JP7077759B2 - Tire simulation method - Google Patents

Description

The present invention relates to a simulation method for calculating a wear state of a tread portion of a tire.

The following Patent Document 1 proposes a simulation method for calculating the wear state of the tread portion of a tire by using a tire model in which the tire is discretized by a finite number of elements. In the simulation method of Patent Document 1 below, the first node constituting the tread contact patch of the tire model is moved to the second node side located inside the tire radial direction of the first node, based on a single rule. , The computer is moving the first node to the second node side. As a result, in the simulation method of Patent Document 1 below, the wear state of the tread portion is calculated.

Japanese Unexamined Patent Publication No. 2017-033076

Since each element constituting the tread portion of the tire model is formed by discretizing the shape of the tread portion of the tire, each element may have a complicated shape. Therefore, the second node may not exist inside the first node in the tire radial direction. In such a case, with the single rule as described above, there is a problem that the computer cannot find the destination of the first node and cannot move the first node. Therefore, in the simulation method of Patent Document 1, even if the calculation of the wear state is interrupted or the calculation can be continued, the calculated wear state of the tread portion deviates from the actual wear state of the tread portion. Therefore, there was room for further improvement in the stable calculation of the wear state.

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

The present invention is a simulation method for calculating the wear state of the tread portion of a tire using a computer, and is a tire model in which the tire is modeled by using a finite number of elements having a plurality of nodes. The process of inputting to the computer and the computer move the first node constituting the outer surface of the tread portion of the tire model among the nodes inward in the tire radial direction to calculate the wear state of the tread portion. The wear calculation step includes a first step of searching for a destination of the first node based on a predetermined first rule, and the first rule in the first step. When the destination of the first node corresponding to the above is not found, the second step of searching for the destination of the first node and the first node based on the second rule different from the first rule are performed. , The step of moving to the searched destination, and the like.

In the tire simulation method according to the present invention, the element includes a side connecting the adjacent nodes, and the node is a plurality of adjacent nodes which are adjacent nodes via the first node and the side. The first rule and the second rule include one said adjacent node that meets predetermined conditions, or a position on one side connecting the adjacent node and the first node. , The destination may be determined.

In the tire simulation method according to the present invention, the condition may be that the adjacent nodes do not form the outer surface of the tread portion.

In the tire simulation method according to the present invention, the condition may be that the adjacent nodes form the outer surface of the tread portion.

In the tire simulation method according to the present invention, the condition may be that the adjacent node of the outer surface of the tread portion constitutes an outer surface that does not touch the road surface.

In the tire simulation method according to the present invention, the condition may be such that the adjacent node is located on the innermost side in the tire radial direction.

In the tire simulation method according to the present invention, the condition is that the adjacent node has the side connecting the adjacent node and the first node, and a straight line extending inward in the radial direction of the tire from the first node. The angle formed may be the minimum.

In the tire simulation method according to the present invention, the condition is that the adjacent node constitutes the side connecting the adjacent node and the first node, the outer surface of the tread portion, and the first node. The angle formed by averaging the normal directions of the plurality of the sides connected to the tire may be the minimum.

In the tire simulation method of the present invention, the computer moves the first node constituting the outer surface of the tread portion of the tire model among the nodes of the tire model inward in the tire radial direction to determine the wear state of the tread portion. Includes a wear calculation step to calculate.

The wear calculation step includes a first step of searching for a destination of the first node based on a predetermined first rule, and the first step of the first node conforming to the first rule in the first step. When the move destination cannot be found, the second step of searching for the move destination of the first node and the first node to the searched move destination based on the second rule different from the first rule. It includes the process of moving.

In the present invention, even if the destination of the first node cannot be found based on the first rule, the destination of the first node can be searched based on the second rule. Therefore, in the present invention, since the first node can be reliably moved inward in the radial direction of the tire, the wear state of the tread portion can be stably calculated.

It is a perspective view which shows an example of the computer for executing 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 flowchart which shows an example of the processing procedure of a preprocessing process. (A) is a diagram for explaining the state before the first node moves, and (b) is a diagram for explaining the state after the first node moves. It is a flowchart which shows an example of the processing procedure of a wear calculation process. (A) shows an example of the first node whose destination is determined based on the first rule, and (b) shows an example of the first node whose destination is determined based on the second rule. It is a figure. It is a figure which shows an example of the 1st node which the moving destination is determined based on the 2nd rule of another Embodiment of this invention. (A) is a diagram showing an example of a first node in which a destination cannot be found based on the first rule, and (b) is a diagram showing an example of a first node in which a destination is determined based on the second rule. Is. It is a figure which shows the 1st node which the moving destination was decided based on the 2nd rule of another embodiment of this invention. It is a figure which shows the 1st node which the moving destination was decided based on the 2nd rule of still another Embodiment of this invention. It is a perspective view which shows the 1st node which the moving destination was decided based on the 2nd rule of still another Embodiment of this invention.

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 wear state of the tread portion of the tire is calculated using a computer.

