JP2021189117A - Tire simulation method, and tire simulation device - Google Patents

Abstract

To provide a tire simulation method that can calculate a state of a post-wear out of a tire tread ground contact surface accurately.SOLUTION: The present invention relates to a tire simulation method and the like for calculating a post wearing-out state of a tire tread ground contact surface. In the simulation method, a tire model with a plurality of nodes, and discretizing a tire using a finite number of factors having a predetermined material characteristic defined is input to a computer. Further, according to the simulation method, the computer is configured to implement; a first step S4 that calculates a physical quantity associated with wearing-out of a tread ground contact surface as to a plurality of tread nodes constituting the tread ground contact surface of the tire model, among nodes; a second step S5 that determines an amount of movement for expressing the wearing-out of each tread node on the basis of the physical quantity; a third step S6 that moves each tread node on the basis of the amount of movement; and a fourth step S7 that updates the material characteristic on the basis of the amount of movement.SELECTED DRAWING: Figure 3

Description

The present invention relates to a tire simulation method and the like.

The following Patent Document 1 proposes a method for creating a tire model in which wear has progressed by using a computer. In this creation method, a step of acquiring wear energy in the ground contact region by rolling analysis using a tire model and a step of changing to a tire model in which wear has progressed based on the amount of wear obtained from the wear energy are carried out. Has been done. Predetermined material characteristics are defined in the tire model.

Japanese Patent No. 5098711

Although the above method takes into consideration the change over time in the material properties of the tire model, the specific method has not been described.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a tire simulation method capable of accurately calculating the state after wear of the tread contact patch of a tire. There is.

The present invention is a tire simulation method for calculating the state of the tread contact surface of a tire after wear, and is a finite number of elements having a plurality of nodes and having predetermined material properties defined. Is used to input a tire model in which the tire is dissociated into a computer, and the computer wears the tread contact surface of the plurality of tread nodes constituting the tread contact surface of the tire model among the nodes. The first step of calculating the physical quantity associated with the tread, the second step of determining the movement amount for expressing the wear of each tread node based on the physical quantity, and the tread based on the movement amount. It is characterized by executing a third step of moving a node and a fourth step of updating the material properties based on the amount of movement.

In the tire simulation method according to the present invention, the first step to the fourth step may be repeated until the computer satisfies a predetermined condition.

In the tire simulation method according to the present invention, the fourth step includes a first calculation step of calculating at least one of a mileage and a mileage of the tire based on the movement amount, and the mileage and the mileage. It may include a second calculation step of calculating the aged material properties based on at least one of the periods.

In the tire simulation method according to the present invention, in the first calculation step, a step of inputting a wear rate defining a wear amount per unit mileage of the tire into the computer and a step of inputting the movement amount into the wear. It may include a step of calculating the mileage by dividing by a rate.

In the tire simulation method according to the present invention, the first calculation step includes a step of calculating the total number of rotations of the tire based on the amount of movement, the total number of rotations of the tire, and the circumference of the tire model. The step of calculating the mileage may be included by multiplying the length with the length.

In the step of calculating the total number of revolutions of the tire in the tire simulation method according to the present invention, the unit wear progress rate that defines the amount of wear per unit wear energy is input to the computer for the tread rubber of the tire. By dividing the step of inputting the wear energy progress rate that defines the wear energy for one rotation of the tire into the computer and the movement amount by the unit wear progress rate and the wear energy progress rate. The total number of rotations of the tire may be calculated.

In the tire simulation method according to the present invention, the step of calculating the mileage may include the step of calculating the peripheral length based on at least one of the rolling speed and the angular velocity of the tire model.

In the tire simulation method according to the present invention, the step of calculating the perimeter calculates the perimeter based on at least one of the rolling speed and the angular velocity, which are the most frequent during the running of the tire. You may.

In the tire simulation method according to the present invention, the first calculation step includes a step of inputting an actual vehicle distance rate that defines a mileage per unit period of the tire into the computer, and a step of inputting the mileage into the actual vehicle distance. The step of calculating the traveling period may be included by dividing by a rate.

In the tire simulation method according to the present invention, in the second calculation step, the tread rubber of the tire is a material that defines the relationship between at least one of the actual vehicle mileage and the actual vehicle travel period of the tire and the material properties. It may include a step of inputting a characteristic change rate into the computer, a step of calculating the material property changed over time based on at least one of the mileage and the running period, and the material characteristic change rate.

The present invention is a simulation device having a calculation processing device for calculating a state after wear of a tread contact surface of a tire, and the calculation processing device has a plurality of nodes and has predetermined material properties. With respect to a tire model acquisition unit that acquires a tire model obtained by dissociating the tire using a finite number of defined elements, and a plurality of tread nodes constituting the tread ground contact surface of the tire model among the nodes. A physical quantity calculation unit that calculates the physical quantity associated with the wear of the tread ground contact surface, a movement amount determination unit that determines the movement amount for expressing the wear of each tread node based on the physical quantity, and the movement amount. May include a moving unit that moves each tread node based on the above, and a material property updating unit that updates the material properties based on the amount of movement.

Since the tire simulation method of the present invention can update the material properties based on the movement amount by providing the above configuration, the state after wear of the tread contact patch of the tire can be calculated accurately. It becomes possible to do.

It is a block diagram which shows an example of the computer (tire simulation apparatus) which executes the tire simulation method. It is sectional drawing which shows an example of a tire. It is a flowchart which shows an example of the processing procedure of the tire simulation method. It is a perspective view which shows an example of a tire model and a road surface model. It is sectional drawing which shows an example of a tire model. It is a partially enlarged view of the tread part of FIG. It is a flowchart which shows an example of the processing procedure of a preprocessing process. (A) is a diagram for explaining an example of a state before each tread node moves, and (b) is a diagram for explaining an example of a state after each tread node moves. It is a flowchart which shows an example of the processing procedure of 4th process. It is a flowchart which shows an example of the processing procedure of the 1st calculation process. It is a flowchart which shows an example of the processing procedure of the 2nd calculation process. It is a graph which shows an example of the material property property change rate. It is a flowchart which shows an example of the processing procedure of the 1st calculation process of another Embodiment of this invention. It is a flowchart which shows an example of the processing procedure of the rotation speed calculation process. It is a flowchart which shows an example of the processing procedure of a mileage calculation process. It is a flowchart which shows an example of the processing procedure of the 1st calculation process of still another Embodiment of this invention. It is a flowchart which shows an example of the processing procedure of the 2nd calculation process of this embodiment. It is a graph which shows an example of the material property property change rate of another embodiment of this invention. It is a graph which shows the relationship between the actual vehicle mileage and a material property. It is a graph which shows the relationship between the amount of wear and the mileage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the tire simulation method of the present embodiment (hereinafter, may be simply referred to as "simulation method"), the state after wear of the tread contact patch of the tire is calculated by using a computer. FIG. 1 is a block diagram showing an example of a computer (tire simulation device) in which a tire simulation method is executed.

