating a method of changing the node coordinates when the node is at the block end or the like. When the node whose coordinates are to be changed is located at the end of the block 11B or the end of the rib, as in the node N6 shown in FIGS. 17A and 17B, it is handled as follows. The normal line Vs on the tread surface 11p of each microelement 10Mi is obtained, and the averaged direction Va is defined as the direction in which the coordinates of the node N6 are changed. At this time, the normal direction Vw of the groove wall surface 18w of each microelement 10Mi is not used. Further, as shown in FIG. 16B, when the groove wall surface 18w is not perpendicular to the tread surface 11p, the node N6 is aligned in the direction Vp projected along the groove wall surface 18w with the average normal direction Va of the node N6. Change the coordinates of. When handled in this manner, the actual wear at the end of the block 11B and the end of the rib can be accurately reproduced.

Next, the magnitude | size which changes a node coordinate is demonstrated. FIG. 18 is a perspective view showing a modeled block. In determining the magnitude of changing the node coordinates, first, set the wear amount W _A of any node (e.g., N1 in FIG. 18) in the tread surface 11p. The value of the integrated friction energy of this node and E _FA. At this time, the wear amount W _i of the coordinate change target node can be obtained by Expression (3).
W _i = W _A × E _Fi / E _FA (3)
Here, E _Fi is the cumulative friction energy of the coordinate change target node, and i is the node number. For example, the wear amount W ₅ of the node N5 is the use of the W _A and E _FA, can be determined by the _{W 5 = W A × E F5} / E FA. Here, E _F5 is the cumulative friction energy at the node N5.

Here the wear amount W _A is determined based on the final amount of wear worn tire model to be created. Also, if the wear information (for example, ease of reduction) of the rubber material with respect to the friction energy is obtained in advance by analysis or experiment, the wear amount is determined using this result and the accumulated friction energy at an arbitrary node. Also good. As described above, if the wear amount of the coordinate change target node is determined based on the wear amount of a certain node and the accumulated friction energy as a reference instead of the absolute value of the wear amount of the coordinate change target node, the wear of the rubber material Even when there is no information (easy to reduce), the wear amount of the coordinate change target node can be determined. The tread shape changing unit 54 obtains the wear amount W _i of each node according to the above procedure, and sets it as the change amount of each node coordinate.

  FIG. 19A is a cross-sectional view of a worn block. FIG. 19-2 is a cross-sectional view showing a state where the tire model block is worn. FIG. 19-3 is a cross-sectional view showing a block of the tire model obtained by correcting the amount of wear at the block end. As shown in FIG. 19A, the end of the block 11B or the end of the rib generally wears round. As can be seen from this, the friction energy at the end of the block 11B or the end of the rib is larger than that at the non-end (FIG. 19-1). When creating a tire model, as shown in FIGS. 19-2 and 19-3, the block 11B constituting the tread pattern is divided into a finite number of minute elements. At this time, if the number of divisions is realistic and practical in consideration of calculation time and data capacity, the local distribution of friction energy cannot be reproduced. As a result, as shown in FIG. 19-2, the shape of the worn tire model block 11B (solid line in FIG. 19-2) is different from the actual worn tire block 11B shape.

In order to suppress this, the wear amount obtained by the equation (3) is corrected for the end portion and the rib end portion of the block 11B of the tire model using the correction coefficient k (see the equation (4)).
W _i = k × W _A × E _Fi / E _FA (4)
Using this equation (4), the tread shape changing unit 54 obtains the wear amount at the end of the block 11B and the rib end of the tire model, and the change amount of the node coordinates at the end of the block 11B and the rib end. To do. Here, considering the actual tire wear state, the correction coefficient k is preferably in the range of 0.01 to 1.00, more preferably 0.1 to 0.8. In this way, as shown in FIG. 19-3, the shape of the block 11B of the worn tire model (solid line in FIG. 19-3) is the shape of the block 11B after the actual tire wear (FIG. 19-). 1).