FIG. 1 is a perspective view showing an example of a computer for executing the simulation method of the present embodiment. The computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with, for example, an arithmetic processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1 and 1a2. Software or the like for executing the simulation method of the present embodiment is stored in the storage device in advance. Therefore, the computer 1 is configured as a simulation device for calculating the wear state of the tread portion of the tire.

FIG. 2 is a cross-sectional view showing an example of a tire in which a wear state of a tread portion is predicted by the simulation method of the present embodiment. The tire 2 of the present embodiment has a carcass 6 extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and a belt layer arranged outside the tire radial direction of the carcass 6 and inside the tread portion 2a. It has 7 tires.

The tread portion 2a is provided with a main groove 9 that extends continuously in the tire circumferential direction. As a result, the tread portion 2a is provided with a plurality of land portions 10 divided by the main groove 9. Further, each land portion 10 is provided with a lateral groove (not shown) extending in the tire axial direction between the main grooves 9 and 9 or between the main groove 9 and the tread ground contact end 2t.

In the present specification, the "tread ground contact end 2t" means that a tire 2 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 contact patch in the tire axial direction.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If so, 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 is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS". The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", "INFLATION PRESSURE" for ETRTO, but 180 kPa if the tires are for passenger cars.

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

The carcass 6 is composed of at least one carcass ply 6A, or one carcass ply 6A in the present embodiment. The carcass ply 6A is connected to the main body portion 6a from the tread portion 2a to the bead core 5 of the bead portion 2c via the sidewall portion 2b, and is connected to the main body portion 6a, and the circumference of the bead core 5 is folded back from the inside to the outside in the tire axial direction. It includes a folded portion 6b. A bead apex rubber 8 extending outward in the radial direction of the tire from the bead core 5 is arranged between the main body portion 6a and the folded portion 6b. Further, the carcass ply 6A has a carcass cord arranged at an angle of, for example, 75 to 90 degrees with respect to the tire equator C.

The belt layer 7 includes two inner and outer belt plies 7A and 7B in which belt cords are arranged at an angle of, for example, 10 to 35 degrees with respect to the tire circumferential direction. These belt plies 7A and 7B are superposed so that the belt cords intersect each other.

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, a tire model modeling the tire 2 is input to the computer 1 (process S1). FIG. 4 is a perspective view showing an example of the tire model 11 and the road surface model 21. FIG. 5 is a cross-sectional view showing an example of the tire model 11. In FIG. 4, the main groove model 12 (shown in FIG. 5), the lateral groove model (not shown), and the mesh (that is, the element F (i)) of the tire model 11 are omitted.

As shown in FIG. 5, in step S1, a finite number of elements F (i) (i = 1, 2, ...) That can be handled by the numerical analysis method based on the information about the tire 2 (shown in FIG. 2). It is discrete with. As a result, the tire model 11 in which the tire 2 is modeled is set. 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 the element F (i), for example, a tetrahedral solid element, a pentahedral solid element, a hexahedral solid element, or the like is preferably used. Each element F (i) has a plurality of nodes 15.

The element F (i) of the present embodiment is provided with a side 16 connecting adjacent nodes 15 and 15. The side 16 extends in a straight line. In each such element F (i), numerical data such as an element number, a node number 15, a coordinate value of the node 15, and a material property (for example, density, Young's modulus and / or attenuation coefficient, etc.) are defined.

The tread portion 11a of the tire model 11 includes a main groove model 12 in which the main groove 9 (shown in FIG. 2) is reproduced, a land portion model 13 in which the land portion 10 (shown in FIG. 2) is reproduced, and a lateral groove (shown in FIG. 2). A horizontal groove model (not shown) that reproduces the reproduction (not shown) is set. The main groove model 12 and the lateral groove model are provided with a groove bottom 12b and a groove wall 12s extending from the groove bottom 12b to the tread ground contact surface 11s. Although the lateral groove model is set for the tire model 11 of the present embodiment, it may be omitted.

The node 15 of the element F (i) includes the first node 17 constituting the outer surface 14 of the tread portion 11a of the tire model 11. The outer surface 14 includes a tread ground contact surface 11s that touches the road surface model 21 described later, and a tie bar 11b (shown in FIG. 9B) having a raised groove bottom. The outer surface 14 may include a buttress surface 11u, a groove bottom 12b, and a groove wall 12s extending inward in the tire radial direction from the tread ground contact end 11t. The tire model 11 is input to the computer 1.

Next, in the simulation method of the present embodiment, a road surface model 21 (shown in FIG. 4) that models a road surface (not shown) is input to the computer 1 (step S2).

In step S2, as shown in FIG. 4, a finite number of elements G (i) (i) that can be handled by the numerical analysis method (finite element method in this embodiment) based on the information on the road surface (not shown). = 1, 2, ...). As a result, the road surface model 21 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 22 and sides 23 connecting the nodes 22 and 22. Further, in the element G (i), numerical data such as an element number and a coordinate value of a node 22 is defined.

In the present embodiment, as the road surface model 21, a road surface model 21 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 21 is stored in the computer 1.

