JP5772161B2 - Tire simulation method and structure simulation method - Google Patents

Description

  The present invention relates to simulating the performance of a tire or structure using computer analysis.

  A method of creating a tire model that can be analyzed by a computer and simulating the performance of the tire has been proposed and put into practical use. For example, in Patent Document 1, a tire model obtained by dividing a tire into a finite number of elements is rolled on a virtual road surface to acquire the friction characteristics of the tire model, and the tire is based on the acquired friction characteristics. A simulation method is described in which the tread surface of the model is recessed to correct the wear state.

JP 2006-160159 A

Oden, J.T. and Lin, T.L., and Bass, J.M., “A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder” Tire Science and Technology, Vol.16, No.1, 1988, pp. 18-43

  The simulation method described in Patent Document 1 performs analysis in a state where the tire and the road surface are in contact with each other, and simulates the performance of the tire. In such a simulation, when the tire begins to slide on the road surface, the shear stress exceeds the maximum static friction between the tire and the road surface. For this reason, the shearing stress (dynamic frictional force) at the start of sliding changes suddenly and becomes unstable, and as a result, the calculation may fail in the analysis of the state in which two objects are in contact.

  For this reason, when the analysis by the simulation which considers the friction at the time of contact is performed, the convergence is improved by giving an inclination to the change of the shear stress in the sliding. A region giving this inclination is called elastic slip (for example, see Non-Patent Document 1). However, when the elastic slip region is increased, the convergence of the solution is improved, but the analysis accuracy of the tangential force such as the shear stress is lowered, which is a so-called trade-off relationship.

  The present invention has been made in view of the above, and an object of the present invention is to reduce calculation time while suppressing a decrease in analysis accuracy in a simulation of a tire or a structure with contact.

  Means for solving the above-described problems include a model creation procedure for creating a tire model that can be analyzed by a computer from a tire to be analyzed when simulating tire performance using a computer, An analysis procedure for performing contact analysis at least twice, wherein in the analysis procedure, the amount of elastic slip in at least one contact analysis is different from the amount of elastic slip in other contact analyses. Is the method.

  In the analysis procedure, when analyzing the characteristic value in the direction perpendicular to the contact surface of the tire model in the analysis procedure, the characteristic value in the direction parallel to the contact surface of the tire model is analyzed. It is preferable to increase the value of the elastic slip amount.

  In the present invention, the amount of elastic slip when analyzing the characteristic value in the direction perpendicular to the contact surface of the tire model is analyzed for γel2 and the characteristic value in the direction parallel to the contact surface of the tire model. If the elastic slip amount γel1 is, the ratio γel2 / γel1 is preferably 5 or more.

  The means for solving the above-described problem is that, in simulating the performance of a structure using a computer, a model creation procedure for creating a structure model that can be analyzed by a computer from a structure to be analyzed; An analysis procedure for performing contact analysis of the structure model at least twice, wherein in the analysis procedure, the amount of elastic slip in at least one contact analysis is different from the amount of elastic slip in other contact analysis, This is a method of simulating a structure.

  In the analysis procedure, when analyzing the characteristic value in the direction perpendicular to the contact surface of the structure model, the characteristic value in the direction parallel to the contact surface of the structure model is analyzed. It is preferable to make the amount of elastic slip larger than the case.

  In the present invention, the amount of elastic slip when analyzing the characteristic value in the direction perpendicular to the contact surface of the structure model is analyzed for γel2, and the characteristic value in the direction parallel to the contact surface of the structure model is analyzed. When the elastic slip amount γel1 is set, the ratio γel2 / γel1 is preferably 5 or more.

  The present invention can shorten the calculation time while suppressing a decrease in analysis accuracy in a simulation of a tire or a structure with contact.