The computer 1 of the present embodiment is configured as a tire simulation device (hereinafter, may be simply referred to as a “simulation device”) 1A. The computer 1 of the present embodiment includes an input unit 2 as an input device, an output unit 3 as an output device, and an arithmetic processing device 4 for calculating a physical quantity of a tire and the like.

As the input unit 2, for example, a keyboard, a mouse, or the like is used. As the output unit 3, for example, a display device, a printer, or the like is used. The arithmetic processing unit 4 includes an arithmetic unit (CPU) 4A for performing various arithmetic operations, a storage unit 4B for storing data, programs, and the like, and a working memory 4C.

The storage unit 4B is a non-volatile information storage device including, for example, a magnetic disk, an optical disk, an SSD, or the like. The storage unit 4B is provided with a data unit 5 and a program unit 6.

The data unit 5 includes an initial data unit 5A for storing information about the tire to be evaluated and road surface (for example, CAD data), a tire model input unit 5B, and a road surface model input unit 5C for inputting a road surface model. Is done. Further, in the data unit 5, the boundary condition input unit 5D in which the boundary condition of the simulation is input, the physical quantity input unit 5E in which the physical quantity calculated by the calculation unit 4A is input, and the simulation end condition and the like are input. The condition input unit 5F is included.

The program unit 6 is a program executed by the arithmetic unit 4A. The program unit 6 includes a tire model acquisition unit 6A for acquiring a tire model, a road surface model acquisition unit 6B for acquiring a road surface model, and an internal pressure filling calculation unit 6C for calculating the shape of the tire model after internal pressure filling. The program unit 6 is associated with a load load calculation unit 6D that defines a load on the tire model after internal pressure filling, a rolling calculation unit 6E that calculates the rolling of the tire model, and wear of the tread contact patch of the tire model. The physical quantity calculation unit 6F for calculating the physical quantity is included. The program unit 6 includes a movement amount determining unit 6G for determining the movement amount for expressing the wear of each tread node of the tire model, a moving unit 6H for moving each tread node, and a material property update for updating the material characteristics. Part 6J is included. The program unit 6 includes a determination unit 6K that evaluates the end condition of the simulation and the state of the tread contact patch after wear.

FIG. 2 is a cross-sectional view showing an example of a tire 11 in which a wear amount is predicted by a tire simulation method (using a simulation device 1A (shown in FIG. 1)). In the present embodiment, pneumatic tires for passenger cars are exemplified, but tires for heavy loads such as trucks and buses, and tires of other categories such as airless tires may be used.

The tire 11 of the present embodiment includes a carcass 16 extending from the tread portion 12 through the sidewall portion 13 to the bead core 15 of the bead portion 14, and a belt arranged on the outer side of the carcass 16 in the radial direction of the tire and inside the tread portion 12. A layer 17 is provided.

The carcass 16 is composed of at least one carcass ply 16A, or one carcass ply 16A in the present embodiment. The carcass ply 16A has a carcass code (not shown) arranged at an angle of, for example, 75 to 90 degrees with respect to the tire equator C.

The belt layer 17 includes two outer belt plies 17A and 17B in which belt cords (not shown) are arranged at an angle of, for example, 10 to 35 degrees with respect to the tire circumferential direction. These belt plies 17A and 17B are overlapped with each other in a direction in which the belt cords intersect with each other.

The tire 11 is provided with a rubber member 11G including a tread rubber 12G arranged on the outside of the belt layer 17 in the tread portion 12 and a sidewall rubber 13G arranged on the outside of the carcass 16 in the sidewall portion 13. There is.

The tread portion 12 (tread rubber 12G) is provided with a main groove 18 that extends continuously in the tire circumferential direction. As a result, the tread portion 12 is provided with a plurality of land portions 19 divided by the main groove 18. Each land portion 19 may be provided with, for example, a block separated by a horizontal groove or the like (not shown).

The main grooves 18 of the present embodiment are arranged between the pair of center main grooves 18A and 18A arranged on both outer sides of the tire equator C in the tire axial direction, and between the center main grooves 18A and the tread ground contact end 12t. It is configured to include a pair of shoulder main grooves 18B and 18B. On the other hand, the land portion 19 of the present embodiment is a center land portion 19A divided between a pair of center main grooves 18A and 18A, and a pair of middle land portions divided by a center main groove 18A and a shoulder main groove 18B. It is configured to include 19B and 19B. Further, the land portion 19 includes a pair of shoulder land portions 19C and 19C divided by a shoulder main groove 18B and a tread ground contact end 12t.

In the present specification, the "tread ground contact end 12t" means that a tire 11 in a state where the rim is assembled to a regular rim and is filled with a regular internal pressure is loaded with a regular load and grounded on a flat surface at a camber angle of 0 degrees. The outermost end of the tread ground contact surface 20 in the tire axial direction.

A "regular rim" is a rim defined for each tire in a standard system including a standard on which the tire 11 is based. For example, "standard rim" for JATTA and "Design Rim" for TRA. For ETRTO, use "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire 11 is based. If it is JATTA, it is "maximum air pressure", and if it is TRA, it is the table "TIRE LOAD". The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", "INFLATION PRESSURE" for ETRTO, but 180 kPa if the tires are for passenger cars.

The "regular load" is the load specified for each tire 11 by the above standard, and is the maximum load capacity for JATTA and the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA. If it is ETRTO, it is "LOAD CAPACITY".

In the present specification, the dimensions and the like of each part of the tire are specified as values measured in a normal state unless otherwise specified. The normal state is a state in which the tire 11 is rim-assembled on a normal rim (not shown), the normal internal pressure is applied, and there is no load.

FIG. 3 is a flowchart showing an example of the processing procedure of the tire simulation method. In the simulation method of the present embodiment, first, the tire 11 (shown in FIG. 2) is discretized by using a finite number of elements having a plurality of nodes and having predetermined material properties defined. The tire model is input to the computer 1 (shown in FIG. 1) (step S1).

In step S1 of the present embodiment, first, as shown in FIG. 1, information (for example, contour data and the like) regarding the tire 11 (shown in FIG. 2) input to the initial data unit 5A is stored in the working memory 4C. Is entered in. Further, the tire model acquisition unit 6A is read into the working memory 4C. Then, the tire model acquisition unit 6A is executed by the calculation unit 4A.

FIG. 4 is a perspective view showing an example of the tire model 21 and the road surface model 25. FIG. 5 is a cross-sectional view showing an example of the tire model 21. FIG. 6 is a partially enlarged view of the tread portion 22 of FIG. In FIG. 4, the mesh (element F (i)) of the tire model 21 shown in FIGS. 5 and 6 is omitted.

As shown in FIG. 5, in step S1 of the present embodiment, based on the information regarding the tire 11 shown in FIG. 2, the tire 11 can handle a finite number of elements F (i) (i) by a numerical analysis method. = 1, 2, ...) Is used to discretize. As a result, the tire model 21 is set in step S1. As the numerical analysis method, for example, a finite element method, a finite volume method, a difference method or a boundary element method can be appropriately adopted, but in the present embodiment, the finite element method is adopted.