Next, in the simulation method of the present embodiment, the computer 1 (shown in FIG. 1) calculates the tire model 11 that rolls the road surface model 21 (pretreatment step S3). FIG. 6 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 11 on the road surface model 21 are defined (step S31). As the boundary conditions, for example, the internal pressure condition of the tire model 11, the load load condition L, the camber angle, the friction coefficient between the tire model 11 and the road surface model 21, and the like are set. Further, as the boundary conditions, an angular velocity V1 corresponding to the traveling speed V, a translational speed V2, and a turning angle (not shown) are set. The translational speed V2 is the speed at which the tire model 11 is in contact with the road surface model 21. These conditions are input to the computer 1 (shown in FIG. 1).

Next, in the pretreatment step S3 of the present embodiment, as shown in FIG. 5, the tire model 11 after the internal pressure filling is calculated (step S32). In step S32, first, the bead portions 11c and 11c of the tire model 11 are restrained by the rim model 27 in which the rim 26 (shown in FIG. 2) of the tire 2 is modeled. Further, the tire model 11 is deformed and calculated based on the evenly distributed load w corresponding to the internal pressure condition. As a result, the tire model 11 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 2 (shown in FIG. 2) is based.

In the deformation calculation of the tire model 11, 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 computer 1 applies the various conditions to create equations of motion, and calculates the deformation of the tire model 11 for each minute time (unit time T (x) (x = 0, 1, ...)). .. Such deformation calculation of the tire model 11 (including rolling calculation of the tire model 11 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 11 after the load is calculated (step S33). In step S33, as shown in FIG. 4, the contact between the tire model 11 after the internal pressure filling and the road surface model 21 is calculated. Next, in step S33, the deformation of the tire model 11 is calculated based on the load load condition L, the camber angle (not shown), and the friction coefficient. As a result, in step S33, the tire model 11 after the load applied to the road surface model 21 is calculated.

Next, in the pretreatment step S3 of the present embodiment, the tire model 11 that rolls the road surface model 21 is calculated (step S34). In step S34, first, as shown in FIG. 4, the angular velocity V1 is set in the tire model 11. Further, the translational speed V2 is set in the road surface model 21. As a result, in step S34, the tire model 11 rolling on the road surface model 21 can be calculated.

As the rolling conditions of the tire model 11, for example, free rolling, braking, driving, turning, and the like can be appropriately set according to the running state of the tire 2 (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 11.

Next, in the simulation method of the present embodiment, the computer 1 calculates the physical quantity associated with the wear of the outer surface 14 of the tread portion 11a (step S4). In step S4, among the nodes 15 of the tire model 11, the first node 17 (shown in FIG. 5) constituting the outer surface 14 of the tread portion 11a is referred to as a physical quantity associated with wear (hereinafter, simply referred to as “physical quantity”). There is.) Is calculated.

The physical quantity calculated in step S4 of the present embodiment is the wear energy at the first node 17. In step S4 of the present embodiment, as shown in FIG. 4, the wear energy E of the first node 17 (shown in FIG. 5) is calculated based on the tire 2 rolling on the road surface model 21.

In step S4, in order to calculate the wear energy E of the first node 17 (shown in FIG. 5), the shear force P and the slip amount Q are measured at the first node 17 (shown in FIG. 5) which is in contact with the road surface model 21. It is calculated. The shearing force P includes a shearing force Px in the tire axial direction x and a shearing force Py in the tire circumferential direction y. The slip amount Q includes a slip amount Qx in the tire axial direction x corresponding to the shear force Px and a slip amount Qy in the tire circumferential direction y corresponding to the shear force Py. The shear forces Px and Py and the slip amounts Qx and Qy of each of these first nodes 17 are calculated for each unit time T (x) of the simulation.

Then, the shear forces Px (i) and Py (i) of each first node 17 are multiplied by the slip amounts Qx (i) and Qy (i) corresponding to the shear forces Px (i) and Py (i). Then, the multiplied value is integrated from the grounding entry to the grounding exit of each first node 17. As a result, the wear energy E at each first node 17 is calculated. The wear energy E of each first node 17 is stored in the computer 1.

Next, in the simulation method of the present embodiment, the computer 1 calculates the wear state of the tread portion 11a (wear calculation step S5). In the wear calculation step S5 of the present embodiment, the first node 17 of the nodes 15 of the tire model 11 is moved inward in the tire radial direction to calculate the wear state of the tread portion 11a. 7A and 7B relate to the wear calculation process of the present embodiment, FIG. 7A is a diagram for explaining a state before the first node 17 is moved, and FIG. 7B is a diagram for explaining a state after the first node 17 is moved. It is a figure to do. Note that FIG. 7 (b) shows the state after moving all the first nodes 17 including the first node 17 shown in (a).

