JP2014051223A - Tire model creation method, simulation device and tire model creation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire model creation method, a simulation device and a tire model creation program, capable of reducing the time for creation and analysis of a tire model.SOLUTION: In a tire model creation method, a simulation device creates a section model constituting one section when dividing a tire model into a plurality of sections in the tire circumferential direction, creates an assembly of a pair pf section models and a prescribed rim model, sets conditions of setting a difference between displacement magnitudes of both the end faces in the tire circumferential direction of the section model to be zero and setting relative displacement between the pair of section models in the radial direction of the rim model to be zero, sets an inflation analysis condition to the pair of section models, develops at least one section model that is in an inflated state in the tire circumferential direction to create an annular aggregate of the section models, and joins the adjacent section models.

Description

  The present invention relates to a tire model creation method, a simulation apparatus, and a tire model creation program. More specifically, the present invention relates to providing a tire model creation method, a simulation apparatus, and a tire model creation program that can reduce tire model creation time and analysis time. .

  In recent years, a simulation apparatus that creates a tire model that can be analyzed by a computer and performs a simulation has been put into practical use. As such a simulation apparatus, a technique described in Patent Document 1 is known.

JP 2011-219027 A

  Generally, since a tire model is composed of hundreds of thousands to millions of elements, there is a problem that enormous time is required for its creation and analysis.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a tire model creation method, a simulation apparatus, and a tire model creation program capable of shortening a tire model creation time and an analysis time.

  In order to achieve the above object, a tire model creation method according to the present invention is a tire model creation method for creating a tire model that can be analyzed by a computer using a simulation device, and the simulation device uses a tire model for tire circumference analysis. A section model creating step for creating a section model constituting one section when divided into a plurality of directions, an assembly model creating step for creating an assembly of a pair of the section model and a predetermined rim model, and the section A constraint condition setting step for setting a periodic boundary condition setting step in which the difference in displacement between both end faces in the tire circumferential direction of the model is zero, and a condition in which the relative displacement between the pair of section models in the radial direction of the rim model is set to zero For the setting step and the pair of section models An inflation analysis condition setting step for setting inflation analysis conditions, an expansion step for developing at least one of the section models in the inflation state in the tire circumferential direction to create an annular assembly of the section models, and an adjacent step And a joining step for joining the section models.

  The simulation apparatus according to the present invention is a simulation apparatus that creates a computer-analysable tire model and performs simulation, and configures one section when the tire model is divided into a plurality of tire circumferential directions. A section model creation unit that creates a model, an assembly model creation unit that creates an assembly of a pair of the section model and a predetermined rim model, and a difference in displacement between both end surfaces of the section model in the tire circumferential direction is zero. A periodic boundary condition setting unit, a constraint condition setting unit for setting a condition for setting a relative displacement between the pair of section models in the radial direction of the rim model to be zero, and inflation analysis for the pair of section models Inflation analysis condition setting section for setting conditions, and inflation A development unit for at least one of the sections model developed in the tire circumferential direction to create an annular assembly of said section models in, characterized in that it comprises a joint for joining said sections model adjacent.

  A tire model creation program according to the present invention is a tire model creation program for creating a computer model capable of being analyzed by a computer, and constitutes one section when the tire model is divided into a plurality of tire circumferential directions. A section model creating step for creating a section model to be performed, an assembly model creating step for creating an assembly of a pair of the section model and a predetermined rim model, and a difference in displacement between both end faces in the tire circumferential direction of the section model A periodic boundary condition setting step in which the relative displacement between the pair of section models in the radial direction of the rim model is set to a zero, and a constraint condition setting step in which the relative displacement between the pair of section models in the radial direction of the rim model is set to zero. Inflation analysis condition setting for setting freight analysis conditions And a step of developing at least one of the section models in an inflated state in a tire circumferential direction to create an annular assembly of the section models, and a joining step of joining adjacent section models to a computer. It is made to perform.

  According to the tire model creation method, simulation apparatus, and tire model creation program according to the present invention, inflation analysis conditions are set for a section model that is a part of the tire model, and a plurality of section models are developed in the tire circumferential direction. Since the tire model is created by joining the tire models, the time required for setting the inflation analysis conditions can be reduced as compared with the configuration in which the inflation analysis conditions are set after the full tire model is created. This has the advantage that the tire model creation time and simulation analysis time can be shortened.

FIG. 1 is a functional block diagram showing a tire simulation apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a tire model for simulation. FIG. 3 is a flowchart showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 4 is an explanatory diagram showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 5 is an explanatory view showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 6 is an explanatory diagram showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 7 is an explanatory view showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 8 is an explanatory diagram showing a tire model creation method by the simulation apparatus shown in FIG. FIG. 9 is a chart showing the results of the performance test of the simulation apparatus according to the embodiment of the present invention. FIG. 10 is a cross-sectional view in the tire meridian direction showing a general pneumatic tire. FIG. 11 is a plan view showing a tread pattern of the pneumatic tire depicted in FIG. 10. FIG. 12 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 11.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Tire simulation device]
FIG. 1 is a functional block diagram showing a tire simulation apparatus according to an embodiment of the present invention.

  The simulation device 1 is a device that creates a tire model, which will be described later, and performs a simulation using the tire model. The simulation device 1 includes a processing device 2, an input device 3, and a display device 4.