As shown in FIGS. 5 and 6, for example, a tetrahedral solid element, a pentahedral solid element, a hexahedral solid element, or the like is used for the element F (i). Each element F (i) has a plurality of nodes 31. Further, each element F (i) is provided with a linear side 32 connecting the nodes 31 and 31. Numerical data such as an element number, a node number 31, and a coordinate value of the node 31 are defined in each of such elements F (i). Further, each element F (i) has material properties (for example, density, Young's modulus, damping coefficient, loss tangent (tanδ)), and / or complex elastic modulus of the tire member (tread rubber 12G, etc.) shown in FIG. Numerical data such as E *) is defined.

In the tread portion 22 of the tire model 21, a main groove model 28 in which the main groove 18 (shown in FIG. 2) is reproduced and a land portion model 29 in which the land portion 19 is reproduced (shown in FIG. 2) are set. To. For the land model 29, for example, a block model separated by a lateral groove model (not shown) may be set.

The main groove model 28 of the present embodiment includes a pair of center main groove models 28A and 28A and a pair of shoulder main groove models 28B and 28B, similarly to the main groove 18 of the tire 11 shown in FIG. On the other hand, the land model 29 of the present embodiment has a center land model 29A, a pair of middle land models 29B and 29B, and a pair of shoulder land parts, similarly to the land portion 19 of the tire 11 shown in FIG. Models 29C, 29C are included.

The tire model 21 includes a carcass ply model 41 that models the carcass ply 16A (shown in FIG. 2) and belt ply models 41A and 41B that model the belt plies 17A and 17B (shown in FIG. 2, respectively). Will be done. Further, the tire model 21 includes rubber including a tread rubber model 22G that models a tread rubber 12G (shown in FIG. 2) and a sidewall rubber model 23G that models a sidewall rubber 13G (shown in FIG. 2). Model 21G is set. The tire model 21 is input to the computer 1 (tire model input unit 5B) shown in FIG.

Next, in the simulation method of the present embodiment, the road surface model 25 (shown in FIG. 4) that models the road surface (not shown) is input to the computer 1 (shown in FIG. 1) (step S2). In step S2 of the present embodiment, first, information about the road surface (not shown) input to the initial data unit 5A shown in FIG. 1 is input to the working memory 4C. Further, the road surface model acquisition unit 6B is read into the working memory 4C. Then, the road surface model acquisition unit 6B is executed by the calculation unit 4A.

As shown in FIG. 4, in step S2, the road surface has a finite number of elements G (i) (i) that can be handled by the numerical analysis method (in this embodiment, the finite element method) based on the information about the road surface (not shown). It is discretized using i = 1, 2, ...). As a result, the road surface model 25 is set in step S2.

The element G (i) is composed of a rigid plane element set to be non-deformable. The element G (i) is provided with a plurality of nodes 38. Further, in the element G (i), numerical data such as an element number and a coordinate value of a node 38 is defined.

In the present embodiment, a road surface model 25 having a smooth surface is exemplified, but if necessary, a fruit such as a fine unevenness such as an asphalt road surface, an irregular step, a dent, a swell, or a rut. Unevenness or the like that is close to the traveling road surface may be provided. The road surface model 25 is input to the computer 1 (road surface model input unit 5C) shown in FIG.

Next, in the simulation method of the present embodiment, the computer 1 (shown in FIG. 1) calculates the rolling tire model 21 (pretreatment step S3). FIG. 7 is a flowchart showing an example of the processing procedure of the preprocessing step S3.

In the pretreatment step S3 of the present embodiment, first, as shown in FIGS. 4 and 5, boundary conditions for grounding the tire model 21 on the road surface model 25 are defined (step S31). As the boundary conditions, for example, the internal pressure condition of the tire model 21, the load-bearing condition L, the camber angle, the friction coefficient between the tire model 21 and the road surface model 25, and the like are set. Further, as the boundary conditions, an angular velocity V1 corresponding to the traveling speed (rolling speed V3), a translational speed V2, and a turning angle (not shown) are set. The traveling speed and the translational speed V2 are speeds on the surface where the tire model 21 is in contact with the road surface model 25. These conditions are input to the computer 1 (boundary condition input unit 5D) shown in FIG.

Next, in the pretreatment step S3 of the present embodiment, the tire model 21 (shown in FIG. 5) after the internal pressure filling is calculated (step S32). In step S32, as shown in FIG. 1, the tire model 21 input to the tire model input unit 5B and the internal pressure conditions input to the boundary condition input unit 5D are read into the working memory 4C. Further, the internal pressure filling calculation unit 6C is read into the working memory 4C. Then, the internal pressure filling calculation unit 6C is executed by the calculation unit 4A.

In step S32, first, as shown in FIG. 5, the bead portions 24 and 24 of the tire model 21 are restrained by the rim model 27 in which the rim 26 (shown in FIG. 2) of the tire 11 is modeled. Further, the tire model 21 is deformed and calculated based on the evenly distributed load w corresponding to the internal pressure condition. As a result, the tire model 21 after filling the internal pressure is calculated. For the internal pressure, for example, it is desirable that the air pressure defined by each standard is set in the standard system including the standard on which the tire 11 (shown in FIG. 2) is based.

In the deformation calculation of the tire model 21, a mass matrix, a rigidity matrix, and a damping matrix of each element F (i) are created based on the shape and material properties of each element F (i). Furthermore, each of these matrices is combined to form the matrix of the entire system. Then, the equations of motion are created by applying the various conditions, and these are calculated for each minute time (unit time T (x) (x = 0, 1, ...)). As a result, the deformation of the tire model 21 is calculated. Such deformation calculation of the tire model 21 (including rolling calculation described later) can be calculated using, for example, commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC. The unit time T (x) can be appropriately set depending on the required simulation accuracy.

Next, in the pretreatment step S3 of the present embodiment, the tire model 21 after the load is calculated (step S33). In step S33, as shown in FIG. 1, the load load condition L, the camber angle (not shown) and the friction coefficient input to the boundary condition input unit 5D are read into the working memory 4C. Further, in step S33, the load load calculation unit 6D is read into the working memory 4C. Then, the load load calculation unit 6D is executed by the calculation unit 4A.

In step S33, first, as shown in FIG. 4, the contact between the tire model 21 after the internal pressure filling and the road surface model 25 is calculated. Next, in step S33, the deformation of the tire model 21 is calculated based on the load-bearing condition L, the camber angle (not shown), and the friction coefficient. As a result, in step S33, the tire model 21 after the load applied to the road surface model 25 is calculated.

Next, in the pretreatment step S3 of the present embodiment, the rolling tire model 21 is calculated (step S34). In step S34, first, as shown in FIG. 1, the angular velocity V1 and the translational velocity V2 input to the boundary condition input unit 5D are read into the working memory 4C. Further, in step S34, the rolling calculation unit 6E is read into the working memory 4C. Then, the rolling calculation unit 6E is executed by the calculation unit 4A.

In step S34, first, as shown in FIG. 4, the angular velocity V1 is set in the tire model 21. Further, a translational speed V2 is set in the road surface model 25. This makes it possible to calculate the tire model 21 rolling on the road surface model 25.

