Tire simulation method, tire simulation device, and program

Abstract

To stabilize tire simulation analysis while reducing the effort required for simulation. [Solution] The tire simulation method includes a tire model creation step S1 in which a tire model before rim assembly is created in a two-dimensional coordinate system, and a rim coordinate setting step S2 in which the shape of the rim is set as rim coordinates in a two-dimensional coordinate system. It also includes a reference point setting step S4 in which, for each of the pair of bead portions of the tire model, one of the nodes constituting the bead side surface or bead bottom surface is set as the tire model reference point, and the coordinates corresponding to the tire model reference point in rim coordinates are set as the rim reference point, and a reference displacement amount acquisition step S5 in which the distance in the tire model width direction between the tire model reference point and the rim reference point is obtained as the reference displacement amount. Furthermore, it includes a deformation analysis step S6 in which nodes constituting the bead side surface and bead bottom surface are set as contact candidate points, a reference displacement amount is set for the contact candidate points, and the tire model is deformed based on the reference displacement amount.

Description

Technical Field

[0001] The present invention relates to a tire simulation method, a tire simulation apparatus, and a program, and particularly relates to tire simulation related to deformation of a tire model.

Background Art

[0002] Conventionally, in simulations for obtaining vibration characteristics and the like of a tire, the internal air of the tire is modeled and analyzed. The internal air model is formed of a mesh with a finite number of elements, and the mesh of the internal air model needs to follow the deformation of the tire model. However, if the internal air model is created before the deformation of the tire model, the mesh of the internal air model may break down because the mesh of the internal model cannot follow the deformation of the tire model when the tire model is deformed.

[0003] In Patent Document 1, a tire vibration performance evaluation method for suppressing mesh breakdown is disclosed, in which a rim is modeled, a contact analysis between the rim model and the tire model is performed to deform the tire model to be equivalent to rim assembly, and an internal air model is set for the deformed tire model.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, when modeling and analyzing the internal air of a tire, there is a problem in that the mesh of the internal air model cannot follow the deformation of the tire model, resulting in mesh failure of the internal air model. In the tire vibration performance evaluation method disclosed in Patent Document 1, it is thought that the mesh failure of the internal air model is suppressed by performing contact analysis before creating the internal air model and then creating the internal air model after deforming the tire model. However, using contact analysis makes the analysis prone to instability due to analysis errors, etc., and it is time-consuming. [Means for solving the problem]

[0006] The tire simulation method according to the present invention is a tire simulation method for determining the state in which the bead portion of a pneumatic tire is mounted on a rim, wherein the rim includes a rim seat surface that abuts the bottom surface of the bead portion, and a rim flange that extends in the rim diameter direction outside the rim width direction of the rim seat surface and abuts the side surface of the bead portion, and the tire simulation method includes a tire model creation step of creating a tire model before rim assembly modeled with a finite number of elements having a plurality of nodes on a two-dimensional coordinate system, a rim coordinate setting step of setting the shape of the rim as rim coordinates on the two-dimensional coordinate system, and the tire The method is characterized by including a reference point setting step of setting one of the nodes constituting the bead side surface or the bead bottom surface in each of the pair of bead portions of the model as the tire model reference point, and setting the coordinates corresponding to the tire model reference point in the rim coordinates as the rim reference point; a reference displacement amount acquisition step of obtaining the distance in the tire model width direction between the tire model reference point and the rim reference point as the reference displacement amount; and a deformation analysis step of setting the nodes constituting the bead side surface and the bead bottom surface as contact candidate points, setting the reference displacement amount for the contact candidate points, and deforming the tire model based on the reference displacement amount. [Effects of the Invention]

[0007] According to the tire simulation method of the present invention, it is possible to stabilize the analysis of tire simulations while reducing the amount of work required for the simulation. [Brief explanation of the drawing]

[0008] [Figure 1] This is a flowchart illustrating a tire simulation method, which is one example of an embodiment. [Figure 2] This figure shows an example of a pneumatic tire from which a tire model is created. [Figure 3] This figure shows a tire model before rim assembly, which is an example of an embodiment. [Figure 4] This figure shows a deformed tire model, which is an example of an embodiment. [Figure 5] This figure shows a tire model and an internal air model, which are examples of embodiments. [Figure 6] This flowchart shows a tire simulation method, which is another example of an embodiment. [Figure 7] This flowchart provides a detailed explanation of the process for correcting the reference displacement. [Figure 8] This figure shows a tire model according to another embodiment. [Figure 9] This figure shows a tire model according to another embodiment. [Figure 10] This is a block diagram of a tire simulation device. [Modes for carrying out the invention]

[0009] Hereinafter, with reference to the drawings, an example of an embodiment of the tire simulation method, tire simulation apparatus, and program according to the present invention will be described in detail. The embodiments described below are merely examples, and the present invention is not limited to these embodiments. Furthermore, forms obtained by selectively combining each component of the embodiments described below are included in the present invention.

