Tire simulation method

Abstract

To provide a simulation method of a tire capable of reducing noise which does not exist in an actual tire.SOLUTION: A simulation method of a tire is given. The simulation method comprises the steps of: inputting a tire model 22 into a computer through finite number of first elements F(i) which have a plurality of a first nodes 31; and inputting a rim model into the computer through finite number of second elements G(i) which have a plurality of second nodes 32. The computer executes: a rim assembly step which configures an assembly model 21 consisting of the rim model 23 and the tire model 22 while making the tire model 22 contact with a contact face 29; and a simulation step which calculates physical amount regarding a tire performance by use of the assembly model 21. The rim assembly step includes a step which makes the tire model 22 contact with the contact face 29 not to overlap the first node 31 with at least one of the second nodes 32 generated on the contact face 29.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to a tire simulation method. [Background technology]

[0002] Patent Document 1 below describes a simulation method for a pneumatic tire assembly, in which a tire FEM model in which tire shape data is divided into multiple elements and a rim division model in which rim shape data is divided into multiple segments are first obtained.

[0003] Next, in this method, boundary conditions are set for the tire FEM model and the rim division model, and each of the multiple segments is set as a rigid body. Then, an analysis is performed to apply force, displacement, and rotation to the tire FEM model assembled to the rim division model, and the force applied to each of the multiple segments is confirmed, thereby analyzing the force transmission distribution from the tire FEM model to the rim division model. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-30820 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when calculating physical quantities related to tire performance in FEM simulations, there is a problem in that the calculation results include noise that cannot occur in an actual tire.

[0006] The present disclosure has been devised in view of the above circumstances, and has as its main object to provide a tire simulation method capable of reducing the above-mentioned noise. [Means for solving the problem]

[0007] The present disclosure relates to a simulation method for evaluating the performance of a tire assembled to a rim, the method comprising the steps of: inputting a tire model obtained by discretizing the tire using a finite number of first elements each having a plurality of first nodes into a computer; and inputting a rim model having a contact surface with the tire model into the computer by discretizing the rim using a finite number of second elements each having a plurality of second nodes, wherein the computer executes a rim assembly step of bringing the tire model into contact with the contact surface to set up an assembly model of the rim model and the tire model; and a simulation step of calculating physical quantities related to the performance of the tire using the assembly model, wherein the rim assembly step includes a step of bringing the tire model into contact with the contact surface so that the first node does not overlap at least one second node that appears on the contact surface. [Effects of the Invention]

[0008] By employing the above steps, the tire simulation method of the present disclosure makes it possible to reduce noise that would not occur in an actual tire. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a computer for executing a tire simulation method according to an embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view showing a tire whose performance is evaluated. [Figure 3] 1 is a flowchart showing a processing procedure of a tire simulation method according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing an example of an assembly model and a road surface model. [Figure 5] FIG. 5 is a cross-sectional view of the assembly model of FIG. 4 taken along the tire axial direction. [Figure 6] 6 is a cross-sectional view taken along the line AA in FIG. 5. [Figure 7]4 is a flowchart showing the procedure of a rim assembling process according to the present embodiment. [Figure 8] This is an AA cross-sectional view of the assembly model in which the overlap between the first node and the second node has been removed. [Figure 9] 10 is a flowchart illustrating a processing procedure of a simulation process according to the present embodiment. [Figure 10] 10 is a flowchart showing a processing procedure of a simulation process according to another embodiment. [Figure 11] FIG. 10 is a diagram showing an assembly model in which a load is applied to the first node on the tread contact surface. [Figure 12] 6 is a graph showing the relationship between axial force and time in Example 1. (a) shows the axial force Fx in the longitudinal direction, (b) shows the axial force Fy in the tire axial direction, and (c) shows the axial force Fz in the vertical direction. [Figure 13] 6 is a graph showing the relationship between axial force and time in Example 2. (a) shows the axial force Fx in the longitudinal direction, (b) shows the axial force Fy in the tire axial direction, and (c) shows the axial force Fz in the vertical direction. [Figure 14] 6 is a graph showing the relationship between axial force and time in a comparative example, where (a) shows the longitudinal axial force Fx, (b) shows the axial force Fy in the tire axial direction, and (c) shows the vertical axial force Fz. [Figure 15] 6 is a graph showing the relationship between the transfer function of the axial force and frequency in Example 1. (a) shows the transfer function of the axial force Fx in the longitudinal direction, (b) shows the transfer function of the axial force Fy in the tire axial direction, and (c) shows the transfer function of the axial force Fz in the vertical direction. [Figure 16] 6 is a graph showing the relationship between the transfer function of the axial force and frequency in Example 2. (a) shows the transfer function of the axial force Fx in the longitudinal direction, (b) shows the transfer function of the axial force Fy in the tire axial direction, and (c) shows the transfer function of the axial force Fz in the vertical direction. [Figure 17] 6 is a graph showing the relationship between the transfer function of axial force and frequency in a comparative example, where (a) shows the transfer function of the axial force Fx in the longitudinal direction, (b) shows the transfer function of the axial force Fy in the tire axial direction, and (c) shows the transfer function of the axial force Fz in the vertical direction. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be understood that the drawings include exaggerated representations and representations that differ from the dimensional ratios of actual structures in order to facilitate understanding of the contents of the disclosure. Furthermore, identical or common elements are designated by the same reference numerals throughout the embodiments, and redundant explanations will be omitted. Furthermore, the specific configurations shown in the embodiments and drawings are intended to facilitate understanding of the contents of the present disclosure, and the present disclosure is not limited to the specific configurations shown in the drawings.

