JP2017125766A - Simulation method for tire and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simulation method for a tire capable of suppressing reduction of simulation efficiency.SOLUTION: The simulation method includes: a tire model creation step for creating a tire model that is a finite element model of a tire including an axle and a rim by dividing the tire into a finite number of multiple elements; a ground portion setting step for setting multiple ground portions in contact with a road surface on which the tire is traveled, in a circumferential direction of the tire; a deployment portion setting step for setting multiple deployment portions in contact with the multiple ground portions of the tire model on a virtual road surface simulating the road surface; a movement step for moving the virtual road surface around the tire model in such a manner that the multiple ground portions of the tire models are successively brought into contact with the deployment portions of the virtual road surface corresponding to the ground portions, in a state where rotations of the axle and the rim of the tire model are restricted; and an analysis step for analyzing characteristics of the tire based on the tire model in the movement step.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a tire simulation method and a computer program.

  As disclosed in Patent Document 1 and Patent Document 2, in tire development, tire characteristics are predicted by simulation using a computer, and tire characteristics are evaluated based on the results of the simulation.

Japanese Patent No. 4050133 Japanese Patent No. 4275991

  When simulating a tire, if the simulation is performed in consideration of the rotation of the tire, the simulation efficiency may be reduced. For example, if simulation calculation is performed for tire movement or tire deformation due to tire rotation, the calculation time until the simulation calculation converges or a calculation error that does not converge is caused. As a result, the calculation cost may increase and the simulation efficiency may decrease.

  An object of an aspect of the present invention is to provide a tire simulation method and a computer program that can suppress a decrease in simulation efficiency.

  According to a first aspect of the present invention, there is provided a simulation method for simulating a tire mounted on a wheel rim supported on an axle using a computer, wherein the tire is divided into a finite number of elements. A tire model creating step of creating a tire model that is a finite element model of the tire including the axle and the rim that can be analyzed by the computer; and a ground contact portion in contact with a road surface on which the tire travels in the tire model. A plurality of contact area setting steps for setting a plurality in the circumferential direction; a deployment area setting step for setting a plurality of deployment areas in contact with each of the plurality of ground contact areas of the tire model on a virtual road surface simulating the road surface; and In a state where rotation of the axle and the rim is constrained, a plurality of tire models A moving step of moving the virtual road surface around the tire model such that the ground contact portion and the developed portion of the virtual road surface associated with the ground contact portion sequentially contact each other, and the tire model in the moving step An analysis step for analyzing the characteristics of the tire is provided based on the tire simulation method.

  According to the first aspect of the present invention, the virtual road surface is moved around the tire model without rotating the axle and rim of the tire model, and the tire rotates on the road surface. The tire characteristics can be analyzed without considering the movement of the tire model due to the rotation or the deformation of the tire model. Therefore, the calculation time until the simulation calculation converges or the occurrence of a calculation error in which the simulation calculation does not converge is suppressed, the calculation cost is reduced, and the decrease in simulation efficiency is suppressed. The number of elements of the virtual road surface that is a finite element model of the road surface is sufficiently smaller than the number of elements of the tire model that is a finite element model of the tire. Therefore, a decrease in simulation efficiency is suppressed by moving the virtual road surface without rotating the axle and rim of the tire model. In addition, after a plurality of ground contact parts are set in the tire model and a development part corresponding to the ground contact part on a one-to-one basis is set on the virtual road surface, the virtual contact surface and the development part are sequentially brought into contact with each other. It is only necessary to move the road surface around the tire model and perform calculations according to the set number of ground contact parts and deployment parts, so that the calculation time is prolonged or the occurrence of calculation errors is suppressed, and the calculation cost is reduced. The decrease in simulation efficiency is suppressed.

  1st aspect of this invention WHEREIN: The contact load calculation step which calculates the contact load which acts on the said tire is included, The said movement step WHEREIN: In the contact of the said contact site | part and the said expansion | deployment site | part, the said contact load is the said contact site part. May also be included.

  By considering the ground load, the tire can be accurately simulated.

  In the first aspect of the present invention, an inertia force calculation step of calculating an inertia force generated by rotation of the tire may be included, and the moving step may include applying the inertia force to the tire model.

  By considering the inertial force, the tire can be accurately simulated.

  1st aspect of this invention WHEREIN: The tire deformation amount calculation step which calculates the distance of the rotation center of the said tire and the contact part of the tread part of the said tire which contacted the said road surface, The said movement step includes the said distance. Applying an inertial force calculated based on the contact portion of the tire model may be included.

  When the tire is in contact with the road surface, a part of the tire is deformed by the contact load, and the distance between the rotation center of the tire and the contact portion of the tread portion of the tire in contact with the road surface is a tire that does not contact the rotation center of the tire and the road surface. This is smaller than the distance between the tread portion and the non-contact portion. The inertial force is calculated based on the distance between the tire rotation center and the contact part of the tread part of the tire that is in contact with the road surface, and the inertial force is applied to the ground contact part of the tire model, thereby simulating the tire more accurately. can do.

  1st aspect of this invention WHEREIN: The travel locus | trajectory calculation step which calculates the travel locus of the said tire based on the slip angle of the said tire is included, The said movement step moves the said virtual road surface based on the said travel locus. May be included.

