Method for creating a tire model and method for designing a tire

Abstract

To provide a method capable of reducing creation cost of a tire model.SOLUTION: A method for creating a numeric value analysis model of a tire having a structural material therein. The method includes: a first step of inputting a first tire model including a structural material model obtained by modeling the structural material by a finite number of elements to a computer; and a second step of allowing a computer to create a second tire model obtained by changing the shape of the structural material model of the first tire model. The second step includes: a step S21 of moving at least one node of elements constituting the structural material model of the first tire model; a step S22 of calculating a distance between at least the one moved node and other node linked with the one node; and a step S23 of re-defining a related element so that at least the one moved node overlaps the other node when the distance is a predetermined threshold or less.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a tire model creation method and the like. [Background technology]

[0002] The following Patent Document 1 describes a method for designing a pneumatic tire. In this method, a basic tire model including an internal structure is set, and nodes constituting the internal structure of this basic tire model are moved to determine a modified tire model in which the tire cross-sectional shape is changed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 94 / 16877 Summary of the Invention [Problem to be solved by the invention]

[0004] However, depending on the position of the node after movement, the shape of the element of the corrected tire model may become distorted. In order to correct such distorted elements, the above method requires re-element division (remeshing) based on the node position after movement, which increases the cost of creating the tire model.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a method etc. capable of reducing the cost of creating a tire model. [Means for solving the problem]

[0006] The present invention is a method for creating a numerical analysis model of a tire having a structural material therein, comprising a first step of inputting a first tire model including a structural material model in which the structural material is modeled with a finite number of elements into a computer, and a second step of the computer creating a second tire model by modifying the shape of the structural material model of the first tire model, wherein the second step comprises the steps of moving at least one node of an element constituting the structural material model of the first tire model, calculating the distance between the at least one moved node and another node linked to this node, and redefining associated elements so that the at least one moved node and the other node overlap when the distance is equal to or less than a predetermined threshold value.

[0007] In the tire model creating method according to the present invention, the redefining step may include moving the moved at least one node onto the other node.

[0008] In the tire model creation method according to the present invention, the second step may change a shape of the structural material model while maintaining relative positions between nodes of elements constituting parts of the first tire model other than the structural material model.

[0009] In the tire model creating method according to the present invention, the structural material may be a bead apex rubber extending from a bead core of a bead portion of the tire radially outward.

[0010] In the tire model creating method according to the present invention, the structural material may be a ply in which a plurality of cords are covered with a topping rubber.

[0011] In the tire model creating method according to the present invention, the second step may change at least one of a thickness, a length in a tire radial direction, and a length in an tire axial direction of the structural material model.

[0012] The present invention is a method for designing a tire having a structural material therein, comprising the steps of: inputting a first tire model into a computer, the first tire model including a structural material model in which the structural material is modeled with a finite number of elements based on predetermined design factors of the tire; inputting constraint conditions related to the design factors and an objective function related to the performance of the tire into the computer; and, by the computer, obtaining an optimal solution of the design factors that optimizes the objective function under the constraint conditions, the step of obtaining the optimal solution includes the steps of creating a second tire model in which a shape of the structural material model of the first tire model is changed, and calculating the objective function based on the second tire model, and the step of creating the second tire model includes the steps of moving at least one node of an element constituting the structural material model of the first tire model, calculating a distance between the at least one moved node and another node linked to this node, and, when the distance is equal to or less than a predetermined threshold, redefining associated elements so that the at least one moved node and the other node overlap. Effect of the Invention

[0013] The tire model creation method of the present invention employs the above steps to prevent elements from becoming distorted, thereby reducing the cost of creating a tire model. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing an example of a computer for executing a tire model creation method and a tire design method. [Diagram 2] FIG. 1 is a cross-sectional view showing an example of a tire. [Diagram 3] 4 is a flowchart showing an example of a processing procedure of a tire model creating method. [Figure 4] FIG. 2 is a cross-sectional view showing an example of a first tire model. [Diagram 5] FIG. 5 is an enlarged view of a bead portion in FIG. [Figure 6]10 is a flowchart showing an example of a processing procedure of a second step. [Figure 7] FIG. 6 is an enlarged view of FIG. [Figure 8] FIG. 13 is a partial enlarged view showing an example of a second tire model in which nodes of elements of a structural material model are moved. [Figure 9] FIG. 13 is a partial enlarged view showing an example of a second tire model redefined so that nodes overlap. [Figure 10] 4 is a flowchart showing an example of a processing procedure of a tire design method. [Figure 11] 13 is a flowchart showing an example of a processing procedure of an optimal solution calculation step. [Figure 12] 10 is a flowchart showing an example of a processing procedure of a second tire model creating step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are intended to enhance understanding of the contents of the invention, and therefore some of the drawings may be exaggerated, and the scales of the drawings may not be strictly consistent.