When the coordinate change target node is located at the end of the block 11B or the rib, and the groove wall surface 18w is not perpendicular to the tread surface (for example, the node N6 in FIG. 17-2), the wear amount W _i is obtained by Expression (5). be able to.
W _i = k × (W _A × E _Fi / E _FA ) × (1 / cos θ) (5)
Here, θ is an angle formed by the normal direction Va obtained by averaging the normal direction Vs of the tread surface 11p shown in FIG. 17B and the direction Vp projected along the groove wall surface 18w. Using this equation (5), the tread shape changing unit 54 obtains the wear amount at the end of the block 11B and the rib end of the tire model, and the change amount of the node coordinates at the end of the block 11B and the rib end. To do.

  A final worn tire model may be created by changing the node coordinates once, but a final worn tire model may be created by repeating the change of node coordinates a plurality of times. This procedure will be described. FIG. 20 is a cross-sectional view showing a procedure for wearing a block by changing the node coordinates a plurality of times. FIG. 21 is a flowchart showing a procedure for creating a final worn tire model by a plurality of node coordinate changes. As shown in FIG. 20, the surface of the block 11B in the final worn tire model is a worn tread surface 11pf. The final wear amount at this time is Wf.

  First, the model creation unit 51 creates an initial tire model. Then, typical use conditions of the tire are determined, and the rolling analysis unit 52 and the friction energy calculation unit 53 of the worn tire model creation device 50 calculate the friction energy per unit area based on the use conditions (step S501). ). Since this procedure has already been described, a description thereof will be omitted. Next, the tread shape changing unit 54 determines the wear amount ΔW (FIG. 20) in one node coordinate change so that the final wear amount Wf is reached by a plurality of node coordinate changes. Then, using (3), (4), and (5), the node coordinates are changed by ΔW (step S502), and an intermediate wear tire model is created (step S503). At this time, it is preferable that the wear amount ΔWmax of the node where the wear amount ΔW becomes the largest in one node coordinate change is 20% or less of the maximum groove depth Gd of the tire model in the initial stage.

  Next, the tread shape changing unit 54 determines whether or not the current wear amount has reached the set final wear amount Wf (step S504). If not reached (step S504; No), typical use conditions of the tire are determined, and the rolling analysis unit 52 and the friction energy calculation unit 53 calculate the friction energy per unit area based on the use conditions. (Step S501). Then, the tread shape changing unit 54 changes the node coordinates on the tread surface 11p with respect to the latest intermediate wear tire model (step S502), and creates a new intermediate wear tire model (step S503). Then, the tread shape changing unit 54 repeats Steps S501 to S503 until the current wear amount reaches the final wear amount Wf. When the current wear amount reaches the set final wear amount Wf (step S504; Yes), a finally required wear tire model is obtained.

  In an actual tire, the form of wear (amount of wear, wear location, or form of wear) changes depending on the progress of wear. In this way, a tire model can be created in consideration of the progress of wear. This makes it possible to create a tire model that reproduces more actual wear. In this example, the wear amount ΔW in changing the node coordinates per time is the same in all the node coordinate changing steps, but the wear amount W may be changed in the node coordinate changing steps.

  In addition, the worn tire model before reaching the final wear amount Wf and the finally obtained wear tire model are changed with respect to the initial tire model while changing the physical property values of the rubber material, the carcass material, etc. in consideration of the change over time. You may let them. Even when the final worn tire model is created by changing the node coordinates once, at least the physical property values of the rubber material among the materials constituting the final worn tire model are different from those of the initial tire model. It may be allowed. In this way, since the change with time of the material constituting the tire can be taken into consideration, the prediction accuracy of the wear form can be improved, and a wear tire model adapted to the actual wear can be created. In changing the physical property value of a rubber material, a carcass material, etc., it is preferable to change at least the physical property value of the rubber material. This is because the change in the physical property value has the most influence on the final worn tire model because the rubber material is worn. For other materials, it is preferable to change the physical property values from materials that are particularly susceptible to change over time. For example, it is preferable to change the physical property value of the resin fiber in either the metal fiber or the resin fiber.