  Generally, when a tire is steered and turned, a deviation occurs between the tire rotation direction (tire circumferential direction) and the tire traveling direction, and a slip angle is generated. Therefore, the development part of the virtual road surface associated with the ground contact part of the tire model that goes straight is different from the development part of the virtual road surface associated with the ground contact part of the tire model that turns. By considering the tire slip angle during turning, the tire can be accurately simulated.

  In the first aspect of the present invention, the moving step may include moving the virtual road surface while inclining the virtual road surface based on a camber angle of the tire.

  By considering the camber angle of the tire, the tire can be simulated more accurately.

  According to the second aspect of the present invention, a computer program for causing a computer to execute the tire simulation method of the first aspect is provided.

  According to the second aspect of the present invention, the calculation time of the simulation calculation or the generation of the calculation error is suppressed, and the calculation cost is suppressed, so that the decrease in the simulation efficiency is suppressed.

  According to the aspects of the present invention, a tire simulation method and a computer program capable of suppressing a decrease in simulation efficiency are provided.

Drawing 1 is a figure showing typically an example of the tire concerning a 1st embodiment. FIG. 2 is a diagram illustrating an example of a tire simulation apparatus according to the first embodiment. FIG. 3 is a flowchart illustrating an example of a tire simulation method according to the first embodiment. FIG. 4 is a diagram schematically illustrating an example of a finite element model of the tire according to the first embodiment. FIG. 5 is a schematic diagram for explaining an example of the tire simulation method according to the first embodiment. FIG. 6 is a schematic diagram for explaining an example of the tire simulation method according to the first embodiment. FIG. 7 is a schematic diagram for explaining an example of the tire simulation method according to the first embodiment. FIG. 8 is a schematic diagram for explaining an example of the tire simulation method according to the first embodiment. FIG. 9 is a diagram showing the effect of the present invention. FIG. 10 is a flowchart illustrating an example of a tire simulation method according to the second embodiment. FIG. 11 is a schematic diagram for explaining an example of a tire simulation method according to the second embodiment. FIG. 12 is a flowchart illustrating an example of a tire simulation method according to the third embodiment. FIG. 13 is a schematic diagram for explaining an example of a tire simulation method according to the third embodiment. FIG. 14 is a schematic diagram for explaining an example of a tire simulation method according to the third embodiment. FIG. 15 is a flowchart illustrating an example of a tire simulation method according to the fourth embodiment. FIG. 16 is a schematic diagram for explaining an example of a tire simulation method according to the fourth embodiment. FIG. 17 is a diagram illustrating an example of a result of comparison between a tire simulation method according to the present invention and a conventional tire simulation method.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. Some components may not be used. In addition, constituent elements in the embodiments described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range.

<First Embodiment>
A first embodiment will be described. FIG. 1 is a diagram schematically illustrating an example of a tire 1 according to the present embodiment. The tire 1 is a pneumatic tire. In the present embodiment, the tire 1 is a passenger car tire. Passenger car tires refer to tires defined in Chapter A of “JATMA YEAR BOOK 2015 (Japan Automobile Tire Association Standard)”. The tire 1 may be a small truck tire defined in Chapter B, or a truck and bus tire defined in Chapter C.

  As shown in FIG. 1, the tire 1 is mounted on a vehicle 100. The vehicle 100 includes a wheel 2 that supports the tire 1, an axle 3 that supports the wheel 2, and a steering device 4 that changes the traveling direction of the tire 1. The tire 1 is attached to the rim of the wheel 2 supported on the axle 3 of the vehicle 100. The tire 1 rotates on the rotation center AX and travels on the road surface 6 while being mounted on the vehicle 100.

  In the following description, a direction parallel to the rotation center (rotation axis) AX of the tire 1 is appropriately referred to as a tire width direction, and a radial direction with respect to the rotation center AX of the tire 1 is appropriately referred to as a tire radial direction. A rotation direction centered on one rotation center AX is appropriately referred to as a tire circumferential direction.

  FIG. 2 is a diagram illustrating an example of the simulation apparatus 5 according to the present embodiment. The simulation device 5 includes a computer. The simulation device 5 performs computer analysis of the characteristics of the tire 1.

  The simulation apparatus 5 includes a processing unit 51, a storage unit 52, and an input / output unit 53. The processing unit 51 and the storage unit 52 are connected via an input / output unit 53. The processing unit 51 includes a processor such as a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory). The processing unit 51 includes a model creation unit 51A that creates an analysis model of the tire 1 and an analysis unit 51B that can execute a simulation of the tire 1. The model creation unit 51A and the analysis unit 51B are connected to the input / output unit 53, respectively. The model creation unit 51 </ b> A and the analysis unit 51 </ b> B can communicate data with each other via the input / output unit 53.

  The model creation unit 51A creates an analysis model of the tire 1. The model creation unit 51 </ b> A creates a finite element model of the tire 1 that can be analyzed by a computer as an analysis model of the tire 1. The model creation unit 51A creates a finite element model of the tire 1 by dividing the tire 1 into a finite number of elements. The model creation unit 51A creates a finite element model of the road surface 6 that can be analyzed by a computer as an analysis model of the road surface 6. The model creation unit 51A creates a finite element model of the road surface 6 by dividing the road surface 6 into a finite number of elements.

  The analysis unit 51B simulates the characteristics of the tire 1 from the finite element model created by the model creation unit 51A using the finite element method. The performance of the tire 1 is evaluated from the analysis result by the analysis unit 51B.

  The storage unit 52 includes at least one of a volatile memory such as a RAM, a nonvolatile memory, a fixed disk device such as a hard disk device, a flexible disk, and a storage device such as an optical disk.