[0010] A tire simulation method, which is an example of an embodiment, will be described in detail using Figures 1 to 3. Figure 1 is a flowchart of a tire simulation method, which is an example of an embodiment. Figure 2 is a diagram illustrating a pneumatic tire 100 on which tire model 1 is created. Figure 3 is a diagram of tire model 1. Figure 3(A) is a diagram showing the entire tire model 1, and Figure 3(B) is an enlarged view of part C of Figure 3(A).

[0011] One example of a tire simulation method is a tire simulation method that analyzes the state in which the bead portion of a pneumatic tire is mounted on a rim. More specifically, it is a tire simulation method that acquires the vibration characteristics of a pneumatic tire based on the state in which the bead portion of the pneumatic tire is mounted on a rim. The one example of a tire simulation method may be performed, for example, using the tire simulation device 30 described later.

[0012] In step S1, the radial cross-sectional shape of the tire model 1 before rim assembly, modeled with a finite number of elements having multiple nodes, is created in a two-dimensional coordinate system (tire model creation step). In the tire model creation step S1, for example, the tire model 1 shown in Figure 3 is created based on the pneumatic tire 100 before rim assembly, as shown in Figure 2.

[0013] Using Figure 2, we will describe in detail the pneumatic tire 100 on which tire model 1, an example of an embodiment, is created. Figure 2 is a cross-sectional view of the pneumatic tire 100.

[0014] As shown in Figure 2, the pneumatic tire 100 has a tread portion 2 which is the part that contacts the road surface, a pair of sidewall portions 3 arranged on both sides of the tread portion 2, and a pair of bead portions 4 arranged on the radially inward side of the sidewall portions 3. The tire model 1 also includes a carcass 5 which is stretched between the pair of bead portions 4, and an inner liner 6 which is arranged on the radially inward side of the carcass 5.

[0015] The tread portion 2 includes a main groove 2A and a land portion 2B defined by the main groove 2A. The land portion 2B is a portion that bulges outward in the tire diameter direction from a position corresponding to the bottom of the main groove 2A.

[0016] The sidewall portion 3 is disposed on both sides of the tread portion 2. The sidewall portion 3 is the portion that protrudes most outward in the tire width direction of the pneumatic tire 100, and is gently curved so as to be convex toward the outside in the tire width direction.

[0017] The bead portion 4 is disposed on the inner side in the tire diameter direction of the sidewall portion 3 and is a portion fixed to the rim. The bead portion 4 has a bead core 7 and a bead filler 8. The bead portion 4 is provided with a bead bottom surface 4A which is the inner surface in the tire diameter direction, and a bead side surface 4B which extends outward in the tire diameter direction connected to the bead bottom surface 4A. These bead portions 4 are fitted to the rim. Further, the bead core 7 and the bead filler 8 are embedded inside the bead portion 4.

[0018] In this specification, the bead portion 4 is defined as the region from the innermost side in the tire diameter direction of the pneumatic tire 100 to the outermost side in the tire diameter direction of the bead filler 8. The bead bottom surface 4A is a surface constituting the outer surface of the pneumatic tire 100 and is defined as the region from the innermost side in the tire diameter direction of the pneumatic tire 100 to the outermost side in the tire diameter direction of the bead core 7. Further, the bead side surface 4B is defined as the region from the outermost side in the tire diameter direction of the bead bottom surface 4A to the outermost side in the tire diameter direction of the bead filler 8.

[0019] As shown in FIG. 2, the carcass 5 is composed of at least one or more, and in this embodiment, it is composed of one carcass ply 5A. This carcass ply 5A includes a main body portion 5a that reaches the bead core 7 of the pair of bead portions 4 through the sidewall portion 3 from the tread portion 2, and a folded-back portion 5b that is connected to the main body portion 5a and is folded back from the inner side to the outer side in the tire width direction around the bead core 7.

[0020] Between the main body portion 5a and the folded portion 5b, a bead filler 8 is provided, extending radially outward from the bead core 7. The carcass ply 5A also includes carcass cords (not shown) arranged at an angle of, for example, 75° to 90° with respect to the tire equator CL. On the inner surface of the carcass 5, an inner liner 6, which forms the inner wall of the tire model 1, is stretched between the pair of bead portions 4.

[0021] The tire model creation process S1 involves creating a tire model 1, as shown in Figure 3(A), on a two-dimensional coordinate system, based on the pneumatic tire 100 described above. In the following explanation, we will use a Cartesian coordinate system, where the tire model width direction and tire model diameter direction are perpendicular, as an example of the two-dimensional coordinate system. In Figure 3, the vertical direction is the tire model diameter direction, and the horizontal direction is the tire model width direction. Furthermore, in the following explanation, the upper side of Figure 3 will be considered the outer side in the tire model diameter direction, and the lower side will be considered the inner side in the tire model diameter direction.

