JP6281190B2 - Tire model creation method, tire cross-section shape determination method, tire model creation device, tire cross-section shape determination device, and program - Google Patents

Description

  The present invention relates to a tire model creation method, a tire cross-section shape determination method, a tire model creation device, a tire cross-section shape determination device, and a program that are created using a computer.

  Conventionally, in the design of the structure and shape of a structure, performance evaluation is performed by making a prototype of the structure and conducting an experiment, and a structure analysis model of the structure is created, including the finite element method Performance evaluation is performed by conducting numerical experiments using various structural analysis methods. And many design searches by so-called trial and error, in which re-production / re-creation of structures and structural analysis models are performed based on the results of the performance evaluation, are performed. Therefore, to design an optimum structure desired by the designer, it has been necessary to spend a great deal of labor, a lot of time, and a lot of trial production costs.

This is also true for tire manufacturers, and the design of pneumatic tires (hereinafter referred to as tires) required a great deal of labor, time, and cost through trial and error trials and numerical experiments. In particular, the cross-sectional shape cut along the plane including the rotation axis of the tire, that is, the shape of the tire cross-section, has a great influence on the tire performance, so that it has been necessary to design it with particular care in order to obtain the desired tire performance.
By the way, various optimum design methods based on numerical calculation for obtaining optimum product performance have been proposed today by improving high-speed processing of numerical calculation by a computer or the like. According to this, it is said that the above problem can be solved and an optimum design can be efficiently performed. However, the tire as a structure has a problem that the optimum design technique is not sufficiently utilized due to the complexity of the method for defining the shape of the tire cross section.

On the other hand, the optimal shape design method used suitably for tire design is known (patent document 1).
In this optimum shape design method, a plurality of base cross-sectional shapes of the product shape are made deformed shapes of the natural vibration mode of the product shape, and a plurality of sample product shapes are generated by linearly combining the base cross-sectional shapes based on the experimental design method. Then, the evaluation value of the product performance of the generated sample product shape is obtained, and the optimum product shape with the evaluation value being the optimum value is extracted based on the evaluation value of the product performance.

JP 2002-15010 A

  When the above-described known optimum shape design method is applied to the tire cross-sectional shape, the deformation shape in the natural vibration mode of the tire cross-sectional shape is the base cross-sectional shape of the tire cross-sectional shape, so the tire size and structure of the tire to be optimized When there are a plurality of tires, the optimum tire cross-sectional shape is obtained using a base cross-sectional shape that differs for each tire size and structure. Accordingly, the optimum tire cross-sectional shape obtained may vary greatly depending on the tire size. For this reason, the above-described optimum shape design method cannot obtain a tire cross-sectional shape having consistent characteristics in the tire cross-sectional shape exceeding the tire size. Such a problem occurs not only in the tire size and structure but also in two tires having different tire cross-sectional shapes. In addition, since the tire cross-sectional shape is different, the tire cross-sectional shape is different, including the tire size being different.

  Therefore, the present invention is a tire model creation method, a tire cross-sectional shape determination method, which can obtain an optimized tire cross-sectional shape having a consistent feature across the tire cross-sectional shape even if the tire cross-sectional shape is different, It is an object of the present invention to provide a program for realizing a tire model creation device, a tire cross-sectional shape determination device, and a tire model creation method.

One embodiment of the present invention is a tire model creation method that is performed by a computer . The method is
A step of determining a plurality of modified tire models having a tire deformed shape obtained by deforming a tire cross-sectional shape of the reference tire model from a reference tire model that is a finite element model reproducing the reference tire;
Creating an analysis target reference tire model, which is a finite element model that reproduces an analysis target reference tire having a tire cross-sectional shape different from that of the reference tire;
Obtaining a shape difference distribution representing a difference in shape between each of the modified tire models and the reference tire model;
In each section of the plurality of sections on the outer circumferential surface of the tire characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the shape difference matches the peripheral length of the corresponding section of the reference tire model to be analyzed As described above, the peripheral length of each section in the distribution of the shape difference is expanded or compressed for each section to obtain a corrected shape difference, and the analysis target reference tire model is obtained using the distribution of the corrected shape difference. Creating a plurality of analysis target base tire models, which are finite element models, by giving deformation to
Creating a trial tire model that is a finite element model by linearly adding a deformation amount from the analysis target reference tire model for each of the generated analysis target base tire models,
A step of determining a plurality of the modified tire models, a step of generating the analysis target reference tire model, a step of obtaining a distribution of the shape difference, a step of generating a plurality of analysis target base tire models, and the trial tire model. The step to create is executed.