[0011] In the tire simulation method of this embodiment (hereinafter sometimes simply referred to as the "simulation method"), the performance of a tire mounted on a rim is evaluated using a computer.

[0012] [computer] 1 is a perspective view showing a computer for executing the tire simulation method of this embodiment. Computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. This main body 1a is provided with, for example, a central processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1 and 1a2. Software for executing the simulation method of this embodiment is also pre-stored in the storage device.

[0013] [tire] 2 is a cross-sectional view showing a tire 2 for which tire performance is evaluated. The tire 2 of this embodiment is configured as, for example, a tire for a passenger car. However, the tire 2 is not limited to a tire for a passenger car.

[0014] The tire 2 of this embodiment is composed of a rubber portion 3, a carcass 6 that extends from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and a belt layer 7 that is arranged radially outside the carcass 6 and inside the tread portion 2a.

[0015] The carcass 6 is composed of at least one carcass ply 6A, one carcass ply in this embodiment. The carcass ply 6A includes a main body portion 6a that extends from the tread portion 2a through the sidewall portion 2b to the bead cores 5 of the bead portions 2c, and a turned-up portion 6b that is continuous with the main body portion 6a and turned back around the bead cores 5 from the inside to the outside in the axial direction of the tire. The carcass ply 6A is formed by layering carcass cords (not shown) that are arranged at an angle of 80 to 90 degrees with respect to the tire equator C, for example, in a mutually intersecting direction.

[0016] The belt layer 7 includes two inner and outer belt plies 7A and 7B 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 7A and 7B are overlapped with the belt cords crossing each other.

[0017] [rim] The rim 11, like a conventional rim, is configured to include a pair of rim seat portions 12, 12, a pair of rim flange portions 13, 13, and a well portion 14. The pair of rim seat portions 12, 12 and the pair of rim flange portions 13, 13 respectively have contact surfaces 16, 16 that come into contact with the tire 2 (bead portions 2c, 2c).

[0018] The rim 11 of this embodiment is integrally formed with a disk portion 17 that extends radially inward from the rim 11. The disk portion 17 is fixed to an axle (tire rotation axis) not shown.

[0019] In this embodiment, the tire 2 is mounted on the rim 11 to form an assembly 10.

[0020] [Tire Simulation Method (First Embodiment)] Next, the simulation method of this embodiment will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the processing steps of the tire simulation method of this embodiment.

[0021] [Enter tire model] In the simulation method of this embodiment, first, a tire model is input into a computer 1 (shown in FIG. 1) (step S1). FIG. 4 is a perspective view showing an example of an assembly model 21 and a road surface model 25. FIG. 5 is a cross-sectional view of the assembly model 21 of FIG. 4 taken along the tire axial direction. FIG. 6 is a cross-sectional view taken along line AA of FIG. 5. In FIG. 4, the assembly model 21 is shown in a simplified form, and the tread pattern of the tread portion 22a, the first element F(i), the second element G(i), etc. are omitted.

[0022] 5 and 6, in step S1 of the present embodiment, the tire (tire to be evaluated) 2 shown in Fig. 2 is discretized (modeled) using a finite number of first elements F(i) having a plurality of first nodes 31. As a result, in step S1, a tire model 22 is set.

[0023] The first element F(i) can be handled by a numerical analysis method. As the numerical analysis method, for example, the finite element method, the finite volume method, the difference method, or the boundary element method (in this embodiment, the finite element method) can be appropriately adopted. For example, a three-dimensional tetrahedral solid element, a pentahedral solid element, or a hexahedral solid element is used as the first element F(i).

[0024] For each first element F(i), numerical data such as an element number, the number of each first node 31, the coordinate values ​​of each first node 31, and the material properties of the tire 2 shown in Fig. 2 (for example, density, Young's modulus, damping coefficient, thermal conductivity, heat transfer coefficient, etc.) are defined. For each of the multiple first nodes 31, physical quantities acting on the tire 2 are calculated in a simulation step S6, which will be described later.