FIG. 1 is a perspective view showing a state in which a tire model is in contact with a road surface model in a tire simulation. FIG. 2 is a diagram illustrating the relationship between the shear stress and the slip amount. FIG. 3 is a diagram showing the relationship between the shear stress and the slip amount. FIG. 4 is a diagram showing the relationship between the amount of elastic slip and the longitudinal spring constant. FIG. 5 is a diagram showing the relationship between the amount of elastic slip and the calculation time. FIG. 6 is an explanatory diagram illustrating an example of the analysis apparatus according to the present embodiment. FIG. 7 is a flowchart of the tire or structure simulation method according to the present embodiment. FIG. 8 is a diagram showing the elastic slip amount in the relationship between the shear stress and the slip amount. FIG. 9 is a diagram showing the elastic slip amount in the relationship between the shear stress and the slip amount.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

  FIG. 1 is a perspective view showing a state in which a tire model is in contact with a road surface model in a tire simulation. 2 and 3 are diagrams illustrating the relationship between the shear stress and the slip amount. In a simulation of a tire (including a pneumatic tire), the tire model 10 may be brought into contact with the road surface model 20 to perform rolling analysis, cornering analysis, or the like. Such an analysis is called contact analysis. As described above, in the tire simulation, when the tire model 10 and the road surface model 20 are brought into contact with each other, it is necessary to consider the friction between the tire model 10 and the road surface model 20. For this reason, a friction analysis is given between the tire model 10 and the road surface model 20, and rolling analysis etc. are performed.

  Coulomb's friction law is generally used as the friction law in rolling analysis and the like. The Coulomb friction slips between two objects in contact when shear stress> maximum static friction force. For this reason, as shown in FIG. 2, the shear stress (dynamic frictional force) τ at the start of sliding (when the slip amount γ exceeds 0) changes rapidly. That is, when the shear stress τ increases between two objects to τmax (maximum shear stress), the slip amount γ starts to increase rapidly while the shear stress remains τmax. Due to this, in the analysis of the state in which two objects are in contact, the calculation does not converge. Therefore, as shown in FIG. 3, when both the shear stress τ and the slip amount γ are in the vicinity of the zero point, a rolling analysis is performed by giving an inclination to the change (Δτmax / Δγel) of the shear stress τ with respect to the change of the slip amount γ. This makes it easy to converge the calculations in the above. This region is called an elastic slip, and the slip amount γel at the maximum shear stress τmax is called an elastic slip amount. When the slip amount γ becomes the elastic slip amount γel, a slip occurs between the two objects.

  In the analysis involving the contact between the tire model 10 and the road surface model 20, the elastic slip amount γel is used. The elastic slip γel affects analysis accuracy (solution accuracy) and calculation time. When the elastic slip γel is increased, the solution is likely to converge and the calculation time is shortened, but the analysis accuracy is lowered. If the elastic slip γel is reduced, the analysis accuracy is improved, but the solution is less likely to converge and the calculation time is lengthened.

  FIG. 4 is a diagram showing the relationship between the amount of elastic slip and the longitudinal spring constant. FIG. 5 is a diagram showing the relationship between the amount of elastic slip and the calculation time. The horizontal axis of FIGS. 4 and 5 is the elastic slip amount γel (expressed as an index with a value that can obtain sufficient accuracy as 1). The vertical axis of FIG. 4 is the spring constant (exponential display), the vertical axis of FIG. 5 is the calculation time (exponential display), and the vertical axes of FIG. 4 and FIG. It is displayed with the index. Taking the calculation of spring characteristics as an example, as shown in FIG. 4, as the amount of elastic slip γel increases, the transverse spring constant KL and the longitudinal spring constant KS become smaller, but the longitudinal spring constant KV hardly changes. Further, as shown in FIG. 5, the calculation time is shortened as the elastic slip amount γel increases.

  As described above, when the displacement and force in the direction perpendicular to the road surface such as the longitudinal spring constant KV are obtained, the elastic slip amount γel hardly affects the analysis accuracy. On the other hand, the amount of elastic slip γel greatly affects the analysis accuracy with respect to displacement and force in the tangential direction (direction parallel to the road surface) such as the lateral spring constant KL and the longitudinal spring constant KS.

  Therefore, the tire or structure simulation method according to the present embodiment, in a series of analyzes including a plurality of contact analyses, differs in the value of elastic slip in at least one contact analysis from the value of elastic slip in other contact analyses. Make it. Specifically, the elastic slip amount γel is increased for the characteristic value that the elastic slip amount γel has little influence on the analysis accuracy, such as the longitudinal spring constant KV, and the lateral spring constant KL and the front and rear spring constant KS, The elastic slip amount γel is reduced for a characteristic value that greatly affects the analysis accuracy of the elastic slip amount γel. By doing in this way, the simulation method of the tire or structure concerning this embodiment reduces calculation time, suppressing the fall of analysis accuracy. Next, an example of an analysis apparatus that realizes the tire or structure simulation method according to the present embodiment will be described.