  The storage unit 52 stores first data used for creating an analysis model of the tire 1 and second data used for simulation of the tire 1.

  The first data includes material data indicating the material characteristics of the constituent members of the tire 1 and physical data indicating the physical characteristics of the constituent members of the tire 1. The constituent members of the tire 1 include, for example, rubber, cords, and beads. The material properties of the constituent members include physical property values and material constants. The material properties of the component include at least one of Young's modulus, Poisson's ratio, yield stress, maximum strength, specific gravity, coefficient of linear expansion, and thermal conductivity. The physical property of the component includes at least one of a cross-sectional area, thickness, shape, and outer dimension.

  The second data includes boundary data indicating boundary conditions. The boundary condition is a condition necessary for the simulation of the analysis model, and includes various conditions given to the analysis model. The boundary condition includes, for example, an initial analysis condition such as a contact condition. The contact condition includes a contact condition between the tire 1 and the road surface 6 and a contact condition between the tire 1 and the wheel 2. Further, the contact condition includes a friction coefficient of the tire 1. The boundary condition includes the running condition of the tire 1. The boundary condition includes a vertical load condition that acts on the tire 1 when the tire 1 and the road surface 6 come into contact with each other. The boundary condition includes a ground load condition that acts on the tire 1 on the road surface 6. The boundary condition includes the internal pressure of the tire 1.

  The storage unit 52 stores a first computer program used for creating an analysis model and a second computer program used for simulating the tire 1.

  The first computer program causes the simulation apparatus 5 including the computer to execute the analysis model creation method according to the present embodiment. The second computer program causes the simulation apparatus 5 including a computer to execute the simulation method according to the present embodiment.

  The model creation unit 51A creates an analysis model of the tire 1 based on the first data and the first computer program. The analysis unit 51B executes a simulation of the tire 1 based on the second data and the second computer program. For example, when the analysis unit 51B executes a simulation of the tire 1, the second data and the second computer program are read into a memory included in the analysis unit 51B. The analysis unit 51B performs a simulation calculation based on the second data and the second computer program.

  The input / output unit 53 is connected to the terminal device 60. The terminal device 60 is connected to the input device 61 and the output device 62. The input device 61 includes at least one of a keyboard, a mouse, and a microphone. The output device 62 includes at least one of a display device such as a flat panel display and a printer.

  Note that at least one of the first data and the second data may be input from the input device 61. At least one of the first computer program and the second computer program may be input from the input device 61. At least one of the first data, the second data, the first computer program, and the second computer program input from the input device 61 is supplied to the processing unit 51 via the terminal device 60 and the input / output unit 53. .

  A computer program (at least one of the first computer program and the second computer program) for realizing the function of the processing unit 51 (at least one of the analysis model creation function and the simulation function) is recorded on a computer-readable recording medium. The program recorded on the recording medium may be read into the processing unit 51.

  Data indicating the analysis model generated by the model generation unit 51A and data indicating the analysis result of the analysis unit 51B are sent from the processing unit 51 to the output device 62 via the input / output unit 53 and the terminal device 60. The output device 62 outputs the data.

  Next, an example of a simulation method for the tire 1 according to the present embodiment will be described. FIG. 3 is a flowchart showing an example of a simulation method for the tire 1 according to the present embodiment. As shown in FIG. 3, the tire 1 simulation method according to the present embodiment divides the tire 1 into a finite number of elements and includes an axle 3 and a rim of the wheel 2 that can be analyzed by a computer. Tire model creation step (step SP10) for creating the tire model 1M, which is a finite element model, analysis condition setting step (step SP20) for setting the analysis conditions of the tire model 1M, and the road surface on which the tire 1 travels in the tire model 1M A ground contact part setting step (step SP30) for setting a plurality of ground contact parts ai in contact with the tire 6 in the tire circumferential direction, and a development part in contact with each of the plurality of ground contact parts ai of the tire model 1M on the virtual road surface 6M simulating the road surface 6. A development site setting step (step S40) for setting a plurality of bi and acting on the tire 1 A contact load calculating step (step S50) for calculating a contact load, a contact step (step SP60) for contacting the tire model 1M and the virtual road surface 6M in a state in which the rotation of the axle and the rim of the tire model 1M is constrained; In a state in which the rotation of the model 1M is constrained, the virtual road surface 6M is placed on the tire model 1M so that the plurality of ground contact parts ai of the tire model 1M and the development part bi of the virtual road surface 6M associated with the ground contact part ai sequentially contact each other. A moving step (step S70) for moving around, and an analyzing step (step SP80) for analyzing the characteristics of the tire 1 based on the tire model 1M in the moving step are included.

  First data for creating a finite element model of the tire 1 as an analysis model is input to the model creating unit 51A. As described above, the first data includes the material characteristics and physical characteristics of the constituent members of the tire 1. For example, design data of the tire 1 (the shape, structure, material, etc. of the tire 1) is input to the model creation unit 51A. For example, three-dimensional CAD (Computer Aided Design) data about the tire 1 may be input to the model creation unit 51A.

  Next, in the model creation unit 51A, a tire model 1M that is a finite element model of the tire 1 is created. The tire model 1M includes a finite element model of the wheel 2 to which the tire 1 is mounted and a finite element model of the axle 3 that supports the wheel 2. In the model creation unit 51A, a virtual road surface 6M that is a finite element model of the road surface 6 is created (step SP10).