[0022] Tire model 1 is created as a two-dimensional model showing a cross-section in the radial direction of the tire, as shown in Figure 3(A). Tire model 1 may be composed of polygonal elements such as triangular and quadrilateral elements, or it may be composed of curved elements. It may also be composed of mixed elements that combine the above elements. Each element does not need to have the same area and may have different areas. Numerical data such as the coordinate values ​​of the nodes and material properties (e.g., density, Young's modulus and / or damping coefficient) are defined for each element.

[0023] Next, in step S2, the rim shape is set as rim coordinates 10 on a two-dimensional coordinate system (rim coordinate setting step). Specifically, as shown in Figure 3(A), the outer surface shape of the rim is set as rim coordinates 10 on the same two-dimensional coordinate system as the tire model 1. Rim coordinates 10 have a rim seat surface 11 that abuts the bead bottom surface 4A of the bead portion 4, and a rim flange 12 that extends in the rim diameter direction on the outside of the rim width direction of the rim seat surface 11 and abuts the bead side surface 4B of the bead portion 4. Here, the rim width direction is the same direction as the tire model width direction, and the rim diameter direction is the same direction as the tire model diameter direction.

[0024] The tire model 1 and rim coordinates 10 may be arranged to overlap each other, as shown in Figure 3. Since rim coordinates 10 exist only as coordinates, even if they overlap with tire model 1, they do not affect the shape of tire model 1, etc.

[0025] Next, in step S3, the tire model 1 is positioned so that its center in the width direction aligns with the center of the rim coordinates 10 in the width direction (tire model positioning step). That is, in step S3, the tire model 1 is positioned so that the tire equator CL, which is the center of the width of the tire model 1, aligns with the center of the rim width.

[0026] Note that the tire model placement step S3 may be omitted. In this case, in the rim coordinate setting step S2, the rim coordinates 10 are set so that the center of the tire model width of tire model 1 and the center of the rim coordinate width of rim coordinate 10 are aligned in a straight line in the diameter direction of the tire model. Alternatively, the rim coordinate setting step S2 may be performed before the tire model creation step S1. In this case, in the tire model creation step S1, tire model 1 is created so that the center of the tire model width of tire model 1 aligns with the center of the rim coordinate width of rim coordinate 10.

[0027] Next, in step S4, one of the nodes constituting the bead bottom surface 4A or bead side surface 4B in each of the pair of bead portions 4 of the tire model 1 is set as the tire model reference point α, and the coordinate corresponding to the tire model reference point α in the rim coordinates 10 is set as the rim reference point β (reference point setting step). In the reference point setting step S4, reference points are set in the pair of bead portions 4 and in the rim coordinates 10 corresponding to the reference points of the pair of bead portions 4. That is, in this embodiment, four reference points are set in the reference point setting step S4.

[0028] In the reference point setting step S4, as described above, one of the nodes constituting the bead bottom surface 4A or the bead side surface 4B is set as the tire model reference point α. In other words, one point on each of the pair of bead sections 4 is set as the tire model reference point α. That is, in the tire model 1, two tire model reference points α are set.

[0029] In the reference point setting step S4, for example, the node at the boundary between the bead bottom surface 4A and the bead side surface 4B is set as the tire model reference point α. In this embodiment, the boundary between the bead bottom surface 4A and the bead side surface 4B is the node that sets the boundary between the bead core 7 and the bead filler 8, as shown in Figure 3(B).

[0030] The rim reference point β is the coordinate of the tire model reference point α in rim coordinate 10. More specifically, the rim reference point β is the coordinate of the same position as the tire model reference point α on the bead bottom surface 4A and the bead side surface 4B on the rim seat surface 11 and the rim flange 12. For example, if the tire model reference point α is the node at the boundary between the bead bottom surface 4A and the bead side surface 4B, then the rim reference point β is the coordinate of the boundary between the rim seat surface 11 and the rim flange 12.

[0031] Next, in step S5, the distance in the tire model width direction between the tire model reference point α and the rim reference point β is obtained as the reference displacement amount L (reference displacement amount acquisition step). In the reference displacement amount acquisition step S5, as shown in Figure 3(B), the distance in the tire model width direction between the tire model reference point α and the rim reference point β is obtained as the reference displacement amount L. Note that even if the tire model reference point α and the rim reference point β are not in the same position in the tire model radial direction, only the distance in the tire model width direction is obtained as the reference displacement amount L.

