JP2015123941A - Tire wear simulation device, method and program of it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate wear while suppressing calculation cost.SOLUTION: Plural rolling conditions having different load, longitudinal force, lateral force, and a camber angle are set (S2), and frictional energy is calculated by analyzing rolling of a tire model in the plural rolling conditions (S3, S4). Then, by interpolation calculation using the frictional energy in the plural rolling conditions, about respective mode of tire traveling, frictional energy during direct advance, increment of frictional energy by the longitudinal force, increment of frictional energy by the lateral force, and increment of frictional energy by the camber angle are respectively calculated (S31-S35), and the frictional energy in the respective mode is calculated by adding them (S6). Integration frictional energy is calculated by multiplying travel frequency to the frictional energy in the respective mode, a wear amount on a tread surface is calculated (S7, S8), and a wear tire model is created by moving the tread surface based on the wear amount (S9).

Description

  The present invention relates to an apparatus, a method and a program for analyzing tire wear due to running by simulation.

  In the development of pneumatic tires, numerical performance analysis methods such as finite element method (FEM) can be used to evaluate the performance of newly designed pneumatic tires without actually manufacturing pneumatic tires and mounting them on automobiles for testing. It has become possible to predict and evaluate using. Such numerical analysis techniques are also used for predicting the wear life of pneumatic tires and predicting the wear progress of uneven wear such as heel and toe wear, and various wear simulation methods have been developed.

  As a pneumatic tire wear simulation method, the tire model is rolled to calculate the friction energy, the wear amount is set according to the calculated friction energy, and the wear model is generated. Methods for predicting progress are known (see, for example, Patent Documents 1 and 2). In addition, in order to predict tire wear in accordance with actual driving conditions, when rolling analysis of the tire model, rolling analysis under multiple conditions is performed and friction energy during driving is calculated based on the driving frequency In some cases (for example, see Patent Documents 1 to 3).

  When predicting wear according to the above driving conditions, in order to calculate the friction energy in each driving mode, the longitudinal force, lateral force, load, etc. generated on the axle in each mode are input as rolling conditions. It is necessary to perform rolling analysis. However, in such a method, when the vehicle to be mounted and the tire mounting position (observation position) are changed, the rolling analysis must be performed under the conditions each time, and the calculation cost is high.

JP 2005-263070 A JP 2010-237023 A JP 2013-083575 A

  The present invention has been made in view of the above points, and an object of the present invention is to provide a tire wear simulation device, a method thereof, and a program capable of predicting wear while suppressing calculation costs.

  A tire wear simulation apparatus according to the present invention includes a model creating unit that creates a tire model in which a tire is divided into a finite number of elements; load, longitudinal force, lateral force, and camber angle as conditions for rolling the tire model A rolling condition setting unit that sets a plurality of reference rolling conditions that are different from each other; a rolling analysis unit that performs a rolling analysis of the tire model under the plurality of rolling conditions; and the rolling A reference friction energy calculation unit for calculating friction energy for each of the plurality of rolling conditions from the result of the analysis; each mode of tire running to be simulated by interpolation calculation using the friction energy under the plurality of rolling conditions; , The frictional energy during straight travel, the increase in frictional energy due to longitudinal force, the increase in frictional energy due to lateral force, and the camber angle Respectively, and by adding the frictional energy increase due to the longitudinal force, the frictional energy increase due to the lateral force, and the frictional energy increase due to the camber angle to the frictional energy at the time of straight travel, A mode friction energy calculation unit that calculates friction energy in each mode; an integrated friction energy calculation unit that calculates cumulative friction energy by multiplying the friction energy of each mode by a running frequency of each mode; A wear amount calculating unit that calculates a wear amount on the tread surface based on friction energy; and a wear model generating unit that generates a worn tire model by moving the tread surface of the tire model based on the wear amount; Is.

  According to the present invention, friction energy is obtained for each of a plurality of reference rolling conditions, and in the process of calculating the friction energy in each mode of tire travel, interpolation using the friction energy in the plurality of rolling conditions is performed. The frictional energy of each component is calculated by calculation. Therefore, wear prediction can be performed while suppressing calculation cost. The friction energy in each mode is calculated by adding the frictional energy increase due to the longitudinal force, the frictional energy increase due to the lateral force, and the frictional energy increase due to the camber angle to the frictional energy during straight travel. In addition, since the friction energy increase due to the camber angle is also calculated and added by the interpolation, the prediction accuracy of the friction energy in each mode can be improved.

The block diagram of the wear simulation apparatus which concerns on embodiment. The block diagram of the mode friction energy calculation part of the apparatus. The flowchart of the same apparatus. The flowchart of the model preparation part of the apparatus. The flowchart of the mode friction energy calculation part of the apparatus. The perspective view which shows an example of a tire model. The figure which shows a rolling condition file. The figure which shows the axial force file of vehicle travel. The graph which shows the experimental data of the relationship between external force and friction energy. (A) is a figure which shows the tread pattern of the pneumatic tire used for the tabletop abrasion test, (b) is a graph which shows the relationship between the camber angle and the amount of wear in a tabletop abrasion test. The graph which shows the interpolation method about the friction energy at the time of straight traveling. The graph which shows the interpolation method about the friction energy by a driving force. The graph which shows the interpolation method about the friction energy by braking force. The graph which shows the interpolation method about the friction energy by lateral force (+). The graph which shows the interpolation method about the friction energy by lateral force (-). The graph which shows the interpolation method about the friction energy by a camber angle (+). The graph which shows the interpolation method about the friction energy by a camber angle (-). Explanatory drawing for showing the method of moving a node in a wear model production | generation process. The conceptual diagram which shows the relationship between the initial model in Example 1, and a wear model. The conceptual diagram of the initial model and wear model in Example 2. FIG. The conceptual diagram which shows the relationship between the initial model in the reference example 1, and a wear model. The conceptual diagram of the initial model and wear model in the reference example 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a tire wear simulation apparatus 10 according to an embodiment includes an input unit 12, a model creation unit 14, a rolling condition setting unit 16, a rolling analysis unit 18, a reference friction energy calculation unit 20, and a mode. A friction energy calculation unit 22, an integrated friction energy calculation unit 24, a wear amount calculation unit 26, a wear model generation unit 28, a determination unit 30, a model update unit 32, and an output unit 34 are included. As shown in FIG. 2, the mode friction energy calculation unit 22 includes a straight traveling energy calculation unit 40, a longitudinal force increase calculation unit 42, a lateral force increase calculation unit 44, a camber angle increase calculation unit 46, and an energy calculation. Part 48.

