How to create a tire simulation model

Abstract

To provide a method for creating tire simulation models that facilitate stable and rapid analysis. [Solution] At least one of the following is performed: moving all first nodes 15 in a direction including the radial direction away from the first interface 11 and moving all second nodes 25 in a direction including the radial direction away from the second interface 21, such that the shortest distance between a plurality of first nodes 15 located at the first interface 11 of the 1-pitch body model 10 and a plurality of second nodes 25 located at the second interface 21 of the 1-pitch tread model 20 is greater than the merge tolerance range.

Description

Technical Field

[0001] This disclosure relates to a method for creating a tire simulation model.

Background Art

[0002] In Patent Document 1, there is disclosed a smooth tire model in which only the internal structure of a pneumatic tire made of rubber, belts, plies, iron, organic fibers, etc., a reinforcing cord, and a reinforcing material obtained by bundling the reinforcing cords in a sheet form is set, a case part model for a plurality of pitches corresponding to the entire circumferential direction, and a tread pattern model for a plurality of pitches corresponding to the entire circumferential direction are combined to create a tire model. Here, the case part model is a model of a portion extending from one bead to the other bead, which is neither a smooth tire part nor a tread part in the pneumatic tire. In this method for creating a tire model, the case part model for one pitch and the tread pattern model for one pitch are combined by multi-point constraint (MPC).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A known method for joining two models is Tie joining, also known as surface-specified MPC. Tie joining is a specification of MPC, and it is a method for joining two models by specifying a surface during joining. The inventors of this case have discovered for the first time that the following problem may arise when creating a full tire model by creating a tire model for one pitch by Tie joining a model of a tread for one pitch and a model of a body for one pitch located radially inward of the tread for one pitch, and then duplicating the resulting tire model in the circumferential direction for the number of pitches.

[0005] In detail, this method involves creating a tire model for one pitch using a tie-in, then duplicating the created pitch model circumferentially for the number of pitches and arranging them to form a single unit. During this process, for all two adjacent pitch models in the circumferential direction, multiple other-side nodes present at the circumferential interface of one pitch model and multiple one-side nodes present at the circumferential interface of the other pitch model are merged. Specifically, due to the periodicity of the pitch model, multiple other-side nodes correspond one-to-one with multiple one-side nodes. These multiple other-side nodes and multiple one-side nodes are then recognized as the same point and merged. Merging means recognizing them as the same point and merging them.

[0006] Here, the nodes on one side and the nodes on the other side that are merged and integrated are two points that are within a short distance of each other, below the merge tolerance range. However, when merging the nodes present at this circumferential interface, one or more pairs of the first nodes and second nodes of the tread model that are within a distance of each other, among the multiple first nodes at the radial interface on the body model side of the tread model for one pitch, are also merged and integrated simultaneously. As a result, it has been found that this creates an analysis instability point, and the calculation is likely to terminate prematurely. This analysis instability point due to the merging of the first and second nodes can also occur when the tread model for one pitch and the body model for one pitch are joined using a joining method other than Tie joining. Therefore, the purpose of this disclosure is to provide a method for creating a tire simulation model that facilitates stable and rapid analysis. [Means for solving the problem]

[0007] To solve the above problems, the method for creating a tire simulation model according to this disclosure includes: a first step of creating a one-pitch body model by dividing a one-pitch body into finite elements in three dimensions; a second step of creating a one-pitch tread model by dividing a one-pitch tread into finite elements in three dimensions; and moving all of the first nodes in a direction including the radial direction from the first interface so that when the relative position of the second interface of the one-pitch tread model with respect to the first interface of the one-pitch body model is positioned at a predetermined position, the shortest distance between a plurality of first nodes present at the first interface of the one-pitch body model and a plurality of second nodes present at the second interface of the one-pitch tread model is greater than the merge tolerance range; and all front The method includes: a third step of moving the second node in a direction including the radial direction from the second interface; a fourth step of creating a one-pitch model by integrating the one-pitch body model and the one-pitch tread model so that they are not relative to each other, with the relative position of the second interface positioned at the predetermined position after the third step; and a fifth step of duplicating the one-pitch model by the number of pitches in the circumferential direction and arranging them side by side, and merging and integrating a plurality of third nodes present on the third interface of one one-pitch model on the other one-pitch model side and a plurality of fourth nodes present on the fourth interface of the other one-pitch model on the one one-pitch model side for all pairs of circumferentially adjacent one-pitch models.

