Simulation method and device

Abstract

To accurately compare rolling resistance between tires with patterns having different pitch lengths.SOLUTION: A method includes: a tire model generation step S1 for generating a plurality of tire models obtained by modeling tires having different numbers of pitches with a finite number of numerically analyzable elements; and a rotating tire model generation step S2 for generating a rotating tire model obtained by rotating the tire model in a circumferential direction on the basis of a relationship of respective number of pitches for one circumference between the tire models. The method also includes a ground contact analysis step S3 for performing ground contact analysis on the plurality of tire models and the rotating tire model to acquire strain data on elements constituting each of the models. In addition, the method includes: a strain history calculation step S4 for calculating strain history of each of the plurality of tire models by integrating the strain data of the tire model for which the rotating tire model is generated and the strain data of the rotating tire model; and an energy loss calculation step S5 for calculating energy loss of the plurality of tire models on the basis of the strain history.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a simulation method and apparatus, and particularly to a prediction simulation of tire performance.

Background Art

[0002] In recent years, in order to improve the development and design efficiency of pneumatic tires, prediction of tire performance such as rolling resistance has been performed by numerical analysis using a computer. For example, Patent Document 1 discloses a tire performance prediction method, an apparatus and a program therefor that can predict tire performance in a short prediction time for a tire having a repeating pattern in the tire circumferential direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the comparison of tire performance, there is a problem that it is impossible to accurately compare the rolling resistance between patterned tire models having different pitch numbers. Note that the tire performance prediction method, the apparatus and the program disclosed in the prior document 1 cannot solve such a problem either.

Means for Solving the Problems

[0005] The simulation method according to the present disclosure is a simulation method for predicting energy loss with the number of points of strain data in the tire circumferential direction matched in at least two tires, including a tire model creation step of creating a plurality of tire models in which tires formed of a tire body and a pattern having a plurality of pitches with a repeating pattern in the circumferential direction and having different numbers of pitches are modeled with a finite number of elements capable of numerical analysis. A rotating tire model creation step of creating a rotating tire model obtained by rotating the tire model in the circumferential direction based on the relationship of the number of pitches per one rotation of the plurality of tire models, and grounding the plurality of tire models and the rotating tire model to a road surface model without rolling them, applying a load in a stationary state, and performing a grounding analysis to obtain strain data for each element constituting each of the plurality of tire models and the rotating tire model. Further, it includes a strain history calculation step of integrating the strain data of the tire model for which the rotating tire model was created and the strain data of the rotating tire model, and calculating the strain history of each of the plurality of tire models in which the number of points of strain data between the plurality of tire models matches, and an energy loss calculation step of calculating the energy loss of the plurality of tire models based on the strain history, and is characterized by including these steps.

Effect of the Invention

[0006] According to the simulation method and apparatus according to the present disclosure, it becomes possible to accurately compare the rolling resistance between patterned tires having different pitch lengths.

Brief Description of the Drawings

[0007]

Figure 1

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Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, with reference to the drawings, an example of an embodiment of a simulation method and apparatus according to the present disclosure will be described in detail. The embodiments described below are merely examples, and the present disclosure is not limited to the following embodiments. Also, forms formed by selectively combining a plurality of the following embodiments and modification examples are included in the present disclosure.

[0009] Using FIG. 1, a tire performance prediction simulation method according to this embodiment will be described in detail. FIG. 1 is a flowchart showing the tire performance prediction simulation method according to this embodiment. According to the flowchart of FIG. 1, each step of the simulation method will be described in detail. Also, in the description of each step, FIGS. 2 to 6 may be referred to for description.

[0010] The simulation method according to this embodiment is a simulation method for predicting energy loss with the number of points of strain data in the tire circumferential direction matched in at least two tires. In this embodiment, the case of two tires will be described, but the simulation method according to the present disclosure can also be applied when there are three or more tires.