  The simulation apparatus 10 can also be realized by using, for example, a general-purpose computer having a mouse and a keyboard as basic hardware. That is, the input unit 12, the model creation unit 14, the rolling condition setting unit 16, the rolling analysis unit 18, the reference friction energy calculation unit 20, the mode friction energy calculation unit 22 (specifically, the straight travel energy calculation unit 40, front and rear Force increase calculation unit 42, lateral force increase calculation unit 44, camber angle increase calculation unit 46 and energy calculation unit 48), integrated friction energy calculation unit 24, wear amount calculation unit 26, wear model generation unit 28, determination unit 30, the model update unit 32 and the output unit 34 can be realized by causing a processor mounted on the computer to execute a program. At this time, the simulation apparatus 10 may be realized by installing the above-described program in a computer in advance, or may be stored in a computer-readable storage medium such as a CD-ROM or DVD, or via the network. This program may be distributed and this program installed on a computer as appropriate.

  Hereinafter, the configuration and functions of the above-described units will be described in order.

[1] Input unit 12
The input unit 12 acquires data (tire design information) about the tire including the cross-sectional shape of the pneumatic tire to be analyzed. Specifically, the dimensions, layout, and materials of each tire member such as tire dimensions such as the outer shape and internal structure of the tire, tread rubber, sidewall rubber, belt, carcass ply, bead core, and chacher constituting the tire Physical property values are entered. The input of such information may be performed using a keyboard, or may be performed through a recording medium, a network, or the like.

[2] Model creation unit 14
The model creation unit 14 creates a tire model obtained by dividing the tire to be simulated into a finite number of elements based on the data input by the input unit 12. A tire model is a tire model that is digitized into an input data format for a computer program created based on numerical and analytical methods. In this embodiment, a finite element method (FEM) is used as a numerical analysis method. Therefore, the tire model is divided into a plurality of elements by element division corresponding to the finite element method, for example, mesh division.

  Specifically, in this example, the model creating unit 14 sets a boundary between the tread pattern and the tire body from the tire cross-sectional shape (cross-sectional shape along the meridian), and then sets a tread pattern of one pitch for the tread pattern. The mesh is divided and developed in the tire circumferential direction to generate a 3D (three-dimensional) pattern FE model. In addition, the cross section of the tire body is divided into meshes and developed in the tire circumferential direction to generate a 3D (three-dimensional) tire body FE model. Then, by synthesizing these 3D pattern FE model and 3D tire body FE model, for example, a tire FE model with a pattern as shown in FIG. 6 is generated as a tire model.

[3] Rolling condition setting unit 16
The rolling condition setting unit 16 sets conditions necessary for rolling the tire model obtained above. Examples of conditions include tire-side conditions such as rim size, air pressure, and rolling conditions, and road-surface conditions include, for example, a friction coefficient.

  In the present embodiment, as the rolling condition, a plurality of rolling conditions that are different from each other in any one or more of a load (vertical load), a longitudinal force, a lateral force, and a camber angle applied to the axle are set. Here, 18 conditions as shown in FIG. 7 are set as rolling conditions. Specifically, the load is set to two conditions of one condition of low load and one condition of high load, and the longitudinal force is set to three conditions of driving force 1 condition, braking force 1 condition and longitudinal force 0, The force is set to three conditions of + lateral force (left turn) 1 condition,-lateral force (right turn) 1 condition and lateral force 0, and the camber angle is α, with a certain camber angle as α [°]. Five conditions of 2α, −α, −2α and 0 are set. For each of the low load and the high load, the straight-running condition (conditions 1 and 10) in which the longitudinal force, the lateral force and the camber angle are 0, and the lateral force adding condition (condition 2) , 3, 11, 12), a longitudinal force addition condition (conditions 4, 5, 13, 14) in which a longitudinal force is added to the straight travel condition, and a camber angle addition condition in which a camber angle is added to the straight travel condition (conditions 4, 5, 13, 14) Conditions 6-9 and 15-18 are set.

[4] Rolling analysis unit 18
The rolling analysis unit 18 performs rolling analysis of the tire model under the plurality of rolling conditions. The rolling analysis is to analyze a change when the tire in contact with the road surface is rotated, that is, the deformation of the tire shape, which is known per se and can be performed using such a known method. .

  In the present embodiment, the rolling analysis unit 18 attaches the tire model to the rim model and applies a predetermined air pressure, and then grounds the tire model on the road surface model and rolls it under the rolling conditions for analysis. Do. Then, time series data of the pressure and displacement of the node (surface node) Ns (see FIG. 6) located on the tread surface is acquired for all the surface nodes. The rolling analysis is performed for all the rolling conditions (18 conditions) set above.