[0016] In the tire model creation method of the present embodiment (hereinafter, sometimes simply referred to as the "creation method"), a numerical analysis model of a tire is created. Fig. 1 is a perspective view showing an example of a computer for executing the tire model creation method and the tire design method.

[0017] The computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a includes, for example, a central processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drives 1a1 and 1a2. The storage device stores software and the like for executing the creation method and design method of this embodiment.

[0018] 2 is a cross-sectional view showing an example of a tire 2. The tire 2 of this embodiment is illustrated as being for a passenger car, but is not particularly limited thereto. The tire 2 may be used for heavy load vehicles such as trucks and buses, or for two-wheeled vehicles. It does not matter whether the tire 2 actually exists or not.

[0019] The tire 2 of this embodiment is provided therein with a structural material 3. The structural material 3 of this embodiment includes a bead apex rubber 4 and a ply 5.

[0020] The bead apex rubber 4 extends from the bead core 6 of the bead portion 2c outward in the radial direction of the tire. The bead apex rubber 4 of this embodiment extends in a tapered shape toward the outer side in the radial direction of the tire.

[0021] The ply 5 in this embodiment is formed by covering a plurality of cords (not shown) with a topping rubber (not shown). The ply 5 includes a carcass ply 7A and a belt ply (a first belt ply 8A and a second belt ply 8B), but is not limited to this embodiment. The ply 5 may include, for example, a band ply (not shown) or the like.

[0022] The carcass ply 7A constitutes the carcass 7 of the tire 2. The carcass ply 7A in this embodiment includes a main body portion 7Aa extending from the tread portion 2a through the sidewall portion 2b to the bead core 6 of the bead portion 2c, and a turn-up portion 7Ab turned up around the bead core 6, but is not limited to this embodiment. The carcass ply 7A may be composed of only the main body portion 7Aa.

[0023] The first belt ply 8A and the second belt ply 8B constitute a belt layer 8 disposed radially outward of the carcass 7. The second belt ply 8B in this embodiment is disposed radially outward of the first belt ply 8A. The belt layer 8 may be constituted by only one of the first belt ply 8A and the second belt ply 8B, or another belt ply (not shown) may be further provided.

[0024] Next, an example of the processing procedure of the creation method of this embodiment will be described. In this embodiment, a first tire model is created by modeling a reference tire 2, and a second tire model is created by modifying the shape of the structural material 3 based on the first tire model. Fig. 3 is a flowchart showing an example of the processing procedure of the tire model creation method.

[0025] In the creating method of this embodiment, first, a first tire model is input to the computer 1 (first step S1). FIG.

[0026] In the first step S1 of this embodiment, for example, based on design information of the tire 2 shown in Fig. 2 (for example, information related to a mold), the tire 2 is discretized into a finite number of elements F(i) (i = 1, 2, ...) that can be handled by a numerical analysis method. As a result, in the first step S1, a first tire model 11 is set (modeled). For example, the finite element method, the finite volume method, the difference method, or the boundary element method can be appropriately adopted as the numerical analysis method. In this embodiment, the finite element method is adopted.

[0027] The first tire model 11 includes a structural material model 13 in which the structural material 3 (shown in FIG. 2) is modeled with a finite number of elements F(i). Furthermore, the first tire model 11 includes a rubber member model 19 in which the rubber members 9 such as the tread rubber 9a shown in FIG. 2 are modeled.

