JPH11201875A - Simulation method of tire performance - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To simulate the wear characteristics of a tire. SOLUTION: A tire to be evaluated is approximated by a tire finite element model 2 which is divided into a finite number of elements 2a, 2b,..., And tire performance is simulated from the tire finite element model 2 using a finite element method. This is a method for simulating tire performance. In the present invention, a running simulation process for simulating a behavior when the tire finite element model 2 mounted on the virtual rim is brought into contact with a virtual road surface and relatively moved, and a wear characteristic of the tire finite element model 2 is obtained from the running simulation process. And information acquisition processing to be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire performance simulation method capable of accurately simulating tire wear characteristics.

[0002]

2. Description of the Related Art
The development of tires was an iterative process of creating prototypes, testing them, and producing further prototypes based on the results of the experiments. This method requires a lot of cost and time for prototype production and experimentation, and thus limits the improvement of development efficiency. In order to overcome such problems, computer simulations using approximation analysis techniques etc. have recently predicted a certain level of performance without prototype tires.
Analyzing methods have been proposed.

[0003] Various analysis methods are used in computer simulation. For example, a method using a finite element method is well known. Finite Element Metho
d) is a method in which a structure is divided into a large number of areas of finite size called finite elements, and each finite element is given relatively simple characteristics to analyze the entire system.

In the conventional analysis of tire performance by the finite element method, at most a load analysis in a non-rolling state of a tire has been the mainstream, and for example, it is necessary to actually perform a running test on the wear characteristics of the tire. there were.

In recent years, a method using wear energy has been proposed as a tire wear evaluation method. This wear energy can be represented by the product of the X-direction and Y-direction shear forces applied to an arbitrary point on the tire tread surface and the slip amounts in the X-direction and Y-direction. That is, at a certain point on the rolling tire tread surface, the pressure and the amount of slip between the road surface are measured in the time from the point where the point touches the road surface until the point separates, and the sum of the values obtained by multiplying them is calculated. It has been found that wear energy is increased, and that a portion having a larger amount of wear energy is more likely to be worn earlier.

Conventionally, in order to calculate such wear energy, a shearing force acting on an arbitrary point on a tread surface,
And measuring the amount of slip is a very difficult and time-consuming task, and can only be evaluated at the points measured, and when evaluating over a wide area on the tire tread surface, it takes an enormous amount of time. I needed it. Also in this case, it is only possible to perform a simulated evaluation of securing a large number of dispersed measurement points, and it is very difficult to measure the edge of a block or a portion where narrow grooves are dense such as a studless tire. Was difficult.

As for the tread pattern, there are many so-called plain treads without grooves, and there is no known tread pattern in which all tread patterns of a tire are modeled as finite elements. Further, inside the tire, there are provided reinforcing layers or the like in which cord materials such as carcass and belts are laminated at different angles, and these are also often analyzed in a simplified model using a single plane shell element or the like. Was.

For this reason, in the simulations so far, it is possible to roughly predict and analyze the performance of the tire, but it is impossible to analyze the wear characteristics of the tire and the effects of the tread pattern and the internal structure on the wear characteristics. Met.

According to the first and second aspects of the present invention, the tire performance and the wear characteristics can be analyzed without passing through a running test and analyzing tire behavior when passing on an arbitrary road surface having steps or protrusions. It is intended to provide a simulation method.

Another object of the present invention is to provide a method of simulating tire performance that enables analysis of the influence of a tread pattern, an internal structure, and the like, in addition to the above objects.

[0011]

According to the first aspect of the present invention, a tire to be evaluated is approximated by a tire finite element model obtained by dividing a tire into a finite number of elements, and the tire is evaluated using a finite element method. A tire performance simulation method for simulating tire performance from the tire finite element model, comprising: a running simulation for simulating a behavior when the tire finite element model mounted on a virtual rim is brought into contact with a virtual road surface and relatively moved. A tire performance simulation method including a process and an information acquisition process of acquiring a wear characteristic of a tire finite element model from the traveling simulation process.