  In order to create a tire model 1M including a finite element model of the tire 1, a finite element model of the wheel 2, and a finite element model of the axle 3, the tire 1 including the axle 3 and the wheel 2 is divided into elements. The tire 1 may be divided into elements by solid elements, or may be divided by shell elements. The solid element is also called a three-dimensional element or a three-dimensional body element. The solid element that divides the tire 1 into elements may be a tetrahedron, a pentahedron, or a hexahedron. The shell element is also called a plate element, a plane element, or a plane stress element. In the shell element, force acts only in the surface direction. The shell element that divides the tire 1 into elements may be triangular or quadrangular.

  Further, the road surface 6 is divided into elements in order to create the virtual road surface 6M. The road surface 6 may be divided into elements by shell elements, for example. The road surface 6 is modeled as a rigid body in a finite element model. The road surface 6 is preferably modeled into a finite element model using rigid elements or surfaces. The virtual road surface 6M may be created with a plurality of elements, or the virtual road surface 6M may be created with a single element. The length and width of the virtual road surface 6M may be determined based on the traveling conditions of the tire 1.

  Next, a material constant is set for each of the elements of the tire 1. As described above, the material constant includes at least one of Young's modulus, Poisson's ratio, yield stress, maximum strength, specific gravity, linear expansion coefficient, and thermal conductivity of the constituent members of the tire 1. In addition, material constants are set for each of the elements of the wheel 2 and the road surface 6.

  As described above, as shown in FIG. 4, the tire model 1M that is a finite element model for the tire 1 including the wheel 2 and the virtual road surface 6M that is a finite element model for the road surface 6 are created.

  Next, the processing unit 51 sets analysis conditions for the tire model 1 (step SP20). The analysis conditions include contact conditions in the simulation. The contact condition includes designation of a member to be contacted (calculation target member). In the present embodiment, the contact between the tire model 1M (the finite element model of the tire 1) and the virtual road surface 6M is designated as the contact condition. Further, as a contact condition, a contact between the finite element model of the tire 1 and the finite element model of the wheel 2 is specified in the tire model 1M.

  The contact condition between the tire model 1M and the virtual road surface 6M includes a friction coefficient (static friction coefficient) between the tire model 1M and the virtual road surface 6M and a contact force (contact load) between the tire model 1M and the virtual road surface 6M. In the tire model 1M, the contact condition between the finite element model of the tire 1 and the finite element model of the wheel 2 is the friction coefficient (static friction coefficient) between the finite element model of the tire 1 and the finite element model of the wheel 2 and The contact force (contact load) between the finite element model of the tire 1 and the finite element model of the wheel 2 is included. The contact condition between the finite element model of the tire 1 and the finite element model of the wheel 2 includes a constraint condition between the finite element model of the tire 1 and the finite element model of the wheel 2.

  Next, as illustrated in FIG. 5, the processing unit 51 sets a plurality of ground contact portions ai in the tire model 1M (step SP30). In addition, the processing unit 51 sets a plurality of development sites bi on the virtual road surface 6M (step S40).

  A plurality of contact portions ai are set in the tire circumferential direction in the tread portion of the tire model 1M. In the present embodiment, the plurality of ground contact portions ai are set at equal intervals in the tire circumferential direction. In the following description, three grounding parts a1, a2, and a3 are set for the sake of simplicity.

  A plurality of development sites bi are set in the traveling direction of the tire model 1M on the virtual road surface 6M. The plurality of development parts bi are parts where the ground contact part ai of the tire model 1M that rotates in the traveling direction on the virtual road surface 6M comes into contact. The plurality of development parts bi are set at equal intervals in the traveling direction of the tire model 1. In this embodiment, a deployment site b1 that contacts the ground contact site a1, a deployment site b2 that contacts the ground site a2, and a deployment site b3 that contacts the ground site a3 are set.

  The distance (arc-shaped distance) between the ground contact part a1 and the ground contact part a2 along the surface of the tread portion of the tire model 1M is equal to the distance between the development part b1 and the development part b2 on the virtual road surface 6M. The distance (arc-shaped distance) between the ground contact part a2 and the ground contact part a3 along the surface of the tread portion of the tire model 1M is equal to the distance between the development part b2 and the development part b3 on the virtual road surface 6M.

  Next, the processing unit 51 calculates a ground load F acting on the tire 1 (step S50). The processing unit 51 calculates the ground load F acting on the tire 1 based on the weight of the vehicle 100, the weight of the tire 1, and the like.

  Next, as illustrated in FIG. 6, the processing unit 51 brings the tire model 1M and the virtual road surface 6M into contact with each other while restraining rotation of the axle and rim of the tire model 1M (step SP60). The processing unit 51 brings the tire model 1M and the virtual road surface 6M into contact so that the ground contact part a1 and the development part b1 come into contact with each other.

  When the tire model 1M is brought into contact with the virtual road surface 6M, the rotation of the axle and rim of the tire model 1M is restricted. Further, the movement of the virtual road surface 6M is also restricted. That is, translation and rotation (turning) of the virtual road surface 6M are also restrained. The translation of the virtual road surface 6M is a movement of the virtual road surface 6M in a direction parallel to the surface of the virtual road surface 6M.

  That is, in the contact step (step SP60), the processing unit 51 restrains the rotation of the axle and rim of the tire model 1M and restrains the movement (translation and rotation) of the virtual road surface 6M, and the tire model 1M and the virtual road surface. 6M is contacted. The tire model 1M and the virtual road surface 6M move relative to each other in a direction orthogonal to the surface of the virtual road surface 6M and come into contact with each other.