[0028] The structural material model 13 of this embodiment includes a bead apex rubber model 14 that models the bead apex rubber 4 (shown in FIG. 2) and a ply model 15 that models the ply 5 (shown in FIG. 2). The ply model 15 of this embodiment includes a carcass ply model 17 that models the carcass ply 7A (shown in FIG. 2). Furthermore, the ply model 15 includes a first belt ply model 18A that models the first belt ply 8A (shown in FIG. 2) and a second belt ply model 18B that models the second belt ply 8B (shown in FIG. 2).

[0029] The rubber member model 19 of this embodiment includes a tread rubber model 19a, a sidewall rubber model 19b, and an inner liner rubber model 19c. Fig. 5 is an enlarged view of the bead portion of Fig. 4.

[0030] For example, a tetrahedral solid element, a pentahedral solid element, or a hexahedral solid element may be used as the element F(i). Each element F(i) has a plurality of nodes 21 and edges 22 that connect (link) adjacent nodes 21, 21. The edges 22 extend linearly. Each element F(i) is defined with numerical data such as an element number, the node 21 number, the coordinate values ​​of the node 21, and material properties (e.g., density, Young's modulus, and / or damping coefficient).

[0031] In this embodiment, for example, meshing software (for example, "ICEM CFD" by ANSYS, Inc.) is preferably used to define the first tire model 11. The first tire model 11 is stored in the computer 1.

[0032] Next, in the creating method of this embodiment, the computer 1 creates a second tire model by modifying the shape of the structural material model 13 of the first tire model 11 (second step S2).

[0033] Regarding the structural material models 13 whose shape is to be changed, for example, structural material models 13 whose design factors (for example, the thickness of the structural material 3 shown in FIG. 2, the length in the tire radial direction, or the length in the tire axial direction) are desired to be changed may be selected. In the second step S2 of this embodiment, a mode in which the shape (in this example, the thickness and the length in the tire radial direction) of the bead apex rubber model 14 among the structural material models 13 of the first tire model 11 is changed is exemplified. Note that in the second step S2, the shape of the ply model 15 shown in FIG. 4 may be changed, or all of the structural material models 13 may be changed. FIG. 6 is a flowchart showing an example of the processing procedure of the second step S2.

[0034] In the second step S2 of this embodiment, first, at least one node 21 of the element F(i) constituting the structural material model 13 of the first tire model 11 is moved (step S21). Fig. 7 is an enlarged view of Fig. 5. Fig. 8 is a partial enlarged view showing an example of the second tire model 12 in which the node 21 of the element F(i) of the structural material model 13 has been moved.

[0035] As shown in Fig. 7, in step S21, the node 21 of the element F(i) of the structural material model 13 of the first tire model 11 is moved based on the design factors (in this example, the thickness of the bead apex rubber 4, etc.) of the structural material 3 that have been changed from the tire 2 shown in Fig. 2. In this embodiment, the node 21 is moved along the edge 22 that constitutes the element F(i), but this is not particularly limited. Furthermore, in step S21 of this embodiment, the edge 22 connected to the moved node 21 is reconstructed as shown in Fig. 8. For example, the above-mentioned meshing software can be used to move the node 21 and reconstruct the edge 22.

[0036] In this manner, in step S21, the nodes 21 of the structural material model 13 of the first tire model 11 are moved to create the second tire model 12 in which the shape of the structural material model 13 (in this example, the thickness of the bead apex rubber model 14, etc.) is changed. Therefore, in the creation method of this embodiment, it is not necessary to create a tire model for each changed design factor (i.e., discretize by element F(i)), and therefore the cost of creating the tire model can be reduced.

[0037] In the second tire model 12, the distance D1 between at least one moved node (hereinafter sometimes referred to as the "moved node") 21a and another node (hereinafter sometimes referred to as the "other node") 21b linked to this node 21 may become small. This may cause the shape of an element F(i) formed by those nodes 21a, 21b to become distorted (for example, the thickness of element F(i) to become smaller than necessary). An element F(i) having such a distorted shape may cause calculations to become unstable in a simulation using the second tire model (tire model) 12.

[0038] In this embodiment, in order to prevent the element F(i) from becoming distorted, when a distance D1 between the moved node 21a and another node 21b is equal to or less than a predetermined threshold, the related element F(i) is redefined (degenerated) so that these nodes 21a, 21b overlap. Fig. 9 is a partial enlarged view showing an example of the second tire model 12 redefined so that the nodes overlap.