  The plurality of sections characterizing the tire cross-sectional shape are sections divided by a plurality of representative points on the tire outer peripheral surface, characterized by a tire cross-sectional shape, in a region between a tire center line position and a bead tip position. It is preferable that there is.

  At this time, it is more preferable that the representative point includes at least a point having the maximum tire width and a point at an end portion in the tire cross-sectional width direction on the tire outer peripheral surface in the arrangement region of the tread rubber.

Further, it is preferable that the analysis target base tire model is obtained by applying a forced displacement to a node on a tire outer peripheral surface of the analysis target reference tire model and performing deformation calculation by the computer .

Alternatively, in the base tire model to be analyzed, the computer applies a forced displacement to nodes on the tire inner peripheral surface of the analysis target reference tire model, or nodes on the tire inner peripheral surface and nodes on the tire outer peripheral surface. It is likewise preferred that it is obtained by performing deformation calculations.

  At this time, when the deformation calculation of the analysis target reference tire model is performed, the Poisson's ratio of each element of the analysis target reference tire model is set to a constant value of 0.1 or less, and the elastic constant and mass density of each element are fixed. It is preferable to assign a virtual physical property value that is a value.

Another aspect of the present invention is a tire cross-sectional shape determination method performed using a computer. The method is
A plurality of trial tires are obtained by linearly adding a deformation amount from the analysis target reference tire model of each of the analysis target base tire models created by the tire model creation method using a computer while changing a weighting coefficient. Creating a model,
An optimized tire in which at least one tire characteristic value satisfies a preset condition by performing a simulation calculation for obtaining the tire characteristic value using the plurality of trial tire models using a computer It possesses a step of finding the cross-sectional shape, and
A computer performs the steps of creating the plurality of trial tire models and finding the optimized tire cross-sectional shape.

Furthermore, it is preferable that the computer has a step of visualizing and displaying a correspondence relationship between a parameter characterizing the tire cross-sectional shape obtained when finding the optimized tire cross-sectional shape and the characteristic value of the tire.

Yet another embodiment of the present invention is a tire model creation device. The device is
A model creating unit that creates a reference tire model that is a finite element model that reproduces a reference tire, and a reference tire model that is a finite element model that reproduces a reference tire that has a cross-sectional shape different from that of the reference tire.
From the reference tire model, a modified tire model setting unit for determining a plurality of modified tire models having a tire deformed shape in which a tire cross-sectional shape of the reference tire model is deformed,
A distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model is obtained, and the distribution of the shape differences in each of a plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape. The peripheral length for each section in the distribution of the shape difference is set for each section so that the peripheral length for each section used for the same matches the peripheral length of the corresponding section of the reference tire model to be analyzed. Analyzing object to create a plurality of analysis target base tire models, which are finite element models, by obtaining a corrected shape difference by stretching or compressing, and using the distribution of the corrected shape difference to deform the analysis target reference tire model A base tire model creation unit;
A trial tire model creation unit that creates a trial tire model that is a finite element model by linearly adding the deformation amounts of the created base tire models to be analyzed.

Yet another embodiment of the present invention is a tire cross-sectional shape determining device. The device is
A model creating unit that creates a reference tire model that is a finite element model that reproduces a reference tire, and a reference tire model that is a finite element model that reproduces a reference tire that has a cross-sectional shape different from that of the reference tire.
From the reference tire model, a modified tire model setting unit for determining a plurality of modified tire models having a tire deformed shape in which a tire cross-sectional shape of the reference tire model is deformed,
A distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model is obtained, and the distribution of the shape differences in each of a plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape. The peripheral length for each section in the distribution of the shape difference is set for each section so that the peripheral length for each section used for the same matches the peripheral length of the corresponding section of the reference tire model to be analyzed. Analyzing object to create a plurality of analysis target base tire models, which are finite element models, by obtaining a corrected shape difference by stretching or compressing, and using the distribution of the corrected shape difference to deform the analysis target reference tire model A base tire model creation unit;
Trial tires that create a plurality of trial tire models by linearly adding the amount of deformation from the reference tire model to be analyzed of each of the plurality of base tire models to be analyzed using a computer while changing the weighting coefficient A model creation unit;
By performing a simulation calculation for obtaining a tire characteristic value using the plurality of trial tire models, an optimized tire cross-sectional shape in which at least one tire characteristic value satisfies a preset condition is found. And an optimum shape determining unit for determining.

Yet another embodiment of the present invention is a computer-readable program that causes a computer to execute a tire model creation method. The program is
From a reference tire model that is a finite element model reproducing the reference tire, a procedure for determining a plurality of modified tire models having a tire deformation shape in which a tire cross-sectional shape of the reference tire model is deformed,
A procedure for creating an analysis target reference tire model, which is a finite element model reproducing an analysis target reference tire having a tire cross-sectional shape different from that of the reference tire,
A procedure for obtaining a distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model;
In each section of the plurality of sections on the outer circumferential surface of the tire characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the shape difference matches the peripheral length of the corresponding section of the reference tire model to be analyzed As described above, the peripheral length of each section in the distribution of the shape difference is expanded or compressed for each section to obtain a corrected shape difference, and the analysis target reference tire model is obtained using the distribution of the corrected shape difference. By creating multiple analysis target base tire models, which are finite element models, by giving deformation to
Creating a trial tire model, which is a finite element model, by linearly adding deformation amounts from the analysis target reference tire model for each of the generated analysis target base tire models, and the procedure is performed by a computer. To execute.

  According to the tire model creation method, tire cross-section shape determination method, tire model creation apparatus, tire cross-section shape determination apparatus, and program described above, the tire cross-section has consistent characteristics beyond the tire cross-section shape even if the tire cross-section shape is different. An optimized tire cross-sectional shape having a shape can be obtained.

It is a block diagram which shows the structure of the tire cross-sectional shape determination apparatus which implements the tire model creation method of this embodiment, and also implements the tire cross-sectional shape determination method of this embodiment. (A) And (b) is profile sectional drawing of an example of the reference | standard tire model and analysis object reference | standard tire model which are used by this embodiment. (A) And (b) is profile sectional drawing of an example of the deformation | transformation tire model which deform | transformed the tire cross-sectional shape of the reference | standard tire model of this embodiment, (c) And (d) is an analysis object base tire model. It is profile sectional drawing of an example. (A)-(c) is a figure explaining deformation | transformation of a tire cross-sectional shape, (d) And (e) is a figure which shows the example of distribution of deformation amount with respect to the peripheral length on a tire model outer peripheral surface. is there. (A) And (b) is a figure explaining the analysis object base tire model of this embodiment. It is a figure explaining the method of creating a trial tire model from the analysis object base tire model of this embodiment. It is a figure explaining the flow of the tire section shape determination method of this embodiment. (A) And (b) is a figure which shows the example of the result of having visualized the correspondence of the parameter which characterizes the tire cross-sectional shape in this embodiment, and the characteristic value of a tire.

  Hereinafter, a tire model creation method, a tire cross-sectional shape determination method, a tire model creation device, a tire cross-sectional shape determination device, and a program according to the present embodiment will be described based on the embodiments shown in the accompanying drawings. The tire model creation method of this embodiment is used as a part of the tire cross-sectional shape determination method of this embodiment.

(Outline of this embodiment)
In general, a tire product having a plurality of tire sizes is desired to have an optimized tire cross-sectional shape having consistent characteristics in the tire cross-sectional shape beyond the tire size. The optimized tire cross-sectional shape is optimized by creating a plurality of trial tire models by the finite element method and performing simulation calculation so that the determined tire performance satisfies the target condition. However, since optimization of the tire cross-sectional shape is performed using different reference tire models for each tire size, there may be cases where the characteristics of the optimized tire cross-sectional shape do not have consistent features independent of the tire size. . For example, when the tire width is 175 size, the tire cross-sectional shape having the largest tire width is the optimized tire cross-sectional shape, and when the tire width is 225 size, the tire cross-sectional shape having the small tread width is the optimized tire cross-sectional shape. There is. On the other hand, in the present embodiