JP5545826B2 - Tire performance prediction method and tire performance prediction apparatus - Google Patents

Description

  The present invention relates to a tire performance prediction method and a tire performance prediction apparatus that predict snow and ice performance related to a tire.

  Conventionally, as a technique for predicting the performance of a tire on snow and ice, a method of actually creating a rubber block sample and measuring the friction coefficient on snow or ice has been used. The method of actual measurement using such a sample requires a mold for preparing the sample and a dedicated measuring device, and there are problems in terms of time, man-hours, and cost.

  In recent years, it has become possible to predict the performance of a tire without actually creating a sample by means of a simulation method such as a finite element method (FEM) or an improvement in computer performance (see Patent Document 1).

JP 2006-168505 A

  By the way, the following two techniques are considered as a prediction technique for predicting the performance on snow and ice. The first prediction technique is based on the two-dimensional CAD information of the tread pattern, and the sum of the tire circumferential direction projection length or the tire width direction projection length among the edge portions (block edge and sipe / groove edge) forming the tread pattern. Is used as an index value of the performance on snow and ice. The second predictive technique uses the tread rubber elasticity index indicating the softness of the tread rubber under the assumption that there is a correlation between the softness of the tread rubber at the operating temperature and the friction coefficient on the snow and ice. It is a method of setting the index value.

  However, the first prediction technique and the second prediction technique do not take into account the behavior such as pressure distribution at the time of tire contact and lift due to shear deformation, and it is not always possible to accurately predict the performance on snow and ice. There is.

  Then, an object of this invention is to provide the tire performance prediction method and tire performance prediction apparatus which can predict the performance on snow and ice regarding a tire accurately.

  In order to solve the above problems, the present invention has the following features. First, a first feature of the present invention is a tire performance prediction method for predicting performance on snow and ice related to a tire, wherein a plurality of tread blocks (tread blocks 22) including an edge portion (block edge and sipe / groove edge) are provided. A creation step (step S1) for creating a block model (block model 220) modeled by elements, and at least the block by deformation analysis in which the block model created in the creation step is subjected to shear deformation in a predetermined direction after being grounded About a contact pressure calculation step (step S4 or step S11) for calculating a contact pressure generated in an edge element (edge element E) composed of an element corresponding to the edge portion of the model, and the block model created in the creation step Measuring the projected length of the edge element in the predetermined direction An index value of the performance of the tread block on snow and ice is calculated from the projection length calculation step (step S12), the contact pressure calculated in the contact pressure calculation step, and the projection length calculated in the projection length calculation step. The gist is to have an index value calculation step (steps S13 and S14) to be calculated.

  The friction characteristics (particularly the edge effect) as the performance on snow and ice are proportional to the contact pressure at the edge portion of the tread block and the effective edge length with respect to the shear deformation direction. In the first feature of the present invention, the contact pressure generated at the edge element of the block model and the projected length of the edge element in the shear deformation direction are calculated, and the calculation result is integrated to calculate the index value of the performance on snow and ice. To do. Accordingly, it is possible to obtain an index value of the performance on snow and ice reflecting the behavior such as the pressure distribution at the time of ground contact and the lift due to shear deformation, and the performance on snow and ice can be accurately predicted.

  A second feature of the present invention relates to the first feature of the present invention, wherein, in the projection length calculation step, the projection length of the edge element in the predetermined direction for the block model deformed in the deformation analysis. The gist is to calculate the length.

  In the first prediction technique, the projection length of the edge part (block edge and sipe / groove edge) on the two-dimensional CAD is calculated. The projection length also changes. In the second feature of the present invention, since the projection length is calculated for the edge element after deformation, the prediction accuracy of the performance on snow and ice can be improved.

  A third feature of the present invention is related to the first or second feature of the present invention, and is summarized in that the predetermined direction includes at least one of a tire circumferential direction and a tire width direction of the block model.