[0032] Next, in step S6, the nodes constituting the bead bottom surface 4A and the bead side surface 4B are set as contact candidate points, a reference displacement amount L is set for the contact candidate points, and the tire model 1 is deformed based on the reference displacement amount L (deformation analysis step). Specifically, the contact candidate points are displaced in the width direction of the tire model based on the reference displacement amount L, and the other nodes follow the displacement of the contact candidate points, thereby deforming the entire tire model 1. Specifically, the pair of bead portions 4 are displaced so as to move closer to the center in the width direction of the tire model, and the entire tire model 1 is deformed accordingly. This makes it possible to deform the tire model 1 to the rim-assembled state. In addition, since the deformation analysis step S6 is a deformation analysis of the tire model 1 alone, analysis errors are less likely to occur.

[0033] The tire simulation method may include an internal air model creation step S7, in which an internal air model 20 is created inside the tire model 1. In the internal air model creation step S7, as shown in Figure 5, the internal air model 20 is created in the internal space of the tire model 1, which has been deformed to the equivalent of a rim assembly in the deformation analysis step S6. Specifically, the internal air model 20 is created to fill the internal space enclosed by the inner wall of the tire model 1 and the rim coordinates 10. This allows the pressure of the internal air in the tire model 1 to be calculated.

[0034] The internal air model 20, like the tire model 1, may be composed of polygonal elements such as triangular and quadrilateral elements, or it may be composed of curved elements. It may also be composed of mixed elements that combine the above elements. Furthermore, each element does not need to have the same area; they may have different areas. The elements constituting the internal air model 20 may have smaller areas as they approach the inner wall of the tire model 1. This prevents underestimation of the volume change (pressure change) of the elements on the inner wall side of the tire model 1 in the internal air model 20. This improves the accuracy of the analysis.

[0035] One example of a tire simulation method may include a three-dimensional unfolding step S8 in which the tire model 1 and the internal air model 20 are unfolded in three dimensions. Specifically, in the three-dimensional unfolding step S8, each node of each element of the tire model 1 and each node of each element of the internal air model 20 are continuously copied in the circumferential direction of the tire at a predetermined angular pitch. Next, adjacent nodes of the tire model 1 and the internal air model 20 in the circumferential direction of the tire are connected to each other, and the two-dimensional elements are re-elemented (remeshed) into three-dimensional elements. This creates a three-dimensional tire model having three-dimensional elements. In the three-dimensional unfolding step S8, since the tire model 1 and the internal air model 20 equivalent to the rim assembly are unfolded in three dimensions, a three-dimensional tire model and a three-dimensional internal air model equivalent to the rim assembly can be created in a short time. Hereinafter, the three-dimensional tire model and the three-dimensional internal air model will be collectively referred to as the three-dimensional tire model.

[0036] One example of a tire simulation method may include a vibration response analysis step S9 in which the vibration characteristics of the tire are obtained by vibration response analysis. Specifically, the analysis is performed using the three-dimensional tire model obtained in the three-dimensional unfolding step S8 to obtain the vibration characteristics of the tire. In addition, the vibration response analysis step S9 may calculate physical quantities related to the vibration characteristics of the tire using conventionally known methods.

[0037] In vibration response analysis step S9, for example, the analysis is performed using a pre-created road surface model. Furthermore, various analysis conditions, such as the contact conditions between the road surface model and the three-dimensional tire model, are set before the analysis is executed. Analysis conditions include the internal air pressure of the three-dimensional tire model, and the stiffness of the road surface model. In other words, analysis conditions are set for both the three-dimensional tire model and the road surface model.

[0038] Figures 6 to 9 will be used to describe in detail another example of the tire simulation method. Figure 6 is a flowchart of the tire simulation method according to another example of the embodiment. Figure 7 is a flowchart explaining the reference displacement correction process. Figure 8 is a diagram explaining the widthwise displacement amount correction process. Figure 9 is a diagram explaining the radial reference point setting process and the radial displacement amount correction process. Note that Figures 8 and 9 correspond to Figure 3(B) of the above embodiment.

[0039] The tire simulation method according to another embodiment differs from the tire simulation method according to the above embodiment in that it includes a reference displacement amount correction step. Steps that are the same as those in the tire simulation method according to the above embodiment are indicated by the same reference numerals and their descriptions are omitted.

[0040] As shown in Figure 6, another example of the embodiment of the tire simulation method includes a reference displacement amount modification step S10, in which the reference displacement amount L of the contact candidate point is modified. The reference displacement amount modification step S10 is performed between the reference displacement amount acquisition step S5 and the deformation analysis step S6.

[0041] The reference displacement amount correction step S10 may include, as shown in Figure 7, a widthwise displacement amount correction step S11 in which the distance in the width direction of the tire model between the node of a contact candidate point other than the tire model reference point α and the coordinate corresponding to the node other than the tire model reference point α in the rim coordinate 10 is obtained as the widthwise displacement amount L1, and the reference displacement amount L of the node other than the tire model reference point α is corrected based on the widthwise displacement amount L1. The widthwise displacement amount correction step S11 corrects the reference displacement amount L of the contact candidate point by replacing the reference displacement amount L set for the contact candidate point with the widthwise displacement amount L1.