[0039] 8, in the second step S2 of this embodiment, a distance D1 between the moved node 21a and another node 21b linked to this node 21 is calculated (step S22). In this embodiment, for all the moved nodes 21a, the distance D1 between the other nodes 21b adjacent to the moved node 21a via the side 22 (linked by the side 22) is calculated. Note that in step S22, the above distance D1 may be calculated only for the other nodes 21b to which the moved node 21a has come closer (i.e., the distance has decreased). These distances D1 are stored in the computer 1.

[0040] Next, in the second step S2 of this embodiment, when the distance D1 is equal to or less than a predetermined threshold, the related element F(i) is redefined so that the moved node 21a overlaps with another node 21b (step S23). The threshold can be set appropriately, for example, as long as it is possible to determine whether the shape of the element F(i) composed of the moved node 21a and the other node 21b is distorted. The threshold is preferably set to, for example, 0.1 to 1.0 mm.

[0041] In step S23 of this embodiment, among all the moved nodes 21a, the nodes 21a that have been moved with the distance D1 equal to or less than the threshold value are overlapped with other nodes 21b as shown in Fig. 9. In this embodiment, the coordinate values ​​of the moved nodes 21a are set to be the same as the coordinate values ​​of the other nodes 21b.

[0042] Furthermore, in step S23, an element F(i) related to the moved node 21a and another node 21b (i.e., an element whose shape is determined to be distorted) is redefined. In this embodiment, the length of the edge 22 (shown in FIG. 8) linking the moved node 21a and another node 21b is set to zero. As a result, in step S23, the element F(i) related to those nodes 21a and 21b is redefined without the need for further element division (remeshing) based on the position of the moved node 21a. Then, in the second step S2, a series of processing procedures is completed, and the second tire model 12 is defined as the tire model 10 in which the design factors of the tire 2 shown in FIG. 2 have been changed.

[0043] In this manner, in the second step S2 of this embodiment, when the distance D1 (shown in FIG. 8) between the moved node 21a and another node 21b is equal to or less than a threshold value, the related element F(i) is redefined so that these nodes 21a and 21b overlap. As a result, the creation method of this embodiment can prevent the shape of the element F(i) from becoming distorted, and therefore can prevent calculations from becoming unstable in a simulation using the tire model 10 (second tire model 12).

[0044] Furthermore, in the second step S2, the related element F(i) is redefined so that the moved node 21a overlaps with another node 21b, so that there is no need to divide the elements again (remesh) based on the position of the moved node 21a as in the above-mentioned Patent Document 1. Therefore, the creation method of this embodiment can reduce the creation cost of the tire model 10 (second tire model 12). The tire model 10 (second tire model 12) is stored in the computer 1.

[0045] In the second tire model 12 (tire model 10), in the portion where the nodes 21a, 21b overlap, the mass, etc. may be defined as high due to the overlap of the material properties defined for each of the nodes 21a, 21b. However, since the ratio of the number of overlapping portions of the nodes 21a, 21b to the total number of the nodes 21 constituting the tire model is small, the change in the mass, etc. of the tire model as a whole is small. Therefore, in the simulation using the second tire model 12, the calculation accuracy is not reduced.

[0046] In the second step S2, when only the node 21a of the structural material model 13 is moved, the shape of the other portion 23 (portion other than the structural material model 13) that does not involve the movement of the node 21 may differ from the shape of the corresponding portion 23 of the first tire model 11 shown in Fig. 7. For this reason, in the second step S2, the shape of the structural material model 13 may be changed while maintaining the relative positions (in this example, the distance D2 in the thickness direction) between the nodes 21, 21 of the element F(i) that constitutes the portion 23 of the first tire model 11 other than the structural material model 13.