[0025] In step S1 of this embodiment, for example, the rubber portion 3, the carcass ply 6A, and the belt plies 7A and 7B shown in Fig. 2 are each discretized by the first element F(i). As a result, a rubber member model (for example, a tread rubber model) 26, a carcass ply model 27, and belt ply models 28A and 28B are set in the tire model 22.

[0026] In this embodiment, after a two-dimensional tire model (cross-sectional model of the tire) 22 is set, the tire model 22 is copied (expanded three-dimensionally) in the tire circumferential direction at a predetermined angle pitch P1 as shown in Fig. 6, thereby setting a three-dimensional model. This allows the tire model 22 to be set in a short time in step S1.

[0027] The angle pitch P1 can be set appropriately based on, for example, the calculation accuracy required for the simulation. Note that the tire model 22 is not limited to being modeled by three-dimensional expansion as described above, and for example, the three-dimensional tire model 22 may be modeled directly. The tire model 22 is input to a computer 1 (shown in FIG. 1).

[0028] [Enter rim model] Next, in the simulation method of this embodiment, as shown in Figures 4 and 5, the rim model 23 is input into the computer 1 (shown in Figure 1) (step S2). In step S2 of this embodiment, the rim 11 is discretized (modeled) using a finite number of second elements G(i) each having a plurality of second nodes 32. As a result, in step S2, the rim model 23 having a contact surface 29 with the tire model 22 is set.

[0029] The second element G(i) is the same as the first element F(i). The second element G(i) is defined by numerical data such as the element number, the number of each second node 32, the coordinate values ​​of each second node 32, and the material properties of the rim 11 shown in FIG. 2 (e.g., density, Young's modulus, damping coefficient, thermal conductivity, heat transfer coefficient, etc.). The second element G(i) may be defined so as to be indeformable even when an external force is applied. Furthermore, at each of the multiple second nodes 32, physical quantities acting on the rim 11 are calculated in a simulation step S6, which will be described later.

[0030] In step S2 of this embodiment, the pair of rim seat portions 12, 12, the pair of rim flange portions 13, 13, and the well portion 14 shown in Figure 2 are each discretized (modeled) using the second element G(i). As a result, a pair of rim seat models 33, 33, a pair of rim flange models 34, 34, and a well portion model 35 are set in the rim model 23. Contact surfaces 29, 29 with the tire model 22 (bead portions 22c, 22c) are set in the pair of rim seat models 33, 33 and the pair of rim flange models 34, 34, respectively.

[0031] In step S2 of this embodiment, the disk portion 17 shown in Fig. 2 is discretized (modeled) using the second element G(i). As a result, the disk model 24 is set integrally with the rim model 23. A tire rotation axis 37 (shown in Fig. 4) is defined in the disk model 24.

[0032] In this embodiment, after the two-dimensional rim model 23 and disc model 24 are set, the rim model 23 and disc model 24 (not shown) are copied (developed into three dimensions) in the tire circumferential direction at a predetermined angle pitch P2, as shown in Figure 6. This makes it possible to set the three-dimensional rim model 23 and disc model 24 in a short time in step S2.

[0033] The angle pitch P2 can be set appropriately based on, for example, the calculation accuracy required for the simulation. In this embodiment, the angle pitch P2 is set to be the same as the angle pitch P1 of the tire model 22. Note that the rim model 23 and the disc model 24 are not limited to being modeled by three-dimensional development as described above; for example, the three-dimensional rim model 23 and the disc model 24 may be modeled directly. The rim model 23 and the disc model 24 are stored in the computer 1 (shown in FIG. 1).

[0034] [Enter road surface model] Next, in the simulation method of this embodiment, as shown in Fig. 4, a road surface model 25 that models the road surface is input to the computer 1 (step S3). In step S3 of this embodiment, based on information about the road surface (not shown), the road surface is discretized using a finite number of elements H(i) (i = 1, 2, ...) that can be handled by a numerical analysis method (in this embodiment, the finite element method). As a result, in step S3, the road surface model 25 is set.

[0035] Element H(i) is defined as a rigid plane element that is defined to be undeformable. Element H(i) has a plurality of nodes 40. Furthermore, element H(i) is defined with numerical data such as an element number and the coordinate values ​​of the nodes 40.

[0036] In step S3 of this embodiment, a road surface model 25 having a smooth surface is defined, but the present invention is not limited to this. For example, a road surface model (not shown) may be defined that has minute irregularities, irregular steps, depressions, undulations, or irregularities similar to those of an actual road surface, such as ruts, as in an asphalt road surface. The road surface model 25 is input to a computer 1 (shown in FIG. 1).