According to a second aspect of the present invention, in the running simulation process, the internal pressure, the axial load, the running speed, the slip angle, the camber angle, the friction coefficient between the tire finite element model and the virtual road surface of the tire finite element model. And the information acquisition processing is performed in the X-direction and the Y-direction shearing forces applied to the nodes of the respective elements on the ground contact surface of the tire finite element model, and the X-direction for the nodes of the respective elements. The tire performance simulation method according to claim 1, wherein the wear energy is calculated based on information including the slip amount in the Y direction.

According to a third aspect of the present invention, in the tire finite element model, a cord reinforcing member including a carcass and a belt; a rubber portion including a sidewall rubber and a bead rubber;
A tire body part element model obtained by dividing a tire body part having a bead core and the same cross-sectional shape continuous in the tire circumferential direction based on a finite element method, and a tire tread pattern disposed on the outer peripheral surface of the tire body part element model and the tire tread pattern. A tread pattern part element model divided into a finite number of elements over the entire circumference in the tire circumferential direction, and the tire body part element model comprises a cord material constituting the cord reinforcing material and a topping covering the cord material A cord reinforcing material element model in which rubber is divided into a finite number of elements, a rubber part element model in which the rubber part is divided into a finite number of elements, and the bead core is divided into a finite number of elements. And a cord reinforcement element model, wherein the cord material is a quadrilateral membrane having anisotropy defined. The topping rubber is a simulation method of tire performance according to claim 1 or 2, wherein the modeled into hexahedral solid elements while being modeled.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, an example is shown that simulates the performance of a radial tire (hereinafter simply referred to as a tire) T for a passenger car as shown in FIG. The tire T has a carcass 16 composed of a ply 16a having a cord folded from the tread portion 12 through the sidewall portion 13 around the bead core 15 of the bead portion 14 and having a cord inclined at substantially 90 degrees with respect to the tire circumferential direction. And a belt layer 17 disposed outside the tire radial direction and inside the tread portion 12.

In the present embodiment, the belt layer 17 is formed by laminating two inner and outer belt plies 17A and 17B in the direction in which the cords intersect at an angle of 20 degrees with respect to the tire circumferential direction. You. In this example, the belt layer 1
7, a band layer 19 in which nylon cords are arranged substantially parallel to the tire circumferential direction is provided on the outer side in the tire radial direction to prevent lifting of the belt layer 17 during high-speed running. In this embodiment, the band layer 19 includes an edge band covering both ends of the belt layer 17 and a full band covering substantially the entire width of the belt layer 17.

The carcass ply 16A is formed by coating an organic fiber cord such as polyester, for example, and the belt plies 17A and 17B are formed by coating a steel cord with a sheet-like topping rubber.
The cord reinforcing material F may include a bead reinforcing filler that reinforces the rigidity of the bead portion 14 in addition to the carcass 16, the belt layer 17, and the band layer 19, if necessary.

The tire T has a tread rubber 20, a sidewall rubber 21,
A bead rubber 22 and the like are provided. The tread rubber 2
Reference numeral 0 denotes a tread base rubber 20a that is disposed on the radially outer surface of the belt layer 17 in the present example, and extends substantially along the surface of the tread portion 12 in the meridional section of the tire, passing near below the groove bottom line of the longitudinal groove G1. And a tread cap rubber 2 disposed outside thereof and in contact with a road surface to transmit various forces.
0b is exemplified.

The sidewall rubber 21 is a portion that is largely bent when the tire rolls, and protects the side portion of the tire T even when it comes into contact with a curb on the road surface. It is preferable to use a flexible rubber having a low rate. The bead rubber 22
Is disposed in the vicinity of the fitting portion in contact with the rim flange, and may be made of, for example, rubber having a relatively large elastic modulus and excellent wear resistance.

