Simulation method, simulation device, and program

Abstract

To provide a simulation method, simulation device, and program using a large model that reflects actual specifications.SOLUTION: A simulation device includes: an acquisition unit that acquires geometric shape information of an uneven surface of an object; a creation unit that associates the geometric shape information of the uneven surface with a three-dimensional planar model composed of elements that can be numerically analyzed by a computer, to create a reference uneven surface model composed of elements that can be numerically analyzed, and further creates an uneven surface model of a preset size larger than the reference uneven surface model by duplicating the reference uneven surface model and joining the plurality of reference uneven surface models; and an analysis unit that brings the uneven surface model and a structural model composed of elements that can be numerically analyzed into contact with each other, moves the structural model relatively over the uneven surface model in a contact state, and acquires a physical quantity generated in at least one of the structural model and the uneven surface model when the structural model is moved relatively over the uneven surface model.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a simulation method, a simulation device, and a program using elements that can be numerically analyzed by a computer, and more particularly to a simulation method, a simulation device, and a program using a large model that reflects actual specifications. [Background technology]

[0002] Currently, tire simulations are being carried out using computer-based numerical analysis such as the finite element method (FEM) to predict or evaluate tire performance without producing prototypes. Numerical analysis using the finite element method is effective in improving the efficiency of tire development. Conventionally, in numerical analysis using the finite element method or the like, a tire model is placed in contact with a flat road model and rolled, and the rolling resistance, cornering characteristics, braking / driving characteristics, etc. of the tire under consideration are evaluated. However, actual road surfaces such as asphalt have various irregularities, and when a tire runs on the actual road surface, there are large differences in the contact pressure or contact area, etc., between the flat road surface and the actual road surface. For this reason, it is thought that there may be differences between tire performance evaluated using a flat road surface in numerical analysis and the results of an evaluation of the performance of an actual vehicle running on the actual road surface.

[0003] For example, Patent Document 1 proposes a method of creating an uneven road surface model having macroscopic unevenness and evaluating the contact characteristics between the uneven road surface model and a tire model or a rubber model. Patent Document 1 discloses a method for evaluating contact characteristics, which includes the steps of creating an uneven road surface model, creating a tire model or a rubber model, and bringing the uneven road surface model into contact with the tire model or the rubber model to calculate an evaluation value of the contact characteristics. The step of creating the uneven road surface model includes the steps of identifying a low-frequency region in the power spectral density distribution of unevenness data of a road surface that includes macro-irregularities and micro-irregularities, creating a new function that can approximate the distribution of the low-frequency region when power spectrum analysis is performed by superimposing trigonometric functions of frequencies in the low-frequency region, and creating an uneven road surface model consisting of macro-irregularities based on the created new function. The road surface unevenness data is unevenness data acquired by measurement using a measuring means capable of acquiring surface unevenness data, and the step of identifying the low-frequency region includes the steps of: performing power spectrum analysis on the road surface unevenness data to create a power spectral density distribution in which the power spectral density is plotted logarithmically against frequency; identifying, as a corner frequency, the frequency at the boundary between the high-frequency side, where the logarithm of the power spectral density decreases linearly, and the low-frequency side, where the logarithm of the power spectral density becomes constant, in the power spectral density distribution; and identifying, as the low-frequency region, a region of frequencies lower than the corner frequency in the power spectral density distribution. The evaluation value is, for example, the friction force between the uneven road surface model and the tire model, the contact area or contact length, the contact pressure distribution, and the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6993201 Summary of the Invention [Problem to be solved by the invention]

[0005] To improve the accuracy of numerical analysis, it is preferable that the road surface model reflects the actual specifications, having a long distance over which the tire model can roll. However, it is extremely difficult to actually measure the road surface and obtain a road surface model that reflects the actual specifications. Furthermore, in the above-mentioned Patent Document 1, an uneven road surface model having macro unevenness is created using unevenness data acquired by measurement using the measurement means as described above. In Patent Document 1, the friction force, contact area or contact length, contact pressure distribution, etc. between the uneven road surface model and the tire model are calculated as evaluation values. However, Patent Document 1 does not describe creating a road surface model having a long distance over which the tire model can sufficiently roll. At present, no numerical analysis has been carried out using a large model, such as a road surface model that reflects actual specifications and has a long enough distance for the tire model to roll.

[0006] An object of the present invention is to provide a simulation method, a simulation device, and a program that use a large model that reflects actual specifications. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, invention [1] is a simulation method comprising: a first step of acquiring geometric shape information of an uneven surface of an object having an uneven surface; a second step of creating a reference uneven surface model composed of elements that can be numerically analyzed by a computer by associating the geometric shape information of the uneven surface with a three-dimensional plane model composed of elements that can be numerically analyzed by a computer; a third step of duplicating the reference uneven surface model and combining multiple reference uneven surface models to create an uneven surface model of a predetermined size that is larger than the reference uneven surface model; a fourth step of bringing the uneven surface model into contact with a structural model composed of elements that can be numerically analyzed by a computer; a fifth step of moving the structural model relatively over the uneven surface model while in contact; and a sixth step of acquiring physical quantities that occur in at least one of the structural model and the uneven surface model when the structural model is moved relatively over the uneven surface model.

[0008] Invention [2] is a simulation method according to invention [1], which includes a step of creating a three-dimensional planar model between the first step and the second step. Invention [3] is a simulation method according to Invention [1] or [2], in which the three-dimensional plane model is a flat surface model divided into a finite number of elements each consisting of a plurality of nodes. Invention [4] is a simulation method according to any one of Inventions [1] to [3], wherein the size of the three-dimensional plane model is equal to or smaller than the size of the range in which geometric shape information of the uneven surface is acquired. Invention [5] is a simulation method according to invention [3], in which the second step is to associate the height information of the position information of the geometric shape information of the uneven surface, which is closest to the node of the flat surface model, with the node. Invention [6] is a simulation method according to invention [3], in which a range is set in advance for the nodes of the flat surface model, and in the second step, the average height information of the height information at positions within the range for the nodes of the flat surface model, among the geometric shape information of the uneven surface, is associated with the nodes. Invention [7] is a simulation method according to invention [3], in which a range is set in advance for the nodes of the flat surface model, and in the second step, an approximation function is calculated using position information within the range for the nodes of the flat surface model, among the geometric shape information of the uneven surface, and the value of the approximation function at the node is associated with the node as height information of the node.

[0009] Invention [8] is a simulation method according to any one of Inventions [1] to [7], in which the third step is to duplicate the reference uneven surface model, and when combining multiple reference uneven surface models, align the edges of the reference uneven surface models to create an uneven surface model of a predetermined size. The invention [9] is a simulation method according to any one of the inventions [1] to [8], which includes a step of creating a structure model that contacts the uneven surface model.

[0010] Invention

[10] is a simulation method according to any one of Inventions [1] to [9], wherein the third step comprises a step of duplicating and combining the reference uneven surface model to create an intermediate uneven surface model that is larger than the reference uneven surface model, and a step of duplicating and combining the intermediate uneven surface model to create an uneven surface model that is larger than the intermediate uneven surface model. Invention

[11] is a simulation method according to any one of Inventions [1] to

[10] , in which the size of the uneven surface model is determined based on analytical information for obtaining geometric shape information or physical quantities of the structure. Invention

[12] is a simulation method according to any one of Inventions [1] to

[11] , wherein, when As is the minimum dimension of an element constituting the uneven surface model, and Ac is the minimum dimension of an element constituting the structural model in the contact area where the uneven surface model and the structural model are in contact, 0.01Ac≦As≦100As.

[0011] Invention

[13] is a simulation method according to any one of Inventions [1] to

[12] , in which Ad≦As is satisfied when the minimum dimension of an element constituting the uneven surface model is As and the minimum dimension of an element constituting the structure model is Ad. Invention

[14] is the simulation method according to any one of Inventions [1] to

[13] , in which the uneven surface model is a rigid body. Invention

[15] is a simulation method according to any one of Inventions [1] to

[14] , in which, when the stiffness of the uneven surface model is Gs and the stiffness of the structural model in the contact region where the uneven surface model and the structural model are in contact is Gc, 10Gc≦Gs. Invention

[16] is the simulation method according to any one of Inventions [1] to

[15] , wherein the structural model is provided with information on the physical properties of the elastomer. Invention

[17] is a simulation method according to any one of Inventions [1] to

[16] , wherein the object having an uneven surface is a road surface, the uneven surface model is a road surface model representing the road surface, and the structure model is a tire model representing a tire.

[0012] Invention

[18] is a simulation device having an acquisition unit that acquires geometric shape information of an uneven surface of an object having an uneven surface; a creation unit that associates the geometric shape information of the uneven surface with a three-dimensional plane model composed of elements that can be numerically analyzed by a computer to create a reference uneven surface model composed of elements that can be numerically analyzed by a computer, and further replicates the reference uneven surface model and combines multiple reference uneven surface models to create an uneven surface model of a predetermined size that is larger than the reference uneven surface model; and an analysis unit that brings the uneven surface model into contact with a structural model composed of elements that can be numerically analyzed by a computer, moves the structural model relatively over the uneven surface model while they are in contact, and acquires physical quantities that occur in at least one of the structural model and the uneven surface model when the structural model is moved relatively over the uneven surface model. Invention

[19] is the simulation device according to invention

[18] , in which the creation unit that creates the uneven surface model creates a three-dimensional plane model composed of elements that can be numerically analyzed by a computer.