  The processing device 2 is, for example, a PC (Personal Computer), and includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 22, and a ROM (Read-Only Memory) 23. The processing device 2 is connected to an external input device 3 and a display device 4 via the input / output unit 24. The ROM 23 stores various programs 23a to 23l described later. The input device 3 is a device for inputting input data such as conditions necessary for creating a tire model (tire design conditions, part selection, characteristic parameter setting change, etc.) and simulation test conditions to the processing device 2. For example, it is composed of a keyboard and a mouse. The display device 4 is a device that displays a condition input screen, a simulation result, and the like, and includes, for example, a PC monitor.

  In the simulation device 1, the CPU 21 of the processing device 2 temporarily stores input data from the input device 3 and various data read from the ROM 23 in the RAM 22. The CPU 21 reads and executes the various programs 23a to 23l stored in the ROM 23 while referring to these data as necessary. Further, the CPU 21 displays the created tire model, simulation result, and the like on the display device 4. Thereby, various functions of the simulation apparatus 1 are realized.

[Pneumatic tire]
FIG. 10 is a cross-sectional view in the tire meridian direction showing a general pneumatic tire. FIG. 11 is a plan view showing a tread pattern of the pneumatic tire depicted in FIG. 10. These drawings show, as an example, a heavy-duty radial tire mounted on a truck or bus. FIG. 11 shows a tread pattern having a pitch variation structure as an example. Reference sign “CL” is a tire equator plane.

  In the configuration of FIG. 10, the pneumatic tire 100 has an annular structure centered on the tire rotation axis, and a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, and a belt layer 14. A tread rubber 15 and a pair of side wall rubbers 16 and 16. The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion. The carcass layer 13 is formed by rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber, and toroidal between the left and right bead cores 11, 11. A tire skeleton is constructed by laying in the shape of a tire. The belt layer 14 is formed by laminating a plurality of belt plies 141 to 144 formed by coating a plurality of belt cords made of steel or an organic fiber material with a coat rubber and rolling it. The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions.

  Further, as shown in FIG. 11, the pneumatic tire 100 includes four circumferential main grooves 17 extending in the tire circumferential direction, and five rows of land portions 18 that are partitioned by the circumferential main grooves 17. With. Each land portion 18 includes a plurality of lug grooves 19 extending in the tire circumferential direction and a plurality of blocks 181 formed by the lug grooves 19. Thereby, a tread pattern based on the block 181 is formed. Each block 181 has an open sipe 182 that penetrates the block 181 in the tire width direction.

  Further, the lug grooves 19 of each land portion 18 are arranged in the tire circumferential direction in a predetermined arrangement pattern having three types of pitch lengths Pa, Pb, and Pc (Pa> Pb> Pc) of large, medium, and small ( Pitch variation structure). For this reason, the circumferential length of each block 181 periodically changes as it goes in the tire circumferential direction. In such a configuration, the frequency of noise generated during running is dispersed, and tire pattern noise is reduced. Moreover, the load load to each block 181 is optimized, and uneven wear is suppressed.

[Tire model]
FIG. 2 is a perspective view showing a tire model for simulation. The figure is a tire model of the pneumatic tire 100 shown in FIG. 10, and shows a state in which the pneumatic tire 100 is filled with a predetermined internal pressure.

  The tire model 10 refers to a model in which a tire is reproduced using a collection of numerical data that can be analyzed by a computer, and includes a mathematical model and a mathematical discretization model. Computer analysis refers to numerical analysis such as finite element method, finite difference method, boundary element method, and the like. The tire model 10 includes components constituting the pneumatic tire 100 (a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, a tread rubber 15, and a pair of sidewall rubbers in FIG. 10). The pneumatic tire 100 is modeled by dividing the three-dimensional shape (16, 16, etc.) into a plurality of finite elements including hexahedral elements, tetrahedral elements, shell elements, membrane elements and the like.

  Here, as shown in FIG. 4, the tire model 10 includes a tread model 1012 in which a tread portion having a plurality of circumferential main grooves 17 (see FIGS. 10 and 11) is modeled, and other portions excluding the tread portion. Can be divided into the modeled casing model 1011. The tread model 1012 is preferably a model corresponding to the tread rubber 15 of the pneumatic tire 100, for example.

  At this time, the mesh size of the tread model 1012 (the size of the finite element that divides the tread model 1012) is preferably equal to or less than one third of the mesh size of the casing model 1011. That is, the tread model 1012 and the casing model 1011 have different mesh sizes, and the mesh size of the tread model 1012 is set to be finer than the mesh size of the casing model 1011. Specifically, in the tread model 1012, the mesh size of the model representing the land portion 18, the lug groove 19, the block 181 and the sipe 182 (see FIG. 11) of the pneumatic tire 100 is 4 of the mesh size of the casing model 1011. It is set to 1/8 or less, preferably 1/7 or less.

  Further, the mesh size of the model showing the groove bottom of the circumferential main groove 17 of the pneumatic tire 100 in the tread model 1012 is the mesh size of the model representing the surrounding land portion 18, lug groove 19, block 181 and sipe 182. It is preferably set to 1/5 or less, and more preferably set to 1/10 or less. That is, the mesh size of the model indicating the groove bottom of the circumferential main groove 17 is set more finely than the mesh size of the model indicating the surrounding land portion 18 and the like. Thereby, the analysis accuracy of the groove crack etc. which generate | occur | produce in the groove bottom of the circumferential direction main groove 17 can be improved.

  Moreover, it is preferable that the tread model 1012 is formed by dividing a model from the tread surface of the land portion 18 to the bottom portion of the sipe 182 with at least two layers of meshes. Thus, by providing two or more layers of meshes in the sipe depth direction, the analysis accuracy of torsional deformation of the sipe 182 can be improved.