[0011] Here, the number of strain data points is the same as the number of pitches of the tire. Although details will be described later, in the simulation method according to the present embodiment, a grounding analysis is performed on a statically grounded tire model. In such an analysis method, for a certain element, strain data of elements at the same position at each pitch is acquired. That is, the number of strain data points for one circumference in the tire circumferential direction of a certain element is the same as the number of pitches of the tire.

[0012] Step S1 creates a plurality of tire models in which tires having a plurality of pitches of repeating patterns in the circumferential direction, formed by a tire body and a pattern, and having different numbers of pitches are modeled with a finite number of elements capable of numerical analysis. The tire to be analyzed has, for example, a plurality of main grooves extending in the tire circumferential direction on the tread surface, and slits (lateral grooves) or sipes extending in a direction intersecting the main grooves, whereby a predetermined pattern is formed in the tire circumferential direction. The tire has a repeating pattern of several tens of pitches (for example, 22 pitches to 90 pitches) over the entire circumference in its circumferential direction.

[0013] Also, in step S1, information necessary for creating a tire model that can be analyzed for the tire to be analyzed is input. Specifically, various dimensional specifications such as the outer shape and internal structure of the tire, material properties such as Young's modulus, Poisson's ratio, and specific gravity for each member such as the tread, belt, and carcass constituting the tire, and furthermore, various conditions such as internal pressure and load as evaluation conditions are input. The input of this information may be performed through a keyboard, a recording medium such as a CD-ROM, or a network.

[0014] Based on the material properties and evaluation conditions input above, in step S1, a tire model (tire finite element model) is created in which a tire having the above tread pattern is modeled with a finite number of elements capable of numerical analysis. Being capable of numerical analysis means, for example, being able to be calculated by a numerical analysis method such as the finite element method (FEM).

[0015] Specifically, taking the tire shape in the natural equilibrium state as the reference shape, this reference shape is modeled by FEM to create a tire model divided into a large number of finite elements by mesh division. Such elements include tetrahedral solid elements, pentahedral solid elements, hexahedral solid elements, etc., and these elements are individually specified using three-dimensional coordinates (for example, X - Y - Z coordinates with the tire traveling direction as the X-axis, the tire width direction as the Y-axis, and the up-down direction as the Z-axis). Note that the method of creating such a tire model itself is known, and it can be modeled using such a known method.

[0016] Step S2 creates a rotating tire model to complement the difference in the number of strain data points between multiple tire models. The rotating tire model is created based on the relationship of the number of pitches between multiple tire models. Specifically, it is determined based on the least common multiple of the number of pitches of each of the multiple tire models and each number of pitches.

[0017] The rotating tire model may be created based on the number n (hereinafter may be referred to as the number n) obtained by dividing the least common multiple of the number of pitches of each of the multiple tire models by each number of pitches. Specifically, for the tire models where the number n is 2 or more, a rotating tire model is created by rotating the tire model by a circumferential angle corresponding to 1 / n pitch until the rotation angle reaches a circumferential angle corresponding to (n - 1) / n pitch. Also, the rotating tire model may be created only for tire models where the number n is 2 or more. That is, the rotating tire model may not be created for a tire model having the same number of pitches as the least common multiple of the number of pitches of each tire model.

[0018] Specifically, for example, the number n obtained by dividing the least common multiple 69 of the 23-pitch tire model and the 69-pitch tire model by each pitch number is 69÷23 = 3 in the case of the 23-pitch tire model. On the other hand, in the case of the 69-pitch tire model, 69÷69 = 1. Based on these, two rotated tire models are created: a tire model obtained by rotating the 23-pitch tire model by 1 / 3 pitch in the circumferential direction and a rotated tire model obtained by rotating it by 2 / 3 pitch in the circumferential direction. Also, in this case, no rotated tire model is created for the 69-pitch tire model. In the following, the 23-pitch tire model and the 69-pitch tire model may be used as examples for explanation.