[0013] Invention

[20] is a simulation device according to invention

[18] or

[19] , wherein the three-dimensional plane model is a flat surface model divided into a finite number of elements each consisting of a plurality of nodes. Invention

[21] is a simulation device according to any one of Inventions

[18] to

[20] , wherein the size of the three-dimensional plane model is equal to or smaller than the size of the range in which geometric shape information of the uneven surface is acquired. Invention

[22] is a simulation device according to any one of Inventions

[18] to

[21] , wherein the creation unit associates height information from the position information of the position closest to the node of the flat surface model among the geometric shape information of the uneven surface with the node. Invention

[23] is a simulation device according to any one of inventions

[18] to

[21] , in which a range is set in advance for the nodes of the flat surface model, and the creation unit associates with the nodes average height information of height information at positions within the range for the nodes of the flat surface model, among the geometric shape information of the uneven surface. Invention

[24] is a simulation device according to any one of inventions

[18] to

[21] , in which a range is set in advance for the nodes of the flat surface model, and the creation unit calculates an approximation function using position information within the range for the nodes of the flat surface model, among the geometric shape information of the uneven surface, and associates the value of the approximation function at the node with the node as height information of the node.

[0014] Invention

[25] is a simulation device according to any one of Inventions

[18] to

[24] , wherein the creation unit that creates the uneven surface model duplicates a reference uneven surface model, and when combining multiple reference uneven surface models, aligns the edges of the reference uneven surface models to create an uneven surface model of a preset size. The invention

[26] is the simulation device according to any one of the inventions

[18] to

[25] , wherein the creating unit creates a structure model that contacts the uneven surface model. Invention

[27] is a simulation device according to any one of Inventions

[18] to

[26] , wherein the creation unit that creates the uneven surface model copies and combines a reference uneven surface model to create an intermediate uneven surface model that is larger than the reference uneven surface model, and copies and combines the intermediate uneven surface model to create an uneven surface model that is larger than the intermediate uneven surface model. Invention

[28] is a simulation device according to any one of Inventions

[18] to

[27] , in which the size of the uneven surface model is determined based on analytical information for obtaining geometric shape information or physical quantities of the structure.

[0015] Invention

[29] is a simulation device according to any one of Inventions

[18] to

[28] , wherein, when the minimum dimension of an element constituting the uneven surface model is As and the minimum dimension of an element constituting the structural model in the contact area where the uneven surface model and the structural model are in contact is Ac, 0.01Ac≦As≦100As. Invention

[30] is a simulation device according to any one of Inventions

[18] to

[29] , wherein Ad≦As is satisfied when the minimum dimension of an element constituting the uneven surface model is As and the minimum dimension of an element constituting the structure model is Ad.

[0016] The invention

[31] is the simulation device according to any one of the inventions

[18] to

[30] , in which the uneven surface model is a rigid body. Invention

[32] is a simulation device according to any one of Inventions

[18] to

[31] , wherein the stiffness of the uneven surface model is Gs, and the stiffness of the structure model in the contact region where the uneven surface model and the structure model are in contact is Gc, and the relationship is 10Gc≦Gs. The invention

[33] is the simulation device according to any one of the inventions

[18] to

[32] , wherein the structure model is provided with information on the physical properties of the elastomer. Invention

[34] is a simulation device according to any one of Inventions

[18] to

[33] , wherein the object having an uneven surface is a road surface, the uneven surface model is a road surface model representing the road surface, and the structure model is a tire model representing a tire.

[0017] The invention

[35] is a program for causing a computer to execute the steps of the simulation method according to any one of the inventions [1] to

[17] as a procedure. [Effects of the Invention]

[0018] According to the present invention, a simulation can be performed using a large model that reflects actual specifications. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating an example of a simulation device used in a simulation method according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic perspective view showing a state in which a structure model according to an embodiment of the present invention is in contact with an uneven surface model. [Figure 3] FIG. 1(a) is a schematic diagram showing an example of a three-dimensional planar model, and FIG. 1(b) is a schematic diagram showing the relationship between the size of the three-dimensional planar model and the acquisition range of geometric shape information of an uneven surface. [Figure 4] (a) is a schematic plan view for explaining a first example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a first example of associating geometric shape information of an uneven surface with a three-dimensional planar model. [Figure 5] (a) is a schematic plan view for explaining a second example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a second example of associating geometric shape information of an uneven surface with a three-dimensional planar model. [Figure 6] (a) is a schematic plan view for explaining a third example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a third example of associating geometric shape information of an uneven surface with a three-dimensional planar model. [Figure 7]1(a) to 1(d) are schematic diagrams showing a first example of a method for creating an irregular surface model in a simulation method according to an embodiment of the present invention. [Figure 8] 5(a) to 5(d) are schematic perspective views showing a second example of a method for creating an uneven surface model in a simulation method according to an embodiment of the present invention. [Figure 9] 10(a) to 10(e) are schematic perspective views showing a third example of a method for creating an uneven surface model in a simulation method according to an embodiment of the present invention. [Figure 10] 1(a) is a schematic diagram showing the tire contact pressure distribution obtained by the simulation method of the present invention, and FIG. 1(b) is a schematic diagram showing the tire contact pressure distribution when the road surface is flat. [Figure 11] FIG. 1(a) is a schematic diagram showing an example of an uneven surface model, and FIG. 1(b) is a schematic diagram showing an example of a structure model. [Figure 12] 1 is a flowchart showing an example of a simulation method according to an embodiment of the present invention in order of steps. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A simulation method and a simulation device according to the present invention, as well as a program for executing the steps of the simulation method as a procedure on a computer or the like, will be described in detail below based on preferred embodiments shown in the accompanying drawings. It should be noted that the drawings described below are illustrative for explaining the present invention, and the present invention is not limited to the drawings shown below. Furthermore, unless otherwise specified, the "orthogonal" and specific angles include a generally accepted error range in the relevant technical field. Furthermore, unless otherwise specified, the numerical values, etc. include a generally accepted error range in the relevant technical field. Furthermore, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0021] [Simulation device] Fig. 1 is a schematic diagram showing an example of a simulation device used in a simulation method according to an embodiment of the present invention. Fig. 2 is a schematic perspective view showing a state in which a structure model according to an embodiment of the present invention and an uneven surface model are in contact with each other. In Fig. 2, symbol DL indicates the rolling direction, and symbol Dw indicates the width direction. The rolling direction DL and the width direction Dw are perpendicular to each other. The simulation method of this embodiment uses, for example, a simulation device 10 shown in FIG. 1, but is not limited to the simulation device 10 shown in FIG. The simulation device 10 is configured using hardware such as a computer. As described above, the simulation method of the present invention uses the simulation device 10 shown in Fig. 1, but the simulation method is not limited to the simulation device 10 as long as it can be executed using hardware and software such as a computer, and may also be a program that causes a computer or the like to execute each step of the simulation method as a procedure. Furthermore, the simulation device 10 is not limited to the configuration shown in Fig. 1.

[0022] The simulation device 10 has a processing unit 12, an input unit 14, and a display unit 16. The processing unit 12 has an acquisition unit 20, a creation unit 22, a display control unit 26, a memory 27, and a control unit 28. In addition, although not shown, the processing unit 12 has a ROM (Read Only Memory) and the like. The processing unit 12 is controlled by a control unit 28. In the processing unit 12, the acquisition unit 20, the creation unit 22, and the analysis unit 24 are connected to a memory 27. Data input to the acquisition unit 20, the creation unit 22, and the analysis unit 24 and various data obtained by the acquisition unit 20, the creation unit 22, and the analysis unit 24 are stored in the memory 27. The memory 27 is not particularly limited, but may be a physical storage medium such as a hard disk drive (HDD), a solid state drive (SSD), or a dynamic random access memory (DRAM), or may be a storage area located on a cloud connected via the Internet.

[0023] In the simulation method described below, various processes are performed in each part of the processing unit 12. In the following description, the explanation of the various processes performed in each part of the processing unit 12 by the control unit 28 is omitted, but the series of processes in each part are controlled by the control unit 28.

[0024] The input unit 14 is an input device such as a mouse and a keyboard for inputting various information in response to an instruction from an operator. When various information is transmitted wirelessly or via the Internet, the input unit 14 has a receiving unit for receiving wireless information or is configured to be connectable to the Internet. The input unit 14 can also input data of a three-dimensional plane model made up of elements that can be numerically analyzed by a computer to the simulation device 10 and store it in the memory 27.

[0025] The display unit 16 displays, for example, the results obtained by the simulation method, and various known displays are used. The display unit 16 also includes devices such as a printer for displaying various information on an output medium. When the display unit 16 transmits various information wirelessly or via the Internet, the display unit 16 has a transmitting unit for transmitting the various information or is configured to be connectable to the Internet.

[0026] The simulation device 10 functionally forms each of the parts of the acquisition unit 20, creation unit 22, and creation unit 22 by executing a program (computer software) stored in a ROM or the like by the control unit 28. As described above, the simulation device 10 may be configured by a computer in which each part functions by executing a program, or may be a dedicated device in which each part is configured with a dedicated circuit, or may be configured to be executed on the cloud.

[0027] The simulation method and simulation device of this embodiment aim to perform simulations using a large model that reflects actual specifications, and can perform simulations using a real road surface model that uses road surface data from a long distance that allows a tire to roll for a long period of time. This allows, for example, simulations of tires as described above to be performed under conditions that are close to those experienced by an actual vehicle, allowing tire performance to be evaluated. As a result, for example, a tire contact pressure distribution based on the real road surface model can be obtained, as shown in FIG. 10(a). The real road surface refers to the actual road surface. In the simulation method and simulation device, a structural model made up of elements that can be numerically analyzed by a computer is brought into contact with an uneven surface model made up of elements that can be numerically analyzed by a computer, and when the structural model is moved relatively over the uneven surface model while in contact, physical quantities occurring in at least one of the structural model and the uneven surface model are acquired.

[0028] The acquisition unit 20 of the simulation device 10 acquires geometric shape information of an uneven surface of an object having an uneven surface. The geometric shape information of the uneven surface is, for example, three-dimensional information of an object having an uneven surface. More specifically, the object having an uneven surface is three-dimensional information of an actual road surface. The geometric shape information of the uneven surface is obtained using, for example, a three-dimensional scanner using laser light or ultrasound, or a tactile roughness measuring device. The geometric shape information of the uneven surface is three-dimensional measurement data or three-dimensional graphic data. Furthermore, the acquisition unit 20 of the simulation device 10 may be, for example, a three-dimensional scanner capable of acquiring geometric shape information of an uneven surface of an object having an uneven surface.