[Tire model creation method]
In the pneumatic tire 100 as described above, there is a problem that groove cracks are generated at the groove wall bottoms of the circumferential main grooves 17 and 22. Such groove cracks are known to be affected by the maximum principal strain at the groove wall bottom of the circumferential main groove.

  For this reason, the creation of the tire model 10 requires that the phenomenon of main strain generation at the groove wall bottom can be accurately reproduced. Specifically, the difference in the groove wall shapes of the circumferential main grooves 17 and 22 (for example, the difference between straight grooves and zigzag grooves), the presence or absence of an open sipe 182, and a stone ejector formed on the groove bottom (not shown) Construction of a tire model 10 that can accurately reproduce the detailed structure of the tread pattern such as the presence or absence of the tire is required.

  However, since the tire model 10 is composed of hundreds of thousands to millions of elements, there is a problem that enormous time is required for its creation and analysis.

  Therefore, in this tire model creation method, the following configuration is adopted in order to shorten the tire model creation time and the analysis time.

  3 to 8 are a flowchart (FIG. 3) and an explanatory diagram (FIGS. 4 to 8) showing a tire model creation method by the simulation apparatus 1 described in FIG. In these drawings, FIG. 4 shows an assembly model of one section model 101A (101B) and the rim model 20. FIG. 5 shows a state in which a predetermined internal pressure is applied to the assembly model of the pair of section models 101A and 101B and the rim model 20. FIG. 6 schematically shows the relationship between the pair of section models 101A and 101B. FIG. 7 shows representative nodes on the surface of the section model 101A (101B). FIG. 8 shows representative nodes of the bead core on one side of the pair of section models 101A (101B).

  In step ST01, the processing device 2 creates a pair of section models 101A and 101B and a rim model 20 (section model creation step) (see FIGS. 3 and 4). Specifically, the CPU 21 of the processing device 2 creates a pair of section models 101A and 101B by reading and executing the section model creation program 23a from the ROM 23. In addition, the CPU 21 creates the rim model 20 by reading and executing the rim model creation program 23b from the ROM 23. Information necessary for creating the section models 101A and 101B and the rim model 20 is input from the input device 3 to the processing device 2 and stored in the RAM 22.

  As shown in FIG. 4, the section model 101A (101B) is a model constituting one section when the tire model 10 (see FIG. 2) is divided into a plurality of sections in the tire circumferential direction. Part of Further, the length in the tire circumferential direction (θ-axis direction) of one section model 101A (101B) can be arbitrarily set. Theoretically, it is sufficient if one section model 101A (101B) is a model obtained by dividing the tire model 10 (see FIG. 2) into at least two sets and four sets. Further, as will be described later, in order to shorten the time required for tire analysis, it is preferable that one section model 101A (101B) is a model when the tire model 10 is divided more finely in the tire circumferential direction.

  For example, in the configuration of FIG. 4, a tire model 10 in which one section model 101A (101B) is divided for each unit pitch length Pa (Pb, Pc) in FIG. 11 by a plane (tire meridian section) including a tire rotation axis. Corresponds to one section. For this reason, one section model 101A (101B) has a thickness of about 2 [deg] in the tire circumferential direction. A second section model 101B is created by duplicating the data of the first section model 101A. For this reason, the paired section models 101A and 101B have the same structure and the same elements and nodes. One section model 101A (101B) is composed of about 13,000 elements. The entire tire model 10 is composed of about 800,000 elements.

  In the configuration of FIG. 4, as described above, one section model 101A (101B) models a section per unit pitch length Pa (Pb, Pc). However, the present invention is not limited to this, and one section model 101A (101B) may be a model representing a section including a plurality of types of pitch lengths, or represents a section per unit period in the tire circumferential direction of the tread pattern. It may be a model.

  The rim model 20 is a model representing a rim (not shown) on which the pneumatic tire 100 is mounted. For example, in the configuration of FIG. 4, the rim model 20 includes annular model portions 201 and 201 that represent the left and right rim flange portions of the rim.

  In step ST02, the processing device 2 sets a cylindrical coordinate system centered on the rotation axis of the rim model 20 (coordinate system setting step). Specifically, the CPU 21 of the processing device 2 sets the cylindrical coordinate system by reading the coordinate system setting program 23c from the ROM 23 and executing it.

  In this cylindrical coordinate system, the rotation axis of the rim model 20 is the Z axis, the center point of the left and right rim flange portions on the Z axis is the origin O, and the r axis is in the direction perpendicular to the Z axis (the radial direction of the rim model 20). The θ axis is taken around the Z axis. When the tire model 10 is inflated to the rim model 20, the rotation axis of the tire model 10 is the Z axis, the intersection of the tire equatorial plane CL and the Z axis of the tire model 10 is the origin O, and the tire radial direction is the r axis. The tire circumferential direction is the θ axis.

  In step ST03, the processing apparatus 2 arranges the pair of section models 101A and 101B on the rim model 20 and creates an assembly model of the section models 101A and 101B and the rim model 20 (assembly model creation step). Specifically, the CPU 21 of the processing device 2 reads the assembly model creation program 23d from the ROM 23 and executes it to create an assembly model of the section models 101A and 101B and the rim model 20.

  In the assembly model of the section models 101A and 101B and the rim model 20, the left and right bead portions of the section model 101A (101B) are fitted to the annular model portions 201 and 201 of the rim model 20, as shown in FIG. The section models 101A and 101B are respectively arranged. As shown in FIG. 5, the pair of section models 101A and 101B have the same structure and are arranged symmetrically with respect to each other about the Z axis in the initial state (no load state).