[5] Reference friction energy calculation unit 20
The reference friction energy calculation unit 20 calculates the friction energy (E) for each of a plurality of rolling conditions from the result of the rolling analysis. The friction energy is calculated in order to evaluate the degree of ease of wear using the energy due to friction when the tread surface contacts the road surface.

Friction energy (E) received from the road surface while an arbitrary node Ns on the tread surface in the contact surface is in contact with the ground (that is, stepping to kicking) is expressed by the following formula (1).

  Here, L is the contact length (the length from contact to release), Px is the circumferential shear pressure, Py is the width direction shear pressure, Sx is the circumferential slip displacement, and Sy is the width direction slip displacement.

  In the present embodiment, the reference friction energy calculation unit 20 calculates the friction energy (E) for all of the plurality of reference rolling conditions. In the present embodiment, the friction energy calculated by the reference friction energy calculation unit 20 is referred to as reference friction energy.

[6] Mode friction energy calculation unit 22
The mode friction energy calculation unit 22 performs, for each tire running mode to be simulated, by interpolation calculation using the reference friction energy, the friction energy during straight travel, the increase in friction energy due to longitudinal force, and the friction due to lateral force. Calculate the amount of increase in energy and the amount of increase in friction energy due to the camber angle, and calculate the amount of increase in friction energy due to longitudinal force, the amount of increase in friction energy due to lateral force, and the amount of increase in friction energy due to camber angle as the friction energy during straight travel. In addition, the friction energy in each mode (hereinafter sometimes referred to as mode friction energy) is calculated.

Each mode of tire traveling is a state in which the vehicle performs circular turning, driving braking, and straight traveling according to the level of lateral G and front and rear G. FIG. 8 shows an example of an axial force file that shows the longitudinal force (Fx), lateral force (Fy), load (Fz), and camber angle (CA) generated on the axle in each mode, along with the traveling frequency. As such an axial force file, it is possible to use a file obtained by actual measurement by running a vehicle with an acceleration sensor or GPS measuring instrument directly on the market or a wear test course, or vehicle simulation. You may use what was obtained by analysis by. Note that G represents gravitational acceleration (1.0 G = 9.806 65 m / s ² ).

In this embodiment, in order to calculate the mode friction energy, an interpolation calculation using the friction energy results of the plurality of representative conditions (18 conditions) is performed. In this case, the mode friction energy (Etotal) is obtained by adding the increase in friction energy due to the longitudinal force, lateral force, and camber angle to the friction energy during straight travel, and is expressed by the following equation (2).

  Here, E_Free is the friction energy at the time of straight traveling, and specifically, is the friction energy at the above-mentioned straight traveling condition (Fx = 0, Fy = 0, CA = 0). ΔE_Fx_CA0 is an increase in frictional energy (Fy = 0, CA = 0) due to the longitudinal force (Fx) from the frictional energy during straight travel. ΔE_Fy_CA0 is an increase in frictional energy (Fx = 0, CA = 0) due to lateral force (Fy) from the frictional energy during straight travel. ΔE_CA is an increase in frictional energy (Fx = 0, Fy = 0) due to the camber angle (CA) from the frictional energy during straight travel.

  For example, the frictional energy at braking 0.15G is the frictional energy during straight running at Fz = 4000N, the frictional energy increase due to Fx = −450N (braking force), the frictional energy increase due to Fy = −300N, and CA = The frictional energy increase by -0.8 ° is added.

  In general, vehicle alignment includes a toe angle and a camber angle. The toe angle is an angle around the vertical axis (Z axis) of the tire, and the camber angle is an angle around the front and rear axis (X axis) of the tire. Lateral force Fy is generated when the angle is set, but the toe angle has a stronger influence on the lateral force than the camber angle and can be considered to be included in the lateral force. Therefore, the difference in toe angle is included in ΔE_Fy_CA0. On the other hand, since the camber angle is also affected by the ground contact shape, it cannot be reproduced by the same method as the toe angle. For this reason, the ΔE_CA term is introduced in this embodiment.

  In order to calculate Etotal, it is necessary to obtain E_Free, ΔE_Fx_CA0, ΔE_Fy_CA0, and ΔE_CA, and in this embodiment, interpolation calculation using the reference friction energy is performed.

  Here, in order to calculate E_Free, ΔE_Fx_CA0, and ΔE_Fy_CA0, the relationship between the external force and the friction energy obtained based on the experimental data is applied. According to the experimental data, as shown in FIG. 9A, the friction energy (E) is proportional to the load (Fz). Further, according to the experimental data, as shown in FIG. 9B, the frictional energy (E) is proportional to the square of the input load (Fx) for the longitudinal force (the square of the driving force, the braking force). Squared). Further, according to the experimental data, as shown in FIG. 9C, the frictional energy (E) is proportional to the square of the input load (Fy) with respect to the lateral force (the square of the lateral force during turning). ).

  As for ΔE_CA, it was found by experiments that the wear energy and the camber angle have a non-linear relationship. That is, for the pneumatic tire having the tread pattern shown in FIG. 10A, the relationship between the camber angle and the amount of wear (wear energy) was examined by a bench friction test. Specifically, a table wear test was performed under three conditions with camber angles of 0 °, −1 °, and −2 °, and the ground contact end (Out_Sh end) on the vehicle outer side in FIG. The amount of wear at the three points of the ground contact end (In_Sh end) and the position near the tread center (S1) was measured. As a result, as shown in FIG. 10B, it was found that the camber angle and the wear energy are in a non-linear relationship, and it is effective to define a quadratic curve.

