JP5814740B2 - Tire simulation method - Google Patents

Description

  The present invention relates to a tire simulation method capable of reducing calculation time and the like.

  In recent years, various tire performance simulation methods using a computer have been proposed. For example, in Patent Documents 1 and 2 below, tire performance including a step of dividing a tire and a rim into a plurality of microelements to create a tire model and a rim model, and a step of fitting both the models. The simulation method is described. Such a simulation method is preferable in that the accuracy of prediction can be improved because performance evaluation can be performed in a state where the tire is actually mounted on the rim instead of the tire alone.

Japanese Patent No. 3650342 Japanese Patent No. 4372498

  However, in any of the above simulation methods, a rim model is created by dividing an actual rim with microelements. Such an operation has a problem that it takes a lot of time to create a model because it is necessary to determine the coordinates of the nodes for dividing the rim into a large number of elements and to store all the coordinates in the computer. It was.

  In addition, as shown in FIG. 11, the rim a normally has a rim seat surface a1 on which the bead portion b of the pneumatic tire is seated and a rim flange surface a2 that supports the outer surface of the bead portion b extending almost vertically. The rim heel part a3 and the like are formed of a curved surface formed of a smooth arc. On the other hand, the microelements used in the finite element method are composed of straight lines in the case of two dimensions and planes in the case of three dimensions, so that curved surfaces such as the rim heel part a3 cannot be accurately expressed. For this reason, in the conventional simulation method, in the step of fitting the tire model to the rim model, there are problems such as unexpected vibrations and deterioration of calculation accuracy.

  The present invention has been devised in view of the above-described problems, and is based on the fact that the contact surface that contacts the tire model of the rim model is defined by a function, while shortening the model creation time and calculating accuracy. The main object is to provide a tire simulation method that can improve the performance.

The invention according to claim 1 of the present invention sets a tire model in which a pneumatic tire is modeled by a finite number of elements, and sets a rim model that models a rim having a contact surface that contacts the tire model. the method comprising, the tire model is a simulation method of tire including the step of setting the tire-rim assembly model fitted tire model to the Rimumoderu giving conditions to be attached to the Rimumoderu, the The tire model is set in a two-dimensional shape in a cross section including a tire rotation axis, the contact surface of the rim model is set in a two-dimensional shape in a cross section including a rotation axis of the rim, and the contact surface of the rim model is a straight line Is defined by smoothly connecting a linear function representing a circular function and a quadratic function representing an arc .

According to a third aspect of the present invention, the step of setting the tire / rim assembly model includes a step of determining contact between the tire model and a contact surface of the rim model, and the step of determining the contact includes: The method includes a step of checking whether each node on the tire model side is inside or outside the surface represented by the function.

  The present invention includes a step of setting a tire model obtained by modeling a pneumatic tire with a finite number of elements, a step of setting a rim model obtained by modeling a rim having a contact surface in contact with the tire model, and the tire model. A tire simulation method including a step of providing a tire / rim assembly model in which the tire model is fitted to the rim model by giving conditions for mounting to the rim model, and defining the contact surface of the rim model by a function It is characterized by that. As described above, the rim model used in the present invention can specify the contact surface by a function. As a result, unlike the conventional rim model, it is not necessary to divide the rim using a large number of minute elements (a large number of nodes). Therefore, the creation time of the rim model is reduced.

  In the present invention, since the contact surface of the rim model is defined using a function, not only a plane but also a curved surface can be defined using a quadratic function or the like. Therefore, the contact surface of the rim model can be expressed smoothly. Thereby, in the step of fitting the tire model to the rim model, occurrence of unexpected vibrations and deterioration of calculation accuracy are suppressed.

It is a flowchart which shows one Embodiment of this invention. It is sectional drawing which visualizes and shows a two-dimensional tire model. It is sectional drawing which visualizes and shows a two-dimensional rim model (only one side). (A) And (b) is sectional drawing which shows embodiment of a rim | limb model. It is sectional drawing explaining the setting method of a tire and rim assembly model. It is sectional drawing explaining a tire and rim assembly model. It is sectional drawing explaining the setting method of the tire rim assembly model of other embodiment. It is a perspective view which shows a three-dimensional tire and rim assembly model. It is sectional drawing which shows the rim model of a comparative example. It is a fragmentary sectional view showing a fitting state of a bead part and a rim of a tire and rim assembly model, (a) is an example and (b) is a comparative example. It is a fragmentary sectional view showing a fitting state of a pneumatic tire and a rim.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a processing procedure of the tire simulation method of the present embodiment, and this processing is executed using a computer (not shown).

  In the present embodiment, first, a tire model obtained by modeling a pneumatic tire with a finite number of elements is set (step S1).

  As shown in FIG. 2, the tire model 2 of the present embodiment is set in a two-dimensional shape having a cross-sectional shape including the tire rotation axis. The tire model 2 is set as numerical data that can be handled by a computer by dividing a pneumatic tire (not shown) to be analyzed into a finite number of minute elements 2a, 2b, 2c. Is done. Specifically, node coordinate values, element shapes, and material properties (for example, density, Young's modulus, damping coefficient, etc.) of each element 2a, 2b, 2c... Are defined and stored in the computer.