  FIG. 6 is an explanatory diagram illustrating an example of the analysis apparatus according to the present embodiment. The analysis device 50 realizes the tire or structure simulation method according to the present embodiment. The analysis device 50 includes a processing unit 50p, a storage unit 50m, and an input / output unit 50io. In addition, an input / output device 60 is connected to the analysis device 50, and an input device 61 and a display device 62 are connected thereto. The input / output device 60 inputs information necessary for realizing the tire or structure simulation method according to the present embodiment to the processing unit 50p or the storage unit 50m via the input / output unit 50io.

  The analysis device 50 is, for example, a computer. The processing unit 50p includes an analysis model creation unit 51, an analysis unit 52, and an elastic slip amount setting unit 53. These execute the tire or structure simulation method according to the present embodiment. The analysis model creation unit 51 is a model (analysis model) that can be analyzed by a computer from a tire or belt or other structure to be analyzed and a contact object of the structure (a road surface when the structure is a tire). Create The analysis unit 52 performs analysis such as contact analysis and rolling analysis using the analysis model created by the analysis model creation unit 51. The elastic slip amount setting unit 53 sets or changes the elastic slip amount γel used in the contact analysis.

  The storage unit 50m stores a computer program including processing procedures of a tire or structure simulation method according to the present embodiment, which will be described later, and various data. The storage unit 50m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory, a hard disk device, or a combination thereof. Further, the processing unit 50p can be configured by combining, for example, a CPU (Central Processing Unit) and a memory.

  The computer program realizes the processing procedure of the tire or structure simulation method according to the present embodiment in combination with the computer program already recorded in the analysis model creation unit 51 or the analysis unit 52 provided in the processing unit 50p. It may be possible. Further, the analysis device 50 uses the dedicated hardware instead of the computer program to realize the functions of the analysis model creation unit 51, the analysis unit 52, and the elastic slip amount setting unit 53 provided in the processing unit 50p. You may do. Next, a tire or structure simulation method according to this embodiment will be described. The analysis apparatus 50 mentioned above implement | achieves the simulation method of the tire or structure which concerns on this embodiment.

  FIG. 7 is a flowchart of the tire or structure simulation method according to the present embodiment. The tire or structure simulation method according to the present embodiment has an analysis procedure for performing contact analysis at least twice. First, in step S101, the analysis model creation unit 51 of the analysis device 50 creates an analysis model of a structure to be analyzed and an analysis model of a contact target that comes into contact with the structure in the course of analysis. Step S101 corresponds to a model creation procedure.

  In this embodiment, the structure to be analyzed is a tire (pneumatic tire), and the contact target is a road surface. For this reason, in step S101, the tire model 10 and the road surface model 20 shown in FIG. 1 are created. The tire model 10 and the road surface model 20 are models used for performing rolling analysis, deformation analysis, and the like using numerical analysis methods such as a finite element method and a finite difference method, and are models that can be analyzed by a computer. Includes dynamic models and mathematical discretization models. Note that the tire or structure simulation method according to the present embodiment can be applied to structures other than tires and objects to be contacted other than road surfaces. In this case, in step S101, the analysis model creation unit 51 creates the structure model and the contact target model as an analysis model.

  In the present embodiment, a finite element method (FEM) is used as an analysis method used in the analysis described later. The analysis method applicable to the tire or structure simulation method according to the present embodiment is not limited to the finite element method, but also includes a boundary element method (BEM), a finite difference method (FDM), and the like. Can be used. Further, the most appropriate analysis method can be selected according to the boundary condition or the like, or a plurality of analysis methods can be used in combination. Since the finite element method is an analysis method suitable for structural analysis, it can be suitably applied particularly to a structure such as a tire.

  In step S101, the analysis model creation unit 51 creates the tire model 10 by dividing the tire into a finite number of elements composed of a plurality of nodes, for example. The road surface model 20 may be created in the same manner as the tire model 10, or may be an analytical model as an elastic body, and may further be an analytical model as a rigid body. Further, the road surface model 20 may be a three-dimensional discretization model or an analysis model as a surface.