  In view of this knowledge, in this embodiment, the mode friction energy calculation unit 22 calculates the mode friction energy (Etotal) as follows. As described above, the mode friction energy calculation unit 22 includes the straight traveling energy calculation unit 40, the longitudinal force increase calculation unit 42, the lateral force increase calculation unit 44, the camber angle increase calculation unit 46, and the energy calculation unit 48. Therefore, it demonstrates in order below.

[7] Linear energy calculation unit 40
The straight travel energy calculation unit 40 calculates the straight travel friction energy E_Free in each mode by interpolation calculation using the relationship between the friction energy under a plurality of rolling conditions with different loads (Fz) and the load. In addition, although the load of the rolling conditions used for interpolation is normally 2 conditions, you may improve calculation precision as 3 conditions or more.

  Specifically, since friction energy (E) is proportional to Fz, a linear function of E and Fz is obtained from the friction energy values of conditions 1 and 10 among the above-mentioned reference friction energies as shown in FIG. Then, an energy value corresponding to the Fz value (Fz1 in the figure) of the mode to be calculated is obtained from the linear function, and this is defined as the frictional energy E_Free at the time of straight travel of the mode. In addition, in FIGS. 11-17, the point showing the friction energy value of condition n (however, n = 1-18) is shown by (n).

[8] Longitudinal force increase calculation unit 42
The longitudinal force increase calculation unit 42 calculates the increase in friction energy ΔE_Fx_CA0 due to the longitudinal force in each mode by interpolation calculation using the relationship between the frictional energy and the longitudinal force under a plurality of rolling conditions with different longitudinal forces (Fx). Is calculated. The longitudinal force of the rolling condition used for the interpolation is usually one condition for each of the positive value and the negative value in addition to the longitudinal force 0, but the calculation accuracy may be improved by setting two conditions or more.

Specifically, since the friction energy (E) is proportional to the square of Fx, the load of two conditions (Fz) for each of the driving force (+ value) and the braking force (− value) of the reference friction energy. ) A linear function of E and the square of Fx (Fx ² ) under the conditions is obtained. FIG. 12A shows the case of the driving force. From the friction energy values of conditions 1 and 4 and conditions 10 and 13, the load of E and Fx ² is obtained for a load (Fz) of 2 conditions. Find each linear function. FIG. 13A shows the case of braking force. From the friction energy values of Condition 1 and Condition 5, Condition 10 and Condition 14, the load of E and Fx ² with respect to the load of two conditions (Fz). Find each linear function.

  When calculating ΔE_Fx_CA0, first, the Fx value (Fx1) of the calculation target mode is divided into a driving force (+ value) and a braking force (−value).

  In the case of driving force (Fx> 0), as shown in FIG. 12A, energy values E1 at low load and energy values E2 at high load are obtained as energy values corresponding to Fx1, respectively, As shown in FIG. 12B, the energy value (E_Fx_CA0) corresponding to the Fz value (Fz1) of the calculation target mode is obtained from the obtained two energy values E1 and E2 by interpolation using a linear function. Then, the frictional energy increase ΔE_Fx_CA0 due to the longitudinal force of the mode is obtained by subtracting the frictional force E_Free during straight travel of the mode from the obtained energy value E_Fx_CA0 (ΔE_Fx_CA0 = E_Fx_CA0−E_Free).

  The case of the braking force (Fx <0) is the same as the case of the driving force except that the linear function shown in FIG. 13A is used, and the longitudinal force in the calculation target mode as shown in FIG. 13B. Is obtained, and by subtracting E_Free from this, the friction energy increase ΔE_Fx_CA0 due to the longitudinal force of the mode is obtained.

[9] Lateral force increase calculation unit 44
The lateral force increase calculation unit 44 calculates the increase in frictional energy ΔE_Fy_CA0 due to the lateral force in each mode by interpolation calculation using the relationship between the frictional energy and the lateral force under a plurality of rolling conditions with different lateral forces (Fy). Is calculated. In addition, although the lateral force of the rolling condition used for the interpolation is usually one condition for each of the + value and the − value in addition to the lateral force of 0, the calculation accuracy may be improved by setting two conditions or more.

Specifically, since the frictional energy (E) is proportional to the square of Fy, the lateral force of each of the reference frictional energy has a positive value and a negative value under two load (Fz) conditions. A linear function of E and the square of Fy (Fy ² ) is obtained. FIG. 14A shows the case of lateral force + value. From the friction energy values of conditions 1 and 2 and conditions 10 and 11, E and Fy ² for a load (Fz) of 2 conditions. And find the linear function. FIG. 15A shows the case of lateral force-value. From the friction energy values of Condition 1 and Condition 3, Condition 10 and Condition 12, E and Fy ² for a load (Fz) of 2 conditions. And find the linear function.

  When calculating ΔE_Fy_CA0, first, the Fy value (Fy1) of the calculation target mode is classified into a positive value and a negative value. In the case of a positive value (Fy> 0), as shown in FIG. 14A, an energy value E3 at a low load and an energy value E4 at a high load are obtained as energy values corresponding to Fy1, respectively, As shown in FIG. 14B, an energy value (E_Fy_CA0) corresponding to the Fz value (Fz1) of the calculation target mode is obtained from the obtained two energy values E3 and E4 by interpolation using a linear function. Then, the frictional energy increase ΔE_Fy_CA0 due to the lateral force of the mode is obtained by subtracting the frictional force E_Free during straight travel of the mode from the obtained energy value E_Fy_CA0 (ΔE_Fy_CA0 = E_Fy_CA0−E_Free). The negative value (Fy <0) is the same as the positive value except that the linear function shown in FIG. 15A is used. As shown in FIG. Is obtained, and by subtracting E_Free from this, the friction energy increase ΔE_Fy_CA0 due to the lateral force of the mode is obtained.