[0019] Also, the rotated tire model may be created based on the number x (hereinafter sometimes referred to as the number x) obtained by dividing each pitch number by the least common multiple of the pitch numbers for one circumference of a plurality of tire models. Specifically, a rotated tire model is created by rotating a tire model with a number x less than 1 by a circumferential angle corresponding to x pitch until the rotation angle becomes a circumferential angle corresponding to (1 - x) pitch.

[0020] Specifically, for example, the number x obtained by dividing each pitch number by the least common multiple 69 of the 23-pitch tire model and the 69-pitch tire model is 23÷69 = 1 / 3 in the case of the 23-pitch tire model. On the other hand, in the case of the 69-pitch tire model, 69÷69 = 1. Based on these, two rotated tire models are created: a tire model obtained by rotating the 23-pitch tire model by 1 / 3 pitch in the circumferential direction and a rotated tire model obtained by rotating it by 2 / 3 pitch in the circumferential direction. Also, in this case, no rotated tire model is created for the 69-pitch tire model.

[0021] Also, as will be described in detail later, the grounding analysis for the tire model and the rotated tire model is performed in a state where they are in contact with the road surface model 20. As a result, the created rotated tire model becomes a tire model in which the contact point with the road surface model is shifted by the amount of rotation compared to the original tire model.

[0022] FIG. 2 is a schematic plan view near the ground contact point of the tire model in contact with the road surface model 20. The horizontal direction in FIG. 2 indicates the tire circumferential direction. FIG. 2(A) shows the pattern of the tire model with 69 pitches. Further, FIG. 2(B) shows the pattern of the tire model with 23 pitches, and FIG. 2(C) shows the pattern of the rotating tire model obtained by rotating the 23-pitch tire model by the circumferential angle corresponding to 1 / 3 pitch. Also, FIG. 2(D) shows the pattern of the rotating tire model obtained by rotating the 23-pitch tire model by the circumferential angle corresponding to 2 / 3 pitch.

[0023] As shown in FIGS. 2(A) to 2(D), since the contact point with the road surface model of the rotating tire model is shifted by the amount of rotation in the circumferential direction, the acquisition angle of the strain data of a certain element is also shifted by the amount of rotation. The element shown in black in FIG. 2(A) indicates the corresponding element at the same position in each pitch of a certain element of the 69-pitch tire model. Similarly, the elements shown by the hatching in FIGS. 2(B) to 2(D) indicate the elements corresponding to the same position in each pitch of a certain element of the 23-pitch tire model. In FIG. 2(B), a certain element in the first pitch of the 23-pitch tire model corresponds to a certain element in the first pitch of the 69-pitch tire model in FIG. 2(A). Similarly, the elements shown by the hatching in FIGS. 2(B) to 2(D) correspond to the elements shown in black in FIG. 2(A). Thereby, it is possible to make the number of points of the strain data and the acquisition angle of the strain data of the 23-pitch tire model the same as those of the 69-pitch tire model.

[0024] Step S3 performs a grounding analysis on the plurality of tire models and rotating tire models created in the above process. In the present embodiment, the grounding analysis is executed by the finite element method. The grounding analysis of the plurality of tire models and rotating tire models may be processed in parallel using one or a plurality of simulation devices 30.

[0025] Using FIGS. 3 and 4, the grounding analysis will be described in detail. FIG. 3 is a side schematic view when performing the grounding analysis of the tire model according to this embodiment. The grounding analysis is performed by grounding the tire model to the road surface model 20 in a stationary state without rolling the tire model, and applying a vertical load based on the above evaluation conditions as shown in FIG. 3. As shown in FIG. 3, the road surface model 20 may be modeled by plane elements having a flat rigid surface, or may also have unevenness on the surface.

[0026] By performing the grounding analysis, strain data for each element constituting the tire model and the rotating tire model is obtained. Specifically, the pattern of the tire has dozens of pitches repeatedly provided on the tire circumference, and each pitch has corresponding elements existing at the same position in each pattern. In one stationary grounding analysis, the strain is calculated for the elements at the same position in each pitch, and these are associated and stored. Such processing is performed for all elements constituting the tire model and the rotating tire model respectively.

