JPH11201874A - Method for simulating tire performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simulate a vibration characteristic of a tire. SOLUTION: A tire to be evaluated is approximated by a tire finite element model 2 obtained by dividing the tire to a finite count of many elements, and performance of the tire is simulated from the model 2 with the use of a finite element method in this simulation method. The tire finite element model 2 is subjected to a run simulation process whereby a behavior of the model when relatively moved in touch with a virtual road face having projections is simulated. An information process is also carried out whereby a vibration characteristic of the model 2 when passing the projections is obtained from the run simulation process.

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 the vibration characteristics of a tire.

[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 is mainly used, so that, for example, the behavior and vibration of a tire when passing on a road surface having steps or protrusions are considered. As for the characteristics, it was necessary to actually perform a running test.

[0005] As for tread patterns, 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, the performance of the tire can be roughly predicted and analyzed. However, the tread pattern and the internal structure for the behavior and vibration characteristics of the tire when passing on a road surface having steps or protrusions can be obtained. It was difficult to analyze the effects of such factors with high accuracy.

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

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

[0009]

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, wherein the tire finite element model mounted on a virtual rim is grounded on a virtual road surface having a non-flat portion including a protrusion, a step or a groove. It includes a traveling simulation process of simulating a behavior at the time of relative movement, and an information acquisition process of acquiring at least a vibration characteristic of a tire finite element model when passing through the non-flat portion from the traveling simulation process. This is a method for simulating tire performance.

Further, in the invention described in claim 2, the running simulation processing includes the step of:
Axial load, running speed, slip angle, camber angle, and running conditions including the friction coefficient between the tire finite element model and the virtual road surface are set and performed, and the information acquisition processing is performed on the rotation axis of the tire finite element model. The tire performance simulation method according to claim 1, wherein the vibration characteristic is obtained by performing processing based on information including a vertical load acting on the tire, a front-rear load, and an internal stress distribution of the tire.

According to a third aspect of the present invention, the tire finite element model includes 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.

[0012]

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 parallel with each other at an angle of 20 degrees with respect to the circumferential direction of the tire. 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 which 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 a 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 crossing 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.

In the present embodiment, the input / output ports are provided with input means I such as a keyboard and a mouse for inputting numerical values for setting a tire finite element model, 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 procedure of the simulation as shown in FIG. 7 and 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.

The tire body portion 1B is formed of 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 this 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, for example, 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 tire tread pattern 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 combining the tread pattern part element model 4 with 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, as shown in FIG. 9A, the tire finite element model 2
Is performed on the virtual road surface 7 having a non-flat portion 9 including a protrusion, a step, or a groove, and a traveling simulation process is performed to simulate the behavior when the relative movement is performed.

As shown in FIG. 8, "mounting 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 Of the tire axial direction W is forcibly displaced to the rim width. The rotation axis CL of the tire finite element model 2 is connected and fixed so that the relative distance r from the rim constraint area of the tire finite element model 2 is always constant, as shown in FIG.

The element model of the virtual road surface 7 is shown in FIG.
It is shown in FIG. In the present embodiment, the virtual road surface 7 is
Shown is a non-flat portion 9 comprising a projection 8. The virtual road surface 7 is modeled as a quadrilateral rigid surface, and the projections 8 are formed by connecting quadrilateral rigid surfaces 8a, 8b, 8c... As shown in an enlarged manner in FIG. In this example, a semi-circular protrusion having a radius of 1 cm is shown as an element.

The predetermined running conditions in the running simulation processing include, for example, the internal pressure of the tire finite element model 2, the axial load acting on the rotation axis 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 performing a running simulation for analyzing the vibration characteristics of the tire finite element model 2 when riding over a protrusion, first, as shown in FIG. After the rim contact area 10 of the bead portion 2 is constrained and an internal pressure is applied, a load is applied to the rotation axis CL of the tire finite element model 2 and pressed against the virtual road surface 7 to make contact therewith. Then, the virtual road surface 7 is moved at a predetermined speed so that the tire finite element model 2 passes through the uneven portion 9.

At this time, the tire finite element model 2 freely supports the rotation axis CL, and rolls by frictional force caused by contact with the virtual road surface 7. Further, when the tire finite element model 2 gets over the protrusion 8, a longitudinal force, a vertical load, and the like are applied to the rotation axis CL.

Further, information acquisition processing for acquiring at least vibration characteristics of the tire finite element model 2 when passing through the non-flat portion 7a is performed from the running simulation processing. This processing is performed, for example, from the tire finite element model 2,
Information including a cornering force that changes over time, a shape of a ground contact surface, or an internal stress distribution can be acquired as numerical information or image information such as animation.