[10] Camber angle increase calculation unit 46
The camber angle increase calculation unit 46 defines a relationship between the friction energy and the camber angle under a plurality of rolling conditions having different camber angles (CA) by a quadratic curve, and performs an interpolation calculation using the quadratic curve. The increase ΔE_CA of the friction energy due to the camber angle in each mode is calculated. In addition, although the camber angle of the rolling condition used for the interpolation is normally set to two conditions for the + value and the − value in addition to the camber angle 0, the calculation accuracy may be improved by setting each of the three conditions or more.

  Specifically, the relationship between E and CA under the two load (Fz) conditions is obtained with a quadratic curve for each of the camber angle having a positive value and a negative value of the reference friction energy. FIG. 16A shows the case of the camber angle + value. From the friction energy values of conditions 1 and 6 and 7, and conditions 10 and 15 and 16, E and Each quadratic function with CA is obtained. FIG. 17A shows the case of the camber angle-value. From the friction energy values of conditions 1 and 8 and 9, and conditions 10 and 17 and 18, E and Each quadratic function with CA is obtained.

  When calculating ΔE_CA, first, the CA value (CA1) of the calculation target mode is classified into a positive value and a negative value. In the case of a positive value (CA> 0), as shown in FIG. 16A, an energy value E5 at a low load and an energy value E6 at a high load are obtained as energy values corresponding to CA1, respectively, As shown in FIG. 16B, the energy value (E_CA) corresponding to the Fz value (Fz1) of the calculation target mode is obtained from the obtained two energy values E5 and E6 by interpolation using a linear function. Then, by subtracting the frictional energy E_Free during straight travel of the mode from the obtained energy value E_CA, a friction energy increase ΔE_CA due to the camber angle of the mode is obtained (ΔE_CA = E_CA−E_Free). The case of −value (CA <0) is the same as the case of + value except that the quadratic curve shown in FIG. 17A is used. As shown in FIG. The frictional energy E_CA by the angle is obtained, and by subtracting E_Free from this, the frictional energy increase ΔE_CA by the camber angle of the mode is obtained.

[11] Energy calculation unit 48
The energy calculation unit 48 calculates the friction energy Etotal in each mode from E_Free, ΔE_Fx_CA0, ΔE_Fy_CA0, and ΔE_CA obtained above based on Expression (2). The calculation is performed for all modes shown in FIG.

[12] Integrated friction energy calculation unit 24
The integrated friction energy calculation unit 24 calculates the integrated friction energy by multiplying the friction energy of each mode obtained above by the running frequency of each mode and integrating the result. That is, by multiplying the wear energy of each mode by the travel frequency of that mode and adding the obtained products, the cumulative friction energy at each surface node in the simulated tire travel can be obtained. Therefore, the accumulated frictional energy is acquired for all surface nodes located on the tread surface.

  The travel frequency is a ratio of each mode when the tire is traveled on the market or a wear test course, and is obtained by actual measurement by actual vehicle travel or by analysis by vehicle simulation as described above. An example thereof is shown in FIG. 8, and the total of the driving frequencies in these modes is 1.

[13] Wear amount calculation unit 26
The wear amount calculation unit 26 calculates the wear amount on the tread surface, that is, the wear amount of each surface node located on the tread pattern surface, based on the accumulated friction energy. The method for calculating the wear amount is not particularly limited, but since the wear amount is generally proportional to the friction energy, the wear information of the rubber material with respect to the friction energy is obtained from analysis and experiment, and the proportional relationship between the friction energy and the wear amount is obtained. And the amount of wear may be calculated from the cumulative friction energy using the proportional relationship.

[14] Wear model generation unit 28
The wear model generation unit 28 generates (creates) a wear tire model by moving the tread surface of the tire model based on the wear amount. That is, the wear model generation unit 28 moves the surface node of the tire model in the vertical direction (tread thickness direction) by the wear amount.

In this embodiment, the surface node is moved, and the internal node is moved in consideration of the amount of movement of the surface node. Specifically, as shown in FIG. 18, the wear model generation unit 28 sets the wear amount to D, sets the distance from the surface node Ns located on the tread surface to the first internal node Nu1 adjacent in the thickness direction, a, first. The distance between the i-th internal node and the (i + 1) -th internal node that are successively adjacent in the thickness direction from the internal node Nu1 is b _i (where i is an integer equal to or greater than _1, and b ₁ and b ₂ are shown in FIG. 18). )), The movement amount of the surface node Ns is set to D, and the movement amount of the i-th internal node Nu1, Nu2 including the first internal node is set to D × b _i / a (D × b ₁ / a, in FIG. 18). D × b ₂ / a). In the example of FIG. 18, Nu3 is not moved because it is the tread bottom. Thereby, the position of the node (initial model position) in the initial tire model indicated by the solid line in FIG. 18 becomes the wear model position indicated by the broken line.

When the movement amount D of the surface node Ns is larger than the a, the wear model generation unit 28 deletes an element including the surface node Ns and subtracts a from the movement amount D (D−a). Is the amount of movement of the surface node after element deletion, and the amount of movement of the i-th internal node including the first internal node after element deletion is set to (D−a) × b _i / a.

FIG. 19 shows an example of a node movement method as the first embodiment. Example 1 is a case where the wear amount D is smaller than the thickness a of the surface element. In this case, each surface node is moved in the thickness direction by the wear amount D, and the i-th internal node is D × in the thickness direction. Move b _i / a. Note that the node Ng at the groove bottom and its internal node are not moved. That is, the movement of the internal node in this embodiment is performed for the node at the bottom of the groove and the node other than the internal node.

