JP5498238B2 - Simulation method and simulation apparatus - Google Patents

Description

  The present invention relates to a simulation method and a simulation apparatus for performing a simulation using a tire model in which a tire is divided into a finite number of elements.

  As a simulation method using a tire model, a finite element method (FEM) described in Patent Document 1 is known. In this finite element method, a tire model is created in accordance with the finite element method for the internal structure of a pneumatic tire such as a reinforcement cord made of rubber, belt, ply, iron / organic fiber, etc. And a road surface model obtained by dividing the road surface into a finite number of elements are set and used for the simulation.

Edited by Bridgestone Co., Ltd. “Fundamentals and Practice of Automobile Tires” Sankaido, January 5, 2006, p. 242

  However, in the above simulation method, when a simulation (flat push analysis) is performed when the tire is in contact with the road surface, the tire model has a degree of freedom of deformation only at the node of the element, and cannot be deformed except at the node. Therefore, the contact point of the tire model with respect to the road surface is only the position of the node. For this reason, in order to obtain a more accurate grounding end, it is necessary to make the element fine. However, if the elements are made finer, the analysis time increases, which is not a realistic measure.

  Therefore, conventionally, it has been proposed to generate a cubic polynomial based on the node of the ground contact end and the four nodes in the vicinity of the node of the ground contact end and use the intersection of the cubic polynomial and the road surface as the ground contact end. Has been.

  However, the intersection of the cubic polynomial and the road surface may be inward of the contact surface rather than the node of the contact end, and a situation inconsistent with the result of the finite element method occurs. For this reason, there has been a problem that smooth sensitivity cannot be obtained in the simulation.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a simulation method and a simulation apparatus that can obtain a more accurate ground contact without increasing the analysis time.

  A first feature of the present invention is a simulation method, a tire model setting step for setting a tire model obtained by dividing a tire into a finite number of elements, and a simulation of the tire model with respect to a road surface by simulation using the tire model. An evaluation value calculating step for calculating an evaluation value at the time of contact, wherein the evaluation value calculating step includes at least a node that is a vertex corresponding to an outer peripheral portion of the tire model of the element and is not in contact with the road surface A step of generating an approximate curve formula based on the separation nodes that are four nodes, a step of calculating a tangent of the approximate curve formula, and a step of calculating an intersection of the tangent and the road surface as a ground contact end It is summarized as having.

  According to the first feature of the present invention, an approximate curve equation is generated based on four separate nodes that are not in contact with the road surface, and further, a tangent line of the approximate curve equation is calculated, the tangent line, the road surface The intersection point is calculated as the ground contact. As a result, the outside of the ground plane can be obtained as a ground end, and a more accurate ground end can be obtained.

  The second feature of the present invention is summarized in that the step of generating the approximate curve equation generates an approximate curve equation of a line connecting the remote nodes.

  The gist of the third feature of the present invention is that the step of calculating the tangent of the approximate curve formula calculates the tangent of the approximate curve formula at the position of the separation node closest to the road surface.

  The gist of the fourth feature of the present invention is that the approximate curve equation is a three-dimensional polynomial.

  A fifth feature of the present invention is a simulation apparatus, which is summarized in that the above-described simulation method is executed.

  As described above, according to the present invention, it is possible to provide a simulation method and a simulation apparatus capable of obtaining a more accurate ground contact without increasing the analysis time.

FIG. 1 is a flowchart for explaining a grounding end correction method according to the present embodiment. FIG. 2 is a diagram illustrating the smooth tire model and an enlarged view of the vicinity of the ground contact portion with the road surface in the smooth tire model.

It is.
FIG. 3 is a diagram illustrating a curve of a cubic polynomial, a tangent line of the cubic polynomial, and a corrected ground end node. FIG. 4 is a diagram illustrating an example of a contact length in the width direction of a conventional tire. FIG. 5 is a diagram illustrating an example of a contact length in the width direction of the tire according to the present embodiment. FIG. 6 is a configuration diagram of a simulation apparatus according to the embodiment of the present invention.