On the outer surface of the tread portion 12, a predetermined tread pattern is formed by, for example, a vertical groove G1 extending in the tire circumferential direction and a horizontal groove G2 extending in a direction intersecting the vertical groove G1. This tread pattern greatly affects tire performance, and the simulation method of the present embodiment makes it possible to analyze the influence of this tread pattern on tire performance, as described later.

As an apparatus for performing the simulation method, for example, as shown in FIG.
U and RO in which the processing procedure of this CPU and the like are stored in advance.
M, a RAM which is a working memory capable of temporarily storing images or numerical values, input / output ports, and a data bus connecting these.

The input / output ports include input means I such as a keyboard and a mouse for inputting numerical values for setting a tire finite element model in this example, a display capable of displaying input results and simulation results, An output unit O such as a printer and an external storage device D such as a hard disk and a magneto-optical disk are connected. The ROM stores in advance the processing procedures of the simulation as shown in FIG. 7, and the contents thereof will be described below.

In the simulation method of the present embodiment,
Such a tire T to be evaluated is approximated by a tire finite element model 2 divided into a finite number of elements 2a, 2b, 2c... As shown in FIG. The tire performance is simulated from the element model 2, and the tire finite element model 2 is
1 shows a tire body element model 3 and a tread pattern element model 4.

As shown in FIGS. 1 and 2, the tire body part element model 3 is obtained by dividing the tire body part 1B based on the finite element method. Here, the tire body portion 1B is a portion where substantially the same material and the same cross-sectional shape are continuous in the circumferential direction in the tire to be evaluated. In this example, the tread cap rubber of the tread rubber 20 from the tire T is used in this example. It is determined as a portion excluding only 20b.

Specifically, the tire body 1B includes a carcass 16, a belt layer 17, and a band layer 19 of the tire.
, A rubber portion including a tread base rubber 20 a, a sidewall rubber 21, and a bead rubber 22 of the tread rubber 20, and a bead core 15.

In the simulation method of the present embodiment, the tire body 1B is divided into a finite number of elements based on the finite element method. An element based on the finite element method is, for example, 2
For a three-dimensional element, such as a quadrilateral element on a dimensional plane, 4
It is desirable that all of the elements be a computer-processable element such as a solid solid element, a solid solid element, a solid solid element, a solid solid element, and the like, and these elements have three-dimensional coordinates XY-
The mutual positional relationship can be specified one by one using Z.

For example, an arbitrary minute area of the belt layer 17 as the cord reinforcing material F is set in the cord reinforcing element model 5, as shown in FIG. In this example, the cord material c of the cord reinforcing material F is modeled by the quadrangular membrane elements 5a and 5b, and the topping rubber t is the hexahedral solid elements 5c and 5c covering the quadrangular membrane elements 5a or 5b.
Examples modeled by d and 5e are shown.

The material definition of the tetrahedral membrane element 5a, which models the cord material c, is such that its thickness is determined, for example, by the cord material c.
, And treated as orthogonally anisotropic materials having different stiffness in the arrangement direction of the cord material c and in the direction orthogonal thereto, and the stiffness in each direction can be treated as being homogenized. The hexahedral solid elements 5c to 5e representing the topping rubber t of the cord reinforcing material F can be defined and handled as a super viscoelastic material like other rubber members.

The tread base rubber portion 10a, the sidewall rubber 21, the bead rubber 22, and the bead core 14 of the tire body 1B are subjected to, for example, a process of modeling with a hexahedral solid element or a pentahedral solid element. Such modeling can be performed using the input means I. In addition, tire body part element model 3
Can relatively easily perform modeling by specifying a two-dimensional shape of a meridional section including a rotation axis of a tire and dividing the two-dimensional shape into elements that are developed in a circumferential direction.

As described above, in the present embodiment, the cord reinforcing material F is not modeled by a single flat shell element as in the prior art, but is changed according to the characteristics of the material, such as the cord material c and the topping rubber t. By modeling
It is possible to simulate tire performance closer to an actual product. Further, when modeling each of the rubber parts 20 to 22, the cord reinforcing material F, and the bead core 14 as finite elements, the material and rigidity can be defined based on the complex elastic modulus of each rubber, cord, bead core, and the like. .