  In step ST04, the processing device 2 sets a periodic boundary condition for the pair of section models 101A and 101B (periodic boundary condition setting step). Specifically, the CPU 21 of the processing device 2 reads the periodic boundary condition setting program 23e from the ROM 23 and executes it, thereby setting the periodic boundary conditions of the section models 101A and 101B.

  As shown in FIG. 6, this periodic boundary condition is an arbitrary node P1i (i = 1 to m: m is an integer) on one end face (tire meridian section) in the θ-axis direction of the first section model 101A. And a difference in displacement amount from a node Q1j (j = 1 to n: n is an integer) on the other end face and corresponding to an arbitrary node P1i is set to zero. Similarly, an arbitrary node P2i (i = 1 to m: m is an integer) on one end surface in the θ-axis direction of the second section model 101B and a node corresponding to one node P2i on the other end surface The difference in displacement from Q2j (j = 1 to n: n is an integer) is set to zero. Further, the above boundary conditions are set for all the nodes on the end faces of the pair of section models 101A and 101B.

  Conceptually, this periodic boundary condition is defined in the r-axis direction, the θ-axis direction, and the Z-axis direction between the node P1i on one end face of the section model 101A (101B) and the corresponding node Q1j on the other end face. This means that the amount of displacement is always equal. Specifically, the periodic boundary conditions are expressed by the following mathematical formulas (1) to (6). Ur, Uθ, and UZ indicate the displacement of each node in the r-axis direction, the θ-axis direction, and the Z-axis direction.

First section model 101A:
Ur (Q1j) -Ur (P1i) = 0 (1)
Uθ (Q1j) −Uθ (P1i) = 0 (2)
UZ (Q1j) −UZ (P1i) = 0 (3)
Second section model 101B:
Ur (Q2j) -Ur (P2i) = 0 (4)
Uθ (Q2j) −Uθ (P2i) = 0 (5)
UZ (Q2j) −UZ (P2i) = 0 (6)

  In the configuration of FIG. 6, the number m of nodes P1i on one end face in one section model 101A (101B) is equal to the number n of nodes Q1j on the other end face (m = n). The nodes P1i and Q1j correspond to each other on a one-to-one basis.

  However, the present invention is not limited to this, and the number m of nodes P1i on one end face and the number n of nodes Q1j on the other end face in one section model 101A (101B) may be different from each other (m ≠ n). In this case, when the node P1i on one end face is projected onto the other end face in the θ-axis direction, the above cycle is performed for a set of an arbitrary node P1i and the node Q1j closest to the node P1i. Each boundary condition is set.

  In step ST05, the processing device 2 sets the interaction between the section model 101A (101B) and the rim model 20 (interaction setting step). Specifically, the CPU 21 of the processing device 2 sets the interaction between the section model 101A (101B) and the rim model 20 by reading and executing the interaction setting program 23f from the ROM 23.

  This interaction refers to a relative motion or a contact phenomenon between the section model 101A (101B) and the rim model 20. Here, the section model 101A (101B) is a flexible body or an elastic body, and is deformed and displaced with respect to the rim model 20 which is a rigid body.

  In step ST06, the processing apparatus 2 sets a constraint condition for the relative displacement in the r-axis direction between the pair of section models 101A and 101B (a constraint condition setting step). Specifically, the CPU 21 of the processing apparatus 2 reads the constraint condition setting program 23g from the ROM 23 and executes it to set the constraint condition for the relative displacement in the r-axis direction between the pair of section models 101A and 101B facing each other. .

  This constraint condition is set so that the relative displacement in the r-axis direction between the pair of section models 101A and 101B becomes zero. Specifically, the relative displacement in the r-axis direction between an arbitrary node on the surface of the first section model 101A and a node on the surface of the second section model 101B corresponding to the node is set to be zero. Is done. In addition, the above constraint conditions are set for all nodes on the surfaces of the pair of section models 101A and 101B.

  This constraint condition conceptually means that the distance in the r-axis direction between the node of the first section model 101A and the corresponding node of the second section model 101B is always constant. Thereby, the r-axis direction balance force acting between the pair of section models 101A and 101B facing each other is naturally satisfied. For example, in the configuration of FIG. 6, the relationship between all the nodes P1i, Q1j, P2i, Q2j on both end faces of the pair of section models 101A, 101B, and the tread surface, inner peripheral surface of the pair of section models 101A, 101B, and For all the nodes M1k (k = 1 to h: h is a natural number) and M2k (k = 1 to h: h is a natural number) on the side surface, the constraint conditions shown in the following equations (7) to (9) are set. ing.

Ur (P1i) + Ur (P2i) = 0 (7)
Ur (Q1j) + Ur (Q2j) = 0 (8)
Ur (M1k) + Ur (M2k) = 0 (9)

  Note that, as described above, this constraint condition is preferably set for all nodes on the surfaces of the pair of section models 101A and 101B.

  However, the present invention is not limited to this, and as shown in FIG. 7, the above constraint conditions may be set only for representative nodes on the surfaces of the pair of section models 101A and 101B. Typical nodes of the section model 101A (101B) include, for example, the apex of the tire cross section, the discontinuity of the external shape, the symmetry point, the edge of the internal wire, and the like.