As the rolling conditions of the tire model 21, for example, free rolling, braking, driving, turning, and the like can be appropriately set according to the running state of the tire 11 (shown in FIG. 2). These rolling conditions can be easily set by appropriately defining the angular velocity V1 and the slip angle (not shown) in the tire model 21. In addition, the front-rear force and the lateral force may be appropriately defined in the tire model 21 for setting the rolling conditions.

Next, in the simulation method of the present embodiment, the computer 1 (shown in FIG. 1) calculates the physical quantity associated with the wear of the tread contact patch 20 (shown in FIG. 2) (first step S4). In the first step S4, among the nodes 31 of the tire model 21 shown in FIGS. 5 and 6, a plurality of tread nodes 35 constituting the tread contact patch 33 of the tire model 21 are associated with wear of the tread contact patch 20. The physical quantity (hereinafter, may be simply referred to as "physical quantity") is calculated.

In the first step S4 of the present embodiment, first, as shown in FIG. 1, the physical quantity calculation unit 6F is read into the working memory 4C. Then, the physical quantity calculation unit 6F is executed by the calculation unit 4A.

The physical quantity calculated in the first step S4 is the wear energy at each tread node 35 (shown in FIG. 6). In the first step S4 of the present embodiment, as shown in FIG. 4, the tire model 21 is rolled on the road surface model 25 (one rotation in this example), and each tread node 35 (shown in FIG. 6) is rotated. The wear energy E is calculated. In the first step S4, it is desirable that the wear energy E is calculated after the force acting on the tire model 21 is rolled to a steady state (stable state).

In the first step S4 of the present embodiment, at the tread node 35 (shown in FIG. 6) that touches the road surface model 25, the shear force P and the slip amount Q (not shown) are measured for each unit time T (x) of the simulation. It is calculated. Then, in the first step S4, the wear energy E at each tread node 35 is calculated based on the shear force P and the slip amount Q. Details of the calculation method of the shear force P, the slip amount Q, the wear energy E and the like are described in, for example, Japanese Patent Application Laid-Open No. 2019-91302. The wear energy E of each tread node 35 is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the simulation method of the present embodiment, the computer 1 determines the movement amount M for expressing the wear of each tread node 35 (second step S5). In the second step S5, first, as shown in FIG. 1, the wear energy E of each tread node 35 (shown in FIG. 6) input to the physical quantity input unit 5E is read into the working memory 4C. Further, in the second step S5, the movement amount determining unit 6G is read into the working memory 4C. Then, the movement amount determination unit 6G is executed by the calculation unit 4A. FIG. 8A is a diagram illustrating an example of a state before each tread node 35 moves. FIG. 8B is a diagram illustrating an example of a state after each tread node 35 has moved.

In the second step S5 of the present embodiment, the wear progress rate A (not shown) is determined based on the dispersion degree V (not shown) of the physical quantity of the tread node 35, as in the procedure of JP-A-2019-91302. Will be done. Then, by multiplying this wear progress rate A by the wear energy E, the movement amount M (shown in FIG. 8A) of each tread node 35 is determined. In the present embodiment, the movement amount M is treated as the wear amount (mm) of the actual tire 11 (shown in FIG. 2). The movement amount M of each tread node 35 is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the simulation method of the present embodiment, the computer 1 moves each tread node 35 based on the movement amount M of each tread node 35 (shown in FIG. 8A) (third step S6). In the third step S6, first, as shown in FIG. 1, the movement amount M of each tread node 35 input to the physical quantity input unit 5E is read into the working memory 4C. Further, in the third step S6, the moving unit 6H is read into the working memory 4C. Then, the moving unit 6H is executed by the arithmetic unit 4A.

The procedure for moving each tread node 35 is not particularly limited. In this embodiment, based on the description in JP-A-2019-91302, as shown in FIG. 8B, the tread node 35 and the inner node 36 located inside the tread node 35 in the radial direction of the tire are used. The tread node 35 is moved along the side 32 connecting the tires.

As shown in FIG. 8A, in the third step S6, the coordinate value 40 when the tread node 35 is moved from the tread node 35 to the inner node 36 by the amount of movement M is calculated. Then, as shown in FIG. 8B, the coordinate value 40 after movement (shown in FIG. 8A) is updated as the coordinate value of the tread node 35. As a result, in the third step S6, each tread node 35 can be moved based on the movement amount M (shown in FIG. 8A).

In the third step S6 of the present embodiment, as shown in FIG. 8B, when the distance L1 between the tread node 35 and the inner node 36 after movement is equal to or less than a predetermined threshold value, the tread node 35 Is removed and the inner node 36 is defined as the new tread node 35. Further, the node 31 located inside the new tread node 35 in the tire radial direction is defined as the new inner node 36. As a result, in the third step S6, the wear of the tread portion 22 can be further advanced. The threshold value of the distance L1 can be appropriately set according to, for example, the required simulation accuracy.

Next, in the third step S6, the tire model 21 after wear is constructed based on the tread node 35 after movement and the element F (i) including the newly set tread node 35. In the present embodiment, the side 32 of the element F (i) is reset based on the moved tread node 35 and the newly set tread node 35. As a result, in the third step S6, the tire model 21 after wear (shown in FIG. 8B) is set. The worn tire model 21 is input to the computer 1 (tire model input unit 5B) shown in FIG.

Next, in the simulation method of the present embodiment, the computer 1 updates the material properties based on the movement amount M (fourth step S7). In the fourth step S7, first, as shown in FIG. 1, the movement amount M (shown in FIG. 8A) of each tread node 35 input to the physical quantity input unit 5E is read into the working memory 4C. Is done. Further, in the fourth step S7, the worn tire model 21 (shown in FIG. 8B) input to the tire model input unit 5B and the material property updating unit 6J are read into the working memory 4C. Then, the material property updating unit 6J is executed by the calculation unit 4A. FIG. 9 is a flowchart showing an example of the processing procedure of the fourth step S7.

The material properties to be updated are not particularly limited. In this embodiment, the material properties to be updated include a complex modulus E * and a loss tangent tan δ.

In the fourth step S7 of the present embodiment, first, at least one of the mileage and the traveling period of the tire 11 (shown in FIG. 2) is based on the movement amount M (shown in FIG. 8A) of each tread node 35. Is calculated (first calculation step S21). In the present embodiment, the mileage and the traveling period are set until the shape of the tire 11 before wear shown in FIG. 2 becomes the shape of the tire model 21 worn at the present time (for example, shown in FIG. 8 (b)). , The distance or period during which the tire 11 is estimated to have traveled. In the first calculation step S21 of this embodiment, the mileage is calculated. FIG. 10 is a flowchart showing an example of the processing procedure of the first calculation step S21.