  The processing unit 51 brings the tire model 1M and the virtual road surface 6M into contact with each other, and applies the ground load F calculated in the ground load calculation step (step SP50) to the contact portion 7 of the tire model 1M in contact with the virtual road surface 6M. Let The contact load F acting on the tire model 1M is a value that simulates the contact load that the tire 1 receives from the road surface 6. In the contact between the ground contact part a1 and the development part b1, a ground load F is applied to the ground contact part a1.

  In the present embodiment, in step SP50, the behavior of the tire model 1M and the behavior of the virtual road surface 6M are simulated until the ground contact part a1 of the tire model 1M and the development part b1 of the virtual road surface 6M come into contact with each other. In addition, a simulation is performed on the tire model 1M when the ground load F acts on the ground contact part a1 of the tire model 1M.

  After contacting the ground contact part a1 of the tire model 1M whose rotation is constrained with the development part b1 of the virtual road surface 6M whose movement is constrained, as shown in FIG. 7, the processing unit 51 includes an axle of the tire model 1M. In the state where the rotation of the rim is constrained, the virtual road surface 6M is placed around the tire model 1M so that the ground contact part a2 of the tire model 1M and the development part b2 of the virtual road surface 6M associated with the ground contact part a2 are in contact with each other. (Step SP70).

  The processing unit 51 moves the virtual road surface 6M around the tire model 1M with the ground load F applied to the tire model 1M. The contact load F applied to the tire model 1M is set to a value simulating the contact load F applied to the tire 1 in actual use. In the contact between the ground contact part a2 and the development part b2, a ground load F is applied to the ground contact part a2.

  The processing unit 51 turns the virtual road surface 6M around the rotation center AX of the tire model 1M while keeping the tire model 1M and the virtual road surface 6M in contact without moving the axle and rim of the tire model 1M. Thus, the ground contact part a2 of the tire model 1M and the development part b2 of the virtual road surface 6M are in contact with each other without rotating the axle and rim of the tire model 1M.

  In the present embodiment, the processing unit 51 simulates the behavior of the tire model 1M and the behavior of the virtual road surface 6M until the ground contact part a2 of the tire model 1M comes into contact with the development part b2 of the virtual road surface 6M. In addition, the processing unit 51 performs a simulation on the tire model 1M when the ground load F is applied to the ground contact part a2 of the tire model 1M. In the present embodiment, the moving speed ω of the virtual road surface 6M that moves around the tire model 1M is set to a value that simulates the rotational speed of the tire 1 in actual use.

  As the virtual road surface 6M moves around the tire model 1M, the position of the contact portion 7 in contact with the virtual road surface 6M changes in the tire model 1M. When the virtual road surface 6M is moved around the tire model 1M, the processing unit 51 continues to apply the ground load F in a direction perpendicular to the surface of the contact portion 7. When the virtual road surface 6M moves around the tire model 1M in a state where the constant ground load F is applied, a state in which the ground load F is applied to the tire 1 in contact with the road surface 6 is appropriately simulated.

  Further, when moving the virtual road surface 6M around the tire model 1M, the processing unit 51 does not cause relative movement between the contact portion 7 of the tire model 1M and the contact portion 8 of the virtual road surface 6M that contacts the contact portion 7. . That is, the processing unit 51 moves the virtual road surface 6M around the tire model 1M in a state where the contact unit 7 and the contact unit 8 are not slid. As a result, a state in which the ground load F is applied to the tire 1 that does not slip on the road surface 6 is simulated.

  After contacting the ground contact part a2 of the tire model 1M and the development part b2 of the virtual road surface 6M, as illustrated in FIG. 8, the processing unit 51 restrains the rotation of the tire model 1M in the tire model 1M. The virtual road surface 6M is moved around the tire model 1M so that the ground contact part a3 and the development part b3 of the virtual road surface 6M associated with the ground contact part a3 are in contact with each other. The processing unit 51 moves the virtual road surface 6M around the tire model 1M with the ground load F applied to the tire model 1M. In the contact between the ground contact part a3 and the development part b3, the ground load F is applied to the ground contact part a3.

  The processing unit 51 simulates the behavior of the tire model 1M and the behavior of the virtual road surface 6M until the ground contact part a3 of the tire model 1M and the development part b3 of the virtual road surface 6M come into contact with each other. Further, the processing unit 51 performs a simulation on the tire model 1M when the ground load F is applied to the ground contact part a3 of the tire model 1M. When moving the virtual road surface 6M around the tire model 1M, the processing unit 51 does not cause relative movement between the contact portion 7 of the tire model 1M and the contact portion 8 of the virtual road surface 6M that contacts the contact portion 7.

  As described above, the processing unit 51 has a one-to-one correspondence with the plurality of ground contact parts ai (a1, a2, a3...) And the ground contact part ai of the tire model 1M in a state where the rotation of the axle and rim of the tire model 1M is constrained. The virtual road surface 6M is moved around the tire model 1M so that the developed portions bi (b1, b2, b3.