Next, as shown in FIG. 4, the tread pattern part element model 4 sets a tread pattern element part obtained by dividing the tread pattern of the tire into a finite number of elements over the entire circumference in the tire circumferential direction. To be obtained. In this example, the pattern element model 4 is a model of the tread cap rubber 20b of the tread rubber. After being set separately from the tire body element model 3, the pattern element model 4 It illustrates what is combined.

In the present embodiment, the tread pattern part element model 4 includes a finite number of tetrahedral elements 4a, 4b
.. Are illustrated over the entire circumference of the tire. Thus, the tread pattern part element model 4
Is modeled separately from the tire body part element model 3, for example, as in the present example, the element can be made more detailed (meshed) than the tire body part element model 3,
This is preferable because the influence of the tread pattern can be analyzed in more detail. In addition, for various tires having the same internal structure and different tread patterns, only the tread pattern element model 4 is set, and the tire body element model 3 can be used in common. There is an advantage that can be improved.

In this embodiment, the tire finite element model 2 is completed by performing a process of connecting the tread pattern part element model 4 to the tire body part element model 3. As shown in FIG. 5, the inner surface or node of the tread pattern element model 4 is defined so as to be forcibly displaced with respect to the surface or node of the tire body element model 3 so that its relative position does not change. Joined.

In the present invention, a running simulation process is performed to simulate the behavior when the tire finite element model 2 mounted on the virtual rim is moved relative to the virtual road surface 7 as shown in FIG. .

The mounting of the tire finite element model 2 on the virtual rim means that the rim contact areas 10 and 10 of the tire finite element model 2 are constrained and the tire shaft between the bead portions of the model 2 is attached as shown in FIG. This means that the directional distance W is forcibly displaced to the rim width. The tire finite element model 2
Of the tire finite element model 2 is fixedly connected so that the relative distance r from the rim restraint area of the tire finite element model 2 is always constant. The virtual road surface 7 is modeled as a quadrilateral rigid surface, and shows a flat road surface.

The predetermined running conditions in the running simulation process include, for example, the internal pressure of the tire finite element model 2, the axial load acting on the rotating shaft CL, the running speed, the slip angle, the camber angle, the tire finite element model 2, and the virtual. It includes the coefficient of friction with the road surface 7 and the like. The internal pressure can be set by applying an evenly distributed load corresponding to the tire internal pressure to the inner surface of the tire finite element model 2.

When a running simulation for analyzing the wear characteristics of the tire finite element model 2 is performed, first, as shown in FIG. Rim contact area 10,
After constraining 10 and applying internal pressure, a load is applied by pressing the virtual road surface 7 against the tread portion of the tire finite element model 2 so as to make contact therewith. Then, the virtual road surface 7 is moved at a predetermined speed. At this time, the tire finite element model 2 freely supports the rotation axis CL, and rolls by frictional force due to contact with the virtual road surface 7.

In this processing, information including a cornering force, a shape of a contact surface, or an internal stress distribution which changes with time is acquired as numerical information or image information such as animation from the tire finite element model 2, for example. Can be.

In this embodiment, information acquisition processing for acquiring at least wear characteristics of the tire finite element model 2 when traveling on the virtual road surface 7 is performed based on the result of the traveling simulation processing. As the information, the shear force in the X direction and the Y direction received by the node of each element on the ground contact surface of the tire finite element model, and the slip amount in the X direction and the Y direction of the node of each element, For example, based on the information
It is characterized in that the wear energy is calculated by multiplying the shear force and the slip amount for each direction and integrating them. This makes it possible to predict and analyze wear energy at any point on the surface of the tire tread in a short time. In this example, the wear energy can be calculated over the entire surface of the tread surface. However, it is of course possible to select any node and calculate the wear energy.