  Further, as shown in FIG. 8, the above constraint conditions may be set for only the representative nodes N11 to N16 and N21 to N26 for the bead cores of the pair of section models 101A and 101B. This is because the bead core has high rigidity and small deformation. In FIG. 8, the node N11 (N21) indicates the center point (center of gravity) of the bead core of the section model 101A (101B), and the nodes N12 to N16 (N22 to N26) are the bead cores of the section model 101A (101B). The vertex on the circumference is shown.

  Furthermore, the above constraint conditions may be set only for the nodes N11 and N21 indicating the center points of the bead cores of the pair of section models 101A and 101B. Alternatively, the constraint condition may be set only for a node indicating the center point of the bead core on both end faces of the pair of section models 101A and 101B.

  In step ST07, the processing apparatus 2 sets inflation analysis conditions for the assembly model of the pair of section models 101A and 101B and the rim model 20 (inflation analysis condition setting step). Specifically, the CPU 21 of the processing device 2 reads the inflation analysis condition setting program 23h from the ROM 23 and executes it, thereby giving a predetermined inflation analysis condition to the assembly model.

  The inflation analysis condition is a setting condition used for inflation analysis, and a rim fitting pressure that acts on the pneumatic tire 100 when the pneumatic tire 100 is attached to the rim and given a predetermined filling air pressure, and Analysis conditions reflecting the filling air pressure. Here, the inflation analysis condition is set for each of the pair of section models 101A and 101B that are tire portions. In the configuration in which the inflation analysis condition is set for the partial section model 101A, the inflation analysis condition is very short compared to the configuration in which the inflation analysis condition is set after the full tire model is created.

  For example, in the configuration of FIG. 5, a pair of section models 101A and 101B are arranged point-symmetrically around the Z axis and assembled to the rim model 20, and these section models 101A and 101B correspond to rim fitting pressure and filling air pressure. Analysis conditions are given. Further, as shown in FIG. 6 and mathematical expressions (1) to (6), the r-axis direction between the node P1i on one end face of one section model 101A (101B) and the corresponding node Q1j on the other end face , The amount of displacement applied in the θ-axis direction and the Z-axis direction is set to be the same (peripheral boundary condition setting step). Further, as shown in FIG. 6 and mathematical expressions (7) to (9), the distances in the r-axis direction of the respective pairs of nodes P1i, P2i; Q1j, Q2j; M1k, M2k corresponding to the pair of section models 101A, 101B It is set constant. Thereby, the r-axis direction balance force acting between the pair of section models 101A and 101B facing each other is naturally satisfied.

  In step ST08, the processing device 2 stores information on the rim model 20 and one section model 101A. That is, only information when one section model 101A of the pair of section models 101A and 101B is fitted to the rim model 20 and inflated is stored. The above information is stored in the RAM 22 by the CPU 21 of the processing device 2. Further, the information of the other rim model 101B is deleted.

  The stored information of the section model 101A includes, for example, the coordinates of the nodes P1i, Q1j, and M1k of the section model 101A, displacements Ur (P1i), Ur (Q1j), Ur (M1k) in the r-axis, θ-axis, and Z-axis directions. ), Physical information regarding the contact force between the section model 101A and the rim model 20, the stress and strain acting on the section model 101A, and the like. Therefore, all of the state of one section model 101A in the inflated state can be reproduced only by this stored information.

  In step ST09, the processing device 2 develops the section model 101A in the θ-axis direction over the entire tire circumference. Specifically, the CPU 21 of the processing device 2 loads the section model expansion program 23i from the ROM 23 and executes it to expand the section model 101A (expansion step). At this time, the CPU 21 reads the information of the section model 101A stored in step ST08 from the RAM 22 and duplicates it, and continuously places the duplicated information in the θ-axis direction. As a result, the plurality of section models 101A are arranged in an annular shape over the entire circumference of the tire, and an annular assembly of the section models 101A is created (not shown).

  In the above configuration, only the information of one section model 101A of the pair of section models 101A and 101B facing each other is duplicated and used (steps ST08 to ST09). However, the present invention is not limited to this, and both pieces of information of the pair of section models 101A and 101B may be stored, and both of them may be used to generate a circular aggregate of the section models 101A and 101B.

  In step ST10, the processing apparatus 2 joins the nodes P1i and Q1j between the end surfaces of the adjacent section models 101A and 101A (joining step). Specifically, the CPU 21 of the processing device 2 reads the node joining program 23j from the ROM 23 and executes it to join the nodes P1i and Q1j between the end faces. Thereby, the tire model 10 (refer FIG. 2) in an inflated state is acquired.

  The joining of the nodes P1i and Q1j is performed by restraining the relative displacement between the node P1i on the joining surface of one section model 101A and the corresponding node Q1j on the joining surface of the other adjacent section model 101A. . In addition, the above-described joining is performed for all sets of nodes P1i and Q1j on the joining surfaces of the adjacent section models 101A and 101A.

  In step ST11, the processing device 2 cancels the peripheral boundary condition (step ST04) and the constraint condition (step ST06), and performs equilibrium calculation. Specifically, the CPU 21 of the processing device 2 reads the equilibrium calculation program 23k from the ROM 23 and executes it, whereby the above processing is performed.

  Note that this step ST11 may be omitted when the torsional deformation of the section model 101A is small.

  Thereafter, the processing device 2 performs a simulation of tire characteristics using the tire model 10 acquired as described above. Specifically, various simulations are performed by the CPU 21 of the processing device 2 reading and executing the simulation program 231 from the ROM 23. Further, necessary test conditions are input from the input device 3, and the display device 4 displays a test condition input screen, a simulation result, and the like.

