JP5993185B2 - Tire rolling simulation method - Google Patents

Description

  The present invention relates to a tire rolling simulation method capable of obtaining a highly accurate simulation result while suppressing calculation cost.

  In recent years, various rolling simulation methods for numerically calculating the state of a pneumatic tire that rolls on a road surface under an arbitrary condition by using a computer have been proposed (see, for example, Patent Document 1).

  In this rolling simulation method, first, a tire model and a road surface model are created by dividing a tire and a road surface to be evaluated using a finite number of elements. Next, the stationary tire model is brought into contact with the road surface model, and the internal pressure and load are defined. Then, by defining angular acceleration or the like in the tire model, the state of the tire model rolling on the road surface model is calculated every minute by the computer.

JP 2002-67636 A

  However, in the rolling simulation method as described above, when a stationary tire model is accelerated rapidly, there is a problem that the tire model is greatly deformed or a large vibration is generated due to friction with the road surface model. Further, although it is conceivable to accelerate the tire model step by step, there is a problem that the calculation cost is increased because it is necessary to repeat the calculation for each acceleration until the desired traveling speed is reached.

  Furthermore, in order to prevent large deformations and vibrations of the tire model due to sudden acceleration, the tire model grounded on the road surface model is temporarily rigidized and accelerated to the desired traveling speed at an early stage. It is also possible to restore it. However, since the rigid tire model cannot follow the road surface model, a large deformation occurs when the tire model rotated by a small angle is restored to the elastic body model again. As a result, the tire model has a problem that large vibrations occur and it is difficult to perform a highly accurate simulation.

  The present invention has been devised in view of the actual situation as described above, and defines an angular velocity corresponding to a traveling speed from the start of calculation of the rolling simulation process in a tire model capable of elastic deformation calculation. The main purpose is to provide a tire rolling simulation method capable of obtaining a highly accurate simulation result while suppressing the calculation cost.

The invention according to claim 1 of the present invention is a method for simulating tire rolling using a computer, in which an elastically deformable tire is modeled with elements that can be handled by a numerical analysis method. A tire model setting step for inputting a tire model capable of elastic deformation calculation, a road surface model setting step for inputting a road surface model obtained by modeling a road surface with elements that can be handled by a numerical analysis method to a computer, and the computer A rolling simulation step of calculating a state in which the tire model rolls on the road surface model based on the traveling speed, internal pressure, and load conditions, and the rolling simulation step includes the tire model as the road surface. In a state where the tire is separated from the model, the angular speed corresponding to the traveling speed is set to the tire mode. And defining a translation speed corresponding to the travel speed in the road model and linearly moving the rotating tire model, and grounding the rotating tire model to the linearly moving road model. And a step of calculating a rolling tire model .

  According to a second aspect of the present invention, in the road surface model, the rolling speed of the tire according to the first aspect is defined, wherein a translational speed corresponding to the travel speed is defined from a calculation start time of the rolling simulation step. This is a simulation method.

  The invention according to claim 3 is the tire rolling simulation method according to claim 1 or 2, wherein the tire model is given the condition of the internal pressure after the calculation of the rolling simulation step is started. .

  The invention according to claim 4 is the tire rolling simulation method according to claim 3, wherein the load condition is given to the tire model after the internal pressure condition is given in the rolling simulation step. It is.

In the invention according to claim 5, the tire model includes a belt model in which a belt layer is modeled by a finite number of elements, the angular velocity ω is the running speed v, and an effective rolling radius of the tire model. 5. The radius of the belt model of the tire model inflated and deformed by the condition of the internal pressure given by the internal pressure condition is obtained from the following equation (1) from r. This is a tire running simulation method as described.
ω = v / r (1)

  The present invention relates to a tire model setting step of inputting a tire model capable of elastic deformation calculation obtained by modeling an elastically deformable tire by an element that can be handled by a numerical analysis method to a computer, and a computer using a numerical analysis method for a road surface. A road surface model setting step for inputting a road surface model modeled by a handleable element, and a state where the tire rolls on the road surface model based on conditions of a predetermined traveling speed, internal pressure and load. A rolling simulation step for calculating is included, and an angular velocity corresponding to a running speed is defined in the tire model from the start of calculation of the rolling simulation step.

  In such a rolling simulation method, the tire model is rolled at a predetermined traveling speed from the start of calculation while preventing large deformation and vibration of the tire model due to sudden acceleration, and the calculation time required for acceleration is eliminated. Calculation costs can be greatly reduced.