  The elements constituting the tire model 10 or the road surface model 20 are, for example, a quadrilateral element in a two-dimensional plane, a solid element such as a tetrahedral solid element, a pentahedral solid element, a hexahedral solid element in a three-dimensional body, a triangular shell element, and a rectangular shell. It is desirable to use an element that can be used by a computer, such as a shell element such as an element or a surface element. In the process of analysis, the elements divided in this way are identified one by one using three-dimensional coordinates in the three-dimensional model and using two-dimensional coordinates in the two-dimensional model.

  When the tire model 10 and the road surface model 20 are created, the process proceeds to step S102, and the load applied to the tire model 10 and the boundary conditions for analysis are set. The load and the boundary condition are input from the input / output device 60 to the analysis device 50. The analysis unit 52 of the analysis device 50 sets the input load and boundary conditions by temporarily storing them in the storage unit 50m as analysis conditions. That is, in the analysis, the analysis unit 52 sets the boundary condition to the tire model 10 and the road surface model 20 and applies the load to the tire model 10.

  Next, proceeding to step S103, the elastic slip amount setting unit 53 of the analysis apparatus 50 sets the elastic slip amount γel by temporarily storing it in the storage unit 50m. In the first analysis, the elastic slip amount setting unit 53 sets the elastic slip amount γel to a predetermined value, and the analysis unit 52 executes the first analysis using the elastic slip amount γel. The predetermined value is set to an appropriate value depending on the specification to be analyzed.

  8 and 9 are diagrams showing the elastic slip amount in the relationship between the shear stress and the slip amount. The elastic slip amount γel is defined in the relationship between the slip amount γ (or the slip speed W) and the shearing force τ. That is, as shown in FIG. 8, the slip amount γel at the maximum shear force τmax or the slip amount −γel at −τmax is the elastic slip amount. As shown in FIG. 9, when the relationship between the slip amount γ and the shear force τ at the start of the slip is smoothed by a non-linear curve CS, the line ES approximated by a straight line at the origin O and the maximum shear force τmax The slip amount (or slip speed) at the intersection is set as the elastic slip amount γel. By doing so, the elastic slip amount γel can be set without depending on the nonlinear curve shape.

  In step S104, the analysis unit 52 reads the set load, boundary condition, and elastic slip amount γel from the storage unit 50m. Then, the analysis unit 52 gives the read boundary condition and the elastic slip amount γel to the tire model 10, and gives the boundary condition to the road surface model 20. And the analysis part 52 loads the load read from the memory | storage part 50m to the tire model 10, and makes the tire model 10 contact the road surface model 20, and performs an analysis. This analysis is a contact analysis and may involve rolling or cornering (the same applies hereinafter). When the analysis is completed, the analysis unit 52 temporarily stores the analysis result in the storage unit 50m.

  When the first contact analysis, that is, the analysis of step S104 is executed, the process proceeds to the next contact analysis. For this reason, in step S105, the load applied to the tire model 10 in the next contact analysis and the boundary condition of the analysis are set. The load and the boundary condition are input from the input / output device 60 to the analysis device 50. The analysis unit 52 of the analysis device 50 sets the input load and boundary conditions by temporarily storing them in the storage unit 50m as analysis conditions. That is, in the next analysis, the analysis unit 52 sets the boundary condition to the tire model 10 and the road surface model 20 and applies the load to the tire model 10.

  In step S106, the elastic slip amount setting unit 53 of the analysis device 50 sets the elastic slip amount γel by temporarily storing it in the storage unit 50m. In this case, if necessary, the elastic slip amount setting unit 53 sets the elastic slip amount γel of the analysis to be executed next as the elastic slip amount γel used in the analysis executed before the analysis to be executed next. Set to a different value. For example, in the following analysis, when analyzing parameters that are easily affected by the elastic slip amount γel, such as the lateral spring constant KL and the front-rear spring constant KS, in order to secure the analysis accuracy, γel, for example, the solution converges. Set to the largest value possible in the range. Further, when analyzing a parameter such as the longitudinal spring coefficient KV that is hardly affected by the elastic slip amount γel, the elastic slip amount γel is set to a small value.