  In the simulation, for example, predetermined test conditions relating to vertical stress, shear stress, and the like are given to the tire model 10, and a prediction result of tire performance is calculated based on this. The tire characteristics include, for example, the contact performance at the time of tire rolling, the running performance and braking performance for road conditions (dry road surface, wet road surface, snow road surface, etc.), cornering performance, crack resistance performance at the groove bottom, and block resistance performance. Uneven wear performance, rolling resistance, low water splash performance, etc. are included.

  4 to 8, one section model 101A models a section per unit pitch length of the tread pattern as described above. At this time, if the tire model 10 is a model of a pneumatic tire (not shown) having a tread pattern having a uniform pitch length in the tire circumferential direction, the stored information of the single section model 101A is duplicated. Then, the tire model 10 can be easily created by developing in the θ-axis direction (step ST09) and joining these section models 101A (step ST10).

  On the other hand, when the tire model 10 is a model of a pneumatic tire 100 having a tread pattern having a pitch variation structure as shown in FIG. 11, a section model 101A of a section having various types of pitch lengths Pa to Pc. Must be created. Therefore, in such a case, the processing device 2 repeats the above-described steps ST01 to ST08 (see FIG. 3), and information on the section model 101A of the section having each type of pitch length Pa, Pb, Pc. Are generated and stored (step ST08). Then, the processing apparatus 2 develops these section models 101A in the θ-axis direction along a predetermined pitch arrangement (arrangement order of pitch lengths Pa, Pb, Pc) (step ST09), and joins these section models 101A. By doing (step ST10), the tire model 10 is created. Thereby, the pitch variation structure can be reproduced on the tire model 10.

  FIG. 12 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 11. This figure shows a tread pattern having a pitch variation structure.

  In the tread pattern of FIG. 11, each block 181 of the land portion 18 has one sipe 182. Further, the circumferential length of the block 181 and the width W of the sipe 182 in the tire circumferential direction change in proportion to the pitch lengths Pa to Pc. In such a case, in creating the section model 101A of the section having each type of pitch length Pa to Pc, a section model 101A corresponding to one pitch length Pa is created, and this section model 101A is set in the θ-axis direction (tire circumference) The section models 101A and 101A corresponding to other types of pitch lengths Pb and Pc can be created. Specifically, the section model 101A can be easily scaled in the θ-axis direction by multiplying the coordinates in the θ-axis direction of the nodes P1i, Q1j, and M1k of the reference section model 101A by a proportional constant. Thereby, the creation time of the section model 101A in the section having each type of pitch length Pa to Pc can be shortened.

  On the other hand, in the tread pattern of FIG. 12, only the circumferential length of the block 181 changes in proportion to the pitch length Pa to Pc, and the width W of the sipe 182 in the tire circumferential direction is the pitch length Pa to Pc. It is constant in the section. In such a case, since the method based on the enlargement / reduction of the section model 101A cannot be adopted, it is necessary to create section models 101A for sections having various types of pitch lengths Pa to Pc.

[effect]
As described above, in the tire model creation method, the simulation apparatus 1 includes the section model creation step ST01 for creating the section model 101A constituting one section when the tire model 10 is divided into a plurality of parts in the tire circumferential direction. An assembly model creation step ST03 for creating an assembly of a pair of section models 101A and 101B and a predetermined rim model 20, and a periodic boundary condition in which the difference in displacement between both end faces of the section model 101A in the tire circumferential direction is zero A setting step ST04, a constraint condition setting step ST06 for setting a condition for setting the relative displacement between the pair of section models 101A and 101B in the radial direction of the rim model 20 to zero, and inflation for the pair of section models 101A and 101B Set analysis conditions Inflation analysis condition setting step ST07, development step ST09 for developing at least one section model 101A in an inflated state in the tire circumferential direction to create an annular assembly of the section models 101A, adjacent section models 101A, The joining step ST10 for joining 101A is performed (see FIG. 3).

  In such a configuration, inflation analysis conditions are set for the section model 101A that is a part of the tire model 10 (step ST07), and a plurality of section models 101A are developed and joined in the tire circumferential direction to create the tire model 10. As a result (steps ST09 and ST10), the time required for setting the inflation analysis conditions can be shortened compared to a configuration (not shown) in which inflation conditions are set after a full tire model is created. This has the advantage that the tire model creation time and simulation analysis time can be shortened.

  In other words, in the configuration in which the inflation analysis conditions are set after the full tire model is created, the time required for the inflation analysis conditions occupies most of the tire model creation time. In particular, in the pneumatic tire 100 including the pitch variation structure and the tread pattern having the block 181 with the sipes 182, the tire model 10 becomes very large, so that the tire model creation time further increases.

  In contrast, the setting time of the inflation analysis condition for the partial section model 101A is very short, and the time for creating the tire model 10 by developing and joining the plurality of section models 101A in the tire circumferential direction is also short. . Therefore, with the above configuration, the total tire model creation time and simulation analysis time can be greatly reduced.

  Further, in the tire model creation method, the tire model 10 includes a tread model 1012 in which a tread portion (see FIGS. 10 and 11) having a plurality of circumferential main grooves 17 and a plurality of land portions 18 is modeled, and the tread portion. And a casing model 1011 that models other parts except for (see FIG. 4). Further, the mesh size of the tread model 1012 is one third or less of the mesh size of the casing model 1011. Thereby, there is an advantage that the analysis accuracy of stress concentration and distortion in the tread portion can be improved. Further, as compared with a configuration in which the mesh of the entire tire model 10 is set uniformly finely, the number of elements can be reduced and the model scale can be reduced, so that there is an advantage that the time required for simulation analysis can be reduced.