  The characteristics of the tire 1 are analyzed based on the tire model 1M and the virtual road surface 6M moved around the tire model 1M (step SP80). The analysis unit 51B turns the virtual road surface 6M around the tire model 1M created by the model creation unit 51A using a second computer program for simulating the characteristics of the tire 1 based on the finite element method, The characteristics of the tire 1 are analyzed. The analysis includes a running simulation that simulates the behavior of the tire 1 when the tire 1 rolls. The analysis also includes a deformation simulation that simulates the deformation of the tire 1 when the ground load F is applied to the tire 1. The analysis also includes a stress simulation that simulates the stress acting on each of the plurality of portions of the tire 1 when the ground load F is applied to the tire 1. The analysis item for the characteristics of the tire 1 may be at least one of air filling simulation, ground contact simulation, rolling state simulation, deformation state simulation, durability simulation, and wear state simulation. . In the analysis, optimization may be performed on at least one of these items.

  The analysis unit 51 evaluates the analysis result. The result of the evaluation is reflected in the design. The simulation device 5 may output at least one of the analysis result and the evaluation result to the output device 62. When the output device 62 includes a display device, at least one of the analysis result and the evaluation result may be displayed on the display device. At least one of the analysis result and the evaluation result output to the output device 62 may be reflected in the design.

  In the simulation, various physical quantities for the tire model 1M are output. For example, the physical quantity of the tire 1 including the stress, strain, displacement amount, displacement direction, strain energy density, principal value, principal direction, and at least one of cord, rubber, and adhesive strength acting on the rubber of the tire 1 is output. .

  Further, for example, physical quantities in the tread rubber and the sidewall rubber of the tire 1 are output by the simulation. Further, vibration generated in the tire model 1M may be output. Further, a simulation may be performed on the deformation of the tire model 1M, and a physical quantity at the time of the deformation may be output. As physical quantities at the time of deformation, for example, the amount of deflection of the sidewall portion of the tire 1, the contact shape in the tread rubber of the tire 1 including the tread portion, the contact pressure distribution, the force acting on the center of the tire 1, the moment, etc. are output. Good.

  Moreover, the rubber state of the tire 1 may be output by simulation. The state of rubber includes one or both of a deformed state and a damaged state. That is, the evaluation items related to rubber include one or both of a deformed state and a damaged state. The deformation state includes at least one of a deformation position, a deformation amount, and a deformation direction. The damage state includes at least one of a crack generation position, a crack amount, a fracture position, a fracture mode, a position where the cord and rubber are separated, and a separation amount.

  Further, based on the result of the simulation, for example, the shear characteristic between the cord and the rubber may be acquired. Moreover, the shear characteristic in rubber may be acquired based on the result of simulation. Further, based on the result of the simulation, for example, the position of the peeled portion (destructed portion) between the cord and rubber may be predicted (evaluated).

  As described above, according to this embodiment, the tire 1 rotates on the road surface 6 by moving the virtual road surface 6M around the tire model 1M without rotating the axle and rim of the tire model 1M. Since the simulation is performed, the characteristics of the tire 1 can be analyzed without considering the movement of the tire model 1M or the deformation of the tire model 1M due to the rotation of the axle and rim of the tire model 1M. Therefore, the calculation time until the simulation calculation converges or the occurrence of a calculation error in which the simulation calculation does not converge is suppressed, the calculation cost is reduced, and the decrease in simulation efficiency is suppressed. The number of elements of the virtual road surface 6M which is a finite element model of the road surface 6 is sufficiently smaller than the number of elements of the tire model 1M which is a finite element model of the tire 1. Therefore, a decrease in simulation efficiency is suppressed by moving the virtual road surface 6M without rotating the tire model 1M.

  In addition, after the plurality of ground contact parts ai are set in the tire model 1M and the development part bi associated with the ground contact part ai on a one-to-one basis is set on the virtual road surface 6M, the plurality of ground contact parts ai and the development parts bi Since the virtual road surface 6M may be moved around the tire model 1M so as to sequentially come into contact with each other and calculation corresponding to the set number of ground contact parts ai and development parts bi may be performed, the calculation time may be prolonged or a calculation error may occur. Is suppressed, the calculation cost is reduced, and the decrease in simulation efficiency is suppressed.

  In the present embodiment, in the movement step (step SP70), the grounding load F is applied to the grounding site ai that is in contact with the development site bi. Thereby, the tire 1 when the ground load F is applied can be accurately simulated.

  In the rolling analysis of the tire 1 by the finite element method, inertia due to the weight and motion of the tire model 1M occurs. Due to the influence of this inertia, abnormal deformation of the tire model 1M occurs and the analysis is often unstable. Therefore, normally, it is necessary to perform a run-up calculation that gradually increases the rolling speed to a steady rolling state. As a result, there is a problem that the calculation time becomes very long. On the other hand, the movement of the tire 1 updates the nodal coordinate system in the tire space position conversion with time increment. Usually, the amount of update calculation of the nodal coordinates is large for the tire model 1M having hundreds of thousands or more elements. There is a high possibility that the inertial force acts on the tire 1 and becomes unstable. On the other hand, since the road surface 6M is often used as a single rigid element having almost no mass, the road surface 6 has a feature that inertia force does not work even if it moves. In the present embodiment, the road surface 6 is rotated and moved without rolling the wheel 2 and the axle 3 of the tire 1 in order to solve the analysis instability due to the inertial force of the tire 1 by utilizing such characteristics. As a result, the inertial force generated in the tire 1 is suppressed, so that the running time is significantly shortened as shown in FIG. Further, since the calculation of the spatial position movement of only the road surface 6 is performed and the calculation of the nodal coordinate update in the tire spatial position movement is unnecessary, the entire tire calculation time can be further shortened.

