Tire model creation device and tire model creation method

Abstract

To provide a tire model creation device which can improve convergence property while keeping analysis accuracy.SOLUTION: A tire model creation device 10 creates a tire model 30 which divides a tire into a finite number of elements. The tire model is given in which: each element is, when a bead core 31 is divided into an element, a rectangular shape when viewed from a tire circumferential direction; an outer periphery of the bead core 31 is a polygonal shape made of the rectangular shapes; and when a center point O is arranged inside of the bead core 31, lines connecting the center point O with respective peripheral points G on two adjacent sides of the polygonal shape are included.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a tire model creating device and a tire model creating method for creating a tire model in which a tire is divided into a finite number of elements. [Background technology]

[0002] A well-known method for analyzing tire characteristics through simulation is the finite element method (FEM), in which the tire is approximated by a tire finite element model (hereinafter referred to as tire model) in which the tire is divided into a finite number of elements, physical properties such as density and elastic modulus are assigned to each element, boundary conditions such as internal pressure and load are assigned to the tire model, and the deformation state of each element is calculated to simulate the deformation, motion state, etc. of the tire.

[0003] In the finite element method, for example, when analyzing tire contact or rolling, the bead side of the tire model is constrained to the hub center or rim model. Therefore, when analysis conditions (load, rotation, translation, slip angle, etc.) are applied to the tire model, large stress is generated in the bead element.

[0004] In the finite element method, a tire structure including a bead core is generally divided into polygonal elements. For example, Patent Document 1 discloses a tire model in which a bead core is divided into triangular elements as viewed in the tire circumferential direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-106886 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the tire model of Patent Document 1, when severe analysis conditions (load of a heavy load, load of high speed rotation, etc.) are applied, the distortion of the bead core and the peripheral elements of the bead core increases, and the residual stress does not converge, and the analysis may diverge. Therefore, when severe analysis conditions are applied, it is required to improve the convergence while maintaining the analysis accuracy.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a tire model creation device and a tire model creation method that are capable of improving convergence while maintaining analysis accuracy. [Means for solving the problem]

[0008] The tire model creation device according to the present invention is a tire model creation device that creates a tire model in which a tire is divided into a finite number of elements, and is characterized in that when the bead core is divided into elements as viewed in the circumferential direction of the tire, each element is made to have a quadrilateral shape, and when the outer periphery of the bead core is made to be a polygonal shape, and when a center point is provided inside the bead core, the quadrilateral shape includes lines connecting the center point and each of the outer periphery points on two adjacent sides of the polygonal shape.

[0009] The tire model creation method according to the present invention is a tire model creation method for creating a tire model in which a tire is divided into a finite number of elements, and is characterized in that when the bead core is divided into elements as viewed in the tire circumferential direction, each element is made to have a quadrilateral shape, and when the outer periphery of the bead core is made to be a polygonal shape, and when a center point is provided inside the bead core, the quadrilateral shape includes lines connecting the center point and each of the outer periphery points on two adjacent sides of the polygonal shape. Effect of the Invention

[0010] According to the tire model creation device and tire model creation method of the present invention, it is possible to improve convergence while maintaining analysis accuracy. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a configuration of a tire model creation device according to an embodiment; [Diagram 2] FIG. 2 is a diagram illustrating an example of a tire model. [Diagram 3] FIG. 3 is an enlarged view of part A in FIG. 2. [Figure 4] FIG. 2 is a flowchart showing a flow of a tire model creation method according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, values, etc. are merely examples for the purpose of easily understanding the present invention, and can be appropriately changed according to the application, purpose, specifications, etc.

[0013] [Tire model creation device] A tire model creating device 10 as an example of an embodiment will be described with reference to Figs. 1 to 3.

[0014] The tire model creation device 10 creates a tire finite element model (hereinafter referred to as tire model 30) using the finite element method (FEM) that simulates tire characteristics. The finite element method approximates a tire by dividing it into a finite number of elements into a tire model 30, gives physical properties such as density and elastic modulus to each element, gives boundary conditions such as internal pressure and load to the tire model 30, calculates the deformation state of each element, and simulates the deformation, motion state, etc. of the tire.

[0015] According to the tire model creation device 10, the bead core 31 is divided into quadrangular elements in the cross-sectional shape seen from the circumferential direction of the tire to create a model, as will be described in detail later. This makes it possible to improve the convergence while maintaining the analytical accuracy in the finite element method.