  Further, in this tire model creation method, the mesh size of the model of the groove bottom of the circumferential main groove 17 in the tread model 1012 is 1/10 or less of the mesh size of the model of the land portion 18. Thereby, there exists an advantage which can improve the analysis precision of the groove crack etc. which generate | occur | produce in the groove bottom of the circumferential direction main groove 17. FIG.

  In the tire model creation method, the tread model 1012 has a model representing the sipe 182 formed in the land portion 18. In addition, a model from the tread surface of the land portion 18 to the bottom portion of the sipe 182 in the tread model 1012 is divided by at least two layers of meshes. Thereby, there exists an advantage which can improve the analysis precision of the torsional deformation of the sipe 182.

  In addition, the tire model creation method includes a tread model 1012 in which the tire model 10 models a tread portion (see FIG. 11) having a pitch variation structure including a plurality of types of pitch lengths Pa to Pc (see FIG. 4). . Further, the simulation apparatus 1 creates a section model 101A corresponding to a section having one pitch length (for example, the pitch length Pa in FIG. 11) in the section model creation step ST01, and this section model 101A is used as a tire circumference. The section model 101A corresponding to other types of pitch lengths (for example, pitch lengths PB and Pc in FIG. 11) is created by scaling in the direction (θ-axis direction). In addition, an assembly model creation step ST03, a periodic boundary condition setting step ST04, a constraint condition setting step ST06, and an inflation analysis condition setting step ST07 are respectively performed for a plurality of types of section models 101A. Further, in a development step ST09, a plurality of types of section models 101A are developed in the tire circumferential direction in a predetermined arrangement order to create an annular assembly of section models 101A. Then, in the joining step ST10, adjacent section models 101A are joined. In such a configuration, the section model 101A serving as a reference is expanded and contracted in the tire circumferential direction to create section models 101A of sections having various types of pitch lengths Pa to Pc. Therefore, the section models 101A are individually created. There is an advantage that the creation time of the section model 101A can be shortened.

  In the tire model creation method, the tire model 10 includes a tread model 1012 that models a tread portion (see FIG. 11) having a pitch variation structure including a plurality of types of pitch lengths Pa to Pc. In the section model creation step ST01, the simulation apparatus 1 creates a plurality of types of section models 101A corresponding to a plurality of types of pitch lengths Pa to Pc, and the assembly model creation step ST03 for the plurality of types of section models 101A. Periodic boundary condition setting step ST04, constraint condition setting step ST06, and inflation analysis condition setting step ST07 are performed. Further, in a development step ST09, a plurality of types of section models 101A are developed in the tire circumferential direction in a predetermined arrangement order to create an annular assembly of section models 101A. Then, in the joining step ST10, adjacent section models 101A are joined.

  In addition, the simulation apparatus 1 includes a section model creation unit (section model creation program 23a) that creates a section model 101A that constitutes one section when the tire model 10 is divided into a plurality of sections in the tire circumferential direction, and a pair of sections. The assembly model creation unit (assembly model creation program 23d) that creates an assembly of the models 101A and 101B and the predetermined rim model 20 and the difference in displacement amount between both end faces in the tire circumferential direction of the section model 101A are set to zero. A periodic boundary condition setting unit (periodic boundary condition setting program 23e) and a constraint condition setting unit (constraint condition setting program for setting a condition in which the relative displacement between the pair of section models 101A and 101B in the radial direction of the rim model 20 is zero. 23g) and a pair of section models 10 An inflation analysis condition setting unit (inflation analysis condition setting program 23h) for setting inflation analysis conditions for A and 101B and at least one section model 101A in the inflation state are developed in the tire circumferential direction A development part (section model development program 23i) for creating an annular assembly of models 101A and a joint part (contact joining program 23j) for joining adjacent section models 101A are provided (see FIG. 1).

  Further, the tire model creation program includes a section model creation step ST01 for creating a section model 101A constituting one section when the tire model 10 is divided into a plurality of sections in the tire circumferential direction, and a pair of section models 101A and 101B. Assembly model creation step ST03 for creating an assembly with a predetermined rim model 20, periodic boundary condition setting step ST04 in which the difference in displacement between both end faces of the section model 101A in the tire circumferential direction is zero, and the diameter of the rim model 20 Constraint condition setting step ST06 for setting a condition for setting the relative displacement between the pair of section models 101A and 101B in the direction to zero, and an inflation analysis condition for setting inflation analysis conditions for the pair of section models 101A and 101B Setup steps T07, development step ST09 for developing at least one section model 101A in an inflated state in the tire circumferential direction to create an annular assembly of section models 101A, and joining step ST10 for joining adjacent section models 101A, 101A Are executed by a computer (simulation apparatus 1).

  FIG. 9 is a chart showing the results of the performance test of the simulation apparatus according to the embodiment of the present invention.

  In this performance test, a ground contact analysis test was performed in which the tire model 10 (see FIG. 2) of the pneumatic tire 100 of the tire size 315 / 80R22.5 having the structure of FIG. 10 and the tread pattern of FIG. 11 was symmetric. This performance test is evaluated as an analysis time reduction effect [%] based on a conventional example, and the smaller the value, the better.