[0042] In the widthwise displacement correction step S11, as shown in Figure 8, nodes other than the tire model reference point α among the contact candidate points are set as the tire model reference point α1, and the coordinates corresponding to the tire model reference point α1 in the rim coordinates 10 are set as the rim reference point β1. Subsequently, the distance in the width direction of the tire model between the tire model reference point α1 and the rim reference point β1 is obtained as the widthwise correction displacement amount L1. The widthwise correction displacement amount L1 is set at the node of the tire model reference point α1, and in the deformation analysis step S6, the node is displaced based on the widthwise correction displacement amount L1. As a result, the accurate distance between the node of the contact candidate point and the coordinate of the rim coordinates 10 corresponding to that node is obtained, so the rim assembly shape of the tire model 1 can be obtained with higher accuracy. The higher accuracy of the rim assembly shape of the tire model 1 contributes to the improvement of analysis accuracy. In the above, the widthwise correction displacement amount L1 was obtained at one node, but the widthwise correction displacement amount L1 may be obtained at multiple nodes.

[0043] As shown in Figure 7, the reference displacement amount correction step S10 may also include a radial reference point setting step S12, in which the node located on the innermost side of the tire model radially on the bead bottom surface 4A is set as the tire model radial reference point α2, and the coordinates on the rim seat surface 11 corresponding to the tire model radial reference point α2 are set as the rim radial reference point β2.

[0044] Furthermore, the reference displacement amount correction step S10 may also include a radial displacement amount correction step as step S13, in which the radial distance of the tire model between the tire model radial reference point α2 and the rim radial reference point β2 when the tire model reference point α is positioned at the same height as the rim reference point β is obtained as the radial displacement amount L2, and the reference displacement amount L of the nodes constituting the bead bottom surface 4A is corrected based on the radial displacement amount L2. Here, positioning the tire model reference point α at the same height as the rim reference point β means arranging the tire model 1 so that the tire model reference point α and the rim reference point β are aligned in a straight line along the width direction of the tire model. The radial displacement amount correction step S13 corrects the reference displacement amount L of a node by setting a new radial displacement amount of the tire model for the node constituting the bead bottom surface 4A.

[0045] In the radial reference point setting step S12, as shown in Figure 9, the innermost node in the radial direction of the tire model on the bead bottom surface 4A is set as the tire model radial reference point α2. In addition, the coordinates corresponding to the tire model radial reference point α2 are set as the rim radial reference point β2. The rim radial reference point β2 is, for example, the innermost coordinate in the radial direction of the tire model on the rim seat surface 11.

[0046] In the radial displacement correction step S13, the radial distance between the tire model radial reference point α2 and the rim radial reference point β2, when the tire model reference point α is positioned at the same height as the rim reference point β, is obtained as the radial correction displacement amount L2, and the radial correction displacement amount L2 is set at the nodes that constitute the bead bottom surface 4A. That is, both the reference displacement amount L and the radial correction displacement amount L2 are set at the nodes that constitute the bead bottom surface 4A. If the widthwise correction displacement amount L1 is set at a node that constitutes the bead bottom surface 4A, then the widthwise correction displacement amount L1 and the radial correction displacement amount L2 are set at that node.

[0047] Nodes for which a radial correction displacement amount L2 is set are displaced in the tire model width direction based on the reference displacement amount L and in the tire model radial direction based on the radial correction displacement amount L2 during the deformation analysis process S6. As a result, by applying radial displacement to the nodes constituting the bead bottom surface 4A, the rim assembly shape of the tire model 1 can be obtained with higher accuracy.

[0048] When actually mounting the pneumatic tire 100 to the rim, even if there is a difference between the shape of the bead bottom surface 4A and the shape of the rim seat surface 11, the bead portion 4 deforms as it is pressed against the rim, and the bead bottom surface 4A and the rim seat surface 11 come into contact with each other while the difference is filled. However, in the present invention, since the deformation of the tire model 1 alone is performed by analysis, if there is a difference between the shape of the bead bottom surface 4A and the shape of the rim seat surface 11, the deformation is performed while maintaining that difference. For example, as shown in Figure 9, if the rim radial reference point β2 is located radially outside the tire model than the tire model radial reference point α2, even after deformation analysis, the tire model radial reference point α2 will be located radially inside the tire model than the rim coordinate 10, and the shape of the tire model 1 after rim assembly may not be accurately reproduced. However, by the radial displacement amount correction step S13, this difference can be filled in the analysis, so the rim assembly shape of the tire model 1 can be obtained with higher accuracy.