[0037] Enter boundary conditions Next, in the simulation method of this embodiment, boundary conditions are input to the computer 1 (shown in FIG. 1) (step S4). The boundary conditions of this embodiment include a first boundary condition for setting the assembly model 21 and a second boundary condition for calculating physical quantities related to tire performance.

[0038] The first boundary conditions in this embodiment include, for example, a contact condition between the tire model 22 and a contact surface 29 (shown in FIGS. 5 and 6) of the rim model 23, a friction coefficient between the tire model 22 and the contact surface 29, and an internal pressure condition of the tire model 22. The internal pressure condition is, for example, an air pressure set for each tire by a standard system including the standard on which the tire 2 (shown in FIG. 2) is based.

[0039] The second boundary conditions in this embodiment include, for example, the contact condition between the tire model 22 and the road surface model 25 shown in Fig. 4, the friction coefficient between the tire model 22 and the road surface model 25, the load condition, the camber angle, and the angular velocity and translational velocity relative to the traveling speed. The load condition is, for example, a load set for each tire by each standard in a standard system including the standard on which the tire 2 is based.

[0040] The boundary conditions (first boundary condition and second boundary condition) are not limited to the above conditions, and for example, some of these conditions may be omitted or new conditions may be included depending on the simulation procedure. The boundary conditions (first boundary condition and second boundary condition) are stored in a computer 1 (shown in FIG. 1).

[0041] [Rim assembly process] Next, in the simulation method of this embodiment, as shown in Figures 4 to 6, the computer 1 (shown in Figure 1) sets an assembly model 21 of the rim model 23 and the tire model 22 (rim assembling step S5). In the rim assembling step S5, as shown in Figures 5 and 6, the tire model 22 is brought into contact with the contact surface 29 of the rim model 23 to set the assembly model 21. Figure 7 is a flowchart showing the processing procedure of the rim assembling step S5 of this embodiment.

[0042] [Contact the tire model to the contact surface] In the rim assembly step S5 of this embodiment, first, the tire model 22 is brought into contact with the contact surface 29 of the rim model 23 so that the first node 31 does not overlap at least one second node 32 appearing on the contact surface 29 (step S51). Here, the overlapping of the first node 31 and the second node 32 means that the first node 31 and the second node 32 are in contact with each other at the same coordinate position, as shown in Fig. 6.

[0043] In step S51 of this embodiment, first, the bead portions 22c, 22c of the tire model 22 are brought into contact with the contact surface 29 of the rim model 23, with no internal pressure condition defined for the tire model 22. The contact of the tire model 22 with the contact surface 29 can be performed in the same manner as in conventional simulation methods, for example, based on the contact condition and friction coefficient included in the first boundary condition.

[0044] Next, in step S51 of this embodiment, the contact state of the tire model 22 with the contact surface 29 is corrected so that the first node 31 does not overlap at least one second node 32 appearing on the contact surface 29. Note that if the first node 31 does not already overlap the second node 32 when the tire model 22 is in contact with the contact surface 29, the correction of the contact state may be omitted.

[0045] The procedure for correcting the contact state is not particularly limited as long as the overlap between at least one second node 32 appearing on the contact surface 29 and the first node 31 is removed (eliminated). In this embodiment, as shown in Fig. 6, one of the tire model 22 and the rim model 23 (in this example, the rim model 23) is moved relative to the other of the tire model 22 and the rim model 23 (in this example, the tire model 22) in the tire circumferential direction. This causes the overlapping first node 31 and second node 32 to move apart. Fig. 8 is a cross-sectional view taken along line AA of the assembly model 21 from which the overlap between the first node 31 and the second node 32 has been removed.

[0046] As described above, in this embodiment, the angle pitch P1 of the tire model 22 and the angle pitch P2 of the rim model 23 are set to be the same. Therefore, in step S51, the first node 31 and the second node 32 (shown in FIG. 6 ), which overlap each other, can be easily and reliably separated by relative movement of the tire model 22 and the rim model 23 in the tire circumferential direction.

[0047] [Define internal pressure conditions] Next, in the rim assembly step S5 of this embodiment, as shown in FIG. 5, an internal pressure condition is defined for the tire model 22 in contact with the contact surface 29 of the rim model 23 (step S52). As shown in FIG. 5, in step S52 of this embodiment, a uniformly distributed load w corresponding to the internal pressure condition included in the first boundary condition is defined over the entire bore surface 41 of the tire model 22. As a result, in step S52, an assembly model 21 can be obtained in which the rim model 23 is attached to the bead portions 22c, 22c of the tire model 22 and is filled with internal pressure. The assembly model 21 of this embodiment includes a disk model 24. The assembly model 21 is stored in the computer 1 (shown in FIG. 1).