[0029] Furthermore, the geometric shape information of the uneven surface may be used as is, or the acquisition unit 20 may correct the geometric shape information of the uneven surface. For example, if the geometric shape information of the uneven surface has a tilt, the tilt is corrected. The tilt correction is not particularly limited, and known methods can be used as appropriate. For example, the tilt is corrected by obtaining an average plane from the three-dimensional data representing the geometric shape information of the uneven surface. In this case, the tilt is corrected by obtaining the plane with the smallest error function in the three-dimensional data representing the geometric shape information of the uneven surface. When acquiring a quadrilateral area with an interior angle of 90° as geometric shape information of an uneven surface, if the quadrilateral is distorted, the acquisition unit 20 corrects the distortion so that the quadrilateral area has an interior angle of 90°. A known method can be used as appropriate to correct the distortion of the quadrilateral area. The geometric shape information of the irregular surface may also be obtained by trimming the shape of the region to a predetermined shape and size.

[0030] For example, the input unit 14 stores geometric shape information of the uneven surface in the memory 27 from outside the simulation device 10 . The geometric shape information of the uneven surface is, for example, measurement data including three-dimensional information, but it is preferably composed of elements that can be numerically analyzed by a computer (modeled) in order to reduce the load of subsequent calculation processing. For example, it is preferably in the form of mesh data used in numerical simulations such as FEM.

[0031] The shape of the region for acquiring geometric shape information of the uneven surface is preferably set in advance, and is preferably, for example, a quadrangle with an interior angle of 90°. A quadrangle with an interior angle of 90° is, for example, a square or a rectangle.

[0032] Here, Figure 3(a) is a schematic diagram showing an example of a three-dimensional planar model, and (b) is a schematic diagram showing the relationship between the size of the three-dimensional planar model and the acquisition range of geometric shape information of the uneven surface. The creation unit 22 associates the geometric shape information of the uneven surface with a three-dimensional planar model composed of elements that can be numerically analyzed by a computer, and creates a reference uneven surface model composed of elements that can be numerically analyzed by a computer. The association of the geometric shape information of the uneven surface with the three-dimensional planar model is executed by the creation unit 22 in a virtual space such as within the computer or on the cloud. The creating unit 22 may be configured to create a three-dimensional plane model made up of elements that can be numerically analyzed by a computer. Data of the three-dimensional plane model created by the creating unit 22 is stored in the memory 27. The above-mentioned three-dimensional plane model composed of elements that can be numerically analyzed by a computer is composed of mesh data used for numerical simulations such as FEM (finite element method). The three-dimensional plane model is a model that includes a plane that exists in three-dimensional space, such as a flat surface model 50 with a rectangular outer shape shown in Figure 3(a).

[0033] The flat surface model 50 can be numerically analyzed by a computer and is a model divided into a finite number of elements 53 each consisting of a plurality of nodes 52. The three-dimensional plane model (flat surface model 50) includes node information. For example, the flat surface model 50 is a quadrangle with all interior angles of 90°. The shape of the elements 53 is also a quadrangle with all interior angles of 90°. The flat surface model 50 shown in FIG. 3(a) is composed of a plurality of quadrangle elements 53. It is preferable that the flat surface model 50 has a square or rectangular outer shape, as this makes it easier to create the uneven surface model 30 described below. 3(a) and 3(b), the first side 50a and the second side 50b are perpendicular to each other. The direction in which the first side 50a extends is the x-direction, and the direction in which the second side 50b extends is the y-direction. The direction perpendicular to the x-direction and the y-direction is the z-direction. A plane that includes only the x and y directions and excludes the z direction is the xy plane, which is within the plane of the flat surface model 50. Nodal information is information about the nodes (vertices) of each element (mesh) that can be numerically analyzed by a computer, and includes position information of the nodes.

[0034] When the shape of the elements 53 constituting the three-dimensional planar model is quadrilateral, it need only be quadrilateral, and is not limited to quadrilaterals with 90° interior angles, and various quadrilateral shapes can be used. Examples of quadrilaterals include rectangles, squares, parallelograms, rhombuses, and trapezoids. In addition, quadrilaterals with different lengths of four sides and different interior angles may also be used. When the three-dimensional planar model is composed of quadrilateral elements 53, the quadrilateral elements 53 may be of the same size and type, or may be of different sizes and types. Furthermore, the shape of the elements 53 may be a triangle other than a rectangle. When the shape of the elements 53 constituting the three-dimensional planar model is a triangle, the shape is not particularly limited as long as it is a triangle. Examples of triangles include a right triangle, an isosceles triangle, an isosceles triangle, a right-angled isosceles triangle, an equilateral triangle, an equiangular triangle, an equilateral triangle, an acute triangle, an obtuse triangle, and a scalene triangle. In addition, triangles whose three side lengths and three interior angles are different may also be used. When the three-dimensional planar model is composed of triangular elements 53, the triangular elements 53 may be of the same size and type, or may be of different sizes and types. Quadrilateral elements and triangular elements may be mixed as the elements 53. Even in this case, the quadrilateral elements 53 and the triangular elements 53 may be the same in size and type, or may be different in size and type. Furthermore, the division of the three-dimensional plane model is, for example, equally divided into elements, but is not limited to this, and the division may be biased, that is, divided randomly.

[0035] In addition, it is preferable to set in advance the size of the three-dimensional plane model (flat surface model 50) and the size of the acquisition range for the geometric shape information of the uneven surface (area 54 for acquiring the geometric shape information of the uneven surface (see Figure 3(b))). 3(b), the size of the flat surface model 50 (three-dimensional plane model) is preferably equal to or smaller than the size of the area 54 (acquisition range of geometric shape information of the uneven surface) for acquiring geometric shape information of the uneven surface. In other words, the size of the area 54 for acquiring geometric shape information of the uneven surface is preferably equal to or larger than the size of the three-dimensional plane model (flat surface model 50). By making the size of the flat surface model 50 equal to or smaller than the size of the region 54 for acquiring geometric shape information of the uneven surface, when associating the uneven surface shape information with the nodes 52 of the flat surface model 50 (three-dimensional planar model), there is no shortage of geometric shape information of the uneven surface to associate with the nodes 52. Therefore, the information of the nodes 52 is not based on extrapolation or approximation, and therefore deviation of the obtained reference uneven surface model 34 from the actual shape is suppressed. When a three-dimensional scanner or tactile roughness measuring device is used to acquire geometric shape information of an uneven surface, the area 54 where geometric shape information of the uneven surface is acquired (acquisition range of geometric shape information of the uneven surface) is the measurement range of the three-dimensional scanner or tactile roughness measuring device, and for example, a measurement range with a rectangular outer shape is set. When a three-dimensional scanner or tactile roughness measuring device is used to acquire geometric shape information of an uneven surface, measurement points are obtained along the scanning direction, and when scanning on a straight line, the measurement points are lined up on a straight line.

[0036] Here, the area 54 from which geometric shape information of the uneven surface is acquired is a real area acquired using, for example, a three-dimensional scanner or a tactile roughness measuring device. The three-dimensional planar model (flat surface model 50) is a virtual area set in a virtual space such as within a computer or on the cloud. The area set as the three-dimensional planar model (flat surface model 50) is a real area virtually set in the virtual space. The size of the flat surface model 50 being equal to or smaller than the size of the area 54 for acquiring geometric shape information of the uneven surface means that the area of ​​the area set as the flat surface model 50 is equal to or smaller than the area of ​​the area 54 acquired using a three-dimensional scanner or tactile roughness measuring device as described above. If the size of the flat surface model 50 is equal to or smaller than the size of the region 54 from which geometric shape information of the uneven surface is acquired, when the flat surface model 50 and the above-mentioned region 54 are virtually superimposed as shown in Figure 3(b), the outer edge of the flat surface model 50 coincides with the outer edge of the region 54, or all of the outer edges of the flat surface model 50 are inside the outer edge of the region 54. When the flat surface model 50 and the region 54 are rectangular, it is preferable that the length of the sides of the flat surface model 50 is equal to or less than the length of the sides of the region 54 from which the geometric shape information of the uneven surface is acquired, and it is preferable that the lower limit of the length of the sides of the flat surface model 50 is equal to or greater than the length (size) of the data acquisition interval for the geometric shape information of the uneven surface.

[0037] The three-dimensional planar model is not limited to being created by the creation unit 22, and may be configured such that data of the three-dimensional planar model is input to the simulation device 10 from outside the simulation device 10 via the input unit 14. In this case, the data of the three-dimensional planar model is stored in the memory 27. The three-dimensional planar model stored in the memory 27 is not limited to one type, and there may be multiple types with different element configurations, element lengths, or sizes of the three-dimensional planar model. Since the geometric shape information of the uneven surface is associated with the three-dimensional planar model to create a reference uneven surface model composed of elements that can be numerically analyzed by a computer, the size of the three-dimensional planar model (flat surface model 50) is the size of the reference uneven surface model 34 described below.

[0038] The creating unit 22 further copies the reference uneven surface model and combines a plurality of reference uneven surface models to create an uneven surface model of a preset size that is larger than the reference uneven surface model. A known method can be used to create the reference uneven surface model. For example, the reference uneven surface model is created by dividing the uneven surface into a finite number of elements each consisting of a plurality of nodes based on the geometric shape information of the uneven surface. For example, if the geometric shape information of the uneven surface is three-dimensional graphic data, it is converted into modeled data using elements that can be numerically analyzed by a computer, and the geometric shape information of the uneven surface is associated with a three-dimensional plane model composed of elements that can be numerically analyzed by a computer to create a reference uneven surface model.