[0027] FIG. 4 is a plane schematic view showing a part of the above pattern developed. The horizontal direction in the figure indicates the tire circumferential direction. For an element a1 in the first pitch, since a2 is at the same position in the second pitch and a3 is at the same position in the third pitch and they correspond to each other, for each pitch around the entire tire, the strain of these corresponding elements is obtained. That is, for all pitches of the tire, the strain of the corresponding elements is calculated. For another element b1 in the first pitch, element b2 in the second pitch, and element b3 in the third pitch, since they also correspond to each other in the same way, for the pitches around the entire tire, the strain of these corresponding elements is obtained. In this way, for all elements within the pattern for one pitch, the strain of the corresponding elements at the same position in each pitch is obtained and stored. In order to perform such a method of obtaining strain data, the number of points of the strain data of the tire model is the same as the number of pitches.

[0028] Specifically, for example, the strain received by element a2 can be regarded as substantially equal to the strain received when the tire model 10 rotates by a circumferential angle corresponding to one pitch and element a1 moves to the position of element a2. Similarly, the strain received by element a3 can be regarded as substantially equal to the strain received when the tire model 10 rotates by a circumferential angle corresponding to two pitches and element a1 moves to the position of element a3. Therefore, from the results of the static ground contact analysis of the tire model 10, it is possible to approximately calculate the strain history of each element when the tire model 10 makes one rotation by referring to the strains of other elements that are continuous in the tire circumferential direction.

[0029] Note that since the strain acting on each element is calculated as the total of six components of strain, namely the vertical strain and the shear strain in each of the tire meridian direction, the tire circumferential direction, and the tire thickness direction, these six components of strain are respectively obtained and stored.

[0030] In step S4, from the strain data at each rotation angle, the strain history corresponding to one rotation (one circumference) of the tire is obtained for each element constituting the tire model 10 and the rotating tire model. FIG. 5 shows the strain history of the vertical strain in the tire circumferential direction, which is one of the six components, for a certain element of two tire models with different pitch numbers. In the graph of FIG. 5, the vertical axis represents strain and the horizontal axis represents the tire circumferential direction angle. Also, 0° and 360° are the contact points in contact with the road surface model 20. The reason why the strain is large near 0° and 360° is that it receives the vertical load and the reaction force from the road surface model 20. Also, the reason why the number of strain data points differs depending on the pitch number is to calculate the strain of the elements at the same position in each pitch of a certain element in one ground contact analysis.

[0031] Also, in step S4, the strain histories of the tire model 10 and the rotating tire model are integrated. Specifically, the strain data of the tire model 10 that was the basis for creating the rotating tire model and the strain data of the rotating tire model are integrated. Specifically, the strain data of the tire model 10 and the rotating tire model are plotted on the same graph. This makes it possible to match the number of points of the strain data in the tire circumferential direction and the tire circumferential angle at which the strain data is acquired among multiple tire models.

[0032] For example, FIG. 6 is a diagram showing the strain history in which the strain data of a certain element of a 23-pitch tire model and a rotating tire model are integrated and the strain history of a certain element of a 69-pitch tire model. The white circles shown in FIG. 6 indicate the strain history of the 69-pitch tire model. On the other hand, the cross marks indicate the strain history of the 23-pitch tire model. Also, the plus marks are the strain history when a grounding analysis is performed on the rotating tire model obtained by rotating the 23-pitch model by a circumferential angle corresponding to 1 / 3 pitch, and the triangular marks are the strain history of the rotating tire model rotated by a circumferential angle corresponding to 2 / 3 pitch.