  That is, in step S106, when the characteristic value in the direction perpendicular to the contact surface of the tire model 10 is analyzed, the amount of elastic slip is larger than that in the case of analyzing the characteristic value in the direction parallel to the contact surface of the tire model 10. It is preferable to increase the value of γel. The characteristic value in the direction perpendicular to the contact surface of the tire model 10 is, for example, the calculation of the deflection with respect to the input value of the stress in the direction perpendicular to the contact surface, such as the longitudinal spring coefficient KV described above. Further, when performing analysis for obtaining characteristic values in a direction parallel to the contact surface of the tire model 10 such as the above-described lateral spring constant KL, front / rear spring constant KS, and other torsion spring characteristics, the perpendicular to the contact surface is also used. After applying a large load to the set value, the contact surface is displaced in each direction and measured. Therefore, it is possible to suppress an increase in calculation time while ensuring analysis accuracy.

  As an example of the analysis for increasing the elastic slip amount γel, the above-described analysis of the longitudinal spring constant KV, etc., for obtaining the force and displacement perpendicular to the contact surface of the analysis target (for example, the tire model 10), and the response thereof are obtained. There are things. Examples of analysis for reducing the amount of elastic slip γel include analysis of a lateral spring constant, cornering analysis, braking / driving analysis, and the like. Also in the analysis of the tire during rolling, by changing the elastic slip amount γel according to the type of analysis, it is possible to obtain an effect that an increase in calculation time can be suppressed while ensuring analysis accuracy.

  The amount of elastic slip γel2 when analyzing the characteristic value in the direction perpendicular to the contact surface of the tire model 10 and the amount of elastic slip γel1 when analyzing the characteristic value in the direction parallel to the contact surface of the tire model 10 The ratio γel2 / γel1 is preferably 5 or more, and more preferably 10 or more. By doing so, the calculation time can be shortened without reducing the analysis accuracy even during a series of calculations, which is suitable when analyzing a lot of data such as orthogonal experiments and optimization calculations. When the analysis including the contact of the tire model 10 is performed three or more times while changing at least one of the elastic slip and the boundary condition, the values of the elastic slip other than γel1 and γel2 are inversely proportional to the value of the contact shear force. Alternatively, the values used for γel1 and γel2 may be used.

  In step S107, the analysis unit 52 reads the set load, boundary condition, and elastic slip amount γel from the storage unit 50m. Then, the analysis unit 52 gives the read boundary condition and the elastic slip amount γel to the tire model 10, and gives the boundary condition to the road surface model 20. And the analysis part 52 loads the load read from the memory | storage part 50m to the tire model 10, and makes the tire model 10 contact the road surface model 20, and performs an analysis. When the analysis is completed, the analysis unit 52 temporarily stores the analysis result in the storage unit 50m. Steps S102 to S108 described above correspond to the analysis procedure.

  Next, it progresses to step S108, and when all the analyzes are not complete | finished, the analysis apparatus 50 repeats step S105 to step S108 until all the analyzes are complete | finished. When all the analyzes are completed, the tire or structure simulation method according to the present embodiment is completed.

  The simulation method for a tire or a structure according to the present embodiment according to the present embodiment includes a plurality of contact analyses, and makes an elastic slip amount γel in at least one contact analysis different from an elastic slip amount γel in another contact analysis. . By doing so, the elastic slip amount γel is increased when analyzing the parameter that the elastic slip amount γel decreases the analysis accuracy, and the elastic slip amount γel is analyzed when the parameter that does not decrease the analysis accuracy is analyzed. The slip amount γel can be reduced. As a result, an increase in calculation time can be suppressed while suppressing a decrease in analysis accuracy in the contact analysis.

(Evaluation example)
In the tire contact analysis, the change in the characteristic value and the calculation time when the elastic slip amount γel was changed was evaluated with respect to the analysis of the spring characteristics (longitudinal spring constant KV, lateral spring constant KL, longitudinal spring constant KS). In Example 1, the value of the elastic slip amount γel is obtained by performing contact analysis with the transverse spring constant KL and the front and rear spring constant KS being values that can obtain sufficient accuracy, and the longitudinal spring constant KV being 20 times that value. Example 1 corresponds to the tire or structure simulation method according to the present embodiment. In Comparative Example 1, contact analysis was performed with the elastic slip amount γel uniformly fixed to a value that provides sufficient accuracy. In Comparative Example 2, contact analysis was performed with the elastic slip amount γel fixed uniformly at 20 times that of Comparative Example 1. The tire size was 195 / 65R15, the air pressure was 230 kPa, and the ground load was 4.2 kN.