[0049] In the radial displacement correction step S13, the radial displacement correction amount L2 may be set only at the radial reference point α2 of the tire model. In this case, in the deformation analysis step S6, the other nodes constituting the bead bottom surface 4A will also be displaced in accordance with the displacement of the radial reference point α2 of the tire model.

[0050] In the above explanation, we provided an example where the reference displacement amount correction step S10 includes the widthwise displacement amount correction step S11 and the radial displacement amount correction step S13. However, the reference displacement amount correction step S10 may include only either the widthwise displacement amount correction step S11 or the radial displacement amount correction step S13.

[0051] Furthermore, the tire simulation method described above can be implemented by having a computer execute each step of the tire simulation method as a procedure using a program that executes the tire simulation method.

[0052] Using Figure 10, an example of an embodiment, the tire simulation device 30, will be described in detail. Figure 10 is a block diagram showing an example of an embodiment, the tire simulation device 30. The tire simulation device 30 is a tire simulation device that analyzes the state in which the bead portion of a pneumatic tire is mounted on the rim. More specifically, it is a tire simulation device that acquires the vibration characteristics of a pneumatic tire based on the state in which the bead portion of the pneumatic tire is mounted on the rim. The tire simulation device 30 has a configuration that enables the execution of the above tire simulation method.

[0053] The tire simulation device 30 consists of a computer equipped with a control device 40 including a processor 41 and memory 42, and performs predictive simulations of tire performance. The tire simulation device 30 may consist of one computer or multiple computers. In addition, some of the functions of the tire simulation device 30 may reside on a server or the like connected via a communication network.

[0054] The control device 40 includes an input unit 43 and an output unit 44. The input unit 43 is an input interface for inputting information necessary for running the simulation, and examples include a keyboard and a mouse. The information input by the input unit 43 includes, for example, analysis conditions and conditions for creating the tire model 1. The output unit 44 is a liquid crystal display, organic EL display, etc., on which output screens such as the input screen and simulation results are displayed.

[0055] The control device 40 has a tire model creation unit 45 that creates the radial cross-sectional shape of the tire model 1 before rim assembly, which is modeled with a finite number of elements having multiple nodes, on a two-dimensional coordinate system. The tire model creation unit 45 creates the tire model 1 based on, for example, a pneumatic tire 100 before rim assembly, as shown in Figure 2.

[0056] Tire model 1 is created as a two-dimensional model showing a cross-section in the radial direction of the tire, as shown in Figure 3(A). Tire model 1 may be composed of polygonal elements such as triangular and quadrilateral elements, or it may be composed of curved elements. It may also be composed of mixed elements that combine the above elements. Each element does not need to have the same area and may have different areas. Numerical data such as the coordinate values ​​of the nodes and material properties (e.g., density, Young's modulus and / or damping coefficient) are defined for each element.

[0057] The control device 40 has a rim coordinate setting unit 46 that sets the shape of the rim as rim coordinates 10 on a two-dimensional coordinate system. As shown in Figure 3(A), the rim coordinate setting unit 46 sets the outer surface shape of the rim as rim coordinates 10 on the same two-dimensional coordinate system as the tire model 1. The rim coordinates 10 have a rim seat surface 11 that abuts the bead bottom surface 4A of the bead portion 4, and a rim flange 12 that extends in the rim diameter direction on the outside of the rim width direction of the rim seat surface 11 and abuts the bead side surface 4B of the bead portion 4.

[0058] The control device 40 may have a tire model placement unit 47 that positions the tire model 1 such that the center of the tire model in the width direction of the tire model 1 aligns with the center of the rim coordinates 10 in the width direction of the tire model 1. The tire model placement unit 47 positions the tire model 1 such that the tire equator CL, which is the width direction center of the tire model 1, aligns with the center of the rim width.

[0059] The control device 40 does not necessarily have a tire model placement unit 47. In this case, the rim coordinate setting unit 46 sets the rim coordinates 10 so that the center of the rim coordinate width of the tire model 1 aligns with the center of the tire model width of the tire model 1. Alternatively, the tire model 1 may be created after the rim coordinates 10 have been set by the rim coordinate setting unit 46. In this case, the tire model creation unit 45 creates the tire model 1 so that the center of the tire model width of the tire model 1 aligns with the center of the rim coordinate width.

[0060] The control device 40 has a reference point setting unit 48 that sets one of the nodes constituting the bead bottom surface 4A or bead side surface 4B in each of the pair of bead portions 4 of the tire model 1 as the tire model reference point α, and sets the coordinate corresponding to the tire model reference point α in the rim coordinate 10 as the rim reference point β. The reference point setting unit 48 sets reference points in the pair of bead portions 4 and in the rim coordinate 10 corresponding to the reference points of the pair of bead portions 4. That is, in this embodiment, the reference point setting unit 48 sets four reference points.