  Next, an example of a method for changing the node coordinates will be described. FIG. 22-1 is a schematic diagram illustrating a block before the node coordinates are changed. As shown in FIG. 22-1, when there are two or more microelements 10Mi of the block 11B forming the tread pattern in the thickness direction of the block 11B, the nodes other than the tread surface 11p depend on the wear amount W. You need to change the coordinates.

FIG. 22-2 and FIG. 22-3 are schematic diagrams showing blocks after changing the node coordinates. Both are examples of changing the node coordinates when the wear amount W does not exceed the thickness (that is, the size in the direction in which wear proceeds) ΔH _E of the microelement 10Mi. In the example shown in FIG. 22-2, the node position of each microelement 10Mi is changed while the ratio of the node position in the thickness direction of the block 11B to the depth of the groove 18 is kept substantially constant. In the example shown in FIG. 22-3, the coordinates of only the nodes on the tread surface 11p of the block 11B are changed so as to decrease the thickness of the block 11B, and the coordinates of the nodes other than the tread surface 11p are not changed. is there.

FIG. 23A is a schematic diagram illustrating a block before the node coordinates are changed. FIG. 23-2 and FIG. 23-3 are schematic diagrams illustrating blocks after the node coordinates are changed. Both are examples of changing the node coordinates when the wear amount W exceeds the thickness ΔH _E of the microelement 10Mi. In the example shown in FIG. 23-2, the node position of each microelement 10Mi is changed while the ratio of the node position in the thickness direction of the block 11B to the depth of the groove 18 is kept substantially constant. In the example shown in FIG. 23-3, the microelement 10Mi having a thickness of 0 or less is deleted. The nodal coordinate change examples in which the wear amount W does not exceed the thickness ΔH _E of the microelement 10Mi can be used in appropriate combination.

Next, an example of a method for changing the node coordinates when the number of minute element divisions in the groove depth direction is different in the tread pattern contact area will be described. FIG. 24-1 is a schematic diagram illustrating a block before the node coordinates are changed. FIGS. 24-2 and 24-3 are schematic diagrams illustrating blocks after changing the node coordinates. Both are examples of changing the node coordinates when the wear amount W does not exceed the thickness ΔH _E of the microelement 10Mi. In the example shown in FIG. 24-2, only the coordinates of the nodes on the tread surface 11p are changed, and the coordinates of the nodes other than the tread surface 11p are not changed. In the example shown in FIG. 24-3, the ratio of the node positions in the thickness direction of the block 11B to the depth of the groove 18 is kept substantially constant, and the node positions of the tread surface 11p and the node positions other than the tread surface 11p are changed. Is. However, the node positions of the microelements 10Mi are changed so that the positions of the groove bottoms 18b ₁ and 18b ₂ are not changed.

FIG. 25A is a schematic diagram illustrating a block before the node coordinates are changed. FIG. 25-2 and FIG. 25-3 are schematic diagrams illustrating blocks after the node coordinates are changed. Both are examples of changing the node coordinates when the wear amount W exceeds the thickness ΔH _E of the microelement 10Mi. In the example shown in FIG. 25B, the microelement 10Mi whose thickness is 0 or less is deleted. In the example shown in FIG. 25-3, the microelements are newly divided again based on the shape after the movement of the nodes existing on the tread surface 11p. The nodal coordinate change examples in which the wear amount W does not exceed the thickness ΔH _E of the microelement 10Mi can be used in appropriate combination.