The analysis was performed according to the following procedure.
(1) The tire model was loaded with a predetermined vertical load on the road surface and brought into contact with the road surface to obtain the displacement in the tire cross-section height direction.
(2) Next, using the calculation result of (1), that is, a state in which a load is applied and grounded, a predetermined forced displacement is given to the road surface in the tire front-rear direction, and in the tire cross-sectional width direction. The displacement amount was acquired.
(3) Next, using the calculation result of (1) again, a predetermined forcible displacement is given to the road surface in the tire width direction, and a displacement amount in the tire cross-sectional width direction is acquired. These series of calculations were automatically analyzed by using a computer and (1) to (3) as one unit.

  Here, the vertical spring constant KV is (vertical load applied to the tire) / (vertical deflection amount). The amount of vertical deflection is the amount of deformation in the cross-sectional height direction of the tire. The lateral spring constant KL and the longitudinal spring constant KS are (lateral force (or longitudinal force)) / (displacement when a set vertical load is applied and then the road surface is displaced in the tire cross-sectional width direction (or longitudinal direction). Amount). The evaluation results are shown in Tables 1 and 2. The evaluation results are displayed as an index when the characteristic value of Comparative Example 1 is 100 and an index when the calculation time of Comparative Example 1 is 100.

  Table 1 shows the value of each spring constant, and Table 2 shows the calculation time. All are values normalized by setting Comparative Example 1 to 100. The analysis accuracy is higher when the value of the spring constant is closer to 100. The calculation time is shorter as the value is smaller. The calculation time is the time required for the analysis of the longitudinal spring constant KV, the lateral spring constant KL, and the longitudinal spring constant KS, which are a series of analyses, in the contact analysis. From these evaluation results, Example 1, that is, the simulation method of the tire or structure according to the present embodiment, is compared with the case where the amount of elastic slip γel is uniformly fixed to a value that provides sufficient accuracy (Comparative Example 1). Thus, the calculation time was reduced by about 20% while the analysis accuracy was the same.

DESCRIPTION OF SYMBOLS 10 Tire model 20 Road surface model 50 Analysis apparatus 50m Storage part 50io Input / output part 50p Processing part 51 Analysis model creation part 52 Analysis part 53 Slip amount setting part 60 Input / output apparatus

Claims (6)

Computer,
From the data of the tire to be analyzed, and the model creation procedure for creating a parsable tire model in the computer,
Running, and analysis procedure carried out at least twice contact analysis of the tire model,
In the analysis procedure, a tire simulation method is characterized in that an elastic slip amount in at least one contact analysis is different from an elastic slip amount in another contact analysis.   In the analysis procedure, when the characteristic value in the direction perpendicular to the contact surface of the tire model is analyzed, the elastic slip is more than in the case of analyzing the characteristic value in a direction parallel to the contact surface of the tire model. The tire simulation method according to claim 1, wherein the amount value is increased.   The amount of elastic slip when analyzing the characteristic value in the direction perpendicular to the contact surface of the tire model is γel2, and the amount of elastic slip when analyzing the characteristic value in the direction parallel to the contact surface of the tire model The tire simulation method according to claim 1 or 2, wherein the ratio γel2 / γel1 is 5 or more when γel1 is set. Computer,
A model creation procedure to create a computer-analysable structure model from the structure data to be analyzed,
Running, and analysis procedure carried out at least twice contact analysis of the structure model,
In the analysis procedure, the amount of elastic slip in at least one contact analysis is different from the amount of elastic slip in other contact analyses.   In the analysis procedure, when analyzing the characteristic value in the direction perpendicular to the contact surface of the structure model, the characteristic value in the direction parallel to the contact surface of the structure model is more than the case of analyzing the characteristic value in the direction parallel to the contact surface of the structure model. The structure simulation method according to claim 4, wherein the amount of elastic slip is increased.   The amount of elastic slip when analyzing the characteristic value in the direction perpendicular to the contact surface of the structure model is γel2, and the elasticity when analyzing the characteristic value in the direction parallel to the contact surface of the structure model 6. The structure simulation method according to claim 4, wherein the ratio γel2 / γel1 is 5 or more when the slip amount is γel1.

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