In the wear calculation step S5 of the present embodiment, the moving destination (hereinafter, may be simply referred to as “moving destination”) 20 of the first node 17 is searched for based on the predetermined first rule or the second rule. Ru. The first rule and the second rule of the present embodiment include a plurality of adjacent nodes 18 that are adjacent to each other via the first node 17 and the side 16, and one adjacent node 18 that meets a predetermined condition. , The position on one side 16 connecting the first node 17 is determined as the movement destination 20. The details of the first rule and the second rule will be described later. Further, the adjacent node 18 includes the first node 17 and another node 17 adjacent to the first node 17. FIG. 8 is a flowchart showing an example of the processing procedure of the wear calculation step S5.

In the wear calculation step S5 of the present embodiment, first, the movement amount M of each first node 17 is calculated based on the wear energy (physical quantity associated with wear) E of each first node 17 (step S51). .. The movement amount M of the present embodiment is defined as the movement amount along the side 16 connecting the first node 17 and the adjacent node 18.

The movement amount M of each first node 17 is calculated by multiplying the wear energy E of the first node 17 by the wear coefficient K. The wear coefficient K is a coefficient indicating the amount of wear per unit wear energy of the tread rubber 2 g of the tire 2 shown in FIG. The wear coefficient K is set in advance based on, for example, an actual vehicle test using the tire 2. Therefore, the movement amount M can be calculated as the amount of wear at each position of the tread portion 2a (shown in FIG. 2) of the tire 2 corresponding to the first node 17. The movement amount M is stored in the computer 1.

Next, in the wear calculation step S5 of the present embodiment, the destination 20 of the first node 17 is searched for based on the first rule (first step S52). As described above, the first rule determines the position on one side 16 connecting one adjacent node 18 and the first node 17 that meet the predetermined conditions as the destination 20. be. The conditions of the first rule can be set as appropriate. The condition of the first rule of the present embodiment is that the adjacent node 18 does not form the outer surface 14 of the tread portion 11a. FIG. 9A is a diagram showing an example of the first node 17 whose destination is determined based on the first rule. FIG. 9B is a diagram showing an example of the first node 17 in which the destination 20 is determined based on the second rule.

At the first node 17 shown in FIG. 9A, there are three adjacent nodes 18 adjacent to the first node 17 via the side 16. Of these adjacent nodes 18, only one adjacent node 18 that meets the conditions of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed) exists. In such a case, in the first step S52, the destination of the first node 17 is moved to a position on one side 16 connecting the one adjacent node 18 and the first node 17 that meet the conditions of the first rule. 20 is determined.

In the first step S52 of the present embodiment, the movement amount M calculated from the wear energy E of the first node 17 is separated from the first node 17 to the adjacent node 18 side along one determined side 16. The position is determined as the destination 20 of the first node 17. By moving the first node 17 to such a destination 20, the first node 17 can be moved inward in the radial direction of the tire, so that the wear state of the tread portion 11a can be calculated. The determined destination 20 is stored in the computer 1.

On the other hand, at the first node 17 shown in FIG. 9B, there are two adjacent nodes 18 adjacent to each other via the first node 17 and the side 16. As described above, the outer surface 14 of the tire model 11 includes the tread contact patch 11s and the tie bar 11b. Therefore, among these adjacent nodes 18, none of the adjacent nodes 18 that meet the conditions of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed) exists. Therefore, in the first step S52, it is not possible to find the destination 20 of the first node 17 that conforms to the first rule. In such a case, in the wear calculation step S5 of the present embodiment, the destination 20 of the first node 17 is searched for in the second step S54 described later.

Next, in the wear calculation step S5 of the present embodiment, it is determined in the first step S52 whether or not the destination 20 of the first node 17 conforming to the first rule is found (step S53). When it is determined in the first step S52 that the destination 20 of the first node 17 is found (“Y” in step S53), the next step S55 is carried out. On the other hand, when it is determined in the first step S52 that the destination 20 of the first node cannot be found (“N” in the step S53), the next second step S54 is carried out.

Next, in the wear calculation step S5 of the present embodiment, the destination 20 of the first node 17 is searched for based on the second rule different from the first rule (second step S54). Similar to the first rule, the second rule of the present embodiment moves the position on one side 16 connecting one adjacent node 18 and the first node 17 that meet the predetermined conditions to the destination. It is decided as 20.

The condition of the second rule of the present embodiment is that the adjacent node 18 is located on the innermost side in the radial direction of the tire. Such a condition also includes the adjacent node 18 that does not satisfy the condition of the first rule of the present embodiment (the adjacent node 18 does not form the outer surface 14 of the tread portion 11a). Therefore, the second rule can more reliably search for the destination 20 of the first node 17 as compared with the first rule.

As shown in FIG. 9B, the first node 17 has two adjacent nodes 18 adjacent to each other via the first node 17 and the side 16 (in this example, one adjacent node 18a and the other). Adjacent node 18b). Of these two adjacent nodes 18a and 18b, there is only one adjacent node 18 that meets the conditions of the second rule (that is, it is located on the innermost side in the radial direction of the tire) (this example). Then, the other adjacent node 18b). In such a case, in the second step S54, one side connecting one adjacent node 18 (in this example, the other adjacent node 18b) and the first node 17 that meet the conditions of the second rule (this example). Then, the destination 20 of the first node 17 is determined at a position above the other side 16b).