[0047] In this embodiment, while maintaining the relative positions between the nodes 21, 21 constituting the carcass ply model 17 and the inner liner rubber model 19c, both of these nodes 21, 21 and the node 21a constituting the bead apex rubber model 14 are moved. As a result, as shown in FIG. 9, the shape of the structural material model 13 can be changed while maintaining the shape of the portion 23 other than the structural material model 13. In this example, the movement of the nodes 21 constituting the carcass ply model 17 and the inner liner rubber model 19c causes the profile of the tire cavity surface 24 to differ from the profile of the tire cavity surface 24 before the movement (shown in FIG. 7). However, the profile of the tire cavity surface 24 is permissible because it does not change information (e.g., the molding surface) on the mold used to create the first tire model 11 (shown in FIG. 4).

[0048] In the second step S2, the shape of the structural material model 13 may be changed while maintaining the profile (outer surface profile from the tire equator C to the bead portion 2c) 25 excluding the tire cavity surface 24 of the first tire model 11. This makes it possible to create the second tire model 12 with the structural material model 13 changed without changing information (e.g., the molding surface) related to the mold used to create the first tire model 11.

[0049] In Fig. 7, when node 21b of the structural material model 13 is moved toward node 21a, it is desirable to also move node 21m (hereinafter sometimes referred to as "middle node") between node 21b and node 21 constituting the outer surface profile 25 shown in Fig. 7. This makes it possible to prevent the shape of element F(i) arranged between the outer surface profile 25 and the structural material model 13 from becoming distorted as node 21b constituting the structural material model 13 is moved.

[0050] The movement amount of the intermediate node 21m can be set appropriately. For example, the movement amount of each intermediate node 21m may be set based on a value obtained by dividing the movement amount of the node 21b constituting the structural material model 13 by the number of intermediate nodes 21m. This allows each intermediate node 21m to be moved evenly by a movement amount smaller than that of the node 21b of the structural material model 13. Therefore, it is possible to effectively prevent the shape of the element F(i) arranged between the structural material model 13 and the maintained outer surface profile 25 from being distorted.

[0051] The tire model 10 (second tire model 12) created in this embodiment can be used in a simulation in which the tire model 10 rolls on a road surface model, for example, based on the procedure described in a patent document (JP Patent Publication No. 2017-193315). For such a simulation, for example, a commercially available finite element analysis application software such as LS-DYNA manufactured by JSOL Corporation is used. Then, the design factors of the tire 2 (shown in FIG. 2) are changed until the physical quantities of the tire model 10 calculated by the simulation become satisfactory. In this way, a tire 2 having desired performance can be designed and manufactured.

[0052] In this embodiment, it is not necessary to create the tire model 10 (second tire model 12) from scratch by discretizing the element F(i) for each changed design factor (for example, the design factor of the structural member 3 shown in FIG. 2). Furthermore, it is possible to prevent the element F(i) of the tire model 10 from becoming distorted. Therefore, with the creation method of this embodiment, a tire 2 having desired performance can be designed and manufactured at low cost.

[0053] Next, a method for designing a tire having a structural material therein (hereinafter, sometimes simply referred to as a "design method") will be described. In the design method of this embodiment, an optimal solution is found for the design factors (e.g., the thickness of the bead apex rubber 4, etc.) of the tire 2 having the structural material 3 shown in Fig. 2 based on a tire model in which an objective function (physical quantity related to tire performance) is optimized. As a result, the design method makes it possible to efficiently design a tire 2 having excellent performance.

[0054] The optimal solution of the design factors is found based on an optimization algorithm using a computer 1 (shown in FIG. 1). The optimization algorithm is for determining optimal design factors (e.g., the above parameters) that satisfy an arbitrary objective function under certain constraint conditions. Examples of the optimization algorithm include a genetic algorithm (GA) and a particle swarm optimization (PSO). Such optimization algorithms are suitable for searching for a global optimal solution while preventing the solution from falling into a local solution. In the calculation method of this embodiment, a particle swarm optimization (PSO) that has a relatively short calculation time is adopted, but a genetic algorithm (GA) or the like may also be adopted.

[0055] In particle swarm optimization (PSO), optimization is performed by creating a first generation containing multiple initial design factors (design variables), finding the objective function for each design factor, and updating each design factor (generational change) so that it approaches the most desirable objective function. Random numbers are used to update each design variable, making it possible to search for optimal conditions over a wide area. Details of particle swarm optimization (PSO) are described in various documents, such as "Particle Swarm Optimization and Nonlinear Systems" in IEICE Fundamentals Review (Institute of Electronics, Information and Communication Engineers), Vol. 5, No. 2, August 2011.