FIG. 20 shows a method for moving nodes according to the second embodiment. In Example 2, the wear amount D is larger than the thickness a of the surface element. In this case, the surface element in the initial model is deleted, and each surface node after the element deletion is moved in the thickness direction by the movement amount (Da). The i-th internal node after element deletion is moved in the thickness direction by (D−a) × b _i / a.

  FIG. 21 shows a method for moving nodes according to the first reference example. Reference Example 1 is an example in which the amount of wear D is smaller than the thickness a of the surface element and the internal nodes are not moved. FIG. 22 shows a method of moving nodes according to Reference Example 2. Reference Example 2 is an example in which the amount of wear D is larger than the thickness a of the surface element and the internal node is not moved. The surface element in the initial model is deleted, and the surface node after the element deletion is moved (D− It is moved in the thickness direction in a).

  In Reference Examples 1 and 2, since the internal nodes are not moved, the thickness of the surface element after wear is small, and the overall mesh is large and dense. Therefore, in the next rolling analysis, there is a possibility that the calculation stops or the calculation time increases. On the other hand, in the first and second embodiments, the density of the entire mesh can be reduced, so that the convergence of calculation in the next rolling analysis is improved and the calculation cost can be reduced.

[15] Determination unit 30
The determination unit 30 determines whether the wear amount from the initial tire model in the worn tire model satisfies a predetermined target wear amount.

[16] Model update unit 32
The model update unit 32 updates the tire model when the determination unit 30 determines that the target wear amount is not satisfied. That is, the model update unit 32 converts the worn tire model generated by the wear model generation unit 28 into the next rolling motion. Set as a tire model for analysis.

[17] Output unit 34
The output unit 34 outputs a worn tire model that satisfies the target wear amount. The output of the worn tire model can be performed by displaying it on a display or printing it with a printer. It may be stored in a storage device such as a hard disk or a recording medium such as a DVD.

  Next, the operation state of the simulation apparatus 10 according to the present embodiment will be described based on the flowcharts of FIGS.

  In step S1, the model creation unit 14 creates a tire model with a pattern. Specifically, as illustrated in FIG. 4, first, in step S <b> 21, the input unit 12 acquires design information of a pneumatic tire to be analyzed. Next, in step S22, the model creation unit 14 sets a boundary between the tread pattern and the tire body from the tire cross-sectional shape. Thereafter, in step S23, the tread pattern of one pitch is divided into meshes for the tread pattern, and then in step S24, the tread pattern divided in mesh is developed in the tire circumferential direction to generate a 3D pattern FE model. In step S25, the cross section of the tire body is mesh-divided, and then in step S26, the mesh-divided tire body cross section is developed in the tire circumferential direction to generate a 3D tire body FE model. Thereafter, in step S27, the 3D pattern FE model obtained above and the 3D tire body FE model are synthesized to generate a patterned tire FE model.

  Next, in step S2, the rolling condition setting unit 16 sets conditions necessary for rolling the tire model. At that time, as the tire-side conditions, as shown in FIG. 7, a plurality of reference rolling conditions having different loads, longitudinal forces, lateral forces, and camber angles applied to the axles are set. Then, the process proceeds to step S3.

  In step S3, the rolling analysis unit 18 performs rolling analysis of the tire model under the plurality of rolling conditions described above, and all the time series data of the pressure and displacement of the surface nodes located on the tread surface are located on the tread surface. Get the surface nodes of.

  Next, in step S4, the reference friction energy calculation unit 20 calculates the reference friction energy for all surface nodes located on the tread surface based on the expression (1) from the result of the rolling analysis, and in step S5. Proceed to

  In step S5, the reference friction energy calculation unit 20 determines whether or not the reference friction energy has been calculated for all the rolling conditions (18 conditions). If not, the process returns to step S3 to calculate all. Steps S3-5 are repeated until If it is determined that the reference friction energy has been calculated for all rolling conditions, the process proceeds to step S6.

  In step S6, the mode friction energy calculation unit 22 calculates the friction energy (mode friction energy) in each tire running mode to be simulated (see FIG. 8) by interpolation calculation using the reference friction energy.

  Specifically, as shown in FIG. 5, in step S31, the straight traveling energy calculation unit 40 performs the interpolation calculation using the relationship between the friction energy and the load under a plurality of rolling conditions with different loads Fz. The frictional energy E_Free during straight running in the mode is calculated (see FIG. 11).

In step S32, the longitudinal force increase calculation unit 42 performs an interpolation calculation using the relationship between the frictional energy and the longitudinal force under a plurality of rolling conditions having different longitudinal forces Fx, and the longitudinal force in the mode is calculated. Fraction energy increase ΔE_Fx_CA0 due to is calculated. Specifically, first, it is determined whether the Fx value (Fx1) of the mode is a driving force (+ value) or a braking force (− value). In the case of a driving force, the rolling condition with the driving force applied is determined. Based on the linear relationship between E and Fx ² obtained using the friction energy, E_Fx_CA0 is calculated (see FIG. 12), and ΔE_Fx_CA0 is further calculated. On the other hand, if the braking force, based on a linear relationship between E and Fx ² obtained using the friction energy in the rolling conditions apply braking force to calculate a E_Fx_CA0 (see FIG. 13), a further ΔE_Fx_CA0 calculate.