In the first calculation step S21 of the present embodiment, first, the wear rate that defines the amount of wear per unit mileage of the tire 11 is input to the computer 1 (step S41). The wear rate can be set as appropriate. In step S41 of the present embodiment, first, the vehicle equipped with the tire 11 (shown in FIG. 2) is driven for a predetermined mileage (km), and then the amount of wear (mm) from the time of new product is reduced. Be measured. Then, as shown in the following formula, the wear amount (mm) is divided by the mileage (km), so that the wear rate (mm / km) that defines the wear amount per unit mileage of the tire 11 is defined. ) Is required.
Wear rate (mm / km) = wear amount (mm) / mileage (km)

The amount of wear of the tire 11 can be appropriately measured. For example, the amount of wear is measured at a plurality of locations (for example, 3 to 10 locations) in the tire circumferential direction of the center land portion 19A (shown in FIG. 2), and the average value of the wear amounts is obtained to obtain the tire. The amount of wear of 11 can be obtained. The amount of wear of the center land portion 19A can be easily obtained by, for example, reducing the groove depth of the center main groove 18A of the tire 11 after wear from the groove depth of the center main groove 18A of the tire 11 before wear. sell.

In the present embodiment, the wear rate is determined based on the measurement result of the wear amount of one tire 11, but the present embodiment is not limited to such an embodiment. For example, the wear rate may be determined based on the measurement result of the wear amount of a plurality of tires 11 (shown in FIG. 2) having the same configuration. In this case, after the wear rates of the plurality of tires 11 are obtained, the average value of the wear rates can be specified as the wear rate. As described above, since the wear rate is obtained from the measurement result of the wear amount of the plurality of tires 11, it is possible to consider the wear rate of the tire 11 which tends to vary depending on the actual running state of each tire 11. The wear rate is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the first calculation step S21 of the present embodiment, the mileage (km) of the tire 11 is obtained by dividing the movement amount (mm) by the wear rate (mm / km) as shown in the following formula. Is calculated (step S42).
Mileage (km) = amount of movement (mm) / wear rate (mm / km)

By the way, in the present embodiment, the movement amount M (shown in FIG. 8A) obtained in the second step S5 is calculated based on the wear energy when the tire model 21 makes one rotation. On the other hand, as described above, the mileage is such that the shape of the tire 11 before wear shown in FIG. 2 becomes the shape of the tire model 21 worn at the present time (for example, shown in FIG. 8B). It is the distance estimated that 11 has traveled. Therefore, the movement amount used for calculating the mileage is the total value of the movement amount M calculated up to the current worn tire model 21 for each tread node 35 of the tire model 21 before wear shown in FIG. (Hereinafter, it may be referred to as "total movement amount N") is adopted. When the initial tread node 35 is deleted, the total value of the movement amount M of the deleted tread node 35 and the movement amount M of the new tread node 35 is adopted as the total movement amount N. ..

Further, since the movement amount M (shown in FIG. 8A) determined in the second step S5 is obtained for each tread node 35, the total movement amount N (total movement amount M) of each tread node 35 is obtained. Value) is also different. For example, if these total movement amounts N are divided by the wear rate, a plurality of mileages will be calculated for one tire 11. Therefore, in step S42 of the present embodiment, one movement amount is determined based on the total movement amount N of each tread node 35 so that one mileage is calculated for one tire 11. To. This movement amount can be obtained, for example, by the average value, median value, minimum value, maximum value, or the like (in this example, the average value) of the total movement amount N of each tread node 35, and the actual tire 11 (FIG. It is treated as the amount of wear (representative wear amount) in (shown in 2). Further, the movement amount may be corrected in consideration of the temperature and the rainy weather rate.

In step S42, the amount of movement (in this example, the average value (mm) of the total amount of movement N of each tread node 35) is divided by the wear rate (mm / km) determined in step S41. As a result, in step S42, the tire 11 travels until the shape of the tire 11 before wear shown in FIG. 2 becomes the shape of the tire model 21 worn at the present time (for example, shown in FIG. 8B). The estimated distance (mileage) is calculated. The calculated mileage of the tire is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the fourth step S7 of the present embodiment, the material properties that have changed over time are calculated based on at least one of the mileage and the traveling period of the tire 11 (second calculation step S22). In the second calculation step S22 of the present embodiment, the material properties that have changed over time are calculated based on the mileage calculated in the first calculation step S21. FIG. 11 is a flowchart showing an example of the processing procedure of the second calculation step S22.

In the second calculation step S22 of the present embodiment, first, the material characteristic change rate of the tread rubber 12G of the tire 11 is input to the computer 1 (step S51). The material property change rate defines the relationship between the actual vehicle mileage of the tire and at least one of the actual vehicle mileage (in this example, the actual vehicle mileage) and the material characteristics. FIG. 12 is a graph showing an example of the rate of change in material properties. In FIG. 12, the rate of change of the complex elastic modulus E * is shown as a representative.

In step S51 of the present embodiment, first, a plurality of vehicles equipped with tires 11 (shown in FIG. 2) having the same configuration are driven so that the actual vehicle mileages are different from each other. Then, after each vehicle has traveled, the material properties of the tread rubber 12G shown in FIG. 2 (including the complex elastic modulus E * and the loss tangent tan δ in this example) are measured. Each tire 11 is mounted on the same type of vehicle under the same conditions (internal pressure, load, etc.).

The material properties (in this example, including the complex elastic modulus E * and the loss tangent tan δ) of the tread rubber 12G (shown in FIG. 2) of each tire 11 are measured based on the same measurement conditions. For the measurement of material properties, for example, a known viscoelasticity test device (not shown) is used in accordance with JIS-K6394. As the viscoelasticity test device of the present embodiment, a dynamic viscoelasticity measuring device "Iplexer 4000N" manufactured by Netchigabo Co., Ltd. is used. An example of the measurement conditions is as follows.
Initial distortion: 10%
Amplitude of dynamic strain: ± 1%
Frequency: 10Hz
Deformation mode: Tension measurement temperature: 70 ° C

Then, in step S51, the relationship between the actual vehicle mileage and the material properties (that is, the rate of change in material properties) is acquired for the tread rubber 12G (shown in FIG. 2) of each tire 11. In this embodiment, the material property property change rate including the complex elastic modulus E * and the loss tangent tan δ is obtained. In FIG. 12, the material property (complex elastic modulus E *) increases as the actual vehicle mileage increases. The material property property change rate is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the second calculation step S22 of the present embodiment, the material properties that have changed over time are calculated based on at least one of the mileage and the running period and the material property change rate (step S52). In step S52 of the present embodiment, among the material characteristic change rates shown in FIG. 12, the material characteristics (complex elastic modulus E in FIG. 12) are the same as the mileage calculated in the first calculation step S21. *) Is acquired. The acquired material properties (including the complex elastic modulus E * and the loss tangent tan δ in this example) are such that the shape of the tire 11 before wear (shown in FIG. 2) is the shape of the tire model 21 at the present time (shown in FIG. 2). For example, by the time it becomes (shown in FIG. 8 (b)), it is specified as a material property that has changed over time. The specified material properties are input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the second calculation step S22 of the present embodiment, the material properties of each element F (i) of the tire model 21 are updated (step S53). In step S53, the material properties of each element F (i) of the tread rubber model 22G of the current worn tire model 21 (including the complex elastic modulus E * and the loss tangent tan δ in this example) are calculated in step S52. Updated to material properties. The tire model 21 with updated material properties is input to the computer 1 (tire model input unit 5B) shown in FIG.