  According to the third feature of the present invention, the performance on the snow and ice in the tire circumferential direction (that is, the performance during braking / driving) and the performance on the snow and ice in the tire width direction (that is, the performance during turning) can be predicted. In addition, when calculating the projection length in the 45 ° right and left direction with respect to the block model as well as the tire circumferential direction or the tire width direction, the performance on snow and ice during braking and turning can be predicted.

  According to a fourth aspect of the present invention, in accordance with any one of the first to third aspects of the present invention, a contact area calculation for calculating a contact area of the block model with respect to the block model deformed in the deformation analysis. The gist is to further include a step.

  The ground contact area affects the friction characteristics as performance on snow and ice. According to the 4th characteristic of this invention, the prediction precision of the on-snow-ice performance can further be improved by calculating the ground-contact area assumed at the time of actual use.

  A fifth feature of the present invention relates to any one of the first to fourth features of the present invention, and in the creating step, a tire model including a plurality of block models and modeling the entire tire is created, In the contact pressure calculation step, a contact pressure is calculated for each of the plurality of block models, in the projection length calculation step, a projection length is calculated for each of the plurality of block models, and in the index value calculation step, The gist is to calculate an index value of the performance of the entire tire on snow and ice from the contact pressure and the projection length calculated for each of the plurality of block models.

  According to the fifth aspect of the present invention, the performance on snow and ice of the entire tire can be predicted by calculating the performance on snow and ice for each of a plurality of block models included in the tire model obtained by modeling the entire tire.

  The sixth feature of the present invention is summarized in that it is a tire performance prediction device (computer 300) that executes the tire performance prediction method according to any one of the first to fifth features of the present invention.

  According to the sixth aspect of the present invention, the performance on snow and ice can be accurately predicted by executing the tire performance prediction method according to any one of the first to fifth aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the tire performance prediction method and tire performance prediction apparatus which can predict the performance on snow and ice regarding a tire accurately can be provided.

It is the schematic which shows the computer as a tire performance prediction apparatus for performing the tire performance prediction method which concerns on embodiment of this invention. It is a flowchart which shows the performance prediction method which concerns on embodiment of this invention. It is a figure which shows an example of the two-dimensional pattern which set the vertical and horizontal area | region (XY area). It is a top view which shows the block model which concerns on embodiment of this invention. It is a perspective view which shows the block model which concerns on embodiment of this invention. It is a flowchart which shows the process which calculates the edge effect which concerns on embodiment of this invention. It is a figure for demonstrating the process which calculates the contact pressure of each edge element which concerns on embodiment of this invention. It is a figure which shows the example which displays the edge effect and contact pressure for every shear deformation direction. It is a perspective view which shows the block model which concerns on other embodiment. It is a perspective view which shows the tire model which concerns on other embodiment.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

[Tire performance prediction device]
First, a tire performance prediction apparatus for executing the tire performance prediction method according to the present embodiment will be described. FIG. 1 is a schematic diagram showing a computer 300 as the tire performance prediction apparatus.

  As shown in FIG. 1, a computer 300 includes a storage unit (not shown) such as a semiconductor memory and a hard disk, a main unit 310 having a processing unit (not shown) such as a CPU, an input unit 320 such as a keyboard and a mouse, And a display unit 330 such as a liquid crystal monitor.

  The computer 300 executes a tire performance prediction program for executing the tire performance prediction method according to the present embodiment. For example, the computer 300 may read and execute the tire performance prediction program from an external storage medium that records the tire performance prediction program. Alternatively, the tire performance prediction program stored (installed) in the storage unit of the computer 300 may be read and executed. The computer 300 may acquire and execute a tire performance prediction program via a network.

[Tire performance prediction method]
Next, the tire performance prediction method according to the present embodiment will be described. FIG. 2 is a flowchart showing a tire performance prediction method according to the present embodiment.

(1) Creation of Block Model In step S1 of FIG. 2, the computer 300 creates a block model using the finite element method based on the design plan (tire shape, structure, material, etc.) of the tire to be analyzed. To do. The block model is obtained by modeling a tire tread block as an assembly of a plurality of elements by element division (so-called mesh division) corresponding to the finite element method. The tread block is a land block that is partitioned by a groove in the tread portion of the tire.