  For each element 2a, 2b, 2c..., For example, a quadrilateral element is suitable as a two-dimensional plane. Further, when creating a three-dimensional tire model, a tetrahedron or a hexahedron solid element suitable for expressing a complicated shape is used.

  In the tire model 2 of the present embodiment, the pattern shape (vertical groove) on the surface of the tread portion is also faithfully reproduced, but these shapes can be omitted.

  The pneumatic tire is reinforced with a fiber cord material such as a carcass or a belt layer, and these fiber cord materials are included in the tire model 2 by using, for example, a shell element 2S in which strength anisotropy is defined. It is desirable to be incorporated into. Further, in a pneumatic tire, an annular bead core made of a non-extensible material is embedded in a bead portion attached to a rim. This is also incorporated into the tire model 2 by using, for example, a rigid element. It is desirable that

  Next, in this embodiment, a rim model obtained by modeling a rim is set (step S2).

  In FIG. 3, the rim model 3 of the present embodiment is visualized. The rim model 3 is defined as a two-dimensional shape having a cross-sectional shape including the center of rotation of the rim, and only the right side is shown in FIG. The rim model 3 has a contact surface 4 that comes into contact with the bead portion of the tire model 2, and the rim model 3 of the present embodiment is configured by only the contact surface 4.

  In the present embodiment, the contact surface 4 of the rim model 3 is smoothly connected to the rim seat surface 4a composed of a straight line extending outward from the base point O in the tire axial direction, and the outer end A of the rim seat surface 4a in the tire axial direction, and is an arc. A heel arc surface 4b, a flange inner surface 4c that is smoothly connected to the outer end B of the heel arc surface 4b in the tire axial direction and extends linearly, and a smooth connection to the outer end C of the flange inner surface 4c. And a flange outer arc surface 4d made of an arc. The flange outer circular arc surface 4d terminates at the outer end D.

  In the contact surface 4, the rim seat surface 4 a made of a straight line has, for example, a linear function y = f 1 (x) {where the section is a point O to a point A}, and the flange inner surface 4 c made of a straight line has, for example, a linear function y = f3 (x) {however, the section is defined by points B to C}. The rim seat surface 4a of the present embodiment is inclined at about 5 ° with respect to the tire axial direction. Similarly, the flange inner surface 4c is also inclined at about 5 ° with respect to the tire radial direction.

  In the contact surface 4, the heel arc surface 4 b made of an arc is a quadratic function y = f 2 (x) {however, the section is a point A to B}, and the flange outer arc surface 4 d made of an arc is a quadratic function The function y = f4 (x) {where the interval is defined by points C to D}.

  Each function is stored in the computer together with the coordinates of the points O and A to D indicating the section. In the present embodiment, the contact surface 4 of the rim model 3 is conditioned as a rigid surface that does not change in view of the fact that the actual rim deformation is minute. However, it is not limited to such conditions.

  As described above, the contact surface 4 of the rim model 3 of the present embodiment is continuous from the base point O to the outer end D and without unevenness using only a straight line defined by a linear function and an arc defined by a quadratic function. Constructed smoothly. In the rim model 3 having such a contact surface 4, it is only necessary to define a function based on the contour shape of the original rim, and there is no need to divide and discretize the rim with a large number of minute elements as in the prior art. . Therefore, the creation time of the rim model 3 is greatly shortened.

  FIG. 3 shows a right rim model 3R having a contact surface 4R that contacts the right bead portion of the tire model 2. As shown in FIG. 4A, the left bead of the tire model 2 is shown. The left rim model 3L having the contact surface 4L in contact with the portion can also be formed in a bilaterally symmetric shape with the right rim model 3R. As shown in FIG. 4A, the left and right rim models 3L and 3R may be separated and independent from each other (hereinafter sometimes referred to as “separation type”), or FIG. 4B. As shown in FIG. 4, they may be connected to each other and integrated (hereinafter sometimes referred to as “integrated type”).

  Next, in the present embodiment, conditions for mounting the tire model 2 on the rim model 3 are given, and a tire / rim assembly model in which the tire model 2 is fitted to the rim model 3 is set (step S3).

  The above process can be executed by various methods. For example, in the case where the rim model 3 is the separation type shown in FIG. 4A, as shown in FIG. 5, the tire model 2 and the rim model 3 are first aligned with each other, and the left and right rim models 3L, 3R are aligned. The rim width Rwa of the tire model 2 is set larger than the width Bw of the bead portion of the tire model 2 so that the contact surface 4 does not interfere with the bead portion of the tire model 2.

  Next, as shown in FIG. 6, the rim widths of the left and right rim models 3L and 3R are moved inward in the tire axial direction so as to become the regular rim width Rw. Further, after the movement, an equally distributed load corresponding to the air pressure is applied to the lumen surface 2 i of the tire model 2. Further, at this time, the contact between the models 2 and 3 is determined, and when it is determined that they are in contact, one model acts as a wall with respect to the other model, and force exchange is performed through the surfaces of each other. At the same time, the deformation of the tire model 2 is calculated. Such a calculation is repeated until a balance of forces is obtained. This method is described in, for example, Patent Document 2 described above.