[0039] The three-dimensional plane model, reference uneven surface model, and uneven surface model, which are composed of elements that can be numerically analyzed by a computer, are not particularly limited as long as they are discretized models that can be numerically calculated, and are composed of mesh data used for numerical simulations such as FEM (finite element method), for example. The elements that make up the reference uneven surface model and the uneven surface model are, for example, computer-analyzable elements such as solid elements (e.g., tetrahedral solid elements, pentahedral solid elements, hexahedral solid elements) for a three-dimensional body, shell elements (e.g., triangular shell elements, quadrilateral shell elements), and surface elements. The elements thus divided are identified one by one in the three-dimensional model using three-dimensional coordinates during the analysis process. The reference uneven surface model is composed of a three-dimensional planar model to which geometric shape information of the uneven surface is associated, and therefore has the same configuration as a three-dimensional planar model. Furthermore, the uneven surface model is composed of a reference uneven surface model, and therefore has the same configuration as a reference uneven surface model. The reference uneven surface model and the uneven surface model further include nodal information. The reference uneven surface model and the uneven surface model will be described in detail later. To duplicate the reference uneven surface model 34 means to create an exact copy of the reference uneven surface model 34 .

[0040] The creation unit 22 creates a structure model that comes into contact with the uneven surface model. The structure model is made up of elements that can be numerically analyzed by a computer. For example, if the structure model is a tire model, the tire model is made up of elements that can be numerically analyzed by a computer. The structure model may be a model of the entire structure, or may be a model of only the portion that comes into contact with the uneven surface model. For example, if the structure model is a tire model, the structure model may be a model of the entire tire, or may be a model of only the portion that comes into contact with the uneven surface model. The structure model is input to the acquisition unit 20 via the input unit 14, for example, and stored in the memory 27. Furthermore, in the acquisition unit 20, when the structure model is a tire model, data of a tire shape that will become the tire model may be stored in advance in the memory 27, and the tire shape data may be called from the memory 27 to set the tire model.

[0041] The analysis unit 24 uses a software program such as Abaqus for numerical analysis (simulation) such as the finite element method. The analysis unit 24 uses numerical analysis such as the finite element method to bring the uneven surface model 30 into contact with the structure model 32 as shown in Fig. 2. The contact between the uneven surface model 30 and the structure model 32 is made in a virtual space such as within a computer or on the cloud. Then, the analysis unit 24 uses numerical analysis such as the finite element method to perform a simulation (rolling analysis) in which the structure model 32 is moved relatively on the uneven surface model 30 while the uneven surface model 30 and the structure model 32 are in contact with each other. The analysis unit 24 acquires, using numerical analysis such as the finite element method, a physical quantity that occurs in at least one of the structure model 32 and the uneven surface model 30 when the structure model 32 is moved relatively on the uneven surface model 30. The surface 30a where the uneven surface model 30 comes into contact with the structure model 32 has unevenness that reflects, for example, the unevenness of an actual road surface. The structure model 32 is moved on the uneven surface model 30 along the rolling direction DL.

[0042] In addition, in the rolling analysis, if the structure model 32 is a tire model, an internal pressure filling process is performed. The internal pressure filling process reproduces the process of assembling a tire onto a rim of a rim size specified by JATMA, ETRTO, TRA, or the like and filling the tire with internal pressure, and is a process of applying a pressure equivalent to the internal pressure of the tire model to the inner surface of the tire model facing the tire cavity region.

[0043] The load and relative movement speed in the contact analysis between the structure model 32 and the uneven surface model 30, as well as which of the structure model 32 and the uneven surface model 30 is to be moved and the movement direction, are stored, for example, in the memory 27. The analysis unit 24 may read out the load and relative movement speed, and which of the structure model 32 and the uneven surface model 30 is to be moved and the movement direction from the memory 27. Furthermore, the load and relative movement speed in the contact analysis between the structure model 32 and the uneven surface model 30 may be input from the input unit 14 and set in the analysis unit 24 . The structural model 32 and the uneven surface model 30 to be moved and the direction of movement may be input from the input unit 14 and set in the memory 27 . Moreover, the simulation conditions for the analysis unit 24 are set in the memory 27 .

[0044] The analysis unit 24 performs a contact analysis between the structure model and the uneven surface model as described below, and then performs a simulation in which the structure model (tire model) and the uneven surface model (actual road surface model) are moved relatively in a direction perpendicular to the load direction at a relative movement speed, and obtains physical quantities occurring in at least one of the structure model and the uneven surface model. The simulation is not particularly limited, and for example, a quasi-static analysis using FEM (finite element method) or a dynamic analysis speed-dependent simulation can be used as appropriate. The physical quantities obtained include the contact length, contact area, contact pressure, friction coefficient, cornering characteristics, and braking / driving characteristics. The above-mentioned analysis unit 24 uses a software program such as Abaqus for numerical analysis such as the finite element method. The above-mentioned contact analysis and acquisition of physical quantities are performed in a virtual space such as within a computer or on the cloud.

[0045] The display control unit 26 causes the display unit 16 to display, for example, the geometric shape information of the uneven surface acquired by the acquisition unit 20, information on the reference uneven surface model, intermediate uneven surface model, and uneven surface model created by the creation unit 22, the progress of the simulation (rolling analysis) performed by the analysis unit 24, the results of the simulation (rolling analysis), physical quantities, etc. The display control unit 26 reads out the geometric shape information of the uneven surface, information on the reference uneven surface model, intermediate uneven surface model, and uneven surface model, the progress of the simulation (rolling analysis), the results of the simulation (rolling analysis), physical quantities, etc. from the memory 27, and causes the display unit 16 to display them. The display control unit 26 can also cause the display unit 16 to display various types of information input via the input unit 14.

[0046] As described above, the control unit 28 controls the processing unit 12 and causes the acquisition unit 20, creation unit 22, and analysis unit 24 of the processing unit 12 to perform various steps performed in the simulation method described below. The control unit 28 also controls the exchange of data between the acquisition unit 20, creation unit 22, and analysis unit 24 and the memory 27. The above-described configuration of the simulation device 10 makes it possible to obtain a large model that reflects actual specifications, thereby enabling simulation to be performed using an actual road surface model that uses road surface data covering a long distance so that tires can be rotated for a long period of time.

[0047] <How to create a reference uneven surface model> Next, a method for creating a reference uneven surface model will be described. Figure 4(a) is a schematic plan view for explaining a first example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a first example of associating geometric shape information of an uneven surface with a three-dimensional planar model. Figure 5(a) is a schematic plan view for explaining a second example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a second example of associating geometric shape information of an uneven surface with a three-dimensional planar model. Figure 6(a) is a schematic plan view for explaining a third example of associating geometric shape information of an uneven surface with a three-dimensional planar model, and (b) is a schematic side view for explaining a third example of associating geometric shape information of an uneven surface with a three-dimensional planar model. In Figures 4(a) and (b), Figures 5(a) and (b), and Figures 6(a) and (b), the same components as those in Figures 3(a) and (b) are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0048] (First example of how to create a reference uneven surface model) As described above, the creation unit 22 associates the geometric shape information of the uneven surface with the three-dimensional planar model in a virtual space such as within a computer or on the cloud. First, a 3D scanner is used to perform 3D measurements of the actual road surface to obtain geometric shape information of the uneven surface. The geometric shape information of the uneven surface is, for example, 3D actual road surface data. The size represented by the 3D actual road surface data is the same as the size of the area 54 from which the geometric shape information is acquired, as shown in FIG. 3(b). The position information of each measurement point of the three-dimensional actual road surface data is expressed, for example, by three coordinates. The three coordinates are the position coordinates in the x-direction, y-direction, and z-direction described above. The three-dimensional actual road surface data is input to the acquisition unit 20 of the simulation device 10. Next, the creating unit 22 associates geometric shape information of an uneven surface, such as three-dimensional actual road surface data, with a three-dimensional plane model such as the flat surface model 50.

[0049] The correspondence between the geometric shape information of the uneven surface, such as the 3D actual road surface data, and the 3D planar model is performed, for example, by virtually superimposing a flat surface model 50 and an area 54 from which the geometric shape information of the uneven surface is acquired, as shown in Fig. 3(b). In this case, if a node 52 on the flat surface model 50 matches a measurement point of the 3D actual road surface data, which is the geometric shape information, the z-coordinate of the position coordinate of the measurement point is corresponded to the node 52 as height information. The virtual superposition of the flat surface model 50 and the area 54 for acquiring geometric shape information of the uneven surface is not particularly limited. If a node 52 on the flat surface model 50 does not match a measurement point of the three-dimensional actual road surface data, the height information of the position information of the position closest to the node on the flat surface model among the geometric shape information of the uneven surface is associated with the node. Specifically, as shown in FIGS. 4(a) and 4(b), when measurement points 55 of three-dimensional actual road surface data are virtually superimposed and mapped onto a flat surface model 50, there is no measurement point 55 that coincides with node P1. In this case, height information of measurement point M1 that is closest to node P1 within the plane of the flat surface model 50 (in the xy plane) is used. The closest position refers to the measurement point that is closest to node P1 within the plane of the flat surface model 50 (in the xy plane). There are no particular limitations on the method for searching for the measurement point that is closest to node P1. For example, node P1 is fitted to the three-dimensional actual road surface data, and a search is made to see if there is a measurement point within the area inside a circle centered on node P1, and the first measurement point found is determined to be the closest measurement point.

[0050] 4(b), in a first example of a method for creating a reference uneven surface model, height information from the position information of measurement point M1, i.e., the z-coordinate value of measurement point M1, is assigned as the height value of node P1 to node P1 of flat surface model 50. In this way, for node P1 with no matching measurement point, height information (z-coordinate value) of the closest measurement point M1 from the geometric shape information is assigned, and a reference uneven surface model 34 is created. When creating a reference uneven surface model by associating the height information in the geometric shape information that has the closest in-plane distance to the node, no approximation using a function is performed, so a reference uneven surface model 34 can be created that directly reflects some of the characteristics of the geometric shape information.