In the second step S54 of the present embodiment, the first node 17 to the adjacent node 18 (in this example, the other adjacent node 18b) along one determined side 16 (in this example, the other side 16b). The position separated from the movement amount M calculated from the wear energy E of the first node 17 on the side is determined as the movement destination 20 of the first node 17. By moving the first node 17 to such a destination 20, the first node 17 can be moved inward in the radial direction of the tire. The determined destination 20 is stored in the computer 1.

Next, in the wear calculation step S5 of the present embodiment, the first node 17 is moved to the searched destination 20 (step S55). As shown in FIG. 7A, the moving destination 20 is located inside the first node 17 in the tire radial direction. By moving the first node 17 to such a destination 20, the wear state of the tread portion 11a can be calculated as shown in FIG. 7 (b). The moved first node 17 is stored in the computer 1.

In step S55, as shown in FIG. 7B, when the distance L1 between the first node 17 and the adjacent node 18 after movement is equal to or less than a predetermined threshold value, the first node 17 is deleted. , Adjacent node 18 is defined as the new first node 17. As a result, in the wear calculation step S5, the wear of the tread portion 11a can be further advanced. The threshold value of the distance L1 can be appropriately set according to, for example, the required simulation accuracy.

If the destination 20 cannot be determined in the second step S54, the first node 17 cannot be moved. In this case, the calculation of the wear state may be interrupted, and the process may be performed again from step S1 (shown in FIG. 3) for inputting the tire model.

Next, in the wear calculation step S5 of the present embodiment, it is determined whether or not all the first nodes 17 have moved to the destination 20 (step S56). When it is determined in step S56 that all the first nodes 17 have moved to the destination 20 (“Y” in step S56), the next step S6 (shown in FIG. 3) is carried out. On the other hand, when it is determined in step S56 that all the first nodes 17 have not moved to the destination 20 (“N” in step S56), another first node 17 is selected (step S58). Steps S51 to S56 are carried out again. As a result, in the wear calculation step S5, all the first nodes 17 can be moved to the searched destination 20. Therefore, in the wear calculation step S5 of the present embodiment, the wear state of the tread portion 11a can be calculated.

In the wear calculation step S5 of the present embodiment, even if the destination 20 of the first node 17 is not found based on the first rule, the destination 20 of the first node 17 is searched based on the second rule. Can be done. Therefore, in the simulation method of the present embodiment, since the first node 17 can be reliably moved inward in the radial direction of the tire, the wear state of the tread portion 11a can be stably calculated. Further, since the moving destination 20 is determined based on the moving amount M calculated as the actual wear amount of the tire 2, it is possible to obtain a calculation result that is closer to the actual wear shape of the tire 2.

Next, in the simulation method of the present embodiment, it is determined whether or not the predetermined end condition is satisfied (step S6). The end condition can be appropriately set, for example, the calculation end time, the amount of wear of the tread portion 11a, and the like. When it is determined in step S6 that the termination condition is satisfied (“Y” in step S6), the next step S7 is carried out. On the other hand, if it is determined in step S6 that the end condition is not satisfied (“N” in step S6), steps S4 to S6 are performed again based on the worn tire model 11. Thereby, in the simulation method of the present embodiment (simulation device 1A (shown in FIG. 1)), the wear state of the tread portion 11a that has been continuously rolled until the end condition is satisfied can be calculated in a pseudo manner.

Next, in the simulation method of the present embodiment, the computer 1 evaluates whether or not the wear state of the tread portion 11a is good (step S7). The evaluation criteria for whether or not the wear state is good is appropriately set based on, for example, the size of the wear amount of the tread portion 11a, the number of calculation steps (wear progress steps) until the predetermined wear amount is reached, and the like. be able to. In step S7 of the present embodiment, for example, based on the magnitude of uneven wear (heel-and-toe wear) of the block model (not shown) separated in the tire circumferential direction in the land model 13 (shown in FIG. 5). Whether the wear condition is good or not is evaluated.

In step S7 of the present embodiment, first, for the tire model 11 after wear, the difference (heel and toe wear) between the outer diameter on the first-come-first-served side and the outer diameter on the second-come-first-served side of the block model (not shown) is calculated. In step S7, when the difference between the outer diameter on the first-come-first-served side and the outer diameter on the second-come-first-served side is within a predetermined range, it is determined that the wear state is good.

When it is determined in step S7 that the wear state of the tread portion 11a is good (“Y” in step S7), the tire 2 is based on the design drawing (CAD data) of the tire 2 shown in FIG. Manufactured (step S8). On the other hand, when it is determined in step S7 that the wear state of the tread portion 11a is not good (“N” in step S7), the tire 2 (shown in FIG. 2) is redesigned (step S9), and steps S1 to S1 to Step S7 is carried out again. Thereby, in the simulation method of the present embodiment, it is possible to reliably design the tire 2 in which the tread portion 2a is in a good wear state.