[0008] According to this disclosure, when merging multiple third nodes into multiple fourth nodes, it is easy to mechanically prevent the first and second nodes from merging. Therefore, it is easy to mechanically prevent the analysis from becoming unstable when merging multiple third nodes into multiple fourth nodes, and the analysis can be performed stably and quickly.

[0009] Furthermore, in the third step, at least one of all the first nodes and all the second nodes may be moved by the same length in the same direction including the radial component.

[0010] This configuration makes it easy to prevent the shortest distance between the first and second nodes from falling below the merge tolerance range using a simple program.

[0011] Furthermore, in the third step, at least one of all the first nodes and all the second nodes may be moved radially.

[0012] This configuration makes it easy to prevent the shortest distance between the first and second nodes from falling below the merge tolerance range using a simple program.

[0013] Furthermore, with respect to a plurality of moving nodes that consist of at least one of the first nodes that have moved from the first interface and the second nodes that have moved from the second interface, the minimum moving distance at the moving node may be 0.01 mm longer than the allowable merge range.

[0014] This configuration makes it less likely for the mesh size to become unbalanced, and facilitates accurate analysis using tire simulation models.

[0015] Furthermore, with respect to a plurality of moving nodes that consist of at least one of the first nodes that have moved from the first interface and the second nodes that have moved from the second interface, the maximum moving distance at the moving node may be 0.01 mm longer than the allowable merge range and 0.09 mm longer than the allowable merge range.

[0016] This configuration makes it less likely for the mesh size to become unbalanced, and facilitates accurate analysis using tire simulation models. [Effects of the Invention]

[0017] The method for creating a tire simulation model described herein facilitates stable and rapid analysis. [Brief explanation of the drawing]

[0018] [Figure 1]It is a flowchart for explaining the procedure of a method for creating a tire simulation model according to an embodiment of the present disclosure. [Figure 2] It is a perspective view of an example of a 1-pitch body model. [Figure 3] It is a perspective view of an example of a 1-pitch tread model. [Figure 4] It is a diagram for explaining an example of a pair of a first node and a second node that are at a distance within the merge allowable range when the second interface is arranged at a predetermined position with respect to the first interface. [Figure 5] It is a perspective view showing a three-dimensional position where there is a pair of a first node and a second node whose distance is within the merge allowable range when a tire model is constructed with a provisional 1-pitch model. [Figure 6] It is a diagram showing the axial direction (tire width direction) existence position of the above-mentioned pair in the tire model constructed with the above-mentioned provisional 1-pitch model. [Figure 7] It is a diagram showing the moving direction of all the first nodes existing on the first interface. [Figure 8] It is a perspective view of an example of a 1-pitch model. [Figure 9] It is a diagram for explaining the relative position of the first node with respect to the second node in the final one. [Figure 10] It is an enlarged view of the periphery of the region indicated by the region R in FIG. 9. [Figure 11] It is a perspective view of an example of a tire simulation model. The [Figure 12] It is a diagram for explaining the displacement amount of the performed simulation. [Figure 13] It is a graph showing the test results in the above-mentioned simulation.

Mode for Carrying Out the Invention

[0019] The method for creating the tire simulation model relating to this disclosure will be described below with reference to the drawings. In the following drawings, identical or similar parts are denoted by the same or similar reference numerals and their descriptions are omitted. The drawings include schematic diagrams, and some diagrams may have different proportions of dimensions than those of reality. Furthermore, the axial, radial, and circumferential dimensions of each part do not necessarily match between different diagrams. In addition, among the components described below, components not described in the independent claim indicating the highest-level concept are optional components and are not essential components. Furthermore, this disclosure is not limited to the embodiments and their modifications described below, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0020] A tire simulation model is created to correspond to, for example, a candidate tire model for a product. Then, simulations are performed using the corresponding tire model, such as simulating traction when rolling on a road surface, such as snow; simulating the relationship between the rate of change in tire orientation per unit time in response to steering wheel turns and lateral force; or simulating the relationship between the normal force acting on the tire and the displacement at the tire center under conditions where the inside of the tire is constrained.