  The computer 300 reads a two-dimensional pattern diagram (two-dimensional pattern data) indicating a tread pattern and selects an arbitrary block from the read two-dimensional pattern diagram. Then, the main point on the selected block (which may include a main line) is input from the two-dimensional pattern diagram. This main point represents the block features such as corners and inflection points that function as nodes necessary for block formation and deformation analysis. By inputting the main points, two-dimensional data composed of points and lines of a two-dimensional pattern can be formed as a block. The two-dimensional pattern diagram of the tread block includes features of the shape of the tread block. That is, the shape features such as the outer shape, the groove (groove), the sipe (thin groove), their depth, and the wall surface angle belong to the line segment of the two-dimensional pattern diagram. Therefore, attribute information is input for each line segment of the tread block formed by the two-dimensional pattern diagram. This attribute information is data belonging to the corresponding line segment in order to represent the geometric features such as the outer shape, groove, sipe, depth, and wall surface angle of the tread block. The attribute information may be input manually by using a keyboard, or may be obtained by reading attribute data for each line segment set in advance in the two-dimensional pattern diagram. Further, division setting is performed for the Z direction (height direction) that is the tire radial direction. In this division setting, all groove and all sipe depth data in the tread block are read to determine the number of divisions. In order to make it possible to independently handle one groove and one sipe, it is preferable to set the number of divisions and the length after division to be smaller than the minimum depth. This division setting corresponds to setting the size in the Z direction (height direction) that is the tire radial direction of the element (small hexahedron) by division. By setting the height direction, division in the height direction (height division) becomes possible. Then, a vertical and horizontal area (XY area) including the corresponding tread block in the two-dimensional pattern diagram is set and divided into a predetermined size.

  FIG. 3 is a diagram illustrating an example of a two-dimensional pattern 20 in which vertical and horizontal areas (XY areas) are set. The two-dimensional pattern 20 includes a tread block 22, and the tread block 22 includes a sipe portion 24. The predetermined size division after setting the XY area is performed such that the cross-sectional shape in the tire circumferential direction is uniform and the elements are arranged in the same vertical and horizontal directions (see FIG. 4). That is, the elements are divided in a two-dimensional grid pattern (lattice pattern) so that the elements are arranged vertically and horizontally. In the division, it is preferable to set the number of divisions and the length after the division so that the length of one side of the divided element is equal to or less than the sipe width. By setting in this way, it becomes possible to express a sipe shape unique to the tire. In this division, it is preferable that any one side of the division is parallel to the shear deformation direction in consideration of the shear deformation direction at the time of deformation analysis. This is because, by making them parallel, it becomes possible to provide a tire model that has a jagged shape due to the corners of the elements generated by the division and eliminates the influence thereof. By doing as described above, an element (small hexahedron) of a predetermined size is formed by vertical and horizontal division and height division.

  Next, the data indicating the wall surface angle and the depth of the groove or sipe is set as inclination / depth information, and a two-dimensional pattern diagram in each divided Z-direction stage is set based on the inclination / depth information. Here, each of the surfaces corresponding to a plurality of cross sections divided by the division setting in the Z direction is defined as a stage. By applying the inclination / depth information to the two-dimensional pattern diagram, it is possible to calculate the arrival position of the wall surface, the groove, and the sipe that reach each stage. A two-dimensional pattern diagram of each stage (surface at each height divided in the Z direction) can be generated based on the arrival position.