This simulation is performed by the finite element method. In general, a procedure of giving various boundary conditions to a finite element model, acquiring information such as forces and displacements of the entire system, and performing a simulation can be performed in accordance with a well-known example. The algorithm of the calculation in this example is an explicit method. For example, based on the shape of the element, material properties of the element, for example, density, Young's modulus, damping coefficient, etc., the mass matrix M, the rigidity matrix K,
Create an attenuation matrix C.

The matrices of the entire system to be simulated are created by combining the above matrices. Also, by appropriately applying the boundary conditions, the following equation of motion is created.

(Equation 1)

A simulation can be performed by sequentially calculating the equation (1) every minute time t by the CPU.
It is preferable that the minute time t in the successive calculation is a time that is 0.9 times or less the minimum time of calculating the transmission time of the stress wave for all elements. Then, based on the result of the simulation, X, X at grounding of each node of each element of the tread pattern element model unit 4 of the tire finite element model 2,
The shear energy in the Y direction and the slip amount in the direction in which each shear force acts are taken out, and the wear energy can be calculated from these values.

The tire has a cornering force,
Many performances such as braking performance, noise performance, wear performance, and rolling resistance performance are required. In particular, in order to analyze these tire performances, a simulation of rolling the tires is required. In the simulation of the present embodiment, since the tire body part element model 2 and the tread pattern part element model 3 are all continuous in the circumferential direction, rolling simulation can be performed, and cornering performance, wear performance, and the effect of damping are taken into consideration. This is preferable in that the prediction and analysis of the hydroplaning performance can be performed by coupling the vibration performance and the fluid.

Although described in detail above, the present invention is not limited to the above embodiment. For example, the tire body 1B
Can be deformed in various modes, such as up to the belt layer and including the tread base rubber 20a in the tread pattern portion. In addition, by variously changing the friction coefficient of the virtual road surface, wear characteristics on various road surfaces such as a snowy road, an icy road, and a sandy ground can be easily analyzed.

[0044]

[Example] The tires simulated this time were 2
35 / 45ZR17LM602 (manufactured by Sumitomo Rubber Industries, Ltd.), showing the wear energy and stress distribution on the tread surface during cornering. The finite element model of this tire is the same as that shown in FIG. 1, the number of nodes is 43896,
The number of elements is 76359.

The virtual road surface was modeled as a flat rigid surface. Then, as shown in FIGS. 8 and 9, the rim contact area 10 of the bead portion of the tire finite element model is restrained, and after the tire internal pressure load is applied, the virtual road surface 7 is pressed against the tire model 2 to apply the load. The simulation was performed by moving the road surface at a predetermined speed with respect to the tire. The tire finite element model has a free rotation axis and rolls due to frictional force due to the movement of the road surface. The coefficient of friction between the tire and the road surface was set to 1.0 together with static friction. The traveling speed of the road surface was 20 km / h per hour, and the slip angle was 4 °.

FIG. 10 shows a distribution of the wear energy obtained by the simulation in the tread pattern element model unit 2 before deformation due to ground contact. In the image, the difference in wear energy is represented by a change in color. The darkest part indicates that the wear energy is the largest.

FIG. 11A shows a comparison between the simulation results and the average wear energy obtained by actual measurement. When the slip angle was examined under two conditions of 0 ° and 4 °, it could be confirmed that the two were very accurately matched.

FIG. 11 (B) shows the average wear energy of two types of tires (tire A and tire B) having different tread patterns by this simulation. When examined under the conditions, it was instantly confirmed that the tire A had smaller wear energy and better wear resistance. in this way,
According to the simulation method, when the pattern of the tire is changed, its wear characteristics can be immediately confirmed.

[0049]

As described above, according to the first and second aspects of the present invention, the tire wear characteristics can be analyzed without performing an actual running test, so that the development efficiency can be greatly improved.