In the example of the method for changing the node coordinates described below, an analysis for giving a forced displacement to the node whose coordinates are changed is executed, and the node coordinate data obtained by the analysis is used as the node coordinate data of the worn tire model. To do. FIG. 26A is a schematic diagram illustrating a block before the node coordinates are changed. FIG. 26B and FIG. 26C are schematic diagrams illustrating blocks after changing the node coordinates. The analysis that gives the forced displacement can use a finite element method, a boundary element method, or other analysis methods. Here, it is not necessary to execute the analysis for giving the forced displacement for the entire tire model, and it is only necessary to execute the analysis only for the tread pattern portion (block 11B and tread bottom surface 19b ₁ ). In this way, the analysis target portion can be reduced, so that the calculation time can be shortened and hardware resources can be used effectively.

In the analysis that gives the forced displacement, the boundary conditions are set as follows. About the node located in the tread surface 11p, the forced displacement according to the friction energy per unit area calculated | required with the above-mentioned friction energy acquisition method is given (FIGS. 26-2, 26-3). The nodes located on the upper surface of the tread bottom surface 19b ₁ and the groove bottom 19b ₂ are constrained so that the displacement becomes zero (FIGS. 26-2 and 26-3). No constraint condition is set for other nodes. Here, when changing the nodal coordinates, the Poisson's ratio is preferably zero. The reason for this will be described.

FIG. 26-2 is an example in which the Poisson's ratio is set to the original value (about 0.5) of the rubber material, and the node is displaced, but as a result, the width of the block 11B is increased, resulting in the grooves 18 ₁ , 18 _2. Will become narrower. FIG. 26-3 is an example in which the Poisson's ratio is set to 0 and the node is displaced. In this way, the width of the block 11B does not increase, so the width of the grooves 18 ₁ and 18 ₂ becomes narrow. There is nothing. In this way, by applying a forced displacement corresponding to the amount of wear to the nodes located on the tread surface 11p, subdivision of the microelements becomes unnecessary. This makes it possible to easily create a worn tire model while suppressing the tread shape from becoming an inappropriate shape. This method is particularly preferable when the displacement of the node is small, that is, when the wear amount is small.

Next, a case where only some of the node coordinates located on the tread surface are changed will be described. In this case, the block 11B and the like may be subdivided using a minute element different from the minute element used in the initial tire model. FIG. 27A is an explanatory diagram of an example in which the minute elements of the initial tire model are hexahedral elements. FIG. 27-2 and FIG. 27-3 are explanatory diagrams illustrating examples of subdivision. When one node N _X1 is changed beyond the thickness of the hexahedron element Ea among the hexahedron elements Ea constituting the block 11B shown in FIG. 27-1, as shown in FIG. It may be re-divided into a tetrahedron element E ₄₁ and one hexahedron element Eb and reconfigured as a block 11B _n1 . Further, as shown in Figure 27-3, and then re-divided and two tetrahedral elements E ₄₁ and one five tetrahedral elements E ₅₁ to the one hexahedral elements Eb, and reconfigured as block 11B _n2 Also good.

28A, 28B, and 28C are explanatory diagrams illustrating examples of subdivision. When the two nodes N _X1 and N _X2 are changed beyond the thickness of the hexahedron element Ea among the hexahedron elements Ea constituting the block 11B shown in FIG. 27-1, as shown in FIG. It may be subdivided into one pentahedron element E ₅₂ and one hexahedron element Eb and reconfigured as a block 11B _n3 .

When three nodes N _X1 , N _X2 , and N _X3 among the hexahedron elements Ea constituting the block 11B shown in FIG. 27A are changed beyond the thickness of the hexahedron element Ea, they are shown in FIG. As described above, the block 11B _n4 may be re-divided into two tetrahedral elements E ₄₂ and one hexahedral element Eb. When four nodes are changed beyond the thickness of the hexahedral element Ea among the hexahedral elements Ea constituting the block 11B shown in FIG. 27-1, the hexahedral element Ea is deleted as shown in FIG. 28-3. Then, the block 11B _n3 may be reconfigured with only the hexahedral element Eb.