  An embodiment of a tire performance prediction method according to the present invention will be described with reference to the drawings. Specifically, (1) grounding edge correction method, (2) simulation device, (3) operation and effect, (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(1) Grounding Edge Correction Method FIG. 1 is a flowchart for explaining a grounding edge correction method for evaluating the behavior of a pneumatic tire using a tire model created using the tire model creation method according to the present embodiment. It is. The processing shown in FIG. 1 is performed, for example, in global analysis (Global Analysis: hereinafter referred to as G analysis), which is an example of a tire model analysis method for evaluating tire performance.

  The simulation apparatus applies a finite element method (FEM) as a numerical analysis method for creating a tire model. In step S31, the simulation apparatus is a smooth tire in which only the internal structure of a pneumatic tire such as a reinforcing cord made of rubber, belt, ply, iron, organic fiber, or a reinforcing material in which the reinforcing cord is bundled into a sheet shape is set. Create a model. A rib tire model may be created instead of the smooth tire model.

  FIG. 2 is a view for explaining the smooth tire model 140 and an enlarged view of the vicinity of a ground contact portion with the road surface 150 of the smooth tire model 140. In step S <b> 31, the simulation apparatus creates a smooth tire model 140 when the tire contacts the road surface 150.

  At this time, the simulation apparatus sets one node as a temporary grounding end node (hereinafter referred to as a temporary grounding end node) 141 among nodes that are vertices corresponding to the outer peripheral portion of the smooth tire model 140, and Four nodes (hereinafter referred to as remote nodes) 142-1, 142-2, 142-3, and 142-4 that are continuous to the temporary grounding end node 141 and are not in contact with the road surface 150 are set.

  Again, returning to FIG. In step S <b> 32, the simulation apparatus generates a cubic polynomial curve which is an approximate curve equation of a line connecting the four remote nodes 142-1, 142-2, 142-3 and 142-4.

  FIG. 3 is a diagram showing a curve of a cubic polynomial. A thick line 151 in FIG. 3 is a third-order polynomial curve 151 that is an approximate curve of a line connecting four separation nodes 142-1, 142-2, 142-3, and 142-4. This cubic polynomial curve 151 indicates that, among the four remote nodes 142-1, 142-2, 142-3 and 142-4, at least the remote node closest to the temporary ground terminal 141 (hereinafter referred to as the nearest remote node). Pass through 142-1.

  Again, returning to FIG. In step S33, the simulation apparatus calculates a tangent to the curve 151 of the cubic polynomial at the nearest remote node 142-1.

  FIG. 3 is a diagram showing a tangent line of the curve 151 of the cubic polynomial at the nearest remote node 142-1. A thin line 152 in FIG. 3 is a tangent line 152 of the curve 151 of the cubic polynomial at the nearest remote node 142-1.

  Again, returning to FIG. In step S34, the simulation apparatus calculates an intersection of the tangent line 152 of the cubic polynomial curve 151 and the road surface 150 as a final ground contact node (hereinafter referred to as a corrected ground contact node).

  FIG. 3 is a diagram illustrating a corrected grounding node. In FIG. 3, the intersection 155 between the tangent line 152 of the cubic polynomial curve 151 and the road surface 150 at the nearest separation node 142-1 is the corrected grounding node.

  Through the above processing, the corrected grounding node 155 is set.

  FIG. 4 is a diagram illustrating an example of a contact length in the width direction of a tire in a conventional simulation method. FIG. 5 is a diagram illustrating an example of a contact length in the width direction of the tire in the simulation method according to the present embodiment. Here, the contact length means the length of the tire in the direction perpendicular to the road surface when the tire contacts the ground. 4 and 5 show the contact lengths when the load is 100%, 97.5%, and 95% of the predetermined value, respectively.

  FIG. 4 shows a case where the intersection of the curve of the cubic polynomial and the road surface is the ground end node, and FIG. 5 shows the intersection of the tangent of the curve of the cubic polynomial and the road surface at the nearest remote node as described above. Is a grounding end node.