[0061] In the reference point setting unit 48, as described above, one of the nodes constituting the bead bottom surface 4A or the bead side surface 4B is set as the tire model reference point α. In other words, one point on each of the pair of bead sections 4 is set as the tire model reference point α. That is, in the tire model 1, two tire model reference points α are set.

[0062] In the reference point setting unit 48, for example, the node at the boundary between the bead bottom surface 4A and the bead side surface 4B is set as the tire model reference point α. In this embodiment, the boundary between the bead bottom surface 4A and the bead side surface 4B is the node that sets the boundary between the bead core 7 and the bead filler 8, as shown in Figure 3(B).

[0063] The rim reference point β is the coordinate of the tire model reference point α in rim coordinate 10. More specifically, the rim reference point β is the coordinate of the same position as the tire model reference point α on the bead bottom surface 4A and the bead side surface 4B on the rim seat surface 11 and the rim flange 12. For example, if the tire model reference point α is the node at the boundary between the bead bottom surface 4A and the bead side surface 4B, then the rim reference point β is the coordinate of the boundary between the rim seat surface 11 and the rim flange 12.

[0064] The control device 40 has a reference displacement amount acquisition unit 49 that acquires the distance in the tire model width direction between the tire model reference point α and the rim reference point β as the reference displacement amount L. As shown in Figure 3(B), the reference displacement amount acquisition unit 49 acquires the distance in the tire model width direction between the tire model reference point α and the rim reference point β as the reference displacement amount L. Even if the positions of the tire model reference point α and the rim reference point β in the tire model radial direction are not the same, only the distance in the tire model width direction is acquired as the reference displacement amount L.

[0065] The control device 40 has a deformation analysis unit 50 that sets the nodes constituting the bead bottom surface 4A and the bead side surface 4B as contact candidate points, sets a reference displacement amount L for the contact candidate points, and deforms the tire model 1 based on the reference displacement amount L. Specifically, the deformation analysis unit 50 displaces the contact candidate points based on the reference displacement amount L, and the other nodes follow the displacement of the contact candidate points, thereby deforming the entire tire model 1. Specifically, the pair of bead portions 4 are displaced so as to move closer to the center in the width direction of the tire model, and the entire tire model 1 is deformed accordingly. This makes it possible to deform the tire model 1 to the rim-assembled state. In addition, since the deformation analysis unit 50 performs deformation analysis on the tire model 1 alone, analysis errors are less likely to occur.

[0066] The control device 40 may have an internal air model creation unit 51 that creates an internal air model 20 inside the tire model 1. In the internal air model creation unit 51, as shown in Figure 5, the internal air model 20 is created in the internal space of the tire model 1 that has been deformed to the equivalent of a rim assembly by the deformation analysis unit 50. Specifically, the internal air model 20 is created to fill the internal space surrounded by the inner wall of the tire model 1 and the rim coordinates 10. This makes it possible to calculate the pressure of the internal air in the tire model 1.

[0067] The internal air model 20, like the tire model 1, may be composed of polygonal elements such as triangular and quadrilateral elements, or it may be composed of curved elements. It may also be composed of mixed elements that combine the above elements. Furthermore, each element does not need to have the same area; they may have different areas. The elements constituting the internal air model 20 may have smaller areas as they approach the inner wall of the tire model 1. This prevents underestimation of the volume change (pressure change) of the elements on the inner wall side of the tire model 1 in the internal air model 20. This improves the accuracy of the analysis.

[0068] The control device 40 may include a three-dimensional unfolding unit 52 that unfolds the tire model 1 and the internal air model 20 in three dimensions. Specifically, the three-dimensional unfolding unit 52 continuously copies each node of each element of the tire model 1 and each node of each element of the internal air model 20 in the circumferential direction of the tire at a predetermined angular pitch. Next, adjacent nodes of the tire model 1 and the internal air model 20 in the circumferential direction of the tire are connected to each other, and the two-dimensional elements are re-elemented into three-dimensional elements (remeshed). This creates a three-dimensional tire model having three-dimensional elements. Since the three-dimensional unfolding unit 52 unfolds the tire model 1 and the internal air model 20 equivalent to a rim assembly, it is possible to create a three-dimensional tire model and a three-dimensional internal air model equivalent to a rim assembly in a short time. Hereinafter, the three-dimensional tire model and the three-dimensional internal air model will be collectively referred to as the three-dimensional tire model.

[0069] The control device 40 may include a vibration response analysis unit 53 that acquires the vibration characteristics of the tire by vibration response analysis. Specifically, the analysis is performed using the three-dimensional tire model acquired by the three-dimensional unfolding unit 52 to acquire the vibration characteristics of the tire. In addition, the vibration response analysis step S9 may calculate physical quantities related to the vibration characteristics of the tire using conventionally known methods.