Next, the case where the minute elements of the initial tire model are pentahedral elements will be described. FIG. 29A is an explanatory diagram of an example in which the minute elements of the initial tire model are pentahedral elements. FIG. 29-2, FIG. 29-3, and FIG. 29-4 are explanatory diagrams illustrating examples of subdivision. When one node N _Y1 is changed beyond the thickness of the pentahedron element Ec among the pentahedron elements Ec constituting the block 11B ′ shown in FIG. 29-1, as shown in FIG. 29-2, It may be subdivided into two tetrahedron elements E ₄₃ and one pentahedron element Ed and reconfigured as a block 11B _n1 ′.

When two nodes N _Y1 and N _{Y2 of the} pentahedron element Ea constituting the block 11B ′ shown in FIG. 29-1 are changed beyond the thickness of the hexahedron element Ea, as shown in FIG. 29-3. Alternatively, it may be re-divided into one tetrahedron element E ₄₃ and one hexahedron element Ed and reconfigured as a block 11B _n2 ′. When three nodes N _Y1 , N _Y2 , N _Y3 among the pentahedron elements Ea constituting the block 11B ′ shown in FIG. 29-1 are changed beyond the thickness of the pentahedron element Ec, FIG. As shown in FIG. 4, the pentahedron element Ec may be deleted, and the block 11B _n3 ′ may be reconfigured using only the pentahedron element Ed.

  By changing the tread shape according to the above procedure (step S108), a worn tire model is created (step S109). FIG. 30A is a perspective view illustrating a block of a tire model in an initial stage. FIG. 30-2 is a perspective view illustrating a block of a worn tire model. As shown in FIG. 30-2, the block 11Bn of the worn tire model has a block thickness reduced from H to Hn due to wear. The amount of wear at this time is H-Hn. As described above, a worn tire model with a predetermined amount of wear can be created by the method for creating a worn tire model according to the present embodiment. Then, using this worn tire model, various tire performances are predicted (step S110).

  Examples of tire performance that can be predicted include, for example, inflated shape, tire shape under load, tire spring characteristics, stress, strain, strain energy, loss energy, rolling resistance, reinforcing cord tension, ground shape, ground pressure, cornering Performance, braking performance, drive performance, wet performance, hydroplaning performance, snow performance, ice performance, slip in the contact surface, contact shear stress, frictional energy, vibration performance, noise performance, bumping over bumps, etc. It is not limited.

(Evaluation example)
An example in which the tire noise performance is predicted using the worn tire model created by the worn tire model creating method according to the present embodiment will be described. Pattern noise between a new tire and a worn tire (30% wear when new) was measured by an actual vehicle running test. In addition, noise simulation was performed on the new tire model and the worn tire model to evaluate the pattern noise. In the noise simulation, the vibration of the contact reaction force, which is an effective parameter for pattern noise prediction, was obtained by rolling analysis of the tire, and the noise index obtained by Fourier transforming the vibration of the contact reaction force was compared. This noise index is a gain of contact reaction force. Here, the contact reaction force refers to a force applied to the tire from the road surface that is generated between the ground contact surface of the tire and the road surface when the tire is rolled by applying a predetermined load to the tire.

  The test conditions are as follows. The test tire is a 235 / 45ZR17 radial tire for passenger cars. This test tire is mounted on a rim of 17 × 8 JJ, and an internal pressure of 220 kPa is applied. The test vehicle is a passenger car with a displacement of 2 liters, and the traveling speed is 40 km / h. A real vehicle running test was performed under these conditions, and a new tire model and a worn tire model of the above size were created and a noise simulation was performed, and the results were compared.

  FIG. 31A is an explanatory diagram of a measurement result of pattern noise by an actual vehicle running test. FIG. 31-2 is an explanatory diagram of an evaluation result by noise simulation. In the actual vehicle running test, the results are organized according to the relationship between the sound pressure of noise and the frequency of noise. In the noise simulation, the results are organized according to the relationship between the noise index and the noise frequency. As a result of the actual vehicle running test, the sound pressure of the worn tire increased around 160 Hz and around 315 Hz with respect to the new tire. On the other hand, in the noise simulation, the worn tire model increased the sound pressure near 160 Hz and 315 Hz compared to the new tire model. From this result, it was confirmed that the worn tire model created by the method for creating a worn tire model according to this example well reproduced the characteristics of the test tire in the pattern noise measurement in the actual vehicle running test.