  Moreover, since the tire model is modeled so that elastic deformation calculation is possible, even if it has an angular velocity and touches the road surface model, it can follow flexibly and prevent large vibrations from occurring. . Therefore, with the method of the present invention, a highly accurate rolling simulation can be performed.

It is a perspective view of the computer apparatus which performs the process of this embodiment. It is sectional drawing which shows the pneumatic tire modeled. (A) is a partial perspective view of a carcass ply, (b) is a partial perspective view of a belt ply. It is a flowchart which shows the simulation method of this embodiment. It is a perspective view which visualizes and shows a tire model and a road surface model. It is a flowchart which shows a tire model setting process. It is sectional drawing of the tire model of FIG. FIG. 4A is a partial perspective view showing a shell element that models the carcass ply of FIG. 3A, and FIG. 4B is a partial perspective view showing a shell element that models the belt ply of FIG. It is a flowchart which shows a condition setting process. (A) is sectional drawing which shows the tire model which carried out expansion deformation, and the tire model to which the load was loaded, (b) is sectional drawing which shows the tire model which carried out expansion deformation, and the tire model before expansion | swelling. It is a perspective view which visualizes and shows the state where a tire model rolls on a road surface model. It is a flowchart which shows a rolling simulation process. It is sectional drawing explaining the process of giving the conditions of internal pressure.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The tire rolling simulation method of the present embodiment (hereinafter simply referred to as “rolling simulation method”) is a rolling state on a road surface of a pneumatic tire (hereinafter also simply referred to as “tire”). Is a method of simulating using a computer.

  As shown in FIG. 1, the computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with an arithmetic processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1, 1a2. Note that a processing procedure (program) for executing the design method of the present embodiment is stored in the storage device in advance.

  As shown in FIG. 2, the tire 2 includes, for example, a carcass 6 extending from the tread portion 2a to the bead core 5 of the bead portion 2c through the sidewall portion 2b, and the outer side of the carcass 6 in the tire radial direction and the tread portion 2a. It has a belt layer 7 arranged inside, and has a general structure that can be elastically deformed.

  The carcass 6 is composed of at least one carcass ply 6A, in this embodiment, one carcass ply 6A. The carcass ply 6A has a main body portion 6a extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and the bead core 5 connected to the main body portion 6a is folded back from the inner side in the tire axial direction. And a folded portion 6b. A bead apex rubber 8 extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b.

  3A, the carcass ply 6A includes a cord array 11 of carcass cords 6c arranged at an angle δ of, for example, 65 to 90 degrees with respect to the tire equator C. It consists of a topping rubber 12 that covers the code array 11.

  As shown in FIG. 2, the belt layer 7 includes at least one sheet disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2a. It consists of two belt plies 7A and 7B.

  As shown in an enlarged view in FIG. 3 (b), the belt plies 7A and 7B are formed by cord arrays 13a and 13b of a belt cord 7c that is inclined at an angle φ of, for example, 10 to 40 degrees with respect to the tire circumferential direction. And topping rubbers 14a and 14b for covering the code arrays 13a and 13b, respectively. The belt cords 7c and 7c of the belt plies 7A and 7B are arranged so as to overlap each other.

  FIG. 4 shows a specific processing procedure of the rolling simulation method of the present embodiment. This rolling simulation method includes a tire model setting step S1 for inputting the tire model 3 (shown in FIG. 5) to the computer 1, a road model setting step S2 for inputting the road surface model 4 (shown in FIG. 5) to the computer 1, and a simulation. It includes a condition setting step S3 for setting conditions, and a rolling simulation step S4 for calculating a state in which the tire model 3 rolls on the road surface model 4 under conditions such as a predetermined traveling speed v.

  In the tire model setting step S1, as shown in FIG. 5, the tire 2 shown in FIG. 2 is modeled by an element 3a that can be handled by numerical analysis, and the modeled tire model 3 is stored in the computer 1. input. As this numerical analysis method, for example, a finite element method, a finite volume method, a difference method, or a boundary element method can be adopted as appropriate, but in this embodiment, a finite element method is adopted.

  FIG. 6 shows a specific processing procedure of the tire model setting step S1 of the present embodiment. First, in this embodiment, step S1a in which the computer 1 models each rubber member constituting the tire 2 is performed. In this step S1a, rubber portions 2g such as the tread rubber 2ga, the side wall rubber 2gb, and the inner liner rubber 2gc shown in FIG. 2 are used, for example, using a three-dimensional solid element 15s as shown in FIG. To divide. Thereby, the rubber member model 15 in which the rubber part 2g is modeled is set.