[0048] In the deformation calculation of the tire model 22 (rim model 23), a mass matrix, a stiffness matrix, and a damping matrix are created for each of the first elements F(i) and second elements G(i) based on the shape and material properties of each of the first elements F(i) and second elements G(i). These matrices are then combined to create a matrix for the entire system. A computer 1 (shown in FIG. 1) then applies the various conditions to create equations of motion and calculates the deformation of the tire model 22 (rim model 23) for each unit time T(x) (x = 0, 1, ...) of the simulation. Such deformation calculations can be performed using commercially available finite element analysis application software such as ABAQUS by Dassault Systèmes. The unit time T(x) can be set appropriately depending on the required simulation accuracy.

[0049] [Simulation process] Next, in the simulation method of this embodiment, the computer 1 (shown in FIG. 1) calculates physical quantities related to the performance of the tire 2 (shown in FIG. 2) using the assembly model 21 (simulation step S6). In the simulation step S6 of this embodiment, as shown in FIG. 4, the assembly model 21 is rolled on a road surface model 25 to calculate physical quantities related to the tire performance. FIG. 9 is a flowchart illustrating the processing procedure of the simulation step S6 of this embodiment.

[0050] [Contact between assembly model and road surface model] In the simulation method of this embodiment, first, contact between the assembly model 21 and the road surface model 25 is calculated (step S61). In step S61 of this embodiment, deformation of the assembly model 21 in contact with the road surface model 25 is calculated based on the contact condition, friction coefficient, load condition L1, and camber angle (not shown) included in the second boundary condition. The load condition L1 is set to the tire rotation axis 37 of the assembly model 21. As a result, the assembly model 21 in contact with the road surface model 25 is calculated.

[0051] [Rolling calculation for assembly model] Next, in a simulation step S6 of this embodiment, the assembly model 21 rolling on the road surface model 25 is calculated (step S62). In step S62 of this embodiment, the assembly model 21 during rolling is calculated based on the angular velocity V1, the translational velocity V2, and the turning angle (not shown) included in the second boundary condition.

[0052] The angular velocity V1 is set to the tire rotation axis 37 of the assembly model 21. The translational velocity V2 is set to the road surface model 25. As a result, in step S62 of this embodiment, the assembly model 21 rolling on the road surface model 25 is calculated.

[0053] [Calculate physical quantities] Next, in a simulation step S6 of this embodiment, physical quantities related to tire performance are calculated using the assembly model 21 rolling on the road surface model 25 (step S63). In this embodiment, it is desirable to calculate the physical quantities after the forces acting on the rolling assembly model 21 reach a steady state (stable state). This makes it possible to evaluate tire performance based on the stable physical quantities.

[0054] In step S63 of this embodiment, physical quantities related to tire performance are calculated for each unit time T(x) of the simulation until a predetermined termination condition is satisfied. As a result, in step S63, physical quantities related to tire performance can be acquired in chronological order. Note that the termination condition can be set, for example, to a calculation termination time, as appropriate.

[0055] However, the FEM simulation method has a problem in that when calculating physical quantities related to tire performance, the calculation results include noise that cannot occur in an actual tire 2 (shown in FIG. 2).

[0056] As a result of extensive research, the disclosers have found that when the first node 31 of the tire model 22 and the second node 32 of the rim model are overlapped as shown in Figure 6, the physical quantities of the tire model 22 and the physical quantities of the rim model 23 are overlapped and calculated at the overlapped position, resulting in large noise being calculated that would not occur in an actual tire 2.

[0057] 8, in the simulation method of this embodiment, the tire model 22 is brought into contact with the contact surface 29 of the rim model 23 so that the first node 31 of the tire model 22 does not overlap with at least one second node 32 appearing on the contact surface 29. As a result, in the simulation method of this embodiment, it is possible to reduce noise that would not occur in an actual tire 2 when calculating physical quantities related to tire performance.

[0058] In order to effectively reduce the above noise, in the rim assembly step S5 (step S51) shown in Fig. 7, it is desirable to bring the tire model 22 into contact with the contact surface 29 so that the first nodes 31 do not overlap any of the second nodes 32 that appear on the contact surface 29, as shown in Fig. 8. This makes it possible to prevent the physical quantities of the tire model 22 and the physical quantities of the rim model 23 from being calculated in an overlapping manner at all of the second nodes 32 in the simulation step S6, making it possible to more reliably reduce noise that would not occur in an actual tire 2.