In step S33, the lateral force increase calculation unit 44 performs an interpolation calculation using the relationship between the frictional energy and the lateral force under a plurality of rolling conditions with different lateral forces Fy, and the lateral force in the mode is calculated. Fraction energy increase ΔE_Fy_CA0 due to is calculated. Specifically, first, it is determined whether the Fy value (Fy1) of the mode is a positive value or a negative value. If the positive value is positive, the frictional energy under the rolling condition to which a positive lateral force is applied is used. Based on the obtained linear relationship between E and Fy ² , E_Fy_CA0 is calculated (see FIG. 14), and ΔE_Fy_CA0 is further calculated. On the other hand, - if the value, - based on the linear relationship between E and Fy ² obtained using the friction energy in the rolling conditions of the lateral force imparted values, calculates E_Fy_CA0 (see FIG. 15), Further, ΔE_Fy_CA0 is calculated.

  Further, in step S34, the camber angle increase calculation unit 46 calculates the friction due to the camber angle in the mode by interpolation calculation using the relationship between the friction energy and the camber angle under a plurality of rolling conditions having different camber angles CA. Calculate the energy increase ΔE_CA. Specifically, first, it is determined whether the CA value (CA1) of the mode is a positive value or a negative value, and in the case of a positive value, the friction energy under the rolling condition with a positive camber angle is used. Based on the obtained quadratic curve of E and CA, E_CA is calculated (see FIG. 16), and ΔE_CA is further calculated. On the other hand, in the case of -value, E_CA is calculated based on the quadratic curve of E and CA obtained by using frictional energy under rolling conditions with a -value camber angle (see FIG. 17), Further, ΔE_CA is calculated.

  After calculating E_Free, ΔE_Fx_CA0, ΔE_Fy_CA0, and ΔE_CA in this way, in step S35, the energy calculation unit 48 calculates the friction energy Etotal in the mode based on the above equation (2). Next, in step S36, the energy calculation unit 48 determines whether or not the mode friction energy Etotal has been calculated for all the modes of tire travel to be simulated (see FIG. 8). Returning to step S31, steps S31 to S36 are repeated until all are calculated. And if it determines with having calculated the mode friction energy Etotal about all the modes, it will progress to step S7.

  In step S <b> 7, the cumulative friction energy calculation unit 24 calculates the cumulative friction energy by multiplying the friction energy of each mode obtained above by the travel frequency of the mode and integrating the result.

  Next, in step S8, the wear amount calculation unit 26 calculates the wear amount of each surface node located on the surface of the tread pattern based on the accumulated friction energy obtained above. Then, the process proceeds to step S9.

  In step S9, the wear model generation unit 28 generates a wear tire model by moving the tread surface of the tire model based on the wear amount obtained above. At this time, in this embodiment, as shown in FIGS. 18 and 19, the surface node is moved, and the internal node is moved in consideration of the movement amount of the surface node. Further, when the movement amount D of the surface node Ns is larger than the thickness a of the surface element, the wear model generation unit 28 deletes the element including the surface node Ns as shown in FIG. The value obtained by subtracting a from (D−a) is used as the movement amount of the surface node after element deletion, and the internal node after element deletion is also moved.

  Next, in step S10, the determination unit 30 determines whether or not the wear amount from the initial tire model satisfies a predetermined target wear amount for the wear tire model obtained as described above. If so, the process proceeds to step S11. The determination by the determination unit 30 may be performed after the worn tire model is generated in this way, or may be performed before the worn tire model is generated, and step S9 may be performed after the determination. Good.

  In step S11, the model update unit 32 sets a worn tire model that does not satisfy the target wear amount as a tire model for the next rolling analysis, and proceeds to step S3. That is, the worn tire model generated in step S9 is designated as a tire model to be subjected to rolling analysis in the next step S3. Then, steps S3 to S11 are repeated until the target friction amount is satisfied in step S10.

  On the other hand, when it is determined in step S10 that the worn tire model satisfies the target friction amount, the process proceeds to step S12, and in step S12, the output unit 34 outputs the worn tire model that satisfies the target wear amount.

  According to the present embodiment configured as described above, friction energy is obtained for each of a plurality of reference rolling conditions, and in the process of calculating the friction energy in each mode of tire travel, the friction energy under the plurality of rolling conditions is calculated. The frictional energy E_Free, ΔE_Fx_CA0, ΔE_Fy_CA0, and ΔE_CA of each component are calculated by interpolation calculation using. Therefore, even if the vehicle or tire mounting position is changed, it is not necessary to perform calculation under the conditions each time, and wear prediction can be performed while suppressing the calculation cost.

  In addition, the friction energy in each mode is the addition of friction energy increase ΔE_Fx_CA0 due to longitudinal force, friction energy increase ΔE_Fy_CA0 due to lateral force, and friction energy increase ΔE_CA due to camber angle to friction energy E_Free when traveling straight Since the friction energy increase due to the camber angle is also calculated and added by the above interpolation, the prediction accuracy of the friction energy in each mode can be improved.

  In particular, when the friction energy increase ΔE_CA due to the camber angle is calculated, the relationship between the friction energy E and the camber angle CA is defined by a quadratic curve, and is calculated using interpolation calculation using the quadratic curve. Since it did in this way, the prediction precision of friction energy can be improved further.

  Further, according to the present embodiment, when creating a worn tire model, the surface nodes on the tread surface are moved, and the internal nodes are moved based on the movement amount and element ratio of the surface nodes. It can be created efficiently, and it is possible to suppress the distortion of the element due to the shape after wear and to perform stable calculation.