The condition of the second rule of the present embodiment is exemplified that the adjacent node 18 is located on the innermost side in the radial direction of the tire, but the present invention is not limited to such an embodiment. FIG. 10 is a diagram showing a first node 17 in which a destination 20 is determined based on the second rule of another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

The condition of the second rule of this embodiment is the angle α1 formed by the adjacent node 18 between the side 16 connecting the adjacent node 18 and the first node 17 and the straight line 31 extending inward in the tire radial direction from the first node 17. Is the minimum.

As shown in FIG. 10, the first node 17 has two adjacent nodes 18 adjacent to each other via the first node 17 and the side 16. Among these adjacent nodes 18, none of the adjacent nodes 18 satisfy the condition of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed). On the other hand, of the two adjacent nodes 18a and 18b, the condition of the second rule (that is, the adjacent node 18 is the side 16 connecting the adjacent node 18 and the first node 17 and the inside in the tire radial direction from the first node 17). There is only one adjacent node 18 that conforms to the angle α1 formed by the straight line 31 extending perpendicular to the vertical line 31 (in this example, the other adjacent node 18b). In such a case, in the second step S54, one side connecting one adjacent node 18 (in this example, the other adjacent node 18b) and the first node 17 that meet the conditions of the second rule (this example). Then, the destination 20 of the first node 17 is determined at a position above the other side 16b).

11 (a) and 11 (b) are enlarged views of the tread portion 11a of still another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

At the first node 17 shown in FIG. 11A, there are four adjacent nodes 18 adjacent to the first node 17 via the side 16. Of these adjacent nodes 18, there are two adjacent nodes 18 that meet the conditions of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed) (in this example, one of the adjacent nodes 18a). And the other adjacent node 18b). In such a case, candidates for the destination 20 of the first node 17 include a position on one side 16a connecting one adjacent node 18a and the first node 17, and the other adjacent node 18b and the first. A position on the other side 16b connecting the one node 17 is included. Therefore, in the first step S52, the destination 20 of the first node 17 that conforms to the first rule cannot be narrowed down to one (that is, one destination 20 is found), and in the process S55, the first node 20 cannot be narrowed down. 17 cannot be moved.

In such a case, in the second step S54, it is desirable that the destination 20 of the first node 17 is narrowed down to one based on the second rule. The condition of the second rule of this embodiment is that among the plurality of adjacent nodes 18 searched by the first rule (for example, one adjacent node 18a and the other adjacent node 18b shown in FIG. 11B). The purpose is to limit one adjacent node 18. The condition of the second rule of this embodiment is that the adjacent node 18 is located on the innermost side in the radial direction of the tire.

As shown in FIG. 11 (b), there is only one adjacent node 18 that meets the conditions of the second rule (that is, it is located on the innermost side in the radial direction of the tire) (in this example, it is located). , The other adjacent node 18b). In such a case, in the second step S54, one side connecting one adjacent node 18 (in this example, the other adjacent node 18b) and the first node 17 that meet the conditions of the second rule (this example). Then, the destination 20 of the first node 17 is determined at a position above the other side 16b).

As described above, in the second step S54 of this embodiment, even if a plurality of adjacent nodes 18 are searched by the first rule, one adjacent node 18 can be limited. Therefore, in this embodiment, since the first node 17 can be reliably moved inward in the radial direction of the tire, the wear state of the tread portion 11a can be stably calculated.

The condition of the second rule of the previous embodiment is exemplified that it is located on the innermost side in the radial direction of the tire, but the condition is not limited to such an embodiment. FIG. 12 is a diagram showing a first node 17 in which a destination 20 is determined based on the second rule of another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

The condition of the second rule of this embodiment is the angle α1 formed by the adjacent node 18 between the side 16 connecting the adjacent node 18 and the first node 17 and the straight line 31 extending inward in the tire radial direction from the first node 17. Is the minimum.

As shown in FIG. 12, the first node 17 conforms to the condition of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed) among the four adjacent nodes 18 of the first node 17. There are two adjacent nodes 18 (in this example, one adjacent node 18a and the other adjacent node 18b). Of these two adjacent nodes 18a and 18b, the condition of the second rule (that is, the adjacent node 18 is the side 16 connecting the adjacent node 18 and the first node 17 and the inside in the tire radial direction from the first node 17). There is only one adjacent node 18 that conforms to the angle α1 formed by the straight line 31 extending perpendicular to the vertical line 31 (in this example, the other adjacent node 18b). In such a case, in the second step S54, one side connecting one adjacent node 18 (in this example, the other adjacent node 18b) and the first node 17 that meet the conditions of the second rule (this example). Then, the destination 20 of the first node 17 is determined at a position above the other side 16b).