  As the three-dimensional solid element 15s, for example, a tetrahedral solid element suitable for expressing a complex shape is preferable. However, a pentahedral solid element or a hexahedral solid element may be used. good. Each solid element 15s is defined with numerical data such as an element number, a node number, a node coordinate value, and material characteristics (for example, density, Young's modulus and / or attenuation coefficient) and stored in the computer 1. .

  Further, when a tread pattern including a vertical groove and a horizontal groove is set on the outer surface of the tread portion 2a, it is desirable that the tread pattern is also reproduced in the tire model 3.

  Next, in this embodiment, step S1b for modeling the carcass ply 6A is performed. In this step S1b, as shown in FIGS. 3 (a) and 8 (a), the code array 11 of the carcass ply 6A is divided using, for example, a quadrilateral membrane element 17a and the topping is used. The rubber 12 is divided by using thin plate-like solid elements 17b and 17b. Then, the film element 17a and the solid elements 17b and 17b are stacked in the thickness direction to set a carcass model 17 in which the carcass 6 is modeled.

  In the membrane element 17a, the diameter of the carcass cord 6c, the angle δ of the carcass cord 6c with respect to the tire circumferential direction, and the like are defined as rigidity anisotropy. On the other hand, the solid elements 17b and 17b are defined as superviscoelasticity that does not cause a volume change. Further, the numerical data such as the element number is defined in each of the elements 17 a and 17 b and stored in the computer 1.

  Next, in the present embodiment, a step S1c for modeling the belt plies 7A and 7B is performed. In this step S1c, as shown in FIG. 3 (b) and FIG. 8 (b), the cord arrays 13a and 13b of the belt plies 7A and 7B are divided using the membrane elements 18a and 18b, and The topping rubbers 14a, 14b are divided using solid elements 19a, 19b, 19c. The membrane elements 18a and 18b and the solid elements 19a, 19b, and 19c are laminated in the thickness direction to set a belt model 20 in which the belt layer 7 is modeled.

  In the membrane elements 18a and 18b, the diameter of the belt cord 7c, the angle φ of the belt cord 7c with respect to the tire circumferential direction, and the like are defined as rigidity anisotropy. Furthermore, superviscoelasticity is defined for the solid elements 19a, 19b, and 19c in the same manner as in the step S1b for modeling the carcass ply 6A. Furthermore, the numerical data such as element numbers are defined in each of the elements 18a, 18b, 19a, 19b, and 19c and stored in the computer 1.

  As described above, the tire models 3 (shown in FIG. 7) that can calculate elastic deformation including the rubber member model 15, the carcass model 17, and the belt model 20 are defined by sequentially processing the steps S1a to S1c. Is done.

  In the road surface model setting step S2, a road surface model 4 obtained by modeling the road surface with elements that can be handled by the numerical analysis method is input to the computer 1. As shown in FIG. 5, the road surface model 4 is modeled in a plate shape by one or more rigid surface elements 21 constituting a single plane. Accordingly, the road surface model 4 is defined so as not to be deformed even when an external force is applied from the tire model 3.

  FIG. 9 shows a specific processing procedure of the condition setting step S3 of the present embodiment. In this condition setting step S3, as shown in FIG. 5, a step S3a of defining an angular velocity ω corresponding to the travel speed v of the tire model 3 to be analyzed in the tire model 3 is performed.

The angular velocity ω is obtained by the following equation (1) from the traveling speed v and the effective rolling radius r of the tire model 3.
ω = v / r (1)

  As shown in FIG. 10 (a), the effective rolling radius r is a dynamic load radius, which is approximated by a radius R1 with respect to the circumferential length of the belt model 20 of the inflated and deformed unloaded tire model 3A. Can be made. Thereby, in the rolling simulation method of the present embodiment, an approximate value of the effective rolling radius r can be obtained without separately calculating the tire model shape given the load condition, and the calculation cost can be reduced.

  Further, as shown in FIG. 10B, the radius R1 of the belt model 20 of the tire model 3A inflated and deformed is a radius R2 with respect to the circumferential length of the tire model 3 before inflating, and the tire It can also be determined approximately from the radius (R2 + R3) / 2 between the model 3 and the radius R3 of the belt model 20 in the circumferential direction. This is based on the fact that the inventors have intensively studied and found that the radius (R2 + R3) / 2 approximates the radius R1.

  Thereby, in the rolling simulation method of the present embodiment, an approximate value of the radius R1 can be obtained without separately performing step S4b (shown in FIG. 11) for providing an internal pressure condition described later, thereby reducing the calculation cost. Yes. Needless to say, the radius R1 may be obtained by separately performing a calculation that gives the condition of the internal pressure.