As described above, the simulation method (simulation apparatus 1A) of the present embodiment has material properties (in this example, the average value (mm) of the total movement amount N of each tread node 35) based on the movement amount M (in this example, the average value (mm) of the total movement amount N of each tread node 35). Then, the complex elastic modulus E * and the loss tangent tan δ can be updated). Therefore, in the simulation method (simulation device 1A) of the present embodiment, the updated material properties are used, so that the wear energy and the transfer amount M are increased in the first step S4 to the fourth step S7 to be carried out next. It can be calculated with accuracy. This makes it possible to accurately calculate the state of the tread contact patch 33 after wear in the present embodiment.

Next, in the simulation method of the present embodiment, the computer 1 determines whether or not the predetermined conditions are satisfied (step S8). In step S8 of the present embodiment, first, as shown in FIG. 1, the conditions for terminating the simulation stored in the condition input unit 5F are read into the working memory 4C. Further, in step S8, the determination unit 6K is read into the working memory 4C. Then, the determination unit 6K is executed by the calculation unit 4A.

The conditions can be appropriately set, for example, the calculation end time, the wear amount of the tread portion 22 shown in FIG. 8B (for example, the total movement amount N (not shown), and the like. The conditions of the present embodiment are input to the condition input unit 5F (shown in FIG. 1) before the simulation method is implemented.

If it is determined in step S8 that the condition is satisfied (“Y” in step S8), the next step S9 is carried out. On the other hand, if it is determined that the conditions are not met (“N” in step S8), the tire model 21 is redefined based on the worn tire model 21 and the updated material properties (step S1). ). Then, the computer 1 re-executes the steps S2 to S8 (including the first step S4 to the fourth step S7). As a result, in the present embodiment, the first step S4 to the fourth step S7 are repeatedly carried out until the above conditions are satisfied, so that the material properties are updated and the rolled tread contact patch 33 is worn. The state can be calculated in a pseudo manner. When the worn tire model 21 constructed in the third step S6 and whose material physical properties are updated in the fourth step S7 is used as it is, the first step S1 to the pretreatment step S3 are omitted. 1 step S4 to step S8 may be carried out repeatedly.

Next, in the simulation method of the present embodiment, the computer 1 evaluates whether or not the state of the tread contact patch 33 after wear is good (step S9). In step S9 of the present embodiment, as shown in FIG. 1, the worn tire model 21 (for example, shown in FIG. 8B) stored in the tire model input unit 5B is read into the working memory 4C. Will be. Further, in step S9, the determination unit 6K is read into the working memory 4C. Then, the determination unit 6K is executed by the calculation unit 4A.

The evaluation criteria for whether or not the condition after wear is good is based on, for example, the size of the wear amount of the tread portion 22 and the number of calculation steps (the number of progress steps of wear) until a predetermined wear amount is reached. It can be set as appropriate. In this embodiment, for example, based on the description in JP-A-2019-91302, for example, the magnitude of uneven wear (heel-and-toe wear) of the block model (not shown) formed on the land model 29 shown in FIG. Based on this, it is evaluated whether or not the condition after wear is good.

When it is determined in step S9 that the state of the tread contact patch 33 after wear is good (“Y” in step S9), based on the design drawing (CAD data) of the tire 11 shown in FIG. The tire 11 is manufactured (process S10). On the other hand, when it is determined in step S9 that the state of the tread contact patch 33 after wear is not good (“N” in step S9), the tire 11 (shown in FIG. 2) is redesigned (step S11). Steps S1 to S9 are carried out again. As a result, in the simulation method of the present embodiment (simulation device 1A (shown in FIG. 1)), the material properties that change over time can be taken into consideration, so that the state of the tread contact patch 20 shown in FIG. 2 after wear can be changed. A good tire 11 can be reliably designed.

The tire model 21 for which the state of the tread ground contact surface 33 after wear has been calculated can be calculated for rolling resistance, the shape of the ground contact surface, braking performance, and drainage performance by, for example, grounding or rolling on the road surface model 25. Etc. may be used for evaluation. By designing (improving) the tire 11 based on these results, it becomes possible to manufacture the tire 11 that can maintain good performance for a long period of time from the time of new product.

In the previous embodiments, in the first calculation step S21 shown in FIG. 10, the movement amount (in this example, in this example, the average value of the total movement amount N of each tread node 35) is divided by the wear rate. By doing so, the mileage of the tire was calculated, but not limited to such an aspect. For example, the mileage (km) may be calculated by multiplying the total number of rotations (times) of the tire 11 by the peripheral length (mm) of the tire model 21. FIG. 13 is a flowchart showing an example of the processing procedure of the first calculation step S21 according to another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiments are designated by the same reference numerals, and the description thereof may be omitted.

In the first calculation step S21 of this embodiment, the total number of rotations of the tire 11 is calculated based on the amount of movement of each tread node 35 (rotation speed calculation step S43). FIG. 14 is a flowchart showing an example of the processing procedure of the rotation speed calculation step S43.

In the rotation speed calculation step S43 of this embodiment, first, for the tread rubber 12G of the tire 11 shown in FIG. 2, the unit wear progress rate (mm / (J / m ² )) that defines the amount of wear per unit wear energy. Is input to the computer 1 (step S61). The unit wear progress rate can be obtained as appropriate. In the step S61 of the present embodiment, the wear amount and the wear energy of the tread rubber 12G of the tire 11 that has been rolled a predetermined distance are measured by using a known wear tester. Then, as shown in the following equation, the wear amount (mm) of the tread rubber 12G ^{is divided by the wear energy (J / m 2} ), so that the unit wear progress rate (mm / (J / m ² )). ) Is required. The unit wear progress rate is input to the computer 1 (physical quantity input unit 5E).
Unit wear progress rate = wear amount / wear energy

Next, in the rotation speed calculation step S43 of this embodiment, the wear energy progress rate ((J / m ² ) / time) that defines the wear energy for one rotation of the tire is input to the computer 1 (step S62). .. The wear energy progress rate can be obtained as appropriate. In the present embodiment, the tire 11 is rotated at least once by using the above-mentioned wear energy measuring device, and the wear energy (that is, the wear energy progress rate) for one rotation is measured. The wear energy progress rate is input to the computer 1 (physical quantity input unit 5E).

Next, in the rotation speed calculation step S43 of this embodiment, as shown in the following formula, the movement amount (mm) is the unit wear progress rate (mm / (J / m ² )), and the wear energy progress rate. By dividing by ((J / m ² ) / times), the total number of rotations (times) of the tire is calculated (step S63).
Total rotation speed = movement amount / unit wear progress rate / wear energy progress rate

The amount of movement can be determined as appropriate. As the movement amount of this embodiment, the average value (mm) of the total movement amount N of each tread node 35 (shown in FIGS. 8A and 8B) is used as in the previous embodiments.