[0056] Fig. 10 is a flow chart showing an example of a processing procedure of a tire design method. In the design method of this embodiment, first, a first tire model 11 (shown in Fig. 4) is input to the computer 1 (step S3). In step S3, the first tire model 11 including a structural material model 13 in which a structural material 3 is modeled with a finite number of elements is set based on predetermined design factors of the tire 2 (shown in Fig. 2).

[0057] The design factors can be set appropriately according to, for example, the type (including the category and tire size) of the tire 2 shown in Fig. 2. The design factors in this embodiment include the thickness of the structural material 3, the length in the tire radial direction, or the length in the tire axial direction.

[0058] The first tire model 11 is set (modeled) in the same procedure as the first step S1 of the creation method shown in Fig. 3. The first tire model 11 is input to the computer 1.

[0059] Next, in the design method of this embodiment, constraint conditions related to design factors and an objective function related to tire performance are input to the computer 1 (step S4). The constraint conditions are conditions (design criteria) that must be satisfied for the tire 2 shown in FIG. 2. Such constraint conditions can be set as appropriate based on, for example, the type of tire 2 (including category and tire size). The constraint conditions of this embodiment include the range of thicknesses of the structural materials 3, the range of lengths in the tire radial direction, or the range of lengths in the tire axial direction. The constraint conditions are stored in the computer 1.

[0060] The objective function is appropriately set based on the performance required for the tire 2 shown in FIG. 2. Examples of the objective function include the spring constant of the second tire model 12 (shown in FIG. 9), parameters related to the contact shape, rolling resistance value, cornering power, and mass. In this embodiment, at least one of the above physical quantities is set as the objective function. These objective functions can be set, for example, by the same procedure as in the patent document (JP Patent Publication No. 2019-217919).

[0061] Next, in the design method of this embodiment, the computer 1 obtains an optimal solution of the design variables that optimizes the objective function under the constraint conditions (optimal solution calculation step S5). Fig. 11 is a flowchart showing an example of the processing procedure of the optimal solution calculation step S5.

[0062] In the optimum solution calculation step S5 of this embodiment, first, the computer 1 creates a second tire model 12 (shown in FIG. 9) by modifying the shape of the structural material model of the first tire model 11 (second tire model creation step S51). In the second tire model creation step S51, a plurality of types of second tire models 12 having different design factors of the structural material 3 are created. The number of second tire models 12 is set to, for example, about 2 to 10 in order to quickly find an optimum solution. FIG. 12 is a flowchart showing an example of the processing procedure of the second tire model creation step S51.

[0063] In the second tire model creation step S51 of this embodiment, first, the computer 1 sets a plurality of design factors (step S61). Each design factor can be appropriately set so as to satisfy constraint conditions. In this embodiment, among the design factors of the tire 2 shown in FIG. 2, a plurality of design factors are set so that only the thickness of the bead apex rubber 4 is different from each other, but this is not limited to such an embodiment. For example, the design factors of the ply 5 may be different, or other design factors may be different. The design factors are stored in the computer 1.

[0064] Next, in the second tire model creation step S51 of this embodiment, the computer 1 moves at least one node 21a of the element F(i) constituting the structural material model 13 of the first tire model 11 (step S62), as shown in Fig. 7. In step S62, the nodes 21a of the element F(i) of the structural material model 13 of the first tire model 11 are moved for each of the multiple design factors set in step S61. The movement of the nodes 21a is performed in the same procedure as step S21 (shown in Fig. 6) of step S21 of the tire model creation method of the previous embodiment.

[0065] In step S62 of this embodiment, a plurality of types of second tire models 12 (shown in FIG. 8) having different design factors are created by moving the nodes 21a of the structural material model 13 of the first tire model 11. Therefore, in step S62 of this embodiment, it is not necessary to create the second tire model 12 from scratch by discretizing the element F(i) for each design factor, and therefore the cost of creating the second tire model 12 can be reduced.