[0059] In this embodiment, the second elements G(i) of the rim model 23 may be set smaller than the first elements F(i) of the tire model 22. This allows the number of second nodes 32 of the second elements G(i) to be set greater than the number of first nodes 31 of the first elements F(i). In this way, in this embodiment, by dividing the rim model 23 into elements finer, the rim model 23 approaches a perfect circle and vibrations of the rim model 23 caused by polygons can be reduced, making it possible to calculate physical quantities related to tire performance with high accuracy. On the other hand, by setting the number of divisions of the first elements F(i) of the tire model 22 greater than the number of divisions of the second elements G(i) of the rim model 23, it is possible to prevent the number of elements of the first elements F(i) from becoming larger than necessary, and suppress increases in calculation time.

[0060] The physical quantity relating to the tire performance is not particularly limited as long as it relates to the tire performance. In this embodiment, for example, the physical quantity acting on the tire rotation axis 37 (shown in FIG. 4) is calculated.

[0061] The physical quantity acting on the tire rotation axis includes, for example, an axial force. In this embodiment, the axial forces include, for example, an axial force Fx in the front-rear direction, an axial force Fy in the tire axial direction, and an axial force Fz in the up-down direction. In this embodiment, for example, the axial forces Fx, Fy, and Fz are each calculated for each unit time T(x) of the simulation. As a result, time-series data of the axial forces Fx, Fy, and Fz can be acquired in step S63. Such time-series data of the axial forces (axial forces Fx, Fy, and Fz) is useful for evaluating vibrations acting on the tire rotation axis 37 during rotation.

[0062] In step S63, for example, in order to evaluate the vibration characteristics of the tire rotation axis 37, a transfer function obtained by subjecting the time series data of the axial forces Fx, Fy, and Fz to FFT (Fast Fourier Transform) may be calculated as a physical quantity related to the tire performance.

[0063] 4 and 5, the assembly model 21 of this embodiment includes a disk model 24. Therefore, in step S63, it is possible to calculate physical quantities related to tire performance (in this example, physical quantities acting on the tire rotation axis 37) taking into account the inertial characteristics of the disk model 24. As a result, the simulation method of this embodiment makes it possible to calculate with high accuracy physical quantities acting on the tire rotation axis (not shown), which is greatly affected by the inertial characteristics of the disk portion 17 shown in FIG. 2. The physical quantities related to tire performance are stored in the computer 1.

[0064] [Evaluating tire performance] Next, in the simulation method of this embodiment, as shown in FIG. 3, the performance of the tire 2 is evaluated (step S7). In this embodiment, the performance of the tire 2 is evaluated based on physical quantities related to the tire performance. The performance evaluation criteria are set appropriately depending on the performance required of the tire 2. Furthermore, the performance evaluation of the tire 2 may be performed by a computer 1 (shown in FIG. 1) or an operator.

[0065] If it is determined in step S7 that the performance of the tire 2 (shown in FIG. 2) is good ("Yes" in step S7), the tire 2 is manufactured based on the design drawing (CAD data) of the tire 2 (step S8). On the other hand, if it is determined in step S7 that the performance of the tire 2 is not good ("No" in step S7), the design factors of the tire 2 are changed (step S9), and steps S1 to S7 are performed again.

[0066] In this way, the simulation method of this embodiment makes it possible to reliably design and manufacture a tire 2 (shown in FIG. 2) having desired performance. As described above, in this embodiment, physical quantities are calculated in which noise that would not occur in an actual tire 2 is reduced. Therefore, the simulation method of this embodiment can evaluate tire performance with high accuracy, making it possible to more reliably design and manufacture a tire 2 having desired performance.

[0067] [Tire simulation method (second embodiment)] In the simulation methods of the above-described embodiments, in the simulation step S6, the assembly model 21 is rolled on the road surface model 25 to calculate physical quantities related to tire performance, but the present invention is not limited to this. Fig. 10 is a flowchart showing the processing procedure of the simulation step S6 of another embodiment. The same components as those in the above-described embodiments are assigned the same reference numerals, and their description may be omitted.

[0068] [Simulation process (second embodiment)] [Load applied to tread contact area] In the simulation step S6 of this embodiment, a load is applied to at least one first node 31 (shown in FIG. 5) appearing on the tread contact surface 42 (step S71). FIG. 11 is a diagram showing the assembly model 21 in which a load L2 is applied to the first node 31 of the tread contact surface 42. In FIG. 11, the first element F(i) and the second element G(i) are omitted.

[0069] In step S71 of this embodiment, the assembly model 21 is not brought into contact with the road surface model 25 (shown in FIG. 4), and the tire rotation axis 37 is set to be immobile, and then a load L2 is applied to at least one first node 31 appearing on the tread contact surface 42. In this way, in step S71, an impact test in which the tread portion 2a (shown in FIG. 2) of the stationary tire 2 is vibrated can be reproduced.

[0070] The magnitude of the load L2 and the time for which the load L2 is applied can be set as appropriate. The magnitude of the load L2 and the time for which the load L2 is applied in this embodiment are set as appropriate based on, for example, an impact test. The load L2 in this embodiment is applied in the vertical direction (z-axis direction).