In step S63, first, as in the above equation, the movement amount (the average value (mm) of the total movement amount N of each tread node 35) is divided ^{by the unit wear progress rate (mm / (J / m 2)).} Will be done. As a result, in step S63, the total wear energy until the shape of the tire 11 before wear shown in FIG. 2 becomes the shape of the tire model 21 worn at the present time (for example, shown in FIG. 8B) is obtained. Will be. Then, as in the above equation, this total wear energy (J / m ² ) is divided by the wear energy progress rate ((J / m ² ) / times), so that the total number of rotations of the tire 11 (times). ) Is calculated. The total number of rotations is input to the computer 1 (physical quantity input unit 5E).

Next, in the first calculation step S21 of this embodiment, the mileage (km) is calculated by multiplying the total rotation speed (times) of the tire 11 and the peripheral length (km / turn) of the tire model 21. (Traveling distance calculation step S44). The perimeter is specified as the distance traveled when the tire model makes one revolution. Such a peripheral length tends to be small during driving, but large during braking, and is not constant. By obtaining the mileage based on such a peripheral length, it is possible to obtain the mileage in consideration of the rolling conditions of the tire 11 including driving and braking. FIG. 15 is a flowchart showing an example of the processing procedure of the mileage calculation step S44.

In the mileage calculation step S44 of this embodiment, first, as shown in FIG. 4, the circumference of the tire model 21 is calculated based on at least one of the rolling speed V3 and the angular velocity V1 of the tire model 21 ( Step S71). The rolling speed V3 (km / sec) of the tire model 21 is defined as the distance traveled per unit time (second). In this embodiment, as shown in the following equation, the rolling speed V3 (km / sec) is divided by the angular velocity V1 (rad / sec) of the tire model 21 and further multiplied by 2π (rad / sec). Can calculate the circumference (km / time) of the tire model.
Tire model circumference = rolling speed V3 / angular velocity V1 x 2π

In step S71, the circumference may be calculated based on at least one of the most frequent rolling speed and angular velocity while the tire 11 is running. As a result, in step S71, among the rolling speeds V3 and the angular velocities V1 that change from moment to moment, the rolling speeds V3 and the angular velocities V1 that are the most frequent are used, so that the mileage can be calculated accurately. Further, in the simulation method of this embodiment, when the state after the wear of the drive wheels is calculated, the frequencies of the rolling speed V3 and the angular velocity V1 when the driving force is generated are the highest. When the driving force is generated, air resistance and rolling resistance also act on the vehicle (not shown) on which the tire 11 shown in FIG. 2 is mounted. Therefore, by using such rolling speed V3 and angular velocity V1, the circumference (km / time) of the tire when the driving force on which the air resistance and the rolling resistance act is generated can be calculated accurately.

Next, in the mileage calculation step S44 of this embodiment, as shown in the following formula, the total number of rotations of the tire obtained in the rotation speed calculation step S43 and the peripheral length of the tire model 21 obtained in the step S71 are obtained. Multiplied to calculate the mileage of the tire 11 (step S72).
Mileage (km) = total number of revolutions (times) x tire model circumference (km / times)

As a result, in the mileage calculation step S44, the mileage until the shape of the tire 11 before wear shown in FIG. 2 becomes the shape of the tire model 21 currently worn (for example, shown in FIG. 8B). Is calculated. The calculated mileage of the tire is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Then, in the second calculation step S22 (shown in FIG. 11) of this embodiment, in the step S52, among the material property characteristic change rates shown in FIG. 12, the mileage calculated in the step S72 (shown in FIG. 15) is used. The material properties (complex elastic modulus E *) at the matching actual vehicle mileage are acquired. Since the mileage of this embodiment is calculated based on the most frequent rolling speed V3 and angular velocity V1 among the rolling speed V3 and the angular velocity V1 (shown in FIG. 4) that change from moment to moment, the material characteristics. Can be calculated accurately.

In the second calculation step S22 of the previous embodiments, the material properties that have changed over time were calculated based on the mileage calculated in the first calculation step S21 (shown in FIG. 9). Not limited. For example, in the second calculation step S22 (shown in FIG. 9), the material properties that have changed over time may be calculated based on the traveling period calculated in the first calculation step S21. FIG. 16 is a flowchart showing an example of the processing procedure of the first calculation step S21 according to still another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiments are designated by the same reference numerals, and the description thereof may be omitted.

In the first calculation step S21 of this embodiment, the actual vehicle distance ratio (km / year) that defines the mileage per unit period of the tire 11 is input to the computer 1 (step S45). The step S45 of this embodiment is carried out after the above-mentioned steps S41 and S42.

The actual vehicle distance ratio can be set as appropriate. In the step S45 of the present embodiment, first, the mileage (km) when the vehicle (not shown) equipped with the tire 11 (shown in FIG. 2) is run for a predetermined running period (year) is measured. Will be done. Then, as shown in the following formula, the mileage (km) is divided by the mileage (year) to obtain the actual vehicle distance ratio (km / year) that defines the mileage per unit period of the tire 11. Desired.
Actual vehicle distance rate = mileage / running period

In this embodiment, the actual vehicle distance ratio is obtained based on the mileage of one vehicle (not shown), but the present invention is not limited to such an embodiment. For example, the actual vehicle distance ratio may be obtained based on the mileage of a plurality of vehicles. In this case, after the actual vehicle distance ratios of a plurality of vehicles are obtained, the average value of those actual vehicle distance ratios can be specified as the actual vehicle distance ratio. The actual vehicle distance ratio is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the first calculation step S21 of this embodiment, the running period of the tire 11 (shown in FIG. 2) is calculated based on the mileage (km) calculated in the step S42 (step S46). In the process S46, as shown in the following formula, the mileage (km) calculated in the process S42 is divided by the actual vehicle distance ratio (km / year) obtained in the process S45 to obtain the tire 11. The travel period is calculated. The traveling period is input to the computer 1 (physical quantity input unit 5E) shown in FIG.
Travel period (year) = mileage (km) / actual vehicle distance rate (km / year)

FIG. 17 is a flowchart showing an example of the processing procedure of the second calculation step S22 of this embodiment. In the second calculation step S22 of this embodiment, the material change rate defining the relationship between the actual vehicle traveling period of the tire 11 and the material properties is input to the computer 1 (step S54). FIG. 18 is a graph showing an example of the rate of change in material properties according to another embodiment of the present invention. In FIG. 18, the rate of change of the complex elastic modulus E * is shown as a representative.

In step S54 of this embodiment, first, a plurality of vehicles equipped with tires 11 (shown in FIG. 2) having the same configuration are driven so that the traveling periods are different from each other. Then, the material properties of the tread rubber 12G shown in FIG. 2 (including the complex elastic modulus E * and the loss tangent tan δ in this example) are measured, respectively. Each tire 11 is mounted on the same type of vehicle under the same conditions (internal pressure, load, etc.).

The measurement of material properties can be carried out in the same procedure as in previous embodiments. Then, in step S54, the relationship between the actual vehicle traveling period and the material properties (that is, the rate of change in material properties) is acquired for these tread rubbers 12G. In this embodiment, the material property property change rate including the complex elastic modulus E * and the loss tangent tan δ is obtained. In FIG. 18, the material property (complex elastic modulus E *) becomes larger as the actual vehicle traveling period becomes longer. The material property property change rate is input to the computer 1 (physical quantity input unit 5E) shown in FIG.