The conditions of the second rule shown in FIGS. 11 and 12 are that the adjacent node 18 is located on the innermost side in the radial direction of the tire, and the adjacent node 18 connects the adjacent node 18 and the first node 17. Although the angle α1 formed by the side 16 and the straight line 31 extending inward in the radial direction of the tire from the first node 17 is the minimum, the present invention is not limited to this aspect. FIG. 13 is a diagram showing the first node 17 in which the destination 20 is determined based on the second rule of still another embodiment of the present invention. In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

The condition of the second rule of this embodiment is that the adjacent node 18 constitutes the side 16 connecting the adjacent node 18 and the first node 17, and the outer surface 14 of the tread portion 11a, and is connected to the first node 17. The angle α2 formed by the average direction 32 of the normal directions 33 and 34 of the side 16 is the minimum. Here, the "averaged direction 32" is an inner product of the vector of the normal direction 33 of one side 16 connected to the first node 17 and the vector of the normal direction 34 of the other side 16.

As shown in FIG. 13, the first node 17 conforms to the condition of the first rule (that is, the outer surface 14 of the tread portion 11a is not formed) among the four adjacent nodes 18 of the first node 17. There are two adjacent nodes 18 (in this example, one adjacent node 18a and the other adjacent node 18b). Of these two adjacent nodes 18a and 18b, the condition of the second rule (that is, the adjacent node 18 constitutes a side 16 connecting the adjacent node 18 and the first node 17 and an outer surface 14 of the tread portion 11a. However, there is only one adjacent node 18 that conforms to the angle α2 formed by the average direction 32 of the normal directions 33 and 34 of the plurality of sides 16 connected to the first node 17). (In this example, the other adjacent node 18b). In such a case, in the second step S54, one side 16 (this) connecting one adjacent node 18 (in this example, the other adjacent node 18b) and the first node 17 that meet the conditions of the second rule. In the example, the destination 20 of the first node 17 is determined at a position above the other side 16b).

Such a condition of the second rule is, for example, in a tire model for a motorcycle, in which the tread radius is smaller and the shape of the element F (i) tends to be complicated as compared with the tire model for a passenger car, the tread portion 11a is satisfied. The adjacent node 18 located inward of the tread ground plane 11s can be effectively searched.

As another condition of the second rule, for example, the adjacent node 18 may not form the outer surface 14 of the tread portion 11a, or may form the outer surface 14 of the tread portion 11a. Since the condition of the second rule includes not only the adjacent node 18 constituting the outer surface 14 of the tread portion 11a but also the adjacent node 18 constituting the outer surface 14 of the tread portion 11a as a search target, the first rule includes the condition. By comparison, the destination 20 of the first node 17 can be searched more reliably.

FIG. 14 is a perspective view showing the first node 17 whose destination is determined based on the second rule of 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.

At the first node 17 shown in FIG. 14, there are four adjacent nodes 18 adjacent to the first node 17 via the side 16 (adjacent nodes 18a to 18d). As described above, the outer surface 14 of the tire model 11 includes the tread contact patch 11s and the tie bar 11b. Therefore, since these adjacent nodes 18 constitute the outer surface 14 of the tread portion 11a, the conditions of the first rule (that is, the adjacent nodes 18 do not form the outer surface 14 of the tread portion 11a) are satisfied. There is no adjacent node 18.

Further, among the four adjacent nodes 18a to 18d, for example, the condition of the second rule of the embodiment shown in FIG. 9B (that is, the adjacent node 18 is located on the innermost side in the radial direction of the tire). Further, the condition of the second rule of the embodiment shown in FIG. 10 (that is, the adjacent node 18 is perpendicular to the side 16 connecting the adjacent node 18 and the first node 17 and the inside in the tire radial direction from the first node 17). The adjacent node 18 conforming to the minimum angle α1 formed with the straight line 31 extending is the adjacent node 18a constituting the tread ground contact surface 11s. Even if the destination of the first node 17 (not shown) is determined at a position on one side 16 connecting the adjacent node 18a and the first node 17, the first node 17 is used as the tire model 11. Cannot be moved inside the tread portion 11a of. Therefore, the wear state of the tread portion 11a cannot be calculated appropriately.

The condition of the second rule of this embodiment is that, of the outer surface 14 of the tread portion 11a, the adjacent node 18 constitutes the outer surface 14 that does not touch the road surface. In this condition, of the four adjacent nodes 18a to 18d, the condition of the second rule (that is, of the outer surface 14 of the tread portion 11a, the outer surface where the adjacent node 18 does not touch the road surface (in this example, the tie bar 11b) is used. There is only one adjacent node 18 that conforms to the configuration (in this example, the adjacent node 18d arranged on the tie bar 11b). In such a case, in the second step S54, the destination of the first node 17 is moved to a position on one side 16 connecting the one adjacent node 18d and the first node 17 that meet the conditions of the second rule. 20 is determined.

As described above, when all the adjacent nodes 18 form the outer surface 14 (tread ground contact surface 11s and tie bar 11b) of the tread portion 11a, the first node 17 is a tire model under the condition of the second rule of another embodiment. Even if the destination 20 that can be moved to the inside of the tire model 11 cannot be determined, the condition of the second rule of this embodiment is that the destination 20 that can move the first node 17 to the inside of the tread portion 11a of the tire model 11 is set. Can be decided. Therefore, the wear state of the tread portion 11a can be appropriately calculated.