[0021] Figure 1 is a flowchart illustrating the procedure for creating a tire simulation model according to one embodiment of the present disclosure. Referring to Figure 1, in this method for creating a tire simulation model, first, in step S1, as shown in Figure 2, a one-pitch body is divided into three-dimensional finite elements using the finite element method (FEM) to create a one-pitch body model 10. The body is the part of the tire other than the tread.

[0022] For example, suppose a tire comprises a tread, shoulder, sidewall, and bead, with the tread including a tread surface that directly contacts the road surface and having a tread pattern engraved on the tread surface. The shoulder consists of a pair of shoulder portions located axially outward from the tread, the sidewall is located radially inward from the shoulder, and the bead has a bead core and a bead filler, which may include a structure made of bundled high-carbon steel, for example.

[0023] Furthermore, the tread, shoulder, and sidewall protect the carcass (not shown), which spans from one bead to the other in the axial direction, and the bead serves to fix both ends of the carcass while simultaneously securing the tire to the rim. A belt (not shown) is provided on the outer diameter side of the carcass, and the tread, made of tread rubber (the rubber layer that contacts the road surface), is positioned on the outer diameter side of the belt, with an inner liner provided inside the carcass. In this case, the body is made up of the parts of the tire other than the tread rubber.

[0024] Next, in step S2, as shown in Figure 3, a 1-pitch tread is divided into three-dimensional finite elements using the finite element method to create a 1-pitch tread model 20. The tread consists of a thick layer of rubber in the part that contacts the road surface. This rubber layer protects the interior (carcass, tube, etc.) from impacts and damage from the road surface, and also plays a role in drive, braking, wear, and handling performance. Tire performance largely depends on the tread, and the characteristics of the tread vary depending on the configuration of the multiple grooves provided therein and the compound of the rubber raw materials. The decomposition of the tread into three-dimensional finite elements depends on the configuration of the multiple grooves provided in the tread. Note that steps S1 and S2 can be performed in either order, and there may be times when they are performed simultaneously.

[0025] Next, in step S3, the provisional positions in three-dimensional space of the multiple first nodes 15 present on the first interface 11 of the one-pitch body model 10 and the multiple second nodes 25 present on the second interface 21 of the one-pitch tread model 20 are determined, assuming that the relative position of the second interface 21 of the one-pitch tread model 20 with respect to the first interface 11 of the one-pitch body model 10 is positioned at a predetermined location. In Figure 2, the areas drawn with dark lines represent the mesh on the first interface 11, and in Figure 3, the areas drawn with dark lines represent the mesh on the second interface 21.

[0026] In this embodiment, the predetermined position is where the first interface 11 coincides with the second interface 21, and the first interface 11 is positioned to coincide with the second interface 21. In the method of this disclosure, it is conceivable that the one-pitch body model 10 and the one-pitch tread model 20 are joined using an adhesive or the like, and no constraint conditions are set on the relative position of the second node 25 with respect to the first node 15. Therefore, for example, a layer of adhesive or the like may be present, so the first interface 11 and the second interface 21 do not necessarily coincide at the predetermined position.

[0027] Figure 4 illustrates an example of pairs of first and second nodes 15 and 25 whose distance is below the merge tolerance range when the second interface 21 is positioned relative to the first interface 11 (a predetermined position). The technical meaning of the merge tolerance range will be explained later. In the example shown in Figure 4, there are three pairs of first and second nodes 15 and 25 whose distance is below the merge tolerance range in a local region of a provisional 1-pitch model in which a 1-pitch body model 10 and a 1-pitch tread model 20 are positioned in predetermined positions. The locations of these three pairs are enclosed in circles and indicated as K1 to K3.

[0028] Figure 5 is a perspective view showing the three-dimensional location of pairs of first node 15 and second node 25 whose distance is below the merge tolerance range when a tire model is constructed using a provisional one-pitch model. Figure 6 shows the axial (tire width direction) location of the above pairs in the tire model constructed using the provisional one-pitch model. In the examples shown in Figures 5 and 6, pairs of first node 15 and second node 25 whose distance is below the merge tolerance range appear at intervals in the circumferential direction, and four such pairs appear at intervals in the axial direction at each circumferential position.

[0029] In step S4, at least one of the following is performed: moving all first nodes 15 in a direction including radially outward from the first interface 11, and moving all second nodes 25 in a direction including radially inward from the second interface 21. This is done so that when the relative position of the second interface 21 with respect to the first interface 11 is positioned at the predetermined position, the shortest distance between the multiple first nodes 15 present on the first interface 11 and the multiple second nodes 25 present on the second interface 21 becomes greater than the allowable merge range.

[0030] In this embodiment, all first nodes 15 present on the first interface 11 are moved by the same distance radially inward from the first interface 11, as indicated by arrow A in Figure 7, so that the shortest distance between the first node 15 and the second node 25 becomes longer than the allowable merge range. In this embodiment, the position of the second node 25 is not moved.

[0031] In the following step S5, the relative position of the second interface 21 with respect to the first interface 11 is positioned at the predetermined position, and then the one-pitch body model 10 and the one-pitch tread model 20 are integrated so that they cannot move relative to each other to create the one-pitch model 30 shown in Figure 8. When integrating the one-pitch body model 10 and the one-pitch tread model 20 so that they cannot move relative to each other, a tie-bonding method may be used, or other known or unknown bonding methods may be used. Figure 9 is a diagram illustrating the relative position of the first node 15 with respect to the second node 25 in the one-pitch model 30, and Figure 10 is an enlarged view of the area around the region indicated by region R in Figure 9. As shown in Figure 10, in the one-pitch model 30, all the first nodes 15 have moved radially inward, resulting in a gap larger than the allowable merge range between the first interface 11 and the second interface 21 after the movement of the first nodes 15.

[0032] In the final step S6, the 1-pitch model 30 is duplicated in the circumferential direction by the number of pitches and arranged in a row. Then, for all pairs of circumferentially adjacent 1-pitch models 30, the multiple third nodes present at the third interface of one 1-pitch model 30 on the other 1-pitch model 30 and the multiple fourth nodes present at the fourth interface of the other 1-pitch model 30 on the first 1-pitch model 30 are merged and integrated. In this way, the tire simulation model 40 shown in Figure 11 is created.

[0033] In the method disclosed herein, the tire simulation model 40 is created by duplicating the same 1-pitch model 30 circumferentially for the number of pitches, arranging them side by side, and integrating them. Therefore, multiple third nodes correspond one-to-one with multiple fourth nodes. However, the three-dimensional positions of the multiple third nodes do not exactly coincide with the three-dimensional positions of the multiple fourth nodes. That is, the number of pitches when the 1-pitch model 30 is arranged around the circumference is not an integer multiple. For example, even a tire with 25 pitches will have a multiplier that includes a small fraction, such as 24.998 pitches. This is because a degree of freedom is required to ensure consistency when creating the tire simulation model 40.

[0034] Therefore, a procedure is required to integrate multiple third nodes and multiple fourth nodes at the corresponding interface of adjacent 1-pitch models 30, and as a result, adjacent 1-pitch models 30 in the circumferential direction are integrated and merged with each other. The procedure of integrating multiple third nodes and multiple fourth nodes as the same point is called merging, and the threshold of the node distance used to determine whether or not to merge is the merge tolerance range. The merge tolerance range is set, for example, to 0.05 mm or more or 0.09 mm or more.

[0035] Next, the effects of the method for creating the tire simulation model 40 of this disclosure will be explained. The inventors found that when a tread model for one pitch and a body model for one pitch are simply merged, when the third and fourth nodes located at the merged interface of adjacent circumferentially connected one-pitch models 30 are merged, the first and second nodes, which happen to be within the mergeable range of multiple first and second nodes located at the merged interface of the tread model and the body model for one pitch, are also merged despite the condition that the first and second nodes are identical points being not met, which causes uncertainty in the analysis.