  In FIG. 9, the conventional example employs a tire model creation method in which inflation analysis conditions are set after a full tire model is created. On the other hand, the tire model creation method according to the embodiment employs the tire model creation method of FIG. 3, creates a partial section model 101A, sets inflation analysis conditions, and sets the section model 101A in the tire circumferential direction. The tire model 10 is created by unfolding and joining.

  As shown in the test results, it can be seen that the inflation analysis time can be greatly shortened in the example. This is because the inflation analysis condition setting time for the partial section model 101A is very short, and the time for developing and joining the plurality of section models 101A in the tire circumferential direction is also short. to cause.

  DESCRIPTION OF SYMBOLS 1 Simulation apparatus, 2 processing apparatus, 3 input apparatus, 4 display apparatus, 10 tire model, 20 rim model, 201 annular model part, 21 CPU, 22 RAM, 23 ROM, 24 input / output part, 101A, 101B section model, 1011 casing Model, 1012 tread model, 100 pneumatic tire, 11 bead core, 12 bead filler, 13 carcass layer, 14 belt layer, 141-144 belt ply, 15 tread rubber, 16 sidewall rubber, 17 circumferential main groove, 18 land , 181 blocks, 182 sipes, 19 lug grooves

Claims (8)

A tire model creation method for creating a tire model that can be analyzed by a computer using a simulation device,
The simulation apparatus includes:
A section model creating step for creating a section model constituting one section when the tire model is divided into a plurality of tire circumferential directions;
An assembly model creating step for creating an assembly of the pair of section models and a predetermined rim model;
Periodic boundary condition setting step in which the difference in displacement between both end faces in the tire circumferential direction of the section model is zero,
A constraint condition setting step for setting a condition in which the relative displacement between the pair of section models in the radial direction of the rim model is set to zero;
An inflation analysis condition setting step for setting inflation analysis conditions for the pair of section models;
An unfolding step of unfolding at least one of the section models in an inflated state in the tire circumferential direction to create an annular assembly of the section models;
And a joining step of joining the section models adjacent to each other. The tire model is composed of a tread model that models a tread portion having a plurality of circumferential main grooves and a plurality of land portions, and a casing model that models other portions excluding the tread portion, and
The tire model creation method according to claim 1, wherein the mesh size of the tread model is equal to or less than one third of the mesh size of the casing model.   The tire model creation method according to claim 2, wherein a mesh size of a model of a groove bottom of the circumferential main groove in the tread model is equal to or less than 1/10 of a mesh size of the model of the land portion. The tread model has a model representing a sipe formed in the land, and
The tire model creation method according to claim 2 or 3, wherein a model from a tread surface of the land portion to a bottom portion of the sipe is divided by at least two layers of meshes in the tread model. The tire model includes a tread model obtained by modeling a tread portion having a pitch variation structure including a plurality of types of pitch lengths, and
The simulation apparatus includes:
In the section model creation step, the section model corresponding to one section having the pitch length is created, and the section model is scaled in the tire circumferential direction to correspond to another type of pitch length. Create
For the plurality of types of section models, perform the assembly model creation step, the periodic boundary condition setting step, the constraint condition setting step and the inflation analysis condition setting step, respectively.
In the expanding step, the plurality of types of section models are expanded in the tire circumferential direction in a predetermined arrangement order to create an annular assembly of the section models,
The tire model creation method according to any one of claims 1 to 4, wherein the adjacent section models are joined in the joining step. The tire model includes a tread model obtained by modeling a tread portion having a pitch variation structure including a plurality of types of pitch lengths, and
The simulation apparatus includes:
In the section model creation step, create a plurality of types of the section models corresponding to the plurality of types of pitch lengths,
For the plurality of types of section models, perform the assembly model creation step, the periodic boundary condition setting step, the constraint condition setting step and the inflation analysis condition setting step, respectively.
In the expanding step, the plurality of types of section models are expanded in the tire circumferential direction in a predetermined arrangement order to create an annular assembly of the section models,
The tire model creation method according to any one of claims 1 to 4, wherein the adjacent section models are joined in the joining step. A simulation apparatus for creating and simulating a tire model that can be analyzed by a computer,
A section model creation unit for creating a section model constituting one section when the tire model is divided into a plurality of tire circumferential directions;
An assembly model creation unit for creating an assembly of the pair of section models and a predetermined rim model;
A periodic boundary condition setting unit that sets the difference in displacement between both end faces in the tire circumferential direction of the section model to zero,
A constraint condition setting unit for setting a condition for setting a relative displacement between the pair of section models in the radial direction of the rim model to be zero;
An inflation analysis condition setting unit for setting inflation analysis conditions for the pair of section models;
A developing section for developing at least one of the section models in an inflated state in a tire circumferential direction to create an annular assembly of the section models;
A simulation apparatus comprising: a joining portion that joins the adjacent section models. A tire model creation program for creating a tire model that can be analyzed by a computer,
A section model creating step for creating a section model constituting one section when the tire model is divided into a plurality of tire circumferential directions;
An assembly model creating step for creating an assembly of the pair of section models and a predetermined rim model;
Periodic boundary condition setting step in which the difference in displacement between both end faces in the tire circumferential direction of the section model is zero,
A constraint condition setting step for setting a condition in which the relative displacement between the pair of section models in the radial direction of the rim model is set to zero;
An inflation analysis condition setting step for setting inflation analysis conditions for the pair of section models;
An unfolding step of unfolding at least one of the section models in an inflated state in the tire circumferential direction to create an annular assembly of the section models;
A tire model creation program that causes a computer to execute a joining step of joining adjacent section models.

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