  As described above, according to the method for creating a worn tire model and the method for predicting a worn tire according to this embodiment, the friction energy per unit area in the contact area of the initial tire model is considered in consideration of typical use conditions of the tire. And a wear tire model is created based on this. In this worn tire model, since the use condition of the tire is taken into consideration, it is possible to reflect not only the amount of wear and the life but also the wear form of the tire. If this worn tire model is used, the performance of the worn tire can be accurately predicted.

  In addition, the method for creating a worn tire model and the method for predicting the worn tire according to this embodiment can be realized by computer simulation, so that it is not necessary to actually measure the friction energy. For this reason, the wear form of the tire and the performance of the worn tire can be predicted efficiently and accurately. Furthermore, since the tread surface is moved in the wear direction by the ratio of the friction energy at an arbitrary position on the tread surface and the friction energy at other positions, even if there is no wear information on the rubber material, the wear amount of the coordinate change target node can be reduced. Can be determined.

  In addition, the method of creating a worn tire model and the method of predicting the performance of a worn tire according to this embodiment are such that a tread pattern land such as a block or a rib is used in determining the moving direction and moving amount of a node located on the tread surface. A process different from that of a node located at a non-end part is executed on a node located at an end part of the part. This makes it possible to create a worn tire model with improved reproduction accuracy of actual tire wear.

  In addition, in the method for creating a worn tire model and the method for predicting the worn tire according to this embodiment, the amount of movement of the node exceeds the dimension of the minute element (the dimension of the minute element in the wear direction and the thickness of the minute element). In this case, for example, a minute element is deleted, or a tread pattern is subdivided to reconstruct a tire model. As a result, a worn tire model can be created even when wear has greatly progressed.

  In addition, in the method for creating a worn tire model and the method for predicting the worn tire according to this embodiment, at least the physical property values of the rubber material among the materials constituting the worn tire model are different from those of the initial tire model. . As a result, the change with time of the material constituting the tire can be taken into consideration, so that the prediction accuracy of the wear form can be improved and a wear tire model adapted to actual wear can be created.

  The method for creating a worn tire model according to this embodiment is realized by executing a prepared program on a computer such as a personal computer or a workstation without using the worn tire model creating device 50. be able to. This program can be distributed via a network such as the Internet. The program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD and being read from the recording medium by the computer.

  As described above, the method for creating a worn tire model, the computer program for creating a worn tire model, the performance prediction method for the worn tire, and the worn tire model according to the present invention are useful for tire wear evaluation. It is suitable for accurately predicting the wear form and the performance of the worn tire.