[0066] Next, in the second tire model creation step S51 of this embodiment, the computer 1 calculates a distance D1 (shown in FIG. 8) between at least one moved node 21a and another node 21b linked to this node 21 (step S63). In step S63, the distances D1 between all moved nodes 21a and the other nodes 21b are calculated for each of a plurality of types of second tire models 12 having different design factors. The calculation of the distance D1 is performed in the same procedure as step S22 (shown in FIG. 6) of the tire model creation method of the previous embodiment. The distance D1 is stored in the computer 1.

[0067] Next, in a second tire model creation step S51 of this embodiment, the computer 1 redefines the associated elements F(i) so that at least one moved node 21a overlaps with another node 21b when the distance D1 is equal to or less than a predetermined threshold (step S64). In step S64 of this embodiment, the associated elements F(i) are redefined in each of the multiple types of second tire models 12 having different design factors. The redefinition of the associated elements F(i) is performed in the same procedure as step S23 (shown in FIG. 6) of the tire model creation method of the previous embodiment.

[0068] In step S64 of this embodiment, when the distance D1 between the moved node 21a and another node 21b is equal to or less than a threshold value, the related element F(i) is redefined so that the nodes 21a, 21b overlap as shown in Fig. 9. As a result, in the design method of this embodiment, it is possible to prevent the shape of the element F(i) of each second tire model 12 from becoming distorted, and therefore it is possible to prevent the calculation from becoming unstable in step S52 (simulation) of calculating the objective function of each second tire model 12.

[0069] Furthermore, in step S64, the related element F(i) is redefined so that the moved node 21a overlaps with another node 21b, and therefore, unlike the above-mentioned Patent Document 1, it is not necessary to divide the elements again (remesh) based on the position of the moved node 21. Therefore, in step S64 of this embodiment, it is possible to reduce the creation cost of each second tire model 12. Each second tire model 12 is stored in the computer 1.

[0070] Next, in an optimal solution calculation step S5 of this embodiment, the computer 1 calculates an objective function based on the second tire model 12 (shown in FIG. 9) (step S52). In step S52, a simulation required to obtain an objective function is performed for each second tire model 12. Such a simulation can be performed, for example, in the same procedure as the physical quantity acquisition step of the patent document (JP Patent Publication No. 2019-217919). As a result, in step S52, the objective function of each second tire model 12 is acquired. The objective function is stored in the computer 1.

[0071] Next, in the optimal solution calculation step S5 of this embodiment, the computer 1 determines whether the objective function is satisfied (step S53). In step S53 of this embodiment, the second tire model 12 having the best objective function is selected from the second tire models 12 having different design factors. Then, it is determined whether the objective function of the selected second tire model 12 satisfies predetermined conditions. The conditions of the objective function to be satisfied are appropriately set according to the type of tire 2 (including category and tire size), etc.

[0072] In step S53, if it is determined that the objective function of the selected second tire model 12 satisfies the predetermined condition ("Y" in step S53), the design factors of the second tire model 12 are determined as the optimum solution (step S54). Then, as shown in Fig. 10, the tire 2 is designed based on the design factors determined as the optimum solution, and the tire 2 is manufactured (step S6). As a result, in the design method of this embodiment, the tire 2 that satisfies the objective function can be efficiently designed and manufactured.

[0073] On the other hand, if it is determined in step S53 that the objective function of the selected second tire model 12 does not satisfy the predetermined condition ("N" in step S53), the second tire model creation steps S51 to S53 are performed again.

[0074] In the optimal solution calculation step S5 of this embodiment, the computer 1 obtains an optimal solution of the design factors that optimize the objective function based on an optimization algorithm under the constraint conditions. For this reason, in step S61 of the second tire model creation step S51 shown in Fig. 12, a plurality of design factors other than the best design variable are updated (generational change) so that the objective function approaches the best design variable under the constraint conditions. The generational change procedure is appropriately performed based on the description of, for example, a patent document (JP Patent Publication No. 2019-217919).

[0075] As a result, in the second tire model creation step S51, a plurality of types of second tire models 12 can be newly created based on the updated design factors. Therefore, in the design method of this embodiment, it is possible to reliably design and manufacture a tire 2 that satisfies the objective function.