Second Embodiment
A second embodiment will be described. Constituent elements that are the same as or equivalent to those in the above-described embodiment are given the same reference numerals, and descriptions thereof are simplified or omitted.

  FIG. 10 is a flowchart illustrating an example of a simulation method for the tire 1 according to the present embodiment. As shown in FIG. 10, in this embodiment, an inertial force calculating step (step SP55) for calculating an inertial force generated by the rotation of the tire 1 is performed, and the inertial force is converted into a tire model in the moving step (step SP70). 1M.

  In FIG. 10, the processing of steps SP10, SP20, SP30, SP40, and SP50 is the same as that of the above-described embodiment, and thus the description thereof is omitted.

  In step SP55, the processing unit 51 calculates an inertia force generated by the rotation of the tire 1. The tire assigned to each contact point of the element in the tire model 1M is mi, the relative speed between the tire 1 and the road surface 6 is Vi, and the tire indicates the distance between the rotation center AX of the tire model 1M and the contact point existing on the surface of the tread portion. When the radius is Ri, the angular velocity of the contacts existing on the surface of the tread portion of the tire model 1M is ω, and the total number of contacts in the tire model 1M is N, the inertial force P acting on the tire model 1M is (1) Calculated based on the formula.

  In step SP55, after the inertial force P is calculated, the processing unit 51 brings the tire model 1M into contact with the virtual road surface 6M (step SP60), and applies the inertial force P to the tire model 1M. The virtual road surface 6M is moved around (step SP70B). That is, simulation is performed, analysis and evaluation are performed in a state where the inertial force P is applied to the contact site ai (a1, a2, a3...) (Step SP80).

  As described above, according to the present embodiment, since the inertial force P is applied to the tire model 1M, the tire 1 can be simulated with high accuracy.

  As shown in FIG. 11, when the tire 1 comes into contact with the road surface 6, a part of the tire 1 is deformed by the ground load F, and the tread portion of the tire 1 that is in contact with the rotation center AX of the tire 1 and the road surface 6. The distance H with the contact portion 7 is smaller than the distance R between the rotation center AX of the tire 1 and the non-contact portion 9 of the tread portion of the tire 1 that does not contact the road surface 6. Therefore, the processing unit 51 performs a tire deformation amount calculating step for calculating the distance H between the rotation center AX of the tire 1 and the contact portion 7 of the tread portion of the tire 1, and calculates the inertial force P based on the distance H. May be. Based on the distance H, the processing unit 51 calculates the inertial force Ps acting on the ground contact part ai of the contact part 7, and calculates the inertial force P acting on the ground contact part ai of the non-contact part 9 based on the distance R. To do. The inertial force Ps acting on the contact portion ai of the contact portion 7 can be calculated by replacing “R” in the equation (1) with “H”. In the movement step (step SP70B), the inertial force Ps calculated based on the distance H is applied to the ground contact part ai existing at the contact portion 7 of the tire model 1M. Thereby, the simulation which considered the deformation | transformation part of the tire 1 is implemented.

<Third Embodiment>
A third embodiment will be described. Constituent elements that are the same as or equivalent to those in the above-described embodiment are given the same reference numerals, and descriptions thereof are simplified or omitted.

  FIG. 12 is a flowchart illustrating an example of a simulation method for the tire 1 according to the present embodiment. As shown in FIG. 12, in the present embodiment, a travel locus calculating step (step SP65) is performed in which the travel locus of the tire 1 is calculated based on the slip angle θ of the tire 1. In the movement step (step SP70C), the processing unit 51 moves the virtual road surface 6M around the tire model 1M based on the travel locus calculated in step S65.

  In FIG. 12, the processing of steps SP10, SP20, SP30, SP40, SP50, and SP60 is the same as that in the above-described embodiment, and thus description thereof is omitted.

  FIG. 13 is a diagram schematically illustrating a state of the tire 1 when the tire 1 is steered and turns. In general, when the tire 1 is turned by being steered, a deviation occurs between the rotation direction of the tire 1 (tire circumferential direction) and the traveling direction of the tire 1, and a slip angle θ is generated. Therefore, the development part bi of the virtual road surface 6M associated with the ground contact part ai of the tire model 1M that goes straight is different from the development part bi of the virtual road surface 6M associated with the ground contact part ai of the turning tire model 1M. . In FIG. 13, the development site bi of the virtual road surface 6 </ b> M associated with the ground contact site ai of the turning tire model 1 </ b> M is arranged along the traveling direction of the tire 1.

  Therefore, when simulating the tire 1 turning on the road surface 6, as shown in FIG. 14, it is necessary to rotate the virtual road surface 6M spirally around the tire model 1M. The radius of the spiral corresponds to the tire radius Ri described above.

  In step SP65, based on the slip angle θ, a spiral traveling locus is set as the traveling direction of the virtual road surface 6M as a relative traveling locus between the tire model 1M and the virtual road surface 6M. The traveling direction of the virtual road surface 6M corresponds to the traveling direction of the tire 1 shown in FIG.

  In step SP70C, the processing unit 51 rotates the virtual road surface 6M around the tire model 1M along a spiral traveling locus. The virtual road surface 6M preferably makes at least one round around the tire model 1M.

  In step SP80, characteristics such as cornering force, rolling resistance, and friction energy can be analyzed and evaluated as the characteristics of the tire 1.