  On the other hand, when the rim model 3 is of the integral type shown in FIG. 4B, the rim width is defined in advance as a normal rim width Rw. For this reason, as shown in FIG. 7, the rotation axes of the tire model 2 and the rim model 3 are aligned, and for example, the width Bw of the bead portion of the tire model 2 is deformed to be smaller than the rim width Rw to interfere with each other. Position it so that it does not. Next, the tire model 2 is inflated and deformed by applying an evenly distributed load corresponding to air pressure to the lumen surface 2 i of the tire model 2. At this time, as in the case described above, when the models 2 and 3 are in contact with each other, if it is determined that they are in contact, one model acts as a wall against the other model, As exchanges take place, the deformation of the tire model 2 is calculated. This method is described in, for example, Patent Document 1 described above.

  By performing these processes, for example, as shown in FIG. 6, a tire / rim assembly model 5 in which the tire model 2 is fitted to the rim model 3 at a predetermined air pressure can be set.

  In step S3, contact determination between the tire model 2 and the contact surface 4 of the rim model 3 is performed. When the rim model 3 having the contact surface 4 defined by the function as in the present embodiment is used, There is also an advantage that the contact determination can be calculated at a higher speed than when using a rim model divided by small elements. That is, conventionally, it must be determined by calculating whether each node of the tire model 2 is inside or outside for each individual element of the rim model 3. On the other hand, in the case of this embodiment, since the contact surface 4 is defined by a function, each node on the tire model 2 side is only inside or outside the surface represented by this function. Can be checked. In addition, since the number (type) of functions is smaller than the number of elements, the present embodiment can perform the above-described determination processing at a higher speed, and has an advantage that does not depend on the division method, such as element division. is there.

  Next, in the present embodiment, various deformation simulations (for example, rolling simulation, grounding shape simulation, durability simulation, etc.) are performed using the tire / rim assembly model 5 (step S4), and the results are as follows. Various physical quantities are acquired (step S5). When the rim model 3 is a separation type, it is desirable to make the translational degrees of freedom of the left and right rim models 3L and 3R coincide.

  In the above embodiment, the two-dimensional tire model 2 and the rim model 3 have been described as examples. However, the present invention is not limited to such an embodiment. That is, as described above, the tire / rim assembly model 5 in which the two-dimensional tire model 2 and the rim model 3 are fitted is developed in the tire circumferential direction, and a three-dimensional tire / rim assembly model is set. It goes without saying.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

  Two-dimensional tire models and rim models for tires subject to analysis of size 195 / 65R15 and 15 × 6.0J rims (compliant with JATMA standards) are set according to the following specifications, respectively, and the model creation time and fitting time The accuracy of was evaluated.

[Specifications of tire / rim assembly of example]
Tire model: In accordance with FIG. 2, the number of elements was 1926.
Rim model: A separation type conforming to FIG. 3 and defined by four types of functions on the left and right.

[Specifications of tire / rim assembly of comparative example]
Tire model: Same as above Rim model: As shown in FIG. 9, it was defined as a separated type and defined by 17 left and right (34 elements in total) microelements e. In FIG. 9, circles indicate nodes.

  First, with respect to the creation time of the rim model, when the example was set to 100, the comparative example was 150, and it was confirmed that it took 50% as much time.

  The time required for the calculation of the fitting step was 131 in the comparative example when the example was 100.

  Further, FIG. 10 shows a state in which the fitting step is completed, and in the comparative example of FIG. 10 (b), the bead portion of the tire model protrudes from the rim model, and the fitting state is accurate. Although not reproduced well, in the example of FIG. 10 (a), it was confirmed that an accurate fitting was obtained.

2 Tire model 3 Rim model 4 Contact surface 5 Tire / rim assembly model

Claims (3)

Setting a tire model in which a pneumatic tire is modeled by a finite number of elements;
Setting a rim model that models a rim having a contact surface in contact with the tire model;
Setting a tire / rim assembly model in which the tire model is fitted to the rim model by giving a condition for mounting the tire model on the rim model,
The tire model is set in a two-dimensional shape in a cross section including a tire rotation axis,
The contact surface of the rim model is set in a two-dimensional shape in a cross section including the rotation axis of the rim,
The tire simulation method , wherein the contact surface of the rim model is defined by smoothly connecting a linear function representing a straight line and a quadratic function representing an arc . A step of developing a tire / rim assembly model obtained by fitting the two-dimensional tire model and the two-dimensional shape rim model in a tire circumferential direction to set a three-dimensional tire / rim assembly model; The tire simulation method according to claim 1. The step of setting the tire / rim assembly model includes the step of determining contact between the tire model and a contact surface of the rim model;
  The tire simulation according to claim 1 or 2, wherein the step of determining the contact includes a step of checking whether each node on the tire model side is inside or outside the surface represented by the function. Method.

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