In the second step S54, the destination 20 of the first node 17 may be searched based on the second rule that combines the plurality of conditions exemplified so far. As a result, in the second step S54, the destination 20 of the first node 17 can be more reliably determined (searched), so that the wear state of the tread portion 11a can be stably calculated.

In the embodiments so far, the condition described as the first rule may be defined as the condition of the second rule, and the condition described as the second rule may be defined as the condition of the first rule. As a result, the conditions of the first rule and the conditions of the second rule are defined according to the shape of the tire model 11 and the shape of the element F (i), so that the destination 20 of the first node 17 can be moved to. You can search more reliably.

The first rule and the second rule of the embodiments so far have been exemplified in that the position on one side 16 connecting the adjacent node 18 and the first node 17 is determined as the movement destination 20. It is not limited to such an aspect. For example, the first rule and the second rule may be determined with one adjacent node 18 as the destination. In the wear calculation step S5 of such an embodiment, since the first node 17 can be directly moved to the adjacent node 18 (the first node 17 is deleted and the adjacent node 18 is used as a new first node 17). Definition), the wear state of the tread portion 11a can be calculated in a short time.

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.

According to the processing procedure shown in FIG. 3, the wear state of the tread portion of the tire model was calculated (Examples 1 to 4). In Examples 1 to 4, according to the processing procedure shown in FIG. 8, the first step of searching for the destination of the first node based on the first rule, and the first step of the first step, which conforms to the first rule. When the destination of the node cannot be found, the second step of searching for the destination of the first node and the first node are moved to the searched destination based on the second rule different from the first rule. A wear calculation process including the process was carried out.

For comparison, wear calculation including the first step of searching for the destination of the first node and the step of moving the first node to the searched destination based on a single rule (first rule). By the process, the wear state of the tread portion of the tire model was calculated (comparative example). The common specifications are as follows.
Tire size: 215 / 55R17
Rim size: 17 x 7J
Internal pressure: 230kPa
Load: 3.51kN
Condition of the first rule: Adjacent nodes do not form the outer surface of the tread part. Condition of the second rule:
Example 1: The adjacent node is located on the innermost side in the radial direction of the tire Example 2: The adjacent node connects the adjacent node and the first node, and
The angle between the first node and the straight line extending inward in the radial direction of the tire is
What is the minimum Example 3: An adjacent node is an edge connecting the adjacent node and the first node,
Multiple sides that make up the outer surface of the tread and connect to the first node
The angle between the normal direction and the average direction is the smallest. Example 4: Of the outer surface of the tread portion, the outer surface where the adjacent node does not touch the road surface.
To compose

As a result of the test, in the comparative example, the movement destination of the first node could not be found based on the first rule, and the state where the first node could not be moved occurred. As a result, in the comparative example, the calculation of the wear state was interrupted, and the wear state could not be calculated stably.

On the other hand, in Examples 1 to 4, even if the destination of the first node was not found based on the first rule, the destination of the first node could be searched based on the second rule. Therefore, in Examples 1 to 4, the first node can be reliably moved inward in the radial direction of the tire, and the wear state of the tread portion can be stably calculated.

S52 First step of searching for the destination of the first node based on the first rule S54 Second step of searching for the destination of the first node based on the second rule S55 Searched for the first node Process to move first

Claims (8)

It is a simulation method for calculating the wear state of the tread part of a tire using a computer.
A process of inputting a tire model, which is a model of the tire, into the computer using a finite number of elements having a plurality of nodes.
The computer includes, among the nodes, a wear calculation step of moving the first node constituting the outer surface of the tread portion of the tire model inward in the tire radial direction to calculate the wear state of the tread portion.
The wear calculation step includes a first step of searching for a destination of the first node based on a predetermined first rule, and a first step.
In the first step, when the destination of the first node that matches the first rule is not found, the destination of the first node is searched based on the second rule different from the first rule. Second step and
The step of moving the first node to the searched destination, and
Tire simulation method including. The element includes an edge connecting adjacent nodes.
The node includes a plurality of adjacent nodes that are adjacent to the first node via the side.
The first rule and the second rule move the position on one adjacent node that meets a predetermined condition or one side connecting the adjacent node and the first node. The tire simulation method according to claim 1, which is determined first. The tire simulation method according to claim 2, wherein the adjacent node does not form the outer surface of the tread portion. The tire simulation method according to claim 2, wherein the adjacent node constitutes the outer surface of the tread portion. The tire simulation method according to claim 4, wherein the condition is that the adjacent node of the outer surface of the tread portion constitutes an outer surface that does not touch the road surface. The tire simulation method according to any one of claims 2 to 5, wherein the adjacent node is located on the innermost side in the radial direction of the tire. The condition is that the angle between the adjacent node connecting the adjacent node and the first node and the straight line extending inward in the radial direction of the tire from the first node is the minimum. The tire simulation method according to any one of claims 2 to 6. The condition is that the adjacent node constitutes the side connecting the adjacent node and the first node, and the normal direction of a plurality of the sides connected to the outer surface of the tread portion and connected to the first node. The method for simulating a tire according to any one of claims 2 to 7, wherein the angle formed with the average direction is the minimum.

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