  Next, it is determined whether or not the elements divided on the XY plane in each stage divided in the Z direction are present in the tread block 22. This determination is made for each element divided into elements on each stage. That is, it is determined whether or not an element exists in the area specified by the position of the selected tread block 22. Then, in each stage divided in the Z direction, it is determined whether or not the element divided on the XY plane is included in the groove. In this determination, it is determined whether or not an element exists in the groove area of the selected tread block 22. Further, it is determined whether or not the element divided on the XY plane hits the sipe portion in each stage divided in the Z direction. In this determination, it is determined whether or not a part of the element exists in the sipe portion of the selected tread block 22. When these determinations are completed, it is possible to determine elements corresponding to any of the outside of the tread block 22, the inside of the groove, and the sipe portion, which do not require deformation analysis for the selected tread block 22. Therefore, processing corresponding to any of the outside of the tread block 22, the inside of the groove, and the sipe portion is deleted, and data of the remaining elements is output. Thereby, block model data based on the voxel mesh in consideration of the groove, sipe portion, wall surface, and outer shape of the tread block 22 can be output.

  FIG. 4 is a diagram showing a three-dimensional block model 220 created by the remaining elements created for the tread block 22. FIG. 5 is a perspective view showing the block model 220. As shown in FIGS. 4 and 5, block models 220 are formed by stacking or arranging small hexahedral elements (voxels) having the same cross-sectional shape and arranged in the same direction. In addition, the sipe part 240 is expressed by a shape in which small hexahedral elements are deleted.

(2) Setting Boundary Conditions Next, in step S2 of FIG. 2, the computer 300 performs setting of a road surface (that is, creation of a road surface model) and setting of boundary conditions. A basic input for deformation analysis is created by the processing in step S2.

  In setting the road surface, the road surface is modeled, and the road surface model that is the modeled road surface is set to the actual road surface state. In road surface modeling, a road surface state is input by modeling a road surface shape by dividing it into elements and selecting and setting a friction coefficient μ of the road surface. For example, depending on the road surface condition, there is a road friction coefficient μ corresponding to dry (DRY), wet (WET), on ice, snow, unpaved, etc., so by selecting an appropriate value for the friction coefficient μ, The road surface condition can be reproduced. A fluid model may be created and provided between the road surface and the block model 220.

  The boundary conditions are necessary for analysis of the block model 220, that is, for simulating the behavior of the tire, and are various conditions given to the block model 220. Specifically, at least one of rotational displacement and straight displacement (displacement may be force or speed) and a predetermined load load are given to the block model 220. In addition, when considering friction with the road surface, only one of rotational displacement (or force or speed) or straight displacement (or force or speed) may be used.

(3) Resetting Boundary Conditions Next, in step S3 of FIG. 2, a plurality of shear deformation directions are designated, and the computer 300 creates an input in which the boundary conditions are changed for each shear deformation direction. Thus, by making it possible to specify a plurality of shear deformation directions, it is possible to capture the performance on snow and ice when the input to the block model 220 changes. For example, in addition to at least one edge effect in the tire circumferential direction (during braking / driving) or the tire width direction (during turning), an edge effect in the 45-degree direction (braking / braking and turning) can be calculated. At the time of deformation analysis, input of a plurality of conditions is performed by automatically changing the boundary conditions by a predetermined program.

(4) Deformation Analysis Next, in step S4 of FIG. 2, the computer 300 deforms by shear deformation after grounding the block model 220 based on the finite element method according to each boundary condition set in step S3. Analysis (simulation of ground contact / shear behavior) is performed, and physical quantities generated in each element of the block model 220 are calculated. Since multiple shear deformation directions are specified, deformation analysis for each shear deformation direction is executed in parallel. As the calculation result of step S4, for example, physical quantities such as a contact area at the time of tire deformation, a contact pressure at the time of tire deformation, an amount of shear deformation, and a shear stress distribution are obtained. In addition, the deformation analysis repeats the deformation analysis of the block model 220 in order to obtain the tire rolling state (in order to obtain a transient state) (for example, repeat the calculation within 1 msec), and each time The boundary condition may be updated. The deformation analysis can employ a predetermined calculation time assuming that the tire deformation is in a steady state.