[0036] Next, I will explain the simulation, which presented some concerns during the analysis. Referring to Figure 12, the inventor set a representative point at the center of the tire simulation model and simulated the displacement amount of the representative point in the height direction indicated by arrow B when a load (a load that is the sum of a vertical load and a moment load corresponding to the motion of turning the steering wheel) was applied to that representative point in order to investigate the lateral slippage.

[0037] Figure 13 is a graph showing the test results in the above simulation. The reference example shown by the dotted line is the analysis result when the analysis was performed using a tire simulation model that simply integrates a tread model for one pitch and a body model for one pitch. The example shows the analysis result when the analysis was performed using a tire simulation model in which no merging occurs between the first and second nodes when the third and fourth nodes are merged by performing step S4 described above.

[0038] In this analysis, as shown in Figure 13, the analysis using the reference example tire simulation model unexpectedly terminated when the displacement reached 3a [mm], and could not be completed. On the other hand, the analysis using the embodiment tire simulation model was able to be completed.

[0039] In the above embodiment, all first nodes 15 present on the first interface 11 are moved by the same distance radially inward from the first interface 11 as indicated by arrow A in Figure 7, so that the shortest distance between the first nodes 15 and the second nodes 25 becomes longer than the allowable merge range. However, as described above, by moving all first nodes 15 in a direction including radially outward from the first interface 11, and moving all second nodes 25 in a direction including radially inward from the second interface 21, when the relative position of the second interface 21 with respect to the first interface 11 is positioned at the predetermined position, the shortest distance between the multiple first nodes 15 present on the first interface 11 and the multiple second nodes 25 present on the second interface 21 becomes greater than the allowable merge range.

[0040] As described above, the method for creating a tire simulation model according to this disclosure includes a first step of creating a one-pitch body model 10 by dividing a one-pitch body into finite elements in three dimensions; a second step of creating a one-pitch tread model 20 by dividing a one-pitch tread into finite elements in three dimensions; and a third step of moving all the first nodes 15 in a direction including the radial direction from the first interface 11 and moving all the second nodes 25 in a direction including the radial direction from the second interface 12, such that when the relative position of the second interface 21 of the one-pitch tread model 20 with respect to the first interface 11 of the one-pitch body model 10 is positioned at a predetermined position, the shortest distance between a plurality of first nodes 15 present at the first interface 11 of the one-pitch body model 10 and a plurality of second nodes 25 present at the second interface 21 of the one-pitch tread model 20 is greater than the merge tolerance range.

[0041] Furthermore, the creation method includes a fourth step of creating a one-pitch model 30 by integrating the one-pitch body model 10 and the one-pitch tread model 20 so that they cannot move relative to each other, with the relative position of the second interface 21 positioned at a predetermined location after the third step, and a fifth step of duplicating the one-pitch model 30 by the number of pitches in the circumferential direction and arranging them side by side, and merging and integrating a plurality of third nodes present at the third interface on the other one-pitch model 30 side of one one-pitch model 30 and a plurality of fourth nodes present at the fourth interface on the one one-pitch model side of the other one one-pitch model 30 for all pairs of two one-pitch models 30 adjacent in the circumferential direction.

[0042] According to this disclosure, when merging multiple third nodes into multiple fourth nodes, it is easy to mechanically prevent the first and second nodes from merging. Therefore, it is easy to mechanically prevent the analysis from becoming unstable when merging multiple third nodes into multiple fourth nodes, and the analysis can be performed stably and quickly.

[0043] Furthermore, in the third step, at least one of all the first nodes 15 and all the second nodes 25 may be moved by the same length in the same direction, including the radial component. With this configuration, it is easy to prevent the shortest distance between the first nodes 15 and the second nodes 25 from falling below the merge tolerance range using a simple program.

[0044] Furthermore, since it is easier to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range with an even simpler program, it is preferable to move only all first nodes 15 by the same length in the same direction including the radially inward component so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range. Alternatively, since it is easier to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range with an even simpler program, it is preferable to move only all second nodes 25 by the same length in the same direction including the radially outward component so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range.