[0070] As described above, the tire simulation method, tire simulation apparatus, and program equipped with the above configuration can suppress the occurrence of analysis errors, stabilize the analysis, and reduce the amount of work required for the simulation, thereby shortening the time required for tire simulation. [Explanation of Symbols]

[0071] 1 Tire model, 2 Tread section, 3 Sidewall section, 4 Bead section, 4A Bead bottom surface, 4B Bead side surface, 5 Bead core, 6 Carcass, 7 Bead core, 8 Bead filler, 10 Rim coordinates, 11 Rim seat surface, 12 Rim flange, 20 Internal air model, 30 Simulation device, 40 Control device, 41 Processor, 42 Memory, 43 Input section, 44 Output section, 45 Tire model creation section, 46 Rim coordinate setting section, 47 Tire model placement section, 48 Reference point setting section, 49 Reference displacement setting section, 50 Deformation analysis section, 51 Internal air model creation section, 52 Three-dimensional unfolding section, 53 Vibration response analysis section

Claims

1. A tire simulation method for determining the state in which the bead portion of a pneumatic tire is mounted on the rim, The rim includes a rim seat surface that abuts the bottom surface of the bead portion, and a rim flange that extends in the rim diameter direction on the outside of the rim width direction of the rim seat surface and abuts the side surface of the bead portion. The aforementioned tire simulation method is, A tire model creation process involves creating a tire model in a two-dimensional coordinate system that is modeled using a finite number of elements with multiple nodes, before the rim is assembled. A step of setting the rim coordinates, which are the shape of the rim and are set as rim coordinates on the two-dimensional coordinate system, A reference point setting step is performed in which, in each of the pair of bead portions of the tire model, one of the nodes constituting the bead side surface or the bead bottom surface is set as the tire model reference point, and the coordinates corresponding to the tire model reference point in the rim coordinates are set as the rim reference point. A process for acquiring a reference displacement amount, in which the distance in the width direction of the tire model between the tire model reference point and the rim reference point is acquired as the reference displacement amount, A deformation analysis step is performed in which the nodes constituting the bead side surface and the bead bottom surface are set as contact candidate points, a reference displacement amount is set for the contact candidate points, and the tire model is deformed based on the reference displacement amount. A tire simulation method, including the following.

2. The tire simulation method according to claim 1, further comprising the step of positioning the tire model such that the center of the tire model in the width direction aligns with the center of the rim coordinates in the width direction of the tire model.

3. The tire simulation method according to claim 1, comprising a widthwise displacement amount correction step of obtaining the distance in the tire model width direction between a node other than the tire model reference point of the contact candidate point and the coordinate corresponding to the node other than the tire model reference point in the rim coordinates as a widthwise correction displacement amount, and correcting the reference displacement amount of the node other than the tire model reference point based on the widthwise correction displacement amount.

4. A radial reference point setting step is performed in which the node located at the innermost radial point of the tire model on the bead bottom surface is set as the radial reference point of the tire model, and the coordinates on the rim seat surface corresponding to the radial reference point of the tire model are set as the radial reference point of the rim. A tire simulation method according to claim 1, comprising: a radial displacement amount correction step of obtaining the radial distance of the tire model between the tire model radial reference point and the rim radial reference point when the tire model reference point is positioned at the same height as the rim reference point, as the radial displacement amount, and correcting the reference displacement amount of the nodes constituting the bead bottom surface based on the radial displacement amount.

5. A program for causing a computer to execute the tire simulation method described in any one of claims 1 to 4.

6. A tire simulation device that determines the state in which the bead portion of a pneumatic tire is mounted on the rim, The rim includes a rim seat surface that abuts the bottom surface of the bead portion, and a rim flange that extends in the rim diameter direction on the outside of the rim width direction of the rim seat surface and abuts the side surface of the bead portion. The tire simulation device is A tire model creation unit that creates a tire model before rim assembly, modeled with a finite number of elements having multiple nodes, in a two-dimensional coordinate system, A rim coordinate setting unit that sets the shape of the rim as rim coordinates on the two-dimensional coordinate system, A reference point setting unit sets one of the nodes constituting the bead side surface or the bead bottom surface in each of the pair of bead portions of the tire model as the tire model reference point, and sets the coordinates corresponding to the tire model reference point in the rim coordinate system as the rim reference point. A reference displacement amount acquisition unit that acquires the distance in the tire model width direction between the tire model reference point and the rim reference point as the reference displacement amount, A deformation analysis unit sets the nodes constituting the bead side surface and the bead bottom surface as contact candidate points, sets the reference displacement amount for the contact candidate points, and deforms the tire model based on the reference displacement amount. A tire simulation device having the following features.

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