According to the third aspect of the present invention, the tire finite element model is a tread pattern element model in which the tread pattern is finite over the entire circumference in the tire body element model having the same cross-section in the tire circumferential direction. Therefore, by performing a running simulation using this tire finite element model, it is possible to simulate a more accurate wear characteristic including the influence of the tread pattern, which is useful for increasing the development efficiency.

Further, regarding the internal structure of the tire, an element model in which each structural material is divided into a finite number of elements such as a cord reinforcing material such as a carcass and a belt layer, a rubber portion such as a side wall rubber, a bead core, and the like is set. By modeling the cord material among the cord reinforcing materials into quadrilateral membrane elements that define anisotropy, and modeling the topping rubber into hexahedral solid elements, including the effects on these wear characteristics It is possible to simulate extremely high-precision wear characteristics, and to study detailed tire design such as tire pattern shape, carcass and belt arrangement, and topping rubber thickness.

[Brief description of the drawings]

FIG. 1 is a perspective view of a tire finite element model of the present invention.

FIG. 2 is a perspective view of a tire body part element model.

FIG. 3 is a conceptual diagram showing element modeling of a cord reinforcing material.

FIG. 4 is a perspective view of a tread pattern part element model.

FIG. 5 is a diagram illustrating a modification of the tire finite element model.

FIG. 6 is a block diagram showing an embodiment of a simulation device according to the present invention.

FIG. 7 is a flowchart illustrating a processing procedure according to the embodiment;

FIG. 8 is a conceptual diagram of a cross section in which a tire finite element model is grounded on a virtual road surface.

FIG. 9 is a plan view in which a tire finite element model is grounded on a virtual road surface.

FIG. 10 is a distribution diagram of wear energy showing the results of this simulation.

FIG. 11A shows a comparison between the simulation and actual measurement values, and FIG.
It is a graph which shows the comparison result of the wear energy of a kind of tire.

FIG. 12 is a sectional view of a tire.

[Explanation of symbols]

 T tire 2 tire finite element model 3 tire body element model 4 tread pattern element model 5 cord reinforcement element model 7 virtual road surface

Claims (3)

[Claims] 1. A tire performance simulation method for approximating a tire to be evaluated by a tire finite element model obtained by dividing the tire into a finite number of elements, and simulating the tire performance from the tire finite element model using a finite element method. A running simulation process for simulating a behavior when the tire finite element model mounted on the virtual rim is relatively moved while being in contact with a virtual road surface, and a wear characteristic of the tire finite element model is obtained from the running simulation process. A method for simulating tire performance, the method comprising: acquiring information to be acquired. 2. The running simulation processing includes setting running conditions including an internal pressure, a shaft load, a running speed, a slip angle, a camber angle, and a friction coefficient between the tire finite element model and a virtual road surface of the tire finite element model. And the information acquisition process includes a shear force in the X direction and a Y direction received by a node of each element of the contact surface of the tire finite element model;
The tire performance simulation method according to claim 1, wherein the wear energy is calculated based on information including slip amounts in the X direction and the Y direction at the nodes of the respective elements. 3. The tire finite element model includes a cord reinforcing material including a carcass and a belt, a rubber portion including a sidewall rubber and a bead rubber, and a tire body portion in which a bead core is continuous with the same sectional shape in the tire circumferential direction. A tire body part element model divided based on a finite element method, and a tread pattern of the tire arranged on the outer peripheral surface of the tire body part element model and divided into a finite number of elements over the entire circumference in the tire circumferential direction. A tread pattern part element model, and the tire body part element model is a cord reinforcing material element in which a cord material constituting the cord reinforcing material and a topping rubber covering the cord material are each divided into a finite number of elements. A model, a rubber part element model obtained by dividing the rubber part into a finite number of elements, and a finite number of And a bead core element model divided into elements, and the cord reinforcing element model is obtained by modeling the cord material into a quadrilateral membrane element with anisotropy defined, and the topping rubber becomes a hexahedral solid element. 3. The method for simulating tire performance according to claim 1, wherein the method is modeled.