[0045] Furthermore, in the third step, at least one of all the first nodes 15 and all the second nodes 25 may be moved radially. With this configuration, it is easy to prevent the shortest distance between the first nodes 15 and the second nodes 25 from falling below the merge tolerance range using a simple program.

[0046] Furthermore, since it is easier to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range with an even simpler program, it is preferable to move only all first nodes 15 radially inward so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range. Alternatively, since it is easier to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range with an even simpler program, it is preferable to move only all second nodes 25 radially outward so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range.

[0047] Furthermore, it is most preferable to move all first nodes 15 by the same distance radially inward so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range, as this makes it easy and mechanical to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range. Alternatively, it is most preferable to move all second nodes 25 by the same distance radially outward so that the shortest distance between the first node 15 and the second node 25 becomes greater than the merge tolerance range, as this makes it even easier to prevent the shortest distance between the first node 15 and the second node 25 from falling below the merge tolerance range with a simpler program.

[0048] Since the mesh size is less likely to become unbalanced and analysis using the tire simulation model can be performed accurately, it is preferable that the minimum movement distance at a moving node is 0.01 mm longer or less than the merge tolerance range for a plurality of moving nodes that consist of at least one of the first nodes 15 that have moved from the first interface 11 and all the second nodes 25 that have moved from the second interface 21.

[0049] Since the mesh size is less likely to become unbalanced and analysis using the tire simulation model can be performed accurately, it is preferable that, with respect to multiple moving nodes composed of at least one of all first nodes 15 that have moved from the first interface 11 and all second nodes 25 that have moved from the second interface 21, the maximum moving distance at a moving node is at least 0.01 mm longer than the merge tolerance range and at least 0.09 mm longer than the merge tolerance range. [Explanation of Symbols]

[0050] 10 1-pitch body model, 11 1st interface, 15 1st node, 20 1-pitch tread model, 21 2nd interface, 25 2nd node, 30 1-pitch model, 40 tire simulation model.

Claims

1. The first step is to create a one-pitch body model by dividing a one-pitch body into finite elements in three dimensions, The second step is to create a one-pitch tread model by dividing one pitch of tread into finite elements in three dimensions, A third step involves moving all of the following in a direction including the radial direction from the first interface and moving all of the second interfaces including the radial direction from the second interface, such that when the relative position of the second interface of the one-pitch tread model with respect to the first interface of the one-pitch body model is positioned at a predetermined position, the shortest distance between a plurality of first nodes present at the first interface of the one-pitch body model and a plurality of second nodes present at the second interface of the one-pitch tread model is greater than the merge tolerance range. A fourth step is to create a one-pitch model by integrating the one-pitch body model and the one-pitch tread model so that they cannot move relative to each other, after the third step has been positioned at the predetermined location of the second interface. A fifth step involves duplicating the aforementioned one-pitch model in the circumferential direction by the number of pitches and arranging them, and for all pairs of two adjacent one-pitch models in the circumferential direction, merging and integrating a plurality of third nodes present at the third interface on the other one-pitch model side of one one-pitch model with a plurality of fourth nodes present at the fourth interface on the first one-pitch model side of the other one-pitch model, A method for creating a tire simulation model, including [specific details].

2. The method for creating a tire simulation model according to claim 1, wherein in the third step, at least one of all the first nodes and all the second nodes is moved by the same length in the same direction including the radial component.

3. A method for creating a tire simulation model according to claim 1 or 2, wherein in the third step, at least one of all the first nodes and all of the second nodes is moved radially.

4. A method for creating a tire simulation model according to any one of claims 1 to 3, wherein, with respect to a plurality of moving nodes comprising at least one of all the first nodes moved from the first interface and all the second nodes moved from the second interface, the minimum moving distance at the moving node is 0.01 mm longer than the merge tolerance range.

5. A method for creating a tire simulation model according to any one of claims 1 to 3, wherein, with respect to a plurality of moving nodes comprising at least one of all the first nodes moved from the first interface and all the second nodes moved from the second interface, the maximum moving distance at the moving node is a distance of 0.01 mm or more longer than the merge tolerance range and a distance of 0.09 mm or less longer than the merge tolerance range.

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