[0033] As shown in FIG. 6, by integrating the strain history of the rotating tire model, the strain history of the 23-pitch tire model has the same number of strain data points as the strain history of the 69-pitch tire model. Also, the tire circumferential angle at which the strain data is acquired is obtained at the same tire circumferential angle as that of the 69-pitch tire model. As described above, even for tire models with different numbers of pitches, by creating a rotating tire model, it is possible to compensate for the difference in the number of strain data points due to the difference in the number of pitches. This enables an accurate comparison of the rolling resistance of multiple tire models.

[0034] In step S5, based on the strain histories of the multiple tire models obtained above, the energy loss for one rotation (one circumference) of the tire model is calculated for the elements constituting the multiple tire models. The calculation of the energy loss can be performed by a known method. For example, for a certain element, the energy loss W during one rotation of the tire for one of the above six components is calculated by the following formula (1). Dcan be calculated.

[0035]

Number

[0036] Thus, for all six components, the energy loss W during one tire rotation is similarly D calculated and summed up. By doing so, the energy loss of the tire for a certain element can be obtained. Then, by calculating and summing this for all elements of the tire, the energy loss W during one rotation of the entire tire can be calculated. Also, since the energy loss W is correlated with the rolling resistance, it is possible to compare the approximate rolling resistance RR by comparing the energy loss W.

[0037] Using the energy loss calculated as described above, it is possible to calculate the rolling resistance RR of the tire. To calculate the rolling resistance RR of the tire, for example, as shown in the following formula (2), the energy loss W during one rotation of the entire tire can be calculated by dividing it by the rolling distance.

[0038]

Number

[0039] Using FIG. 7, a simulation device 30 for implementing the simulation method according to this embodiment will be described in detail.

[0040] FIG. 7 is a block diagram showing a simulation apparatus 30 according to the present embodiment. The simulation apparatus 30 is configured by a computer including a control device 40 including a processor 41 and a memory 42, and executes an analysis of energy loss during one rotation of a tire. The simulation apparatus 30 may be configured by one computer or may be configured by a plurality of computers. Also, a part of the functions of the simulation apparatus 30 may exist in a server or the like connected via a communication network.

[0041] The simulation apparatus 30 includes an input unit 43 and an output unit 44. The input unit 43 is an input interface for inputting information necessary for executing the simulation, and examples thereof include a keyboard and a mouse. Information input by the input unit 43 includes, for example, analysis conditions, creation conditions of the tire model 10, and the like. The output unit 44 is a liquid crystal, an organic EL display, or the like on which an input screen, a simulation result, an output screen such as a calculation result, and the like are displayed.

[0042] The simulation apparatus 30 includes a tire model creation unit 45, a rotating tire model creation unit 46, a grounding analysis unit 47, a strain history calculation unit 48, and an energy loss calculation unit 49 as means for performing the above simulation. Also, the simulation apparatus 30 may include a rolling resistance calculation unit 50 that calculates rolling resistance based on the energy loss. Also, the tire model creation unit 45 and the rotating tire model creation unit 46 may be integrated.

[0043] The simulation device 30 is configured to calculate energy loss using the finite element method (FEM). The processor 41 reads and executes a simulation program to realize the functions of the tire model creation unit 45, the rotating tire model creation unit 46, the grounding analysis unit 47, the strain history calculation unit 48, the energy loss calculation unit 49, and the rolling resistance calculation unit 50. The memory 42 is composed of, for example, RAM, ROM, a hard disk, etc., and stores a simulation program, various setting information necessary for the execution of the simulation including the above-described analysis conditions, and simulation results, etc.

[0044] As described above, according to the simulation method and device having the above configuration, when calculating the energy loss W to the rolling resistance RR of a plurality of tires by grounding analysis, based on the relationship of the number of pitches of the plurality of tire models, a rotating tire model is created, and by complementing the difference in the number of acquired strain data points due to the difference in the number of pitches of the tire models, an accurate comparison of the rolling resistance RR between tire models with different numbers of pitches becomes possible.

[0045] In the above embodiment, the strain history is obtained for all elements of the tire model to calculate the energy loss W. However, for example, when evaluating the rolling resistance RR by changing only the tread pattern for the tire that is the basis of development, the energy loss W may be calculated only for the elements of the tread portion, and the improvement width of the rolling resistance RR with respect to the base tire may be evaluated.