  Further, in the condition setting step S3, as shown in FIG. 5 and FIG. 9, the step S3b of defining the translation speed T corresponding to the travel speed v in the road surface model 4 and the tire model 3 on the road surface model 4 Step S3c for setting boundary conditions for rolling is performed. The boundary condition includes a friction coefficient between the tire model 3 and the road surface model 4 and the like.

  In the rolling simulation step S4, as shown in FIG. 11, the computer 1 is in a state in which the tire model 3 rolls on the road surface model 4 based on predetermined conditions of the traveling speed v, the internal pressure, and the load. Calculation (hereinafter referred to as “rolling calculation”).

  In the rolling calculation, deformation calculation of the tire model 3 is mainly performed. In this deformation calculation, the mass matrix, stiffness matrix and damping matrix of each element are created based on the shape and material properties of each element, and the matrix of the entire system is created by combining these matrices. .

  Then, equations of motion are created by applying the various conditions, and these are sequentially calculated and stored in the computer 1 in increments of minute time increments Δt (for example, 1 μsec). Thereby, physical quantities such as coordinate values, stress, and strain of each element of the rolling tire model 3 can be calculated in time series.

  The above-mentioned rolling calculation can be performed using, for example, engineering analysis application software using a finite element method (for example, LS-DYNA developed and improved by Livermore Software Technology, USA).

  FIG. 12 shows a specific processing procedure of the rolling simulation step S4. In this rolling simulation step S4, first, step S4a for starting rolling calculation is performed. As shown in FIG. 5, the tire model 3 is arranged at a position away from the road surface model 4 at the start of the rolling calculation. The tire model 3 rotates at the angular velocity ω from the calculation start time. Further, the road surface model 4 moves linearly at the translation speed T from the calculation start time.

  Next, a process S4b is performed in which deformation calculation is performed by giving the condition of the internal pressure to the rotating tire model 3. Specifically, as shown in FIG. 13, the rim contact areas 3r and 3r of the tire model 3 are restrained so as not to be deformed, and the width W of the bead portion 2c of the tire model 3 is forcibly displaced equally to the rim width. . Further, conditions are defined so that the tire radial direction distance R5 between the rotation shaft 3s of the tire model 3 and the rim contact area 3r is always equal to the rim radius. Further, an evenly distributed load w corresponding to the internal pressure condition is set on the entire lumen surface of the tire model 3.

  Then, the computer 1 performs a balance calculation of the tire model 3 under these conditions, and the displacement of each node when the tire model 3 is filled with the internal pressure is calculated. Thereby, in the tire model 3, the rubber member model 15, the carcass model 17, and the belt model 20 are expanded and expanded, and the tire model 3A after expansion and deformation is calculated.

  Next, a step S4c of performing deformation calculation by giving the load condition to the tire model 3A after the expansion deformation is performed. In the present embodiment, as shown in FIG. 11, the tire model 3A is moved to the road surface model 4 side and brought into contact with the ground, and a load L is applied to the rotating shaft 3s of the tire model 3A in the vertical direction. For example, the standard maximum load of the tire 2 (shown in FIG. 2) is adopted as the value of the load L.

  Accordingly, it is possible to calculate a tire model 3B in which a load L is applied to the tire model 3A after the expansion deformation and rolls on the road surface model 4. In the present embodiment, the tire model 3A is moved to the road surface model 4 side, but the road surface model 4 may be moved to the tire model 3A side.

  Further, since the tire model 3B is modeled so that elastic deformation calculation is possible as described above, even if the tire model 3B contacts the road surface model 4 while rotating at an angular velocity ω, the tire model 3B can follow flexibly. Vibration can be prevented from occurring. Therefore, in the rolling simulation method of the present embodiment, a highly accurate rolling simulation can be performed.

  As described above, in the rolling simulation method of this embodiment, the tire model 3B is rotated at the angular velocity ω from the start of the calculation while preventing large deformation and vibration of the tire model 3B due to sudden acceleration, so that the calculation required for acceleration is performed. The calculation cost can be greatly suppressed by eliminating time.

  Next, step S4d for determining whether or not the vibration of the tire model 3B is sufficiently damped is performed. In this step S4d, when it is determined that the vibration of the tire model 3B is sufficiently damped, a step S4f for setting the next test condition is performed. If it is determined that the vibration is not sufficiently attenuated, the time is advanced (step S4e), and the tire model 3B is rolled on the road surface model 4 for a while to attenuate the vibration. Thereby, the vibration of the tire model 3B can be sufficiently attenuated to test the running performance, and a more accurate simulation can be performed. In this embodiment, it is determined that the tire model 3B is sufficiently damped when the amplitude of the vertical force vibration is ± 0.1 kN or less.