(5) Calculation of Edge Effect and Ground Contact Area Next, in step S5 of FIG. 2, the computer 300 uses the physical quantity obtained in step S4, and the friction characteristics on snow and ice of the block model 220, specifically, each Calculate the edge effect in each shear deformation direction and the contact area during shearing. In the calculation of the contact area, the contact area is calculated for the block model 220 in a deformed state in the deformation analysis.

  FIG. 6 is a flowchart showing processing for calculating the edge effect. The processing flow shown in FIG. 6 is executed for each shear deformation direction.

  In step S11 of FIG. 6, the contact pressure of each edge element is calculated. As shown in FIG. 7, the edge element E includes an element corresponding to the edge of the tread block of the tire (hereinafter referred to as a block edge element) and an element corresponding to the edge of the sipe (hereinafter referred to as sipe edge) on the ground contact surface of the block model 220. Element). If the contact pressure of each edge element E has already been calculated in step S4 in FIG. 2, it may be used.

  In step S12 of FIG. 6, the projection length of each edge element E in the shear deformation direction is calculated. Here, the projection length of each edge element E in the shear deformation direction is calculated for the block model 220 in a deformed state in the deformation analysis.

  In step S13 of FIG. 6, the projection length calculated in step S12 is weighted with the contact pressure calculated in step S12. Specifically, for each edge element E, the multiplication result of the projection length calculated in step S12 and the contact pressure calculated in step S12 is calculated as an edge effect in units of edge elements. As a result, the edge effect of all edge elements E is obtained.

  In step S14, the edge effects of all the block elements 220 are calculated by integrating the edge effects of all the edge elements E.

(6) Result Output In step S6 of FIG. 2, the computer 300 converts the edge effect, the contact pressure, the contact area, etc. for each shear deformation direction calculated in step S5 into a visualization file and displays them.

  FIG. 8 is a diagram illustrating an example of displaying the edge effect and the contact pressure for each shear deformation direction. As shown in FIG. 8, in this embodiment, the contact pressure distribution display, the edge effect distribution by the chart graph, and the like are visualized for each of the tire width direction, the 45-degree direction, and the tire circumferential direction. In each block model 220 shown in FIG. 8, hatched portions indicate that the contact pressure is high. Further, it can be seen from the chart of the edge effect distribution shown in FIG. 8 that a good edge effect is obtained when the shear deformation directions are 45 ° and 225 ° directions. On the other hand, when the shear deformation directions are 135 ° and 315 °, it is understood that the edge effect is not obtained.

(7) Actions / Effects As described above, the tire performance prediction method according to the present embodiment uses the simulation using the finite element method to apply deformation close to the actual behavior of the tread block 22 using the block model 220. By reproducing, the tire performance of the tread block 22 on snow and ice can be predicted easily and with high accuracy.

  In this embodiment, the contact pressure generated at each edge element E of the block model 220 and the projected length of each edge element E in the shear deformation direction are calculated, and these calculation results are integrated to obtain an index value of the performance on snow and ice. calculate. Accordingly, it is possible to obtain an index value of the performance on snow and ice reflecting the behavior such as the pressure distribution at the time of ground contact and the lift due to shear deformation, and the performance on snow and ice can be accurately predicted.

  In the present embodiment, since the projection length is calculated for each edge element E after deformation, the prediction accuracy of the performance on snow and ice can be improved.

  In this embodiment, the performance on the snow and ice in the tire circumferential direction (that is, the performance during braking / driving) and the performance on the snow and ice in the tire width direction (that is, the performance during turning) can be predicted. In addition, by calculating the projection length in the 45 ° direction to the left and right with respect to the block model 220, the performance on snow and ice during braking and turning can be predicted.

  In the present embodiment, by calculating the ground contact area for each edge element E after deformation, the ground contact area assuming actual use can be calculated, and the prediction accuracy of the performance on snow and ice can be further increased.

[Other Embodiments]
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

(Modification 1)
In the above embodiment, the block model 220 is configured as an assembly of small hexahedral elements (voxels). However, as illustrated in FIG. 9, the block model 220 is configured as an assembly of complex shaped elements. May be. However, when the block model 220 is configured as an assembly of elements having a complicated shape, it is difficult to create the block model 220, and a long creation time is required. It is preferable to configure the block model 220 as an aggregate of these.