[0051] (Second example of how to create a reference uneven surface model) In a second example of a method for creating a reference uneven surface model, a flat surface model 50 and an area 54 for acquiring geometric shape information of the uneven surface are virtually superimposed, and when a node 52 on the flat surface model 50 coincides with a measurement point of the three-dimensional actual road surface data, the z-direction coordinate of the position coordinate of the measurement point is associated with the node 52 as height information, in the same manner as in the first example of a method for creating a reference uneven surface model described above. When a node 52 on the flat surface model 50 does not match a measurement point of the three-dimensional actual road surface data, a range is set in advance for the node of the flat surface model, and the average height information of the height information at positions within the range relative to the node of the flat surface model, among the geometric shape information of the uneven surface, is associated with the node. Specifically, as shown in Figures 5(a) and (b), when measurement points 55 of three-dimensional actual road surface data are virtually superimposed and mapped on a flat surface model 50, there is no measurement point 55 that coincides with node P1. In this case, the average height information of a total of five measurement points M1 to M5 that exist within a range D that is preset for node P1 is used. More specifically, the average value of the z-direction coordinates of measurement points M1 to M5 is used to obtain data point 56 that indicates the average value of the z-direction coordinates of measurement points M1 to M5. The height information of data point 56 is the average height information of the height information at positions that exist within range D.

[0052] 5(b), in a second example of a method for creating a reference uneven surface model, height information of data point 56, i.e., the z-coordinate value of data point 56, is assigned as the height value of node P1 to node P1 of flat surface model 50. In this way, the average value of the height information (z-coordinate values) of measurement points M1 to M5 present within range D is assigned to node P1, which does not have a matching measurement point, to create a reference uneven surface model 34. By associating the node with the average value of the position information of measurement points within a predetermined range D in a plane as height information, the average height information of the geometric shape information can be used for the node, thereby creating a reference uneven surface model 34 that suppresses noise when measuring the geometric shape information. The above-mentioned range D is the area inside a circle centered on the node. The above-mentioned range D is preferably within the element length of the elements 53 of the flat surface model 50, as this allows for a high degree of agreement between the uneven surface model 30 and the actual road surface. Furthermore, the method of searching for measurement points within the range D previously set for the above-mentioned node P1 is not particularly limited, but for example, node P1 is fitted to three-dimensional actual road surface data, and measurement points that exist in the area inside a circle centered on node P1, which corresponds to range D, are determined to be measurement points that exist within range D.

[0053] (Third example of how to create a reference uneven surface model) In a third example of a method for creating a reference uneven surface model, a flat surface model 50 and an area 54 for acquiring geometric shape information of the uneven surface are virtually superimposed, and when a node 52 on the flat surface model 50 coincides with a measurement point of three-dimensional actual road surface data, the z-direction coordinate of the position coordinate of the measurement point is associated with the node 52 as height information, in the same manner as in the first example of the method for creating a reference uneven surface model described above. If the nodes 52 on the flat surface model 50 do not match the measurement points of the three-dimensional actual road surface data, a range is set in advance for the nodes of the flat surface model, and an approximation function is calculated using position information within the range for the nodes of the flat surface model from the geometric shape information of the uneven surface, and the value of the approximation function at the nodes is associated with the nodes as height information. 6(a) and 6(b), when measurement points 55 of the 3D actual road surface data are virtually superimposed and mapped onto the flat surface model 50, there is no measurement point 55 that coincides with node P1. In this case, position information for a total of nine measurement points M1 to M9 that exist within a range D that is preset for node P1 is used. That is, information on the x-coordinates, y-coordinates, and z-coordinates of measurement points M1 to M9 is used.

[0054] In a third example of a method for creating a reference uneven surface model, an approximation function is calculated using measurement points M1 to M9, for example, in an xz plane defined by the x and z directions, as shown in FIG. 6(b). This allows, for example, the approximation function to generate a curve F shown in FIG. 6(b). In this case, curve F represented by the approximation function includes point 57, which corresponds to the x-coordinate value of node P1. Position information for point 57 is expressed by the x-coordinate value and the z-coordinate value. The z-coordinate value (height information) of point 57 is assigned as the height value of node P1. In this way, for node P1, which does not have a matching measurement point, an approximation function is calculated using measurement points M1 to M9 that exist within range D. For node P1, which does not have a matching measurement point, the value of the approximation function at the position of node P1 is assigned to node P1 as the node's height information, thereby creating a reference uneven surface model 34. An approximation function is calculated using the position information of measurement points within a predetermined range D in the plane of the node, and the value of the approximation function at the node position is associated with node P1 as the node height information.This sets the node height as the value of the approximation function of the geometric shape information, allowing the shape of the road surface to be simplified and a reference uneven surface model 34 to be created that suppresses noise when measuring the geometric shape information.

[0055] The above-mentioned range D is the area inside a circle centered on the node. The above-mentioned range D is preferably within the element length of the elements 53 of the flat surface model 50, as this allows for a high degree of agreement between the uneven surface model 30 and the actual road surface. The approximation function is not particularly limited, but when approximating on a two-dimensional plane, approximation functions such as trigonometric functions, periodic functions similar to trigonometric functions, combinations of polynomials, Lagrange interpolation, Hermite interpolation, or approximation using spline functions can be used. The approximation function may be an approximation in three-dimensional space. In this case, the approximation function represents a surface such as a curved surface. Information on the x-, y-, and z-coordinates of the measurement points M1 to M9 is used to calculate the approximation function. For example, the height information of the nodes can be obtained using a spline surface obtained by the approximation function or a curved surface obtained by Lagrange interpolation or Hermite interpolation.

[0056] When associating geometric shape information of an uneven surface such as actual road surface data with a three-dimensional plane model such as the flat surface model 50, a value based on the geometric shape information, a value based on average height information of the geometric shape information, or a value of an approximate function is assigned to a node as height information. At this time, the value assigned to the node as height information may be scaled. The scale includes a positive multiplier that increases the value and a negative multiplier that decreases the value. Furthermore, in order to associate geometric shape information of an uneven surface such as actual road surface data with a three-dimensional plane model such as the flat surface model 50, a value based on the geometric shape information, a value based on average height information of the geometric shape information, or a value of an approximate function may be assigned to a node as height information, and then the height information, i.e., the scale in the x and y directions other than the z direction, may be changed.

[0057] <How to create a rough surface model> Next, a method for creating a rough surface model will be described. Figures 7(a) to (d) are schematic diagrams showing a first example of a method for creating an uneven surface model in a simulation method according to an embodiment of the present invention. Figures 8(a) to (d) are schematic perspective views showing a second example of a method for creating an uneven surface model in a simulation method according to an embodiment of the present invention. Figures 9(a) to (e) are schematic perspective views showing a third example of a method for creating an uneven surface model in a simulation method according to an embodiment of the present invention. In FIGS. 7(a) to 7(d), 8(a) to 8(d), and 9(a) to 9(e), the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0058] (First example of how to create a rough surface model) As described above, the uneven surface model is created by the creation unit 22 in a virtual space such as within a computer or on the cloud. First, a 3D scanner is used to perform 3D measurements of the actual road surface, and 3D actual road surface data, for example, is obtained as geometric shape information of the uneven surface. The 3D actual road surface data is input to the acquisition unit 20 of the simulation device 10. Next, the creation unit 22 uses the reference uneven surface model 34 shown in Fig. 7(a) obtained by associating the three-dimensional actual road surface data (geometric shape information of the uneven surface) with the flat surface model 50 (three-dimensional plane model). The method described above is used to create the reference uneven surface model 34. The reference uneven surface model 34 is made up of elements that can be numerically analyzed by a computer, and has an outer shape that is, for example, rectangular. Next, the reference uneven surface model 34 is further duplicated and a plurality of reference uneven surface models 34 are combined to create an uneven surface model 30 of a preset size larger than the reference uneven surface model 34 . In this case, for example, the reference uneven surface model 34 is mirror-copied around one long side 34c, and the two reference uneven surface models 34 are combined to create an intermediate uneven surface model 35 that is larger than the reference uneven surface model 34, as shown in Figure 7(b). When combining multiple reference uneven surface models 34, the edges of the reference uneven surface models 34 are aligned to combine them. Mirror replication is the process of replicating an object in a mirror image. In mirror replication, the coordinates of the overlapping nodes are the same.

[0059] Next, the intermediate uneven surface model 35 is mirror-copied around one of the short sides 34d of the reference uneven surface model 34, and the two intermediate uneven surface models 35 are combined to create an intermediate uneven surface model 35a that is larger than the reference uneven surface model 34, as shown in Figure 7(c). Next, the intermediate uneven surface model 35a is mirror-copied around one of the four sides, side 35c, and the two intermediate uneven surface models 35a are joined to create the uneven surface model 30 shown in Fig. 7(d). When joining the intermediate uneven surface models 35, 35a, the edges of the intermediate uneven surface models 35, 35a are aligned to join them.

[0060] The uneven surface model 30 shown in Fig. 7(d) has, for example, an area eight times that of the reference uneven surface model 34. In the uneven surface model 30 shown in Fig. 7(d), the surface 34a of the reference uneven surface model 34 corresponds to the face 30a of the uneven surface model 30 shown in Fig. 2 described above. As described above, when the uneven surface model 30 is created by mirror-duplicating the reference uneven surface model 34, the coordinates of the nodes where the reference uneven surface model 34 overlap will match. This eliminates the need to modify the node information, and multiple reference uneven surface models 34 can be easily combined, making it easy to create the uneven surface model 30.