  Next, step S4f is performed in which test conditions for evaluating the running performance of the tire 2 are set in the tire model 3B. Examples of the test conditions include conditions such as a slip angle and a camber angle during rolling of the tire model 3B. Then, under this test condition, the tire model 3B is deformed and calculated until an end time specified in advance.

  Next, step S4h for determining whether the end time has elapsed is performed. In this step S4h, when it is determined that the end time has elapsed, step S4i for outputting the physical quantity of the next tire model is performed. On the other hand, if it is determined that the end time has not elapsed, the time is advanced (step S4h), and the deformation calculation of the tire model 3B is continued. The end time is appropriately determined according to the simulation to be executed.

  In step S4i of outputting the physical quantity of the tire model, data calculated by rolling calculation is output. This data includes, for example, the longitudinal force and lateral force of the tire model 3B, and the motion performance of the tire 2 can be evaluated. From these output results, necessary tire internal structure, profile change, pattern improvement, internal pressure or rubber material improvement, etc. are performed, and the development period of the tire 2 can be greatly shortened.

  In the present embodiment, by defining the angular velocity ω in the tire model 3B and defining the translation speed T in the road surface model 4, the state in which the tire model 3B rolls on the road surface model 4 is calculated. However, the present invention is not limited to this. For example, the state of rolling on the road surface model 4 may be calculated by defining the angular speed ω and the translation speed T in the tire model 3B.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Based on the rolling simulation method of the present invention, the angular velocity ω was obtained from the effective rolling radius r shown in Table 1, and the rolling simulation of the tire model was performed and evaluated. For comparison, after the calculation of the rolling simulation process is started, a stationary elastically deformable tire model is accelerated to an angular velocity ω (Comparative Example 1), or a rigid tire model is accelerated to an angular velocity ω. The method (Comparative Example 2) for restoring the model of the elastic body later was also evaluated in the same manner. The common specifications are as follows.
Tire size: 225 / 50R18
Rim size: 18 × 7.5J
Internal pressure: 230 kPa
Load: 4.5kN
Traveling speed v: 50km / h
The test method is as follows.

<Time until vertical load vibration satisfies ± 0.25% or less and angular velocity vibration satisfies ± 0.7% or less and travel speed v is reached>
From the start of the rolling simulation process until the longitudinal load vibration of each test tire model satisfies ± 0.25% or less and the angular velocity vibration satisfies ± 0.7% or less, and the rolling speed reaches the travel speed v. The time was measured. The shorter the time is, the better the calculation cost can be reduced.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tire of the example can obtain a highly accurate simulation result while suppressing the calculation cost.

1 Computer 2 Tire 3 Tire Model 4 Road Model

Claims (5)

A method of performing tire rolling simulation using a computer,
A tire model setting step for inputting a tire model capable of elastic deformation calculation, in which an elastically deformable tire is modeled with an element that can be handled by a numerical analysis method to the computer,
A road surface model setting step of inputting a road surface model obtained by modeling a road surface with an element that can be handled by a numerical analysis method to a computer, and the tire model based on conditions of a predetermined traveling speed, internal pressure, and load. Including a rolling simulation step of calculating a state of rolling on the road surface model,
The rolling simulation step is a step of defining and rotating an angular velocity corresponding to the traveling speed in the tire model in a state where the tire model is separated from the road surface model,
Defining a translational speed corresponding to the traveling speed in the road surface model and moving it linearly;
And a step of calculating a rolling tire model by bringing the rotating tire model into contact with the road model moving in a straight line .
  The tire rolling simulation method according to claim 1, wherein a translational speed corresponding to the travel speed is defined in the road surface model from a start time of calculation of the rolling simulation process.   The tire rolling simulation method according to claim 1, wherein the tire model is given the condition of the internal pressure after the calculation of the rolling simulation step is started.   The tire rolling simulation method according to claim 3, wherein in the rolling simulation step, the load condition is given to the tire model after the internal pressure condition is given. The tire model includes a belt model in which a belt layer is modeled by a finite number of elements,
The angular velocity ω is determined by the following equation (1) from the traveling speed v and the effective rolling radius r of the tire model.
The tire running simulation method according to any one of claims 1 to 4, wherein the effective rolling radius is set to a radius of the belt model of a tire model inflated and deformed by being given the internal pressure condition.
ω = v / r (1)

Images