(Modification 2)
In the above embodiment, the case of predicting the performance on snow and ice for one block model 220 has been described. However, after the tire performance prediction method according to the above embodiment is performed on each tread block on the tread pattern, the performance on snow and ice as the whole tire can be predicted by expanding the result two-dimensionally.

(Modification 3)
In the above embodiment, the edge effect, which is one of the snow and ice performances, has been described. It is also possible to predict.

(Modification 4)
It is also possible to perform the tire performance prediction method according to the above embodiment with the tire model of the entire tire using the detailed pattern model and calculate the edge effect as the entire tire at a time.

  In this case, in step S1 in the above embodiment, as shown in FIG. 10, a tire model 100 including a plurality of block models 220 and modeling the entire tire is created. In step S11, the contact pressure is calculated for each of the plurality of block models 220. In step S12, the projection length is calculated for each of the plurality of block models 220. In step S13, an index value (edge effect) of the performance on snow and ice of the entire tire is calculated from the contact pressure and projection length calculated for each of the plurality of block models 220. Thereby, the performance on snow and ice is calculated for each of the plurality of block models 220 included in the tire model 100 that models the entire tire, and the performance on snow and ice of the entire tire can be predicted.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  E ... Edge element, 22 ... Tread block, 24 ... Sipe part, 100 ... Tire model, 220 ... Block model, 240 ... Sipe part, 300 ... Computer, 310 ... Body part, 320 ... Input part, 330 ... Display part

Claims (8)

A tire performance prediction method for predicting snow and ice performance related to a tire,
A creation step for creating a block model in which a tread block including an edge portion is modeled by a plurality of elements,
A contact pressure calculation step of calculating a contact pressure generated in an edge element corresponding to the edge portion of the block model by a deformation analysis in which the block model created in the creation step is grounded and deformed in a predetermined direction after being grounded;
A projection length calculation step of calculating a projection length of the edge element in the predetermined direction for the block model created in the creation step;
An index value calculation step of calculating an index value of the performance of the tread block on snow and ice from the contact pressure calculated in the contact pressure calculation step and the projection length calculated in the projection length calculation step. Tire performance prediction method.   2. The tire performance prediction method according to claim 1, wherein, in the projection length calculation step, a projection length of the edge element in the predetermined direction is calculated for the block model deformed in the deformation analysis. 3. .   The tire performance prediction method according to claim 1 or 2, wherein the predetermined direction includes at least one of a tire circumferential direction and a tire width direction of the block model.   The tire performance prediction according to any one of claims 1 to 3, further comprising a contact area calculation step of calculating a contact area of the block model for the block model in a deformed state in the deformation analysis. Method. In the creating step, a tire model including a plurality of block models and modeling the entire tire is created,
In the contact pressure calculation step, a contact pressure is calculated for each of the plurality of block models,
In the projection length calculation step, a projection length is calculated for each of the plurality of block models,
5. The index value of the performance on snow and ice of the entire tire is calculated from the contact pressure and the projection length calculated for each of the plurality of block models in the index value calculating step. The tire performance prediction method according to claim 1.   In the contact pressure calculation step, a plurality of specified shear deformation directions are subjected to deformation analysis in parallel, and together with the contact pressure, a contact area at the time of tire deformation, a shear deformation amount, and a shear stress distribution are calculated,
  The tire performance prediction method according to any one of claims 1 to 5, wherein a deformation analysis of the block model is repeatedly executed in order to obtain a tire rolling state.   The edge element includes an element corresponding to an edge of a tread block of a tire and an element corresponding to an edge of a sipe on a ground contact surface of the block model,
  The tire performance prediction method according to any one of claims 1 to 6, wherein a length of one side of the edge element is equal to or less than a sipe width. Tire performance prediction apparatus characterized by performing the tire performance prediction method according to any of claims 1-7.

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