[0061] (Second example of how to create a rough surface model) Also, for example, the reference uneven surface model 34 shown in Fig. 8(a) is used, which is obtained by associating three-dimensional actual road surface data (geometric shape information of the uneven surface) with the flat surface model 50 (three-dimensional plane model) in the creation unit 22. The reference uneven surface model 34 shown in Fig. 8(a) has, for example, a rectangular outer shape. Next, the reference uneven surface model 34 shown in Figure 8(a) is mirror-copied around one short side 34d, and the two reference uneven surface models 34 are combined to create an intermediate uneven surface model 35 that is larger than the reference uneven surface model 34, as shown in Figure 8(b). When combining multiple reference uneven surface models 34, the edges of the reference uneven surface models 34 are aligned and combined. 8(c), the reference uneven surface model 34 is joined to one short side 34d of the reference uneven surface model 34 in the intermediate uneven surface model 35 so as to form a mirror copy. In this way, an intermediate uneven surface model 35 is created in which multiple reference uneven surface models 34 are joined in the longitudinal direction. Next, for example, the intermediate uneven surface model 35 is mirror-copied around one long side of the reference uneven surface model 34, and the two intermediate uneven surface models 35 are joined. This results in the uneven surface model 30 shown in Figure 8(d). As described above, in the case of mirror-copied models, the coordinates of overlapping nodes match, making joining easy. When joining the intermediate uneven surface models 35, the edges of the intermediate uneven surface models 35 are aligned to join them.

[0062] (Third example of how to create a rough surface model) Furthermore, for example, the uneven surface model 30 can be created only by copying without using mirror copying. In this case, first, the creation unit 22 creates the reference uneven surface model 34 shown in Fig. 9(a) by associating the three-dimensional actual road surface data (geometric shape information of the uneven surface) with the flat surface model 50 (three-dimensional plane model). The reference uneven surface model 34 shown in Fig. 9(a) has, for example, a rectangular outer shape. Next, the reference uneven surface model 34 is duplicated, and the short side 34d of the reference uneven surface model 34 is joined with the short side 34e of the reference uneven surface model 34 as shown in Figure 9(b) to create an intermediate uneven surface model 35 (see Figure 9(d)). At this time, the edges of the reference uneven surface models 34 are aligned and joined, but as shown in Figure 9(c), the coordinates of the nodes on the short side 34d of the reference uneven surface model 34 and the short side 34e of the reference uneven surface model 34 may not match. In other words, a discontinuous area is created at the joint of the reference uneven surface model 34, resulting in an area that is inappropriate for performing numerical analysis. 9(c), the coordinate N1 of the end of the short side 34d of the reference uneven surface model 34 does not match the coordinate N2 of the end of the short side 34e of the reference uneven surface model 34. In this case, the coordinate N1 of the end of the short side 34d of the reference uneven surface model 34 is aligned with the coordinate N2 of the end of the short side 34e of the reference uneven surface model 34. The method for aligning the coordinate N1 and the coordinate N2 is not particularly limited, but for example, the coordinate N2 may be set to the coordinate N1, or the coordinate N1 may be set to the coordinate N2, or the coordinate N1 and the coordinate N2 may be aligned with coordinates intermediate between the coordinates N1 and N2.

[0063] As described above, the coordinates of the ends of the connecting edges of the reference uneven surface model 34 are aligned so that no areas inappropriate for analysis are generated when duplicating. This creates the intermediate uneven surface model 35 shown in Figure 9(d). The intermediate uneven surface model 35 is then duplicated and combined to create the uneven surface model 30 shown in Figure 9(e). In this way, by duplicating and combining the reference uneven surface model 34, it is possible to create an uneven surface model 30 of a predetermined size that is larger than the reference uneven surface model 34. The number of copies is determined appropriately depending on the size of the uneven surface model 30 to be created. It is also preferable that the size of the uneven surface model 30 to be created is an even multiple of the size of the reference uneven surface model 34. This makes it possible to create a large model that reflects actual specifications, and for example, it is possible to create an actual road surface model of a long distance that can accommodate long-distance tire rotation as the uneven surface model.

[0064] The creation unit 22 that creates the uneven surface model 30 copies and combines the reference uneven surface models 34 to create an intermediate uneven surface model 35 that is larger than the reference uneven surface model 34, and copies and combines the intermediate uneven surface models 35 to create an uneven surface model 30 that is larger than the intermediate uneven surface model 35. When combining the intermediate uneven surface models 35, the edges of the intermediate uneven surface models 35 are aligned and combined. Creating the uneven surface model 30 using only mirror copying is preferable because the coordinates of overlapping nodes match, allowing for efficient creation of the uneven surface model without increasing the number of processes. For this reason, creating an uneven surface model using only mirror copying is particularly suitable for creating large-sized uneven surface models. When creating the uneven surface model 30, a rough surface model of a predetermined size can be created by repeatedly duplicating the reference uneven surface model and the intermediate uneven surface model. However, when creating the uneven surface model 30, it is preferable to determine the number of times to replicate the reference uneven surface model and the number of times to replicate the intermediate uneven surface model in accordance with the size of the uneven surface model 30, and then replicate the reference uneven surface model and the intermediate uneven surface model according to the determined number of times. This allows the uneven surface model to be created efficiently. For example, an object having an uneven surface is a road surface, and the uneven surface model is a road surface model that represents the road surface. The road surface model is made up of elements that can be numerically analyzed by a computer.

[0065] <Physical quantity> Next, the physical quantities will be described. FIG. 10(a) is a schematic diagram showing the tire contact pressure distribution obtained by the simulation method of the present invention, and (b) is a schematic diagram showing the tire contact pressure distribution when the road surface is flat. Physical quantities are obtained by simulation using the above-mentioned simulation device 10. Specifically, a tire model is used as the structural model, and an actual road surface model is used as the uneven surface model. A rolling analysis is performed in which the tire model rolls on the actual road surface model, and the contact area and contact pressure are obtained as physical quantities. As a result, for example, the tire contact area 40 and contact pressure distribution 41 shown in FIG. 10(a) are obtained. On the other hand, Figure 10(b) shows the tire contact area 42 and contact pressure distribution 43 when the road surface is flat. Figure 10(b) was obtained under the same conditions as the simulation used to obtain the contact pressure distribution 41 in Figure 10(a), except that the actual road surface model was a flat road model.

[0066] It can be seen that the contact pressure distribution 41 shown in FIG. 10(a) obtained by the simulation method has a smaller contact area than the contact pressure distribution 43 on a flat road shown in FIG. 10(b). In the contact pressure distribution 43 on a flat road shown in Figure 10(b), the tire is rolling on a flat road surface, with the tread and road surface in continuous contact over a wide area. On the other hand, in the contact pressure distribution 41 shown in Figure 10(a), the tire is rolling on an uneven surface model (real road surface model). Therefore, the contact shape is discrete due to contact between the tread and the convex parts of the road surface. Comparing Figure 10(a) and Figure 10(b), the contact area in Figure 10(a) is reduced by 95.5% compared to the contact area in Figure 10(b). By using this uneven surface model, it is possible to obtain physical quantities under conditions close to those experienced by an actual vehicle.

[0067] The range for acquiring geometric shape information of the uneven surface (area 54 for acquiring geometric shape information of the uneven surface (see Figure 3(b))) is preferably equal to or larger than the contact area where the uneven surface model and the structure model come into contact, but is not larger than 20 times the contact area. Here, the contact area where the uneven surface model and the structure model come into contact is the contact area when the structure model is a tire model and comes into contact with the uneven surface model under a specified load at a specified internal pressure. The contact area 42 shown in Figure 10(b) corresponds to the contact area where the uneven surface model and the structure model come into contact. The contact area 42 is the area surrounded by the contact length Lc and the contact width Wc. The lower limit of the range for acquiring geometric shape information on an uneven surface is preferably the contact area when the tire comes into contact with a flat road model under a specified load at a specified internal pressure. This makes it possible to simulate the process from the tire's depression into the road surface to its release from the road surface using actual road surface data, and to represent the deformation of the tire tread caused by the various irregularities present on the actual road surface and the resulting grip force. For this reason, when performing an analysis assuming that a tire is rolling on an actual road surface, it is preferable that the range for acquiring geometric shape information of the uneven surface has at least a contact area 42 with contact length Lc and contact width Wc as shown in Figure 10(b). The upper limit of the range for acquiring geometric shape information of the uneven surface is preferably 20 times or less the contact area (ground contact area 42 (see FIG. 10(b)) when the uneven surface model is in contact with the tire under a specified load at a specified internal pressure, taking into consideration the measurement time, etc. 20 times the contact area corresponds to one circumference of the tire.

[0068] Here, the specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of the "TIRE LOAD LIMITS, VARIOUS COLD DINFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. Furthermore, the specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of the "TIRE LOAD LIMITS AT VARIOUS COLLIDING PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO. However, in JATMA, for passenger car tires, the specified internal pressure is 180 kPa, and the specified load is 88% of the maximum load capacity.

[0069] The size of the uneven surface model is preferably determined based on analytical information for acquiring geometric shape information or physical quantities of the structure. As described above, the uneven surface model is composed of elements that can be numerically analyzed by a computer. Therefore, the larger the uneven surface model, the greater the number of elements. This may result in the simulation taking longer than necessary. For example, in the case of tire rolling analysis, the size of the uneven surface model is determined by the tire size, rolling speed, and rolling analysis time.

[0070] Here, FIG. 11(a) is a schematic diagram showing an example of an uneven surface model, and (b) is a schematic diagram showing an example of a structure model. As shown in Fig. 11(a), the uneven surface model 30 is composed of, for example, three-dimensional shell elements 31. The three-dimensional shell elements 31 are an example of elements that can be numerically analyzed by a computer. Among the multiple three-dimensional shell elements 31, the smallest dimension is As. As shown in Fig. 11(b), the tire tread portion 32a of the structure model 32 is composed of, for example, three-dimensional solid elements 33. The three-dimensional solid elements 33 are an example of elements that can be numerically analyzed by a computer. Of the multiple three-dimensional solid elements 33, the smallest dimension of the three-dimensional solid elements 33 that make up the contact region is Ac. When the minimum dimension of an element constituting the uneven surface model is As and the minimum dimension of an element constituting the structural model in the contact area where the uneven surface model and the structural model are in contact is Ac, it is preferable that 0.01Ac≦As≦100As.

[0071] When considering contact between a tire and a road surface, it is safe to assume that only the tire deforms because the road surface has a higher rigidity than the tire. In this case, if the element dimensions of the uneven surface model are very small compared to the element dimensions of the tire model, the tire model will not deform in accordance with the shape of the road surface model, which may result in a decrease in calculation accuracy, i.e., simulation accuracy. Furthermore, if the element dimensions of the uneven surface model are large, the tire will not have an uneven shape that simulates the actual road surface, and deformation will only be in accordance with the element dimensions of the uneven surface model. Therefore, a model with higher calculation accuracy will be obtained if the element dimensions of the uneven surface model and the structure model are similar or if the element dimensions of the structure model are slightly smaller. For this reason, as mentioned above, it is preferable that 0.01Ac≦As≦100As. Furthermore, the condition 0.01Ac≦As≦100As is effective for analyses in which input to a structural model due to unevenness is important, and is suitable for calculating the force or moment acting on the rotation axis (not shown) of a tire model in a rolling analysis of a tire model and an uneven road surface model.

[0072] Furthermore, when the minimum dimension of an element constituting the uneven surface model is As and the minimum dimension of an element constituting the structure model is Ad, it is preferable that Ad≦As. As described above, the tire tread portion 32a of the structure model 32 shown in Fig. 11(b) is made up of three-dimensional solid elements 33. Of the plurality of three-dimensional solid elements 33, the smallest dimension is Ad. As mentioned above, Ad≦As is effective for analysis to grasp detailed deformation at the contact interface when an uneven surface model contacts a structural model, and is suitable for evaluating the contact area and contact pressure of an actual road surface in rolling analysis of a tire model and an uneven road surface model.

[0073] The irregular surface model is preferably rigid, so that the structure model deforms but the irregular surface model does not. When defining a rough surface model as a rigid body, rigid elements may be used for the elements that make up the rough surface model, or the material type of the rigid body may be defined in the material definition of the elements that make up the rough surface model. Here, a rigid body means that when the structure model comes into contact with the irregular surface model and the structure model and the irregular surface model are subsequently moved relative to each other, the amount of deformation of the irregular surface model is zero. When analyzing the contact between the tire and the road surface, the rigidity of the road surface is sufficiently high compared to the rigidity of the tire, so the deformation or energy absorption amount of the road surface is very small, and there is no problem in analysis even if it is treated as a rigid body.

[0074] In numerical analysis, the time increment Δt is determined by the coolant condition in the explicit method, so attention must be paid to the element length. However, if the irregular surface model is defined as a rigid body, the irregular surface model is excluded from the coolant condition, so the time increment Δt does not become smaller even if the element length becomes smaller. The time increment Δt is expressed by the following formula: In the formula, L is the characteristic length of the element, E is Young's modulus, and ρ is the density of the element.

[0075]

number

[0076] Furthermore, when the stiffness of the uneven surface model is Gs and the stiffness of the structure model in the contact region where the uneven surface model and the structure model are in contact is Gc, it is preferable that 10Gc≦Gs. Note that stiffness is the modulus of elasticity. When contact between the tire and the road surface is assumed, the material properties of the road surface may be defined as equivalent to concrete. If the material properties of the road surface are defined as equivalent to concrete, it is preferable to determine the element length of the uneven surface model taking into account the above-mentioned coolant conditions. The upper limit of the stiffness Gc of the structure model relative to the stiffness Gs of the uneven surface model is not particularly limited, but is preferably 200,000 times, i.e., more preferably 10 Gc≦Gs≦200,000 Gc.

[0077] Furthermore, it is preferable that information on the physical properties of the elastomer is added to the structure model. In this case, the creation unit 22 adds the physical properties of the elastomer to the elements that make up the structure model. In the case where the structure model is a tire model that models a tire, it is also preferable to add information on the physical properties of the elastomer. In the case of a tire model, if the tire tread rubber that comes into contact with the road surface is modeled, it is more preferable to add information on the physical properties of the elastomer to the tread model of the tire model. The physical property values ​​of the elastomer include, for example, viscoelasticity and elasticity. More specifically, the information on the physical property values ​​of the elastomer includes, for example, information on the rubber component, silica, carbon black, silane coupling agent, etc.

[0078] Information on rubber components includes information on natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), and chloroprene rubber (CR). The method for imparting the physical properties of the elastomer to the structural model is not particularly limited, and any method used in numerical analysis software can be used as appropriate. Viscoelasticity includes, for example, the Prony series and parallel rheology frameworks. As for elasticity, it is preferable to use a hyperelastic model (Neo-Hookean, Yoeh, etc.).

[0079] [Simulation method] Next, the simulation method of this embodiment will be described. FIG. 12 is a flowchart showing an example of a simulation method according to an embodiment of the present invention in the order of steps. First, for an object having an uneven surface, geometric shape information of the uneven surface is obtained (step S10 (first step)). In step S10 (first process), geometric shape information of the uneven surface is acquired using, for example, a three-dimensional scanner or a tactile roughness measuring device. Three-dimensional measurement data representing the geometric shape information of the uneven surface is obtained. The geometric shape information of the uneven surface is input to the acquisition unit 20 via, for example, the input unit 14 and stored in the memory 27. For example, the object having an uneven surface is a road surface. In this case, the geometric shape information of the uneven surface includes unevenness information of the road surface. The geometric shape information of the uneven surface may be corrected for tilt, distortion, or trimmed. The shape and size of the area 54 (see FIG. 3(b)) for acquiring geometric shape information of the uneven surface are preferably set in advance, and the size of the area 54 (see FIG. 3(b)) for acquiring geometric shape information of the uneven surface is preferably larger than the size of the three-dimensional planar model. Furthermore, the shape of the area 54 for acquiring geometric shape information of the uneven surface is preferably, for example, a rectangle with interior angles of 90°. The range for acquiring geometric shape information of the irregular surface is preferably equal to or larger than the contact area where the irregular surface model and the structure model come into contact, as described above, but is not larger than 20 times the contact area.

[0080] Next, the geometric shape information of the uneven surface is associated with a three-dimensional plane model composed of elements that can be numerically analyzed by a computer, and a reference uneven surface model composed of elements that can be numerically analyzed by a computer is created (step S12 (second step)). Data of the reference uneven surface model is stored in memory 27. In step S12 (second process), the method of associating the geometric shape information of the uneven surface with the three-dimensional planar model can be exemplified by the first to third examples of the method of creating the reference uneven surface model described above. The three-dimensional planar model is preferably a flat surface model 50 (see FIG. 3(a)) whose outer shape is square or rectangular. In step S12 (second process), for example, if the geometric shape information of the uneven surface is three-dimensional graphic data, it is converted into modeled data using elements that can be numerically analyzed by a computer, and the geometric shape information of the uneven surface is associated with a three-dimensional plane model to create a reference uneven surface model. The reference uneven surface model is composed of mesh data used for numerical simulation such as FEM (finite element method), etc. The method for creating the reference uneven surface model is as described above.

[0081] Next, the reference uneven surface model is duplicated and multiple reference uneven surface models are combined to create an uneven surface model of a preset size larger than the reference uneven surface model (step S14 (third step)). Data of the uneven surface model is stored in memory 27. In step S14 (third step), data of the reference uneven surface model is read from memory 27, and an uneven surface model is created using the reference uneven surface model, but the method for creating an uneven surface model of a predetermined size larger than the reference uneven surface model is not particularly limited. For example, the methods shown in Figures 7(a) to (d), 8(a) to (d), and 9(a) to (e) above can be used as appropriate.

[0082] Step S14 (third process) includes, for example, duplicating a reference uneven surface model, aligning the edges of the reference uneven surface models when combining multiple reference uneven surface models, and creating an uneven surface model of a predetermined size. Also, for example, step S14 (third step), i.e., the step of creating an uneven surface model, includes a step of duplicating and combining the reference uneven surface model to create an intermediate uneven surface model that is larger than the reference uneven surface model, and a step of duplicating and combining the intermediate uneven surface model to create an uneven surface model that is larger than the intermediate uneven surface model. In the process of creating the uneven surface model, an uneven surface model of a predetermined size can be created by repeatedly copying the reference uneven surface model and the intermediate uneven surface model. However, since this allows for efficient creation of the uneven surface model, it is preferable to determine the number of times to copy the reference uneven surface model and the number of times to copy the intermediate uneven surface model according to the size of the uneven surface model, and to perform copying of the reference uneven surface model and the intermediate uneven surface model according to the determined number of times.

[0083] Next, the data of the uneven surface model is read from memory 27, and in analysis unit 24, using numerical analysis such as the finite element method, the uneven surface model is brought into contact with a structural model composed of elements that can be numerically analyzed by a computer (step S16 (fourth step)). The structure model is in contact with the uneven surface model, and is, for example, a tire model representing a tire. The structure model may be created in advance and stored in the memory 27, and may be read out from the memory 27 in step S16 (fourth process).

[0084] The simulation method may also include a step of creating a three-dimensional plane model (step S11). In this case, for example, the step of creating a three-dimensional plane model (step S11) may be included between the first step (step S10) and the second step (step S12) or before the second step (step S12). In step S11, for example, the flat surface model 50 shown in FIG. 3(a) is created by the creation unit 22 as a three-dimensional plane model. The three-dimensional plane model (flat surface model 50 (see FIG. 3(a))) may be created by the creation unit 22. Alternatively, for example, data of the three-dimensional plane model may be input to the simulation device 10 from outside the simulation device 10 via the input unit 14. A plurality of types of three-dimensional plane models (flat surface models 50 (see FIG. 3(a))) may be stored in the memory 27, and the three-dimensional plane models may be read out from the memory 27. The simulation method may also include a step of creating a structure model (step S15). In this case, the created structure model is stored in memory 27. When the uneven surface model and the structure model are brought into contact with each other, the structure model is read out from memory 27. The contact between the irregular surface model and the structure model is based on preset conditions, which are stored in the memory 27, for example, and read out from the memory 27.