1 is a partial cross-sectional view showing a cross section of a tire cut along a meridian plane including a rotation axis of the tire. It is explanatory drawing which shows the structure of the vibration characteristic evaluation apparatus of the tire which concerns on this Example. It is a flowchart which shows the procedure of the preparation method of the wear tire model which concerns on a present Example. It is a perspective view showing an example of a tire model. It is a schematic diagram which shows the state of rolling analysis. It is a perspective view showing the axis | shaft of a tire model. It is a side view which shows the relationship between a tire model and a road surface model. It is a front view which shows the relationship between a tire model and a road surface model. It is explanatory drawing which shows the example which divided | segmented the ground-contact surface where a cap tread contact | connects the ground into a microelement. It is explanatory drawing which shows the example which divided | segmented the ground-contact surface where a cap tread contact | connects the ground into a microelement. It is a top view which shows the ground-contact plane divided into nine by the quadrilateral element. It is a top view which shows the ground-contact plane divided into nine by the quadrilateral element. It is a perspective view which shows one of the division elements containing the contact surface of a tire model. It is a perspective view which shows one of the division elements containing the contact surface of a tire model. It is a perspective view which shows one of the division elements containing the contact surface of a tire model. It is explanatory drawing which shows an example of the method of determining the earthing | grounding of a division | segmentation element surface. It is explanatory drawing which shows an example of the method of determining the earthing | grounding of a division | segmentation element surface. It is explanatory drawing which shows the other example of the method of determining the earthing | grounding of a division | segmentation element surface. It is explanatory drawing which shows the other example of the method of determining the earthing | grounding of a division | segmentation element surface. It is explanatory drawing which shows the other example of the method of determining the earthing | grounding of a division | segmentation element surface. It is a flowchart which shows the procedure which calculates the friction energy per unit area. It is a flowchart which shows the procedure which determines whether it is the division | segmentation element surface to earth | ground. It is a flowchart which shows the calculation procedure of a nodal area. It is a conceptual diagram which shows integrated friction energy distribution in the surface of the block contained in a tread grounding area | region. It is explanatory drawing which shows the method of changing a node coordinate, when a node exists in a block inside. It is explanatory drawing which shows the method of changing a node coordinate, when a node exists in a block inside. It is explanatory drawing which shows the method of changing a node coordinate, when a node exists in a block edge part. It is explanatory drawing which shows the method of changing a node coordinate, when a node exists in a block edge part. It is a perspective view which shows the modeled block. It is sectional drawing of the worn block. It is sectional drawing which shows the state with which the block of the tire model was worn out. It is sectional drawing which shows the block of the tire model calculated | required by adding correction | amendment to the abrasion loss of a block edge part. It is sectional drawing which shows the procedure which wears a block by multiple times of node coordinate change. It is a flowchart which shows the procedure which produces a final wear tire model by multiple times of node coordinate change. It is a schematic diagram which shows the block before changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block before changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block before changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block before changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block before changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is a schematic diagram which shows the block after changing a node coordinate. It is explanatory drawing which shows the example whose microelement of an early tire model is a hexahedral element. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example whose microelement of an early tire model is a pentahedral element. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is explanatory drawing which shows the example of a subdivision. It is a perspective view which shows the block of the tire model in the initial stage. It is a perspective view which shows the block of a wear tire model. It is explanatory drawing which shows the measurement result of the pattern noise by a real vehicle running test. It is explanatory drawing which shows the evaluation result by noise simulation.

Explanation of symbols

10 tire 10M tire model 10M ₁ , 10Mi microelement 11 cap tread 11p tread surface 11B block 11pf wear tread surface 11s groove wall 18 groove 18w groove wall surface 18b ₁ , 19b ₂ groove bottom 19b ₁ tread bottom surface 40 road surface 40M road surface model 50 wear tire Model creation device 50m Storage unit 50p Processing unit 51 Model creation unit 52 Rolling analysis unit 53 Friction energy calculation unit 54 Tread shape change unit

Claims (15)