  In particular, when analyzing the heel and toe wear, the influence of the alignment of the vehicle is large, and the progress of the heel and toe wear progresses as the running progresses. Since it is a step that calculates energy and repeatedly calculates until the target friction amount is reached, wear progress prediction of heel and toe wear can be performed efficiently and accurately, and a stable solution can be obtained. it can.

  Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Wear simulation apparatus, 14 ... Model preparation part, 16 ... Rolling condition setting part, 18 ... Rolling analysis part, 20 ... Standard friction energy calculation part, 22 ... Mode friction energy calculation part, 24 ... Integrated friction energy calculation part , 26 ... wear amount calculation unit, 28 ... wear model generation unit, 46 ... camber angle increase calculation unit

Claims (6)

A model creation unit for creating a tire model by dividing a tire into a finite number of elements;
A rolling condition setting unit that sets a plurality of reference rolling conditions in which any one or more of load, longitudinal force, lateral force, and camber angle are different as conditions for rolling the tire model;
A rolling analysis unit that performs rolling analysis of the tire model under the plurality of rolling conditions;
A reference friction energy calculation unit for calculating friction energy for each of the plurality of rolling conditions from the result of the rolling analysis;
By interpolation calculation using the frictional energy in the plurality of rolling conditions, for each of the tire running modes to be simulated, the frictional energy during straight travel, the increase in frictional energy due to longitudinal force, and the frictional energy due to lateral force are calculated. The amount of increase and the amount of increase in friction energy due to the camber angle are calculated. A mode friction energy calculation unit for calculating the friction energy in each mode by adding minutes;
An integrated friction energy calculation unit that calculates the integrated friction energy by multiplying the friction energy of each mode by the running frequency of each mode and integrating the friction energy;
A wear amount calculation unit for calculating a wear amount on the tread surface based on the accumulated friction energy;
A wear model generating unit that generates a worn tire model by moving a tread surface of the tire model based on the wear amount;
Wear simulation apparatus for tires having The mode friction energy calculation unit defines a relationship between the friction energy and the camber angle under a plurality of rolling conditions having different camber angles as a quadratic curve, and performs interpolation calculation using the quadratic curve in each mode. A camber angle increase calculation unit for calculating an increase in friction energy due to the camber angle;
The tire wear simulation apparatus according to claim 1. The wear model generation unit is configured such that the wear amount is D, the distance from a surface node located on the tread surface to a first internal node adjacent in the thickness direction is a, and the i-th one is sequentially adjacent from the first internal node in the thickness direction. The distance between the internal node and the (i + 1) th internal node is b _i (where i is an integer equal to or greater than 1), the movement amount of the surface node is set to D, and the movement amount of the i-th internal node including the first internal node Is set to D × b _i / a,
The tire wear simulation device according to claim 1 or 2. If the movement amount D of the surface node is larger than the a, the element including the surface node is deleted, and the value obtained by subtracting the a from the D is used as the movement amount of the surface node after the element deletion, and the element deletion The amount of movement of the subsequent i-th internal node is set to (D−a) × b _i / a.
The tire wear simulation apparatus according to claim 3. A model creation step for creating a tire model by dividing the tire into a finite number of elements;
A rolling condition setting step for setting a plurality of reference rolling conditions that differ in any one or more of load, longitudinal force, lateral force, and camber angle as conditions for rolling the tire model;
A rolling analysis step for performing rolling analysis of the tire model under the plurality of rolling conditions;
A reference friction energy calculating step for calculating a friction energy for each of the plurality of rolling conditions from the result of the rolling analysis;
By interpolation calculation using the frictional energy in the plurality of rolling conditions, for each of the tire running modes to be simulated, the frictional energy during straight travel, the increase in frictional energy due to longitudinal force, and the frictional energy due to lateral force are calculated. The amount of increase and the amount of increase in friction energy due to the camber angle are calculated. A mode friction energy calculating step for calculating the friction energy in each mode by adding a minute;
An integrated friction energy calculating step of calculating the integrated friction energy by multiplying the friction energy of each mode by the running frequency of each mode and integrating the friction energy;
A wear amount calculating step for calculating a wear amount on the tread surface based on the accumulated friction energy;
A wear model generation step of generating a wear tire model by moving a tread surface of the tire model based on the wear amount;
A tire wear simulation method comprising: A program for analyzing tire wear by simulation,
On the computer,
A model creation function to create a tire model by dividing the tire into a finite number of elements;
A rolling condition setting function for setting a plurality of reference rolling conditions in which any one or more of a load, a longitudinal force, a lateral force, and a camber angle are different as conditions for rolling the tire model;
A rolling analysis function for performing rolling analysis of the tire model under the plurality of rolling conditions;
A reference friction energy calculation function for calculating friction energy for each of the plurality of rolling conditions from the result of the rolling analysis;
By interpolation calculation using the frictional energy in the plurality of rolling conditions, for each of the tire running modes to be simulated, the frictional energy during straight travel, the increase in frictional energy due to longitudinal force, and the frictional energy due to lateral force are calculated. The amount of increase and the amount of increase in friction energy due to the camber angle are calculated respectively, and the amount of increase in friction energy due to the longitudinal force, the amount of increase in friction energy due to the lateral force, and the increase in friction energy due to the camber angle are calculated as the friction energy when traveling straight A mode friction energy calculation function for calculating the friction energy in each mode by adding minutes;
An integrated friction energy calculation function for calculating the integrated friction energy by multiplying the friction energy of each mode by the running frequency of each mode and integrating the friction energy;
A wear amount calculating function for calculating a wear amount on the tread surface based on the accumulated friction energy;
A wear model generation function for generating a wear tire model by moving the tread surface of the tire model based on the wear amount;
Tire wear simulation program to realize

Images