[0071] [Calculate physical quantities] Next, in a simulation step S6 of this embodiment, physical quantities related to tire performance are calculated (step S72) using the assembly model 21 (shown in FIG. 11) in which a load L2 is applied to the first node 31. In step S72 of this embodiment, physical quantities related to tire performance are calculated for each unit time T(x) of the simulation from when the load L2 is applied to the first node 31 until a predetermined termination condition is satisfied. As a result, in step S72, physical quantities related to tire performance can be acquired in chronological order. Note that the termination condition can be set, for example, to a calculation termination time, as appropriate.

[0072] The physical quantity relating to the tire performance is not particularly limited as long as it relates to the tire performance. In this embodiment, similar to the previous embodiments, for example, the physical quantity acting on the tire rotation axis 37 (time-series data of the axial force and a transfer function) is calculated.

[0073] 8, in the simulation method of this embodiment, the tire model is brought into contact with the contact surface 29 of the rim model 23 so that the first node 31 of the tire model 22 does not overlap with at least one second node 32 appearing on the contact surface 29. As a result, in the simulation method of this embodiment, it is possible to reduce noise that would not occur in an actual tire 2 when calculating physical quantities related to tire performance.

[0074] In this embodiment, the load L2 is applied to the first node 31 of the tread contact surface 42 of the stationary assembly model 21 to calculate the physical quantities related to tire performance, but the present invention is not limited to this. For example, the load L2 (shown in FIG. 11) may be applied to the first node 31 of the tread contact surface 42 of the assembly model 21 while the assembly model 21 is rolling on the road surface model 25 shown in FIG. 4 to calculate the physical quantities related to tire performance. In this way, the simulation method of this embodiment makes it possible to evaluate the vibration performance of a tire when riding over a protrusion.

[0075] Although particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the illustrated embodiments and can be modified and implemented in various forms. [Example]

[0076] The performance of the tires was evaluated based on the procedure shown in FIG. 3 (Example 1, Example 2, and Comparative Example).

[0077] In the rim assembly process of Examples 1 and 2, the tire model was brought into contact with the contact surface based on the processing procedure shown in Fig. 7 so that the first node did not overlap at least one second node appearing on the rim model contact surface, as shown in Fig. 8. The size of the second elements of the rim model of Example 2 was set smaller than that of the rim model of Example 1 (the number of elements was eight times larger).

[0078] In the rim assembling process of the comparative example, as shown in FIG. 6, the tire model was brought into contact with the contact surface so that the first node overlapped the second node appearing on the contact surface of the rim model.

[0079] In the simulation process for Example 1, Example 2, and Comparative Example, the assembly model was rolled on the road surface model, and then a load L2 was applied to the first node that appeared on the tread contact surface. Then, physical quantities related to tire performance (vibration performance of the tire when riding over a protrusion) were calculated. The common specifications are as follows: Tire size: 195 / 65R15 Rim size: 15 x 6.5J Internal pressure: 230kPa Load condition L1: 4000N Rolling speed: 100km / h Load L2: 100N

[0080] Figures 12(a) to 12(c) are graphs showing the relationship between axial force (front-rear direction, tire axial direction, and vertical direction) and time for Example 1. Figures 13(a) to 13(c) are graphs showing the relationship between axial force (front-rear direction, tire axial direction, and vertical direction) and time for Example 2. Figures 14(a) to 14(c) are graphs showing the relationship between axial force (front-rear direction, tire axial direction, and vertical direction) and time for a comparative example.

[0081] The axial force of the comparative example (shown in FIG. 14) was different from the axial force acting on an actual tire and had an overall irregular waveform. On the other hand, the axial forces of Examples 1 and 2 (shown in FIGS. 12 and 13) had a regular waveform similar to the axial force acting on an actual tire. This is because Examples 1 and 2 were able to reduce noise that would not occur in an actual tire. In particular, the axial force Fy in the tire axial direction of Examples 1 and 2 was calculated to have a more regular waveform than the axial force Fy of the comparative example.

[0082] Figures 15(a) to 15(c) are graphs showing the relationship between the transfer function of the axial force (front-rear direction, tire axial direction, and up-down direction) and frequency in Example 1. Figures 16(a) to 16(c) are graphs showing the relationship between the transfer function of the axial force (front-rear direction, tire axial direction, and up-down direction) and frequency in Example 2. Figures 17(a) to 17(c) are graphs showing the relationship between the transfer function of the axial force (front-rear direction, tire axial direction, and up-down direction) and frequency in the comparative example.