In creating a worn tire model,
A procedure for creating an initial tire model by dividing a tire in a new state into a finite number of microelements,
A procedure for setting typical use conditions assumed to be experienced by the worn tire model to be created;
Under the typical use conditions set, a procedure for rolling analysis of the initial tire model;
A procedure for obtaining friction energy per unit area in the tread contact area of the initial tire model by the rolling analysis,
The amount of wear at an arbitrary position on the tread surface of the initial tire model is set, and the amount of wear at the other position is determined by the ratio between the friction energy at the arbitrary position and the friction energy at another position on the tread surface. Procedures to determine,
A procedure for creating a worn tire model by moving the tread surface by the determined wear amount;
A method for creating a worn tire model, comprising: In creating a worn tire model,
An initial tire model creation procedure for creating an initial tire model by dividing a tire into a finite number of minute elements;
A worn tire model creating procedure for creating a worn tire model from the initial tire model, and the worn tire model creating procedure comprises:
A procedure for setting typical use conditions assumed to be experienced by the worn tire model to be created;
Under the typical use conditions set, a procedure for rolling analysis of the initial tire model;
A procedure for obtaining friction energy per unit area in the tread contact area of the initial tire model by the rolling analysis,
The amount of wear at an arbitrary position on the tread surface of the initial tire model is set, and the amount of wear at the other position is determined by the ratio between the friction energy at the arbitrary position and the friction energy at another position on the tread surface. Procedures to determine,
A procedure for creating an intermediate wear tire model by moving the tread surface by the determined wear amount;
The wear tire model creation procedure is executed a plurality of times, and the latest intermediate wear tire model is used in place of the initial tire model in the second and subsequent wear tire model creation procedures. How to create a tire model.   When there are a plurality of typical use conditions, the friction energy is an accumulated friction energy obtained by multiplying the friction energy per unit area obtained under each use condition by a weighting factor of the use condition and integrating the friction energy. The method for creating a worn tire model according to claim 1 or 2.   The amount of movement of the tread surface is such that the largest amount of movement on the tread surface is 20% or less of the maximum groove depth of the initial tire model. A method for creating a worn tire model described in 1.   The frictional energy is calculated from the nodes of the microelements and nodes located on the tread surface, and the movement of the tread surface is realized by changing the coordinates of the nodes located on the tread surface. The method for creating a worn tire model according to any one of claims 1 to 4. For the nodes located on the tread surface and at the non-end portion of the tread pattern land, the normal direction of all tread surfaces of the microelements including the nodes is moved in an average direction,
For the nodes located on the tread surface and at the end of the tread pattern land portion, the direction of the average of the normal directions of all tread surfaces except the groove wall surface of the microelements including the nodes is defined as the groove wall surface. Along the projected direction and positioned at the end of the tread pattern land so that it is less than or equal to the amount of movement determined based on the frictional energy of the node located at the end of the tread pattern land. 6. The method for creating a worn tire model according to claim 5, wherein a movement amount of the node is corrected.   Further, the amount of movement of the node located at the end of the land portion of the tread pattern is defined as a direction obtained by averaging the normal directions on all tread surfaces except the groove wall surface and a direction in which the direction is projected along the groove wall surface. The method for creating a worn tire model according to claim 6, wherein correction is performed using a corner.   6. When moving the tread surface, if the amount of movement of a node located on the tread surface is larger than the dimension of the microelement including the node, the microelement is deleted. 8. A method for creating a worn tire model according to any one of 7 above.   The method for creating a worn tire model according to any one of claims 5 to 7, wherein when the tread surface is moved, minute elements of the tread portion including the tread surface are subdivided.   When moving the tread surface, a forced displacement corresponding to the wear amount is applied to the nodes located on the tread surface, the nodes located on the groove bottom and the nodes located on the tread bottom are restrained, and the Poisson's ratio is further reduced. The method for creating a worn tire model according to any one of claims 5 to 7, characterized in that:   11. The wear according to claim 1, wherein the created wear tire model has a physical property value of at least a rubber material different from that of the initial tire model among materials constituting the wear tire model. How to create a tire model.   A computer program for creating a worn tire model, wherein the method for creating a worn tire model according to any one of claims 1 to 11 is realized on a computer.   A worn tire performance prediction method, wherein the worn tire model is predicted by using the worn tire model created by the worn tire model creation method according to claim 1. Set typical usage conditions assumed to be experienced by the worn tire model to be created,
Rolling analysis of the initial tire model created by dividing the tire in a new state into a finite number of minute elements under the set typical use conditions,
By the rolling analysis, the friction energy per unit area in the tread area of the initial tire model is obtained,
The amount of wear at an arbitrary position on the tread surface of the initial tire model is set, and the amount of wear at the other position is determined by the ratio between the friction energy at the arbitrary position and the friction energy at another position on the tread surface. Decide
A worn tire model produced by moving the tread surface by a determined amount of wear.   15. The worn tire model according to claim 14, wherein the created worn tire model has a physical property value of at least a rubber material constituting the worn tire model different from that of the initial tire model.

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