The information includes a vertical load acting on the rotation axis CL of the tire finite element model 2 before and after the passage,
It is preferable to acquire information including the longitudinal load and the internal stress distribution of the tire. Thereby, in the present simulation method, the tire finite element model 2 when passing through the non-flat portion 9
Can analyze the complex behavior and vibration characteristics.

This simulation is performed by the finite element method. In general, a procedure for giving various boundary conditions to a finite element model and acquiring information such as force and displacement of the entire system can be performed according to 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 element's mass matrix M, rigidity matrix K, damping matrix C
Create

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, as the information acquisition processing, it is preferable to acquire information including a vertical load, a longitudinal load, and an internal stress distribution of the tire that can act on the rotation axis CL of the tire finite element model 2.

Tires are required to have many performances such as cornering force, braking performance, noise performance, wear performance, and rolling resistance performance. In particular, in order to analyze these tire performances, a simulation of rolling the tires is required. Becomes In the simulation of this embodiment, the tire body part element model 2, the tread pattern part element model 3
Are continuous in the circumferential direction, so rolling simulation is possible, and cornering performance, wear performance,
If the effect of damping is taken into account, it is possible to predict and analyze hydroplaning performance by coupling with vibration performance and 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, as for the non-flat portion of the virtual road surface, the protrusions are exemplified, but steps, grooves, and even protrusions are continuous, and various road surfaces such as snowy roads, icy roads, and sandy grounds with various friction coefficients are changed. Can be deformed.

[0044]

[Example] The tires simulated this time were 2
35 / 45ZR17LM602 (manufactured by Sumitomo Rubber Industries, Ltd.), and a vertical load, a front-rear load, and the like acting on a rotating shaft when the vehicle crosses a virtual road surface having a protrusion were examined. The finite element model of this tire is the same as that shown in FIG. 1, with 43896 nodes and 76359 elements.
It is.

The virtual road surface was modeled as a rigid surface having projections shown in FIGS. 9A and 9B. Then, after confining the bead portion of the tire finite element model and applying a tire internal pressure load, the tire model is pressed against a virtual road surface to apply a load, and the road surface is moved at a predetermined speed with respect to the tire, when riding over a protrusion. Was simulated.
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 60 km / h.

FIG. 10 shows an image of the present simulation at the moment when the tire passes over the protrusion. In the image, a stress distribution diagram is represented by a change in color.

FIG. 11 is a graph showing the vertical reaction force and the longitudinal reaction force generated on the rotation axis of the tire model, with the vertical axis representing the force and the horizontal axis representing the time. The solid line is the measurement result of the actual tire, and the dotted line is the result of the present simulation. The two have a good correlation, indicating the high accuracy of this simulation.

[0048]

As described above, according to the first and second aspects of the present invention, the behavior and vibration characteristics of the tire when passing through an arbitrary road surface having steps or protrusions without performing an actual running test are analyzed. Can greatly improve the development efficiency.

According to the third aspect of the present invention, the tire finite element model is a tread pattern part element model in which the tread pattern is converted into a finite element over the entire circumference in the tire body part element model having the same cross section in the tire circumferential direction. Therefore, by performing a running simulation using the tire finite element model, it is possible to simulate the tire performance with high accuracy, including the influence of the tread pattern, and to improve 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 sidewall rubber, and a bead core, is set. By modeling the cord material among the cord reinforcement materials into quadrilateral membrane elements that define anisotropy, and modeling the topping rubber into hexahedral solid elements, it simulates highly accurate tire performance. It is possible to study detailed tire design such as tire pattern shape, arrangement of carcass and belt, and thickness of topping rubber.

[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. 9A is a perspective view in which a tire finite element model is grounded on a virtual road surface, and FIG. 9B is a partially enlarged view of a non-flat portion thereof.

FIG. 10 is a side view showing a tread surface of a tire finite element model when the vehicle goes over a protrusion.

FIGS. 11A and 11B are force-time graphs showing the simulation results.

FIG. 12 is a sectional view of a tire.

[Explanation of symbols]

 T tire 2 tire finite element model 3 tire body part element model 4 tread pattern part element model 5 cord reinforcement element model 7 virtual road surface 9 virtual road surface non-flat part

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 of 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 having a non-flat portion including a protrusion, a step or a groove, and A tire performance simulation method, comprising: from a running simulation process, an information acquisition process for acquiring at least a vibration characteristic of a tire finite element model when passing through the non-flat portion. 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. The information acquisition processing is characterized in that the vibration characteristics are acquired by performing processing based on information including a vertical load acting on a rotation axis of a tire finite element model, a front-rear load, and an internal stress distribution of a tire. The method for simulating tire performance according to claim 1, wherein 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.