[0083] The transfer functions of Examples 1 and 2 (shown in FIGS. 15 and 16) differ from the transfer function of the Comparative Example (shown in FIG. 17) in that the peaks of the transfer functions due to the tire eigenmode are clearly shown. This is because Examples 1 and 2 are able to reduce noise that would not occur in an actual tire.

[0084] Thus, compared to the comparative example, Examples 1 and 2 were able to reduce noise that would not occur in an actual tire. Furthermore, in Example 2, the elements of the rim model were set smaller (the number of elements was larger) compared to Example 1, so the peaks of the transfer function due to the tire eigenmode were more clearly indicated.

[0085] [Note] The present disclosure includes the following aspects.

[0086] [Disclosure 1] A simulation method for evaluating the performance of a tire mounted on a rim, comprising: inputting a tire model obtained by discretizing the tire using a finite number of first elements having a plurality of first nodes into a computer; and inputting a rim model having a contact surface with the tire model into the computer by discretizing the rim using a finite number of second elements having a plurality of second nodes, The computer a rim assembling step of bringing the tire model into contact with the contact surface to set an assembly model of the rim model and the tire model; a simulation step of calculating physical quantities related to the performance of the tire using the assembly model; the rim-assembling step includes a step of bringing the tire model into contact with the contact surface so that the first node does not overlap at least one second node appearing on the contact surface. How to simulate tires. [Disclosure 2] The tire simulation method described in Disclosure 1, wherein the rim assembly process brings the tire model into contact with the contact surface so that the first node does not overlap any of the second node appearing on the contact surface. [Disclosure 3] the assembly model has a tire rotation axis, The tire simulation method according to Disclosure 1 or 2, wherein the simulation step includes a step of calculating a physical quantity acting on the tire rotation axis. [Disclosure 4] a step of inputting a road surface model obtained by modeling a road surface into the computer; The tire simulation method according to any one of Disclosures 1 to 3, wherein the simulation step includes a step of rolling the assembly model on the road surface model and calculating the physical quantities. [Disclosure 5] The rim is integrally formed with a disk portion extending from the rim in the wheel radial direction, the assembly model includes a disk model that models the disk portion, The tire simulation method according to Disclosure 4, wherein the step of calculating the physical quantity calculates the physical quantity taking into account inertial characteristics of the disc model. [Disclosure 6] The tire model has a tread contact surface, A tire simulation method according to any one of Disclosures 1 to 5, wherein the simulation step includes a step of applying a load to at least one first node appearing on the tread contact surface and calculating the physical quantity. [Explanation of symbols]

[0087] 21 Assembly Model 22 tire models 23 rim model 29 Contact surface 31 First Node 32 Second Node

Claims

1. A simulation method for evaluating the performance of a tire mounted on a rim, comprising: inputting a tire model obtained by discretizing the tire using a finite number of first elements having a plurality of first nodes into a computer; and inputting a rim model having a contact surface with the tire model into the computer by discretizing the rim using a finite number of second elements having a plurality of second nodes, The computer a rim assembling step of bringing the tire model into contact with the contact surface to set an assembly model of the rim model and the tire model; a simulation step of calculating physical quantities related to the performance of the tire using the assembly model; the rim-assembling step includes bringing the tire model into contact with the contact surface while separating all of the second nodes and the first nodes in the tire circumferential direction so that the first nodes do not overlap with all of the second nodes appearing on the contact surface. How to simulate tires.

2. The step of inputting the tire model includes: copying the two-dimensional tire model in the tire circumferential direction at a predetermined angle pitch P1 to set a three-dimensional tire model; the step of inputting the rim model includes setting a three-dimensional rim model by copying the two-dimensional rim model in the tire circumferential direction at a predetermined angular pitch P2; The angular pitch P2 is set to be the same as the angular pitch P1, 2. The tire simulation method according to claim 1, wherein the rim assembling step moves one of the tire model and the rim model relative to the other of the tire model and the rim model in the tire circumferential direction, thereby separating the first node and the second node that overlap with each other.

3. the assembly model has a tire rotation axis, 3. The tire simulation method according to claim 1, wherein the simulation step includes a step of calculating a physical quantity acting on the tire rotation axis.

4. a step of inputting a road surface model obtained by modeling a road surface into the computer; 4. The tire simulation method according to claim 1, wherein the simulation step includes a step of rolling the assembly model on the road surface model and calculating the physical quantities.

5. The rim is integrally formed with a disk portion extending from the rim in the wheel radial direction, the assembly model includes a disk model that models the disk portion, The tire simulation method according to claim 4 , wherein the step of calculating the physical quantity calculates the physical quantity taking into account inertial characteristics of the disc model.

6. The tire model has a tread contact surface, 6. The tire simulation method according to claim 1, wherein the simulation step includes a step of applying a load to at least one first node appearing on the tread contact surface and calculating the physical quantity.

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