  As described above, according to the present embodiment, the tire 1 at the time of turning can be accurately simulated by considering the slip angle θ of the tire 1 at the time of turning. Moreover, the cornering characteristics of the tire 1 can be analyzed and evaluated in a short time.

<Fourth embodiment>
A fourth embodiment will be described. Constituent elements that are the same as or equivalent to those in the above-described embodiment are given the same reference numerals, and descriptions thereof are simplified or omitted.

  FIG. 15 is a flowchart illustrating an example of a simulation method for the tire 1 according to the present embodiment. As shown in FIG. 15, in the present embodiment, a camber angle setting step (step SP68) for setting the camber angle α of the tire 1 is performed. In the moving step (step SP70D), the processing unit 51 moves around the tire model 1M while inclining the virtual road surface 6M based on the camber angle α of the tire 1 set in step S68.

  In FIG. 15, the processes of steps SP10, SP20, SP30, SP40, SP50, SP60, and SP80 are the same as those in the above-described embodiment, and thus description thereof is omitted.

  FIG. 16 is a diagram schematically illustrating a state where the camber angle α of the tire 1 is set and the virtual road surface 6M is inclined with respect to the rotation center AX based on the camber angle α. In step SP70D, the processing unit 51 rotates the virtual road surface 6M around the tire model 1M while inclining the virtual road surface 6M based on the camber angle α.

  As described above, according to the present embodiment, the tire 1 can be simulated more accurately by considering the camber angle α of the tire 1. Moreover, the cornering characteristics of the tire 1 can be analyzed and evaluated in a short time.

<Example>
Next, an embodiment according to the present invention will be described with reference to FIG. The inventor performs a simulation on the cornering force of the tire 1 according to the above-described embodiment, and calculates the simulation time required for the simulation calculation by the simulation method according to the embodiment of the present invention and the simulation method according to the conventional example. The calculation time required for was compared.

  In the simulation method according to the example and the simulation method according to the conventional example, the cornering force of the tire 1 having a tire size of 315 / 80R22.5 was simulated. As analysis conditions, the air pressure of the tire 1 is 830 [kPa], the contact load acting on the tire 1 is 36.77 [kN], the relative speed between the tire 1 and the road surface 6 is 80 [km / h], and the slip angle is 2 [°].

  The simulation method according to the embodiment is a method of rotating the virtual road surface 6M without rotating the tire model 1M. The simulation method according to the conventional example is a method in which the tire model 1M is rotated and the virtual road surface 6M is translated.

  Assuming that the calculation time of the simulation method according to the conventional example is 100, the calculation time of the simulation method according to the example is 30. That is, according to the present invention, it was confirmed that the simulation calculation time can be greatly shortened.

  Further, as a result of comparing the calculation result of the cornering force and the actual tire measurement result, when the calculation error of the simulation method according to the conventional example is set to 100, the calculation error of the simulation method according to the example is also 100. That is, it was confirmed that the simulation method according to the present invention can obtain the same simulation accuracy as the simulation method according to the conventional example.

  As described above, by performing the simulation calculation by the simulation method according to the present invention, it is possible to significantly reduce the simulation calculation time while maintaining the simulation accuracy, and to confirm that the simulation efficiency is good.

DESCRIPTION OF SYMBOLS 1 Tire 1M Tire model 2 Wheel 3 Axle 4 Steering device 5 Simulation device 6 Road surface 6M Virtual road surface 7 Contact part 8 Contact part 9 Non-contact part 51 Processing part 51A Model creation part 51B Analysis part 52 Storage part 53 Input / output part 60 Terminal device 61 Input device 62 Output device 100 Vehicle

Claims (7)

A simulation method for simulating a tire mounted on a wheel rim supported on an axle using a computer,
A tire model creating step of creating a tire model which is a finite element model of the tire including the axle and the rim, which is parsed by the computer, by dividing the tire into a finite number of elements;
A ground contact part setting step for setting a plurality of ground contact parts in the tire circumferential direction in contact with a road surface on which the tire travels in the tire model;
A deployment site setting step for setting a plurality of deployment sites in contact with each of the plurality of ground contact sites of the tire model on a virtual road surface simulating the road surface;
In a state in which rotation of the axle and the rim of the tire model is constrained, the plurality of ground contact parts of the tire model and the development part of the virtual road surface associated with the ground contact part sequentially contact each other. A moving step of moving a virtual road surface around the tire model;
Based on the tire model in the moving step, an analysis step for analyzing the characteristics of the tire;
Tire simulation method including Including a contact load calculating step of calculating a contact load acting on the tire;
The moving step includes applying the ground load to the ground contact part in contact between the ground contact part and the deployment part.
The tire simulation method according to claim 1. An inertial force calculating step of calculating an inertial force generated by the rotation of the tire,
The moving step includes applying the inertial force to the tire model.
The tire simulation method according to claim 1 or 2. A tire deformation amount calculating step of calculating a distance between a rotation center of the tire and a contact portion of a tread portion of the tire that has contacted the road surface;
The moving step includes applying an inertial force calculated based on the distance to the contact portion of the tire model.
The tire simulation method according to claim 3. A travel locus calculating step for calculating a travel locus of the tire based on a slip angle of the tire,
The moving step includes moving the virtual road surface based on the travel locus,
The tire simulation method according to any one of claims 1 to 4. The moving step includes moving the virtual road surface while inclining based on a camber angle of the tire.
The tire simulation method according to any one of claims 1 to 5.   A computer program that causes a computer to execute the tire simulation method according to any one of claims 1 to 6.

Images