  As is clear from the comparison between FIG. 4 and FIG. 5, in this embodiment, the change in the contact length is larger than in the conventional case, and a contact length closer to the actual measurement value can be obtained.

(2) Simulation Device FIG. 6 shows an outline of a computer 300 as a simulation device that executes a simulation method according to an embodiment of the present invention. As shown in FIG. 6, the computer 300 includes a main unit 310 including a storage unit (not shown) such as a semiconductor memory and a hard disk, a processing unit (not shown), an input unit 320, and a display unit 330. . The processing unit executes the simulation method described with reference to FIG. 1 and the grounding node correction method described with reference to FIG.

  The computer 300 may be provided with a removable storage medium (not shown) and a driver capable of writing / reading the storage medium. A program for executing the simulation method described with reference to FIG. 1 and the grounding node correction method described with reference to FIG. 1 is recorded in a storage medium in advance, and the program read from the storage medium is executed. Also good. The program may be stored (installed) in the storage unit of the computer 300 and executed. Although not shown, the computer 300 may be connectable to a network, for example. You may acquire the program which performs a simulation method and via a network.

(3) Action / Effect According to the simulation method of the present embodiment, a curve of a cubic polynomial that is an approximate curve of a line connecting the four remote nodes 142-1, 142-2, 142-3, and 142-4 is obtained. The tangent line 152 of the cubic polynomial 151 at the nearest remote node 142-1 is calculated, and the intersection of the tangent line 152 and the road surface 150 is calculated as the corrected ground contact node 155.

  As a result, the analysis time does not increase as a result of making the elements in the finite element method fine as in the prior art. Further, the intersection of the cubic polynomial and the road surface is closer to the contact surface than the contact point node. The situation which becomes inward and contradicts the result of the finite element method is suppressed.

  As a result, an increase in analysis time can be prevented and a more accurate grounding end can be obtained.

(4) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

  In the embodiment, the case where the corrected ground end node is calculated in the G analysis has been described. However, the present invention can also be applied to other analysis methods.

  In the above-described embodiment, the simulation apparatus is the PC 300. However, the present invention can be similarly applied when other apparatuses such as a server and a mobile phone are used.

  In the above-described embodiment, the three-dimensional polynomial is used as the approximate curve formula. However, the present invention can be similarly applied to a case where another polynomial is used or an approximate curve formula obtained by the least square method is used. .

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  140: Smooth tire model, 141: Temporary ground contact node, 142-1, 142-2, 142-3, 142-4 ... Remote node, 150 ... Road surface, 151 ... Cubic polynomial curve, 152 ... Tangent, 155 ... Correction Ground terminal node, 300 ... computer, 310 ... main body, 320 ... input unit, 330 ... display unit

Claims (5)

A tire model setting step for setting a tire model in which a tire is divided into a finite number of elements;
An evaluation value calculating step for calculating an evaluation value at the time of contact of the tire model with respect to a road surface by simulation using the tire model;
The evaluation value calculating step includes:
Of the nodes corresponding to the outer periphery of the tire model of the element, one node is set as a temporary ground end node that is a temporary ground end node, and from the temporary ground end node in the tire circumferential direction. Generating an approximate curve equation based on remote nodes that are at least four nodes that are continuous along the road and are not in contact with the road surface;
Calculating a tangent of the approximate curve equation;
Calculating the intersection of the tangent and the road surface as a ground contact,
In the step of generating the approximate curve equation,
The temporary ground contact node and the separation node are set within a range of 90 degrees extending from the intersection of a line orthogonal to the road surface and the road surface through the center of the tire model in the tire circumferential direction. Simulation method.   The simulation method according to claim 1, wherein the step of generating the approximate curve formula generates an approximate curve formula of a line connecting the remote nodes. 3. The simulation method according to claim 1, wherein the step of calculating a tangent of the approximate curve equation calculates a tangent of the approximate curve equation at a position of the remote node closest to the road surface among the four nodes .   The simulation method according to claim 1, wherein the approximate curve equation is a three-dimensional polynomial.   A simulation apparatus that executes the simulation method according to claim 1.

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