[0016] As shown in Fig. 1, the tire model creation device 10 includes a control device 11, an input device 12, and a display device 13, each of which will be described in detail later. The tire model creation device 10 may be configured with one computer or multiple computers. In addition, some of the functions of the tire model creation device 10 may reside in a server or the like connected via a communication network. Furthermore, the tire model creation device 10 may be a simulation device that simulates tire characteristics using the finite element method.

[0017] The control device 11 has a central processing unit (CPU) which is an arithmetic processing unit, and storage units such as a random access memory (RAM) and a read only memory (ROM), and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM. The control device 11 will be described in detail later.

[0018] The input device 12 is an input interface for inputting information required for creating the tire model 30, and an example of the input device 12 is a keyboard. Examples of the information input by the input device 12 include the creation conditions of the tire model 30. The input device 12 is connected to the control device 11.

[0019] The display device 13 is a display on which an input screen, an output screen for simulation results, etc. are displayed, and examples thereof include a liquid crystal display, an organic EL display, etc. The display device 13 is connected to the control device 11.

[0020] 2 and 3, the control device 11 creates a tire model 30 based on input information from the input device 12. The tire model 30 is a three-dimensional model in which the tire is divided into a finite number of elements as described above. Although Fig. 2 and Fig. 3 show a part of a two-dimensional cross section divided into a plurality of elements in the tire width direction and radial direction (as viewed from the tire circumferential direction), the tire model 30 is a three-dimensional model divided into a plurality of elements also in the tire circumferential direction.

[0021] Among the functions of the control device 11, modeling of the bead core 31 of the tire model 30 according to the present invention will be described below. Here, the bead core 31 is a part that fixes both ends of the carcass cord and has the function of fixing the tire to the rim, and is generally a structure in which high carbon steel is bundled. However, the control device 11 can also model components other than the bead core 31 by dividing them into a finite number of elements.

[0022] For example, the control device 11 can also model the bead cover that covers the periphery of the bead core 31, the bead feeler which is a reinforcing rubber layer with a triangular cross section that increases the rigidity of the bead core 31, the plies which are reinforcing materials that make up the carcass of the tire, and the steel chafer that surrounds the outside of the carcass by dividing them into a finite number of elements.

[0023] 3, the control device 11 models the bead core 31 of the tire model 30 based on information about the cross-sectional shape as seen from the circumferential direction of the tire. The control device 11, which will be described in detail later, models the bead core 31 by dividing it into quadrangular elements in the cross-sectional shape as seen from the circumferential direction of the tire. This makes it possible to improve the convergence while maintaining the analysis accuracy in the finite element method.

[0024] Conventionally, the bead core of a tire model is modeled by dividing it into triangular elements in the cross section seen from the circumferential direction of the tire. In addition, for example, when analyzing the contact or rolling of a tire, the side of the bead part of the tire model is constrained to the hub center or rim model. In such a tire model, when severe analysis conditions (load of a large load, load of high speed rotation, etc.) are given, the distortion of the bead core and the surrounding elements of the bead core becomes large, and the residual stress does not converge, and the analysis may diverge.

[0025] According to the tire model creation device 10 of the present embodiment, the bead core 31 is divided into quadrangular elements for modeling, so that the aspect ratio of the elements is smaller than that of the conventional model in which the bead core is divided into triangular elements, and the analysis accuracy and convergence can be improved. Here, the aspect ratio refers to the ratio of the long side to the short side of an element.

[0026] Furthermore, according to the tire model creation device 10 of the present embodiment, the bead core 31 is modeled by dividing it into quadrangular elements. This reduces the number of element divisions compared to the conventional case in which the bead core is modeled by dividing it into triangular elements, thereby improving convergence.

[0027] 1 again, the control device 11 has a bead core outer peripheral shape setting unit 21, a bead core center point setting unit 22, a bead core outer peripheral point setting unit 23, and an element division unit 24. The bead core outer peripheral shape setting unit 21, the bead core center point setting unit 22, the bead core outer peripheral point setting unit 23, and the element division unit 24 are realized by the CPU executing programs stored in the ROM or RAM.

[0028] 3, the bead core outer periphery shape setting section 21 sets the outer periphery of the bead core 31 to approximate a polygon P in a cross section seen from the circumferential direction of the tire. In this embodiment, the bead core 31 is set to approximate a hexagon. However, the present invention is not limited to this, and any polygon that approximates the outer periphery of the bead core 31 may be used.