[0076] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified and carried out in various forms. EXAMPLES

[0077] A first tire model was created by modeling the tire shown in Fig. 2, and a second tire model was created by modifying the shape of the bead apex rubber model of the first tire model (Example and Comparative Example). In the Example and Comparative Example, a step of moving the nodes of the elements constituting the structural material model of the first tire model was carried out to create the second tire model.

[0078] In the embodiment, based on the processing procedure shown in Fig. 6, a process of calculating the distance between the moved node and other nodes linked to this node, and a process of redefining related elements so that the moved node and other nodes overlap when the distance is equal to or less than a threshold were performed. Meanwhile, in the comparative example, similar to the above-mentioned Patent Document 1, element division (remeshing) was performed again based on the node position after movement. Then, the creation costs of the second tire model were compared between the embodiment and the comparative example. The threshold value is as described in the specification.

[0079] As a result of the test, the time required to create one second tire model was reduced by about 0.5 to 1.0 hour in the example compared to the comparative example, and therefore the cost of creating a tire model was reduced in the example compared to the comparative example.

[0080] In addition, in the embodiment, since no work by an operator (such as remeshing) is required, the creation of the second tire model can be automated. Therefore, in a design method for finding an optimal solution for tire design factors using an optimization algorithm, a series of steps including the creation of the second tire model, the calculation of the objective function, and the identification of the optimal solution can be automated, enabling efficient tire design. [Explanation of symbols]

[0081] S21 Process of moving joints S22: Calculate the distance between nodes S23: Redefining elements so that nodes are duplicated

Claims

1. 1. A method for creating a numerical analysis model of a tire having an internal structure, comprising: a first step of inputting a first tire model including a structural material model in which the structural material is modeled using a finite number of elements into a computer; a second step of generating a second tire model by changing a shape of the structural material model of the first tire model, the second step includes a step of moving at least one node of an element that configures the structural material model of the first tire model; calculating a distance between at least one of the moved nodes and other nodes linked to the moved node; and redefining associated elements such that the at least one moved node overlaps with the other node when the distance is equal to or less than a predetermined threshold value; The structural material is a bead apex rubber extending from a bead core of a bead portion of the tire to an outer side in a radial direction of the tire. How to create a tire model.

2. A method for creating a tire model as described in claim 1, wherein the structural material is a ply in which a plurality of cords are covered with a topping rubber.

3. A method for creating a numerical analysis model of a tire having an internal structural material, comprising: a first step of inputting a first tire model including a structural material model in which the structural material is modeled using a finite number of elements into a computer; a second step of generating a second tire model by changing a shape of the structural material model of the first tire model, the second step includes a step of moving at least one node of an element that configures the structural material model of the first tire model; calculating a distance between at least one of the moved nodes and other nodes linked to the moved node; and redefining associated elements such that the at least one moved node overlaps with the other node when the distance is equal to or less than a predetermined threshold value; The structural material is a ply in which a plurality of cords are covered with a topping rubber. How to create a tire model.

4. A method for creating a tire model described in any one of claims 1 to 3, wherein the second step changes at least one of the thickness, the radial length, and the axial length of the structural material model.

5. A method for creating a tire model described in any one of claims 1 to 4, wherein the redefining step moves at least one of the moved nodes onto the other nodes.

6. A method for creating a tire model described in any one of claims 1 to 5, wherein the second step changes the shape of the structural material model while maintaining the relative positions between nodes of elements that constitute parts of the first tire model other than the structural material model.

7. 1. A method for designing a tire having an internal structure, comprising: inputting a first tire model into a computer, the first tire model including a structural material model in which the structural material is modeled with a finite number of elements based on predetermined design factors of the tire; inputting constraints on the design factors and an objective function on the performance of the tire into the computer; The computer, and determining an optimal solution of the design variables that optimizes the objective function under the constraint conditions; The step of obtaining the optimal solution includes a step of creating a second tire model by modifying a shape of the structural material model of the first tire model; and calculating the objective function based on the second tire model. The step of creating the second tire model includes a step of moving at least one node of an element constituting the structural material model of the first tire model; calculating a distance between at least one of the moved nodes and other nodes linked to the moved node; and redefining associated elements such that the at least one moved node and the other node overlap when the distance is equal to or less than a predetermined threshold. How tires are designed.

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