Next, in the second calculation step S22 of this embodiment, among the material characteristic change rates shown in FIG. 18, the material characteristics in the actual vehicle traveling period that coincides with the traveling period calculated in the step S46 (shown in FIG. 16). (In FIG. 18, the complex elastic modulus E *) is calculated (step S55). This acquired material property is specified as a material property that has changed over time from the time of new product. The specified material properties are input to the computer 1 (physical quantity input unit 5E) shown in FIG. Then, in step S53, the material properties specified in step S55 are updated as the material properties of each element F (i) of the tread rubber model 22G of the tire model 21.

As described above, in this embodiment, even if the material change rate (relationship with the actual vehicle mileage) shown in FIG. 12 is not obtained, the material change rate (relationship with the actual vehicle travel period) shown in FIG. 18 is determined. By using the specified), the material properties that have changed over time can be obtained from the calculated running period.

In the embodiments so far, the material properties of each element F (i) of the tread rubber model 22G shown in FIG. 8 (b) have been updated, but the present invention is not limited to such an embodiment. For example, the material properties of each element F (i) such as another rubber model 21G such as the sidewall rubber model 23G, the carcass ply model 41, and the belt ply models 41A and 41B may be updated. In this case, for each component of the tire 11 whose material properties are updated (shown in FIG. 2), for example, the rate of change in material properties as shown in FIGS. 12 and 18 is obtained.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

Based on the processing procedure shown in FIG. 3, the state after wear of the tread contact patch of the tire was calculated (Example 1 and Example 2). In Examples 1 and 2, the material properties of the elements of the tire model were updated from the amount of movement of the tread nodes based on the processing procedures shown in FIGS. 9 to 11. Then, in Example 1 and Example 2, the first step to the fourth step were repeatedly carried out until the predetermined conditions were satisfied.

FIG. 19 is a graph showing the relationship between the actual vehicle mileage and the material properties. As shown in FIG. 19, in the tire model of Example 1, a tread rubber having a smaller rate of change in material properties than that of the tire model of Example 2 was defined.

For comparison, the state of the tread contact patch of the tire after wear was calculated based on the description in JP-A-2019-91302 (comparative example). In the comparative example, similarly to Example 1 and Example 2, the first step to the fourth step were repeatedly carried out until the predetermined conditions were satisfied. Further, in the comparative example, as shown in FIG. 19, the state of the tread ground contact surface after wear was calculated without considering the change with time of the material property (that is, the rate of change of the material property is zero). The common specifications are as follows.
Tire size: 215 / 55R17
Rim size: 17 x 7J
Internal pressure: 230kPa
Load: 3.51kN

FIG. 20 is a graph showing the relationship between the amount of wear and the mileage. As shown in FIG. 20, in Examples 1 and 2, the state of early wear was calculated as compared with the comparative example in which the change with time of the material physical properties was not taken into consideration. Such a state after wear of Example 1 and Example 2 shows the same tendency as that of an actual tire. Therefore, in Examples 1 and 2, the state after wear of the tread contact patch of the tire could be calculated more accurately than in Comparative Example.

As shown in FIG. 19, since the tire model of the first embodiment defines the tread rubber having a smaller rate of change in material properties as compared with the tire model of the second embodiment, as shown in FIG. In Example 1, the amount of wear with respect to the mileage could be calculated smaller than that in Example 2. As described above, in the first and second embodiments, the difference in the material physical properties of the tread rubber with time can be appropriately taken into consideration, so that the state after the wear of the tread contact patch of the tire can be calculated accurately. Was done.

S4 1st process S5 2nd process S6 3rd process S7 4th process

Claims (11)

A tire simulation method for calculating the state of the tread contact patch of a tire after wear.
A tire model in which the tire is discretized is input to a computer using a finite number of elements having a plurality of nodes and having predetermined material properties defined.
The computer
A first step of calculating the physical quantity associated with the wear of the tread contact patch for a plurality of tread nodes constituting the tread contact patch of the tire model among the nodes.
A second step of determining the amount of movement for expressing the wear of each tread node based on the physical quantity, and
A third step of moving each tread node based on the amount of movement, and
A fourth step of updating the material properties based on the amount of movement is performed.
Tire simulation method. The tire simulation method according to claim 1, wherein the computer repeatedly carries out the first step to the fourth step until a predetermined condition is satisfied. The fourth step includes a first calculation step of calculating at least one of the mileage and the running period of the tire based on the movement amount.
The tire simulation method according to claim 1 or 2, comprising a second calculation step of calculating the material properties that have changed over time based on at least one of the mileage and the mileage. The first calculation step includes a step of inputting into the computer a wear rate that defines the amount of wear per unit mileage of the tire.
The tire simulation method according to claim 3, further comprising a step of calculating the mileage by dividing the movement amount by the wear rate. The first calculation step includes a step of calculating the total number of revolutions of the tire based on the amount of movement.
The tire simulation method according to claim 3, further comprising a step of calculating the mileage by multiplying the total rotation speed of the tire by the peripheral length of the tire model. The steps of calculating the total number of rotations of the tire include a step of inputting a unit wear progress rate, which defines the amount of wear per unit wear energy, into the computer for the tread rubber of the tire.
The process of inputting the wear energy progress rate, which defines the wear energy for one rotation of the tire, into the computer, and
The tire simulation method according to claim 5, wherein the total rotation speed of the tire is calculated by dividing the movement amount by the unit wear progress rate and the wear energy progress rate. The tire simulation method according to claim 5 or 6, wherein the step of calculating the mileage includes a step of calculating the circumference based on at least one of a rolling speed and an angular velocity of the tire model. The tire simulation method according to claim 7, wherein the step of calculating the perimeter is to calculate the perimeter based on at least one of the rolling speed and the angular velocity, which are the most frequent during the running of the tire. .. The first calculation step includes a step of inputting an actual vehicle distance rate that defines a mileage per unit period of the tire into the computer.
The tire simulation method according to claim 3, further comprising a step of calculating the traveling period by dividing the traveling distance by the actual vehicle distance ratio. The second calculation step is a step of inputting to the computer a material property change rate that defines the relationship between at least one of the actual vehicle mileage and the actual vehicle travel period of the tire and the material property of the tread rubber of the tire. When,
The tire simulation method according to any one of claims 3 to 9, further comprising a step of calculating the material characteristics that have changed over time based on at least one of the mileage and the traveling period and the material property change rate. .. It is a simulation device having an arithmetic processing unit that calculates the state after wear of the tread contact patch of a tire.
The arithmetic processing unit has a tire model acquisition unit that acquires a tire model in which the tire is discretized by using a finite number of elements having a plurality of nodes and having predetermined material properties defined.
A physical quantity calculation unit that calculates the physical quantity associated with the wear of the tread contact patch for a plurality of tread nodes constituting the tread contact patch of the tire model among the nodes.
A movement amount determining unit that determines a movement amount for expressing wear of each tread node based on the physical quantity, and a movement amount determining unit.
A moving portion that moves each tread node based on the amount of movement,
A material property updating unit that updates the material property based on the movement amount is included.
Tire simulation device.

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