[0085] When the uneven surface model is a real road surface model and the structural model is a tire model, for example, the tire is brought into contact with the uneven surface model at a specified load under a specified internal pressure. The structure model may be a model of the entire structure, or may be a model of only the portion that comes into contact with the uneven surface model. For example, if the structure model is a tire model, the structure model may be a model of the entire tire, or may be a model of only the portion that comes into contact with the uneven surface model.

[0086] Next, using numerical analysis such as the finite element method, a simulation is performed in which the structure model is moved relatively over the uneven surface model while the uneven surface model and the structure model are in contact with each other (step S18 (fifth step)). Next, when the structure model is moved relatively on the irregular surface model, a physical quantity occurring in at least one of the structure model and the irregular surface model is acquired (step S20 (sixth step)). The acquired physical quantity is stored in memory 27. In step S18 (fifth step), for example, when the uneven surface model is an actual road surface model and the structure model is a tire model, a simulation is performed in which the tire model rolls on the actual road surface model. Then, in step S20 (sixth step), physical quantities are obtained from the results of numerical analysis such as the finite element method. In the case of a tire model, the physical quantities include, for example, contact patch length, contact patch area, contact pressure, cornering characteristics, braking / driving characteristics, etc. All of these can be obtained by numerical analysis such as the finite element method.

[0087] The simulation method uses the above-described steps to perform a simulation using a large model that reflects actual specifications. Therefore, for example, a simulation can be performed using a long-distance road surface model that allows a tire to roll for a sufficiently long time. This allows, for example, a simulation of a tire under conditions similar to those experienced in actual vehicle driving, allowing tire performance to be evaluated. As a result, for example, a tire contact pressure distribution based on the actual road surface model can be obtained, as shown in FIG. 10(a). The simulation method described above can be implemented by causing a computer to execute each step of the simulation method as a procedure using a program that executes the simulation method.

[0088] The present invention is basically configured as described above. Although the simulation method, simulation device, and program of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0089] 10 Simulation equipment 12 Processing Unit 14 Input section 16 Display 20 Acquisition Department 22 Creation Department 24 Analysis Department 27 Memory 28 Control Unit 30 Rough surface model 30a side 31 3D shell elements 32 Structural Model 32a Tire tread 33 3D solid elements 34 Reference rough surface model 34a surface 34c long side 34d, 34e short side 35, 35a Intermediate rough surface model 40, 42 ground area 41, 43 Ground pressure distribution 50 Flat Surface Models 50a First Side 50b Second Side 52, P1 node 53 elements 54 areas 55 measurement points D range M1, M2, M3, M4, M5, M6, M7, M8, M9 measurement points N1, N2 coordinates

Claims

1. a first step of acquiring geometric shape information of an object having a textured surface; a second step of associating the geometric shape information of the irregular surface with a three-dimensional plane model made up of elements that can be numerically analyzed by a computer, thereby creating a reference irregular surface model made up of elements that can be numerically analyzed by a computer; a third step of duplicating the reference uneven surface model and combining a plurality of reference uneven surface models to create an uneven surface model of a predetermined size larger than the reference uneven surface model; a fourth step of bringing the uneven surface model into contact with a structural model composed of elements that can be numerically analyzed by a computer; a fifth step of relatively moving the structure model on the uneven surface model while the structure model and the uneven surface model are in contact with each other; and a sixth step of acquiring a physical quantity occurring in at least one of the structure model and the uneven surface model when the structure model is moved relatively on the uneven surface model.

2. 2. The simulation method according to claim 1, further comprising a step of creating a three-dimensional plane model between said first step and said second step.

3. 2. The simulation method according to claim 1, wherein the three-dimensional plane model is a flat surface model divided into a finite number of elements each consisting of a plurality of nodes.

4. 2. The simulation method according to claim 1, wherein the size of the three-dimensional planar model is equal to or smaller than the size of the acquisition range of the geometric shape information of the uneven surface.

5. 4. The simulation method according to claim 3, wherein the second step associates height information of position information of a position closest to the node of the flat surface model, among the geometric shape information of the uneven surface, with the node.

6. 4. The simulation method according to claim 3, wherein a range is set in advance for the node of the flat surface model, and the second step associates average height information of height information at positions within the range relative to the node of the flat surface model, among the geometric shape information of the uneven surface, with the node.

7. 4. The simulation method according to claim 3, wherein a range is set in advance for the nodes of the flat surface model, and the second step calculates an approximation function using position information of the geometric shape information of the uneven surface that exists within the range for the nodes of the flat surface model, and associates the value of the approximation function at the nodes with the nodes as height information of the nodes.

8. 2. The simulation method according to claim 1, wherein the third step comprises duplicating the reference uneven surface model, and when combining a plurality of reference uneven surface models, aligning edges of the reference uneven surface models to create the uneven surface model of the predetermined size.

9. The simulation method according to claim 1 , further comprising the step of creating the structure model in contact with the irregular surface model.

10. the third step is to create an intermediate uneven surface model larger than the reference uneven surface model by duplicating and combining the reference uneven surface model; and replicating and combining the intermediate rough surface models to create the rough surface model that is larger than the intermediate rough surface model.

11. The simulation method according to claim 1 , wherein the size of the irregular surface model is determined based on geometric shape information of the structure or analytical information for acquiring the physical quantity.

12. 2. The simulation method according to claim 1, wherein, when As is the minimum dimension of the elements constituting the uneven surface model and Ac is the minimum dimension of the elements constituting the structure model in the contact region where the uneven surface model and the structure model come into contact, 0.01Ac≦As≦100As.

13. 2. The simulation method according to claim 1, wherein Ad≦As is satisfied, where As is the minimum dimension of the elements constituting the uneven surface model, and Ad is the minimum dimension of the elements constituting the structure model.

14. The simulation method according to claim 1 , wherein the uneven surface model is a rigid body.

15. When the stiffness of the uneven surface model is Gs and the stiffness of the structure model in a contact region where the uneven surface model and the structure model are in contact is Gc, The simulation method according to claim 1 , wherein 10Gc≦Gs.

16. The simulation method according to claim 1 , wherein the structural model is provided with information on physical properties of an elastomer.

17. the object having an irregular surface is a road surface, and the irregular surface model is a road surface model representing the road surface; The simulation method according to claim 1 , wherein the structural model is a tire model representing a tire.

18. an acquisition unit that acquires geometric shape information of an object having an uneven surface; a creating unit that associates the geometric shape information of the uneven surface with a three-dimensional plane model that is made up of elements that can be numerically analyzed by a computer, creates a reference uneven surface model that is made up of elements that can be numerically analyzed by a computer, and further creates an uneven surface model of a predetermined size that is larger than the reference uneven surface model by duplicating the reference uneven surface model and combining multiple reference uneven surface models; a simulation device having an analysis unit that brings the uneven surface model into contact with a structure model composed of elements that can be numerically analyzed by a computer, moves the structure model relatively on the uneven surface model while the model is in contact, and acquires physical quantities that occur in at least one of the structure model and the uneven surface model when the structure model is moved relatively on the uneven surface model.

19. 19. The simulation device according to claim 18, wherein the creation unit that creates the uneven surface model creates the three-dimensional plane model that is configured with elements that can be numerically analyzed by the computer.

20. 19. The simulation device according to claim 18, wherein the three-dimensional plane model is a flat surface model divided into a finite number of elements each composed of a plurality of nodes.

21. 19. The simulation device according to claim 18, wherein the size of the three-dimensional planar model is equal to or smaller than the size of an acquisition range of the geometric shape information of the uneven surface.

22. The simulation device according to claim 20 , wherein the creation unit associates height information of position information of a position closest to the node of the flat surface model, among the geometric shape information of the uneven surface, with the node.

23. 21. The simulation device according to claim 20, wherein a range is set in advance for the node of the flat surface model, and the creation unit associates average height information of height information at positions within the range relative to the node of the flat surface model, among the geometric shape information of the uneven surface, with the node.

24. 21. The simulation device according to claim 20, wherein a range is set in advance for the nodes of the flat surface model, and the creation unit calculates an approximation function using position information of the geometric shape information of the uneven surface that exists within the range for the nodes of the flat surface model, and associates the value of the approximation function at the nodes with the nodes as height information of the nodes.

25. 19. The simulation device according to claim 18, wherein the creation unit that creates the uneven surface model duplicates the reference uneven surface model, and when combining multiple reference uneven surface models, aligns edges of the reference uneven surface models to create the uneven surface model of the predetermined size.

26. The simulation device according to claim 18 , wherein the creation unit creates the structure model in contact with the uneven surface model.

27. the creation unit that creates the irregular surface model creates an intermediate irregular surface model that is larger than the reference irregular surface model by duplicating and combining the reference irregular surface model, The simulation apparatus according to claim 18 , wherein the intermediate rough surface models are duplicated and combined to create the rough surface model that is larger than the intermediate rough surface model.

28. 19. The simulation device according to claim 18, wherein the size of the uneven surface model is determined based on geometric shape information of the structure or analytical information for acquiring the physical quantity.

29. 19. The simulation device according to claim 18, wherein, when As is the minimum dimension of the elements constituting the uneven surface model and Ac is the minimum dimension of the elements constituting the structure model in a contact region where the uneven surface model and the structure model are in contact, 0.01Ac≦As≦100As.

30. 19. The simulation device according to claim 18, wherein Ad≦As is satisfied, where As is the minimum dimension of the elements constituting the uneven surface model, and Ad is the minimum dimension of the elements constituting the structural model.

31. The simulation device according to claim 17 , wherein the uneven surface model is a rigid body.

32. When the stiffness of the uneven surface model is Gs and the stiffness of the structure model in a contact region where the uneven surface model and the structure model are in contact is Gc, The simulation device according to claim 18, wherein 10Gc≦Gs.

33. 19. The simulation device according to claim 18, wherein the structural model is provided with information on physical properties of an elastomer.

34. the object having an irregular surface is a road surface, and the irregular surface model is a road surface model representing the road surface; The simulation device according to claim 18, wherein the structural model is a tire model representing a tire.

35. A program for causing a computer to execute the steps of the simulation method according to any one of claims 1 to 17 as a procedure.

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