Explanation of Signs

[0046] 10 Tire model, 20 Road surface model, 30 Simulation device, 40 Control device, 41 Processor, 42 Memory, 43 Input unit, 44 Output unit, 45 Tire model creation unit, 46 Rotating tire model creation unit, 47 Grounding analysis unit, 48 Strain history calculation unit, 49 Energy loss calculation unit, 50 Rolling resistance calculation unit

Claims

1. A simulation method for predicting energy loss with the number of points of strain data in the tire circumferential direction made to match in at least two tires, a tire model creation step of creating a plurality of tire models in which a tire body and the tires formed by the pattern having a plurality of pitches in the circumferential direction and having different numbers of pitches are modeled with a finite number of elements capable of numerical analysis; a rotating tire model creation step of creating a rotating tire model obtained by rotating the tire model in the circumferential direction based on the relationship of the number of pitches per one circumference of the plurality of tire models; a grounding analysis step of grounding the plurality of tire models and the rotating tire model to a road surface model without rolling, applying a load in a stationary state, and performing a grounding analysis to obtain the strain data for the elements constituting each of the plurality of tire models and the rotating tire model; a strain history calculation step of integrating the strain data of the tire model for which the rotating tire model was created and the strain data of the rotating tire model, and calculating the strain history of each of the plurality of tire models in which the number of points of the strain data between the plurality of tire models matches; an energy loss calculation step of calculating the energy loss of the plurality of tire models based on the strain history, the simulation method comprising the steps.

2. The rotating tire model creation step creates the rotating tire model by rotating the tire model with the number n being 2 or more by a circumferential angle corresponding to 1 / n pitch until the rotation angle becomes a circumferential angle corresponding to (n−1) / n pitch, based on the number n obtained by dividing the least common multiple of the number of pitches per one circumference of the plurality of tire models by each of the number of pitches. The simulation method according to claim 1.

3. The rotation tire model creation step creates the rotation tire model obtained by rotating the tire model with the number x less than 1 by the circumferential direction angle corresponding to x pitches until the rotation angle becomes the circumferential direction angle corresponding to (1 - x) pitches, based on the number x obtained by dividing each pitch number by the least common multiple of the pitch numbers for one round of the plurality of tire models. The simulation method according to claim 1.

4. The simulation method according to claim 1, wherein the grounding analysis of the plurality of tire models and the rotation tire model is performed by parallel processing.

5. In the grounding analysis step, the strain data is acquired only for the elements constituting the pattern of the plurality of tire models and the rotation tire model. The simulation method according to claim 1.

6. The simulation method according to any one of claims 1 to 5, including a rolling resistance calculation step of calculating the rolling resistance of the plurality of tire models based on the energy loss.

7. A simulation device for predicting energy loss with the number of points of strain data in the tire circumferential direction made to match in at least two tires, A tire model creation unit that creates a plurality of tire models that are numerically analyzable with a finite number of elements, formed by a tire body and the pattern, having a plurality of pitches of a repeating pattern in the circumferential direction and having different pitch numbers respectively; A rotation tire model creation unit that creates a rotation tire model obtained by rotating the tire model in the circumferential direction based on the relationship of each pitch number for one round of the plurality of tire models; A grounding analysis unit that grounds the plurality of tire models and the rotation tire model to a road surface model without rolling them, applies a load in a stationary state, and performs a grounding analysis to acquire the strain data for the elements constituting each of the plurality of tire models and the rotation tire model; A strain history calculation unit that integrates the strain data of the tire model for which the rotating tire model was created and the strain data of the rotating tire model, and calculates the strain history of each of the plurality of tire models in which the number of points of the strain data among the plurality of tire models matches; An energy loss calculation unit that calculates the energy loss of the plurality of tire models based on the strain history, and a simulation device including the same.

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