[0029] The bead core center point setting unit 22 sets the centroid of the polygon P set by the bead core outer peripheral shape setting unit 21 as the center point O. Here, the centroid has the general meaning of the centroid, and is the point at which the figure is balanced when the centroid is used as the fulcrum. For example, if the polygon P is a rectangle or a hexagon, the intersection point connecting the diagonals of the rectangle or hexagon becomes the centroid, or center point O. This makes it possible to set the center point O at a substantially equal distance from each side of the polygon P. Therefore, the divided rectangular elements do not have distorted shapes, and the aspect ratio of the elements can be reduced.

[0030] The bead core outer periphery point setting unit 23 sets the midpoint of each side of the polygon P set by the bead core outer periphery shape setting unit 21 as the outer periphery point G. Here, the midpoint is a point on each side of the polygon P that is equidistant from the vertex of the adjacent polygon P. This prevents the divided quadrangular elements from having a distorted shape, and makes it possible to reduce the aspect ratio of the elements. However, the present invention is not limited to this, and the outer periphery points may be points other than the midpoints.

[0031] The element dividing unit 24 divides, as elements, a quadrangle including lines connecting the center point O set by the bead core center point setting unit 22, two adjacent outer periphery points G among the outer periphery points G set by the bead core outer periphery point setting unit 23, and a vertex of a polygon sandwiched between the two adjacent outer periphery points G. Note that this quadrangle is one in which the center point O faces a vertex of the polygon and faces two adjacent outer periphery points G.

[0032] [How to create a tire model] A tire model creating method according to an embodiment will be described with reference to FIG.

[0033] The tire model creation method creates a tire model 30 by a finite element method that simulates tire characteristics based on the above-mentioned functions of the control device 11 according to the following procedure. Among the functions of the control device 11, a method of modeling the bead core 31 of the tire model 30 according to the present invention will be described below.

[0034] In step S11, the control device 11 causes the bead core outer periphery shape setting unit 21 to set the outer periphery of the bead core 31 so as to approximate a polygon P in the cross section seen in the circumferential direction of the tire.

[0035] In step S12, the control device 11 causes the bead core center point setting unit 22 to set the centroid of the polygon P set in step S11 as the center point O.

[0036] In step S13, the control device 11 sets, as outer periphery points G, the midpoints of the sides of the polygon P set in step S11 by the bead core outer periphery point setting unit 23.

[0037] In step S14, the control device 11 divides into elements a quadrangle including lines connecting the center point O set in step S12 by the element division unit 24, two adjacent outer perimeter points G among the outer perimeter points G set in step S13, and the vertices of the polygon sandwiched between the two adjacent outer perimeter points G.

[0038] It should be noted that the present invention is not limited to the above-described embodiment and its modified examples, and various modifications and improvements are possible within the scope of the matters described in the claims of this application. [Explanation of symbols]

[0039] 10 Tire model creation device, 11 Control device, 12 Input device, 13 Display device, 21 Bead core outer periphery shape setting unit, 22 Bead core center point setting unit, 23 Bead core outer periphery point setting unit, 24 Element division unit, 30 Tire model, 31 Bead core

Claims

1. A tire model creation device that creates a tire model by dividing a tire into a finite number of elements, When dividing the bead core into the elements as viewed in the tire circumferential direction, each of the elements is formed in a quadrangular shape, The quadrangular shape is a polygonal shape having an outer periphery of the bead core, and includes lines connecting the center point and each of outer periphery points on two adjacent sides of the polygonal shape when a center point is provided inside the bead core. Tire model creation device.

2. 2. The tire model creation device according to claim 1, The outer periphery points are midpoints of the sides of the polygonal shape. Tire model creation device.

3. 3. The tire model creating device according to claim 1, further comprising: The center point is the centroid of the polygonal shape. Tire model creation device.

4. A tire model creation method for creating a tire model in which a tire is divided into a finite number of elements, comprising the steps of: When dividing the bead core into the elements as viewed in the tire circumferential direction, each of the elements is formed in a quadrangular shape, The quadrangular shape is a polygonal shape having an outer periphery of the bead core, and includes lines connecting the center point and each of outer periphery points on two adjacent sides of the polygonal shape when a center point is provided inside the bead core. How to create a tire model.

5. 5. A tire model creation method according to claim 4, further comprising the steps of: The outer periphery points are midpoints of the sides of the polygonal shape. How to create a tire model.

6. 6. A tire model creation method according to claim 4, further comprising the steps of: The center point is the centroid of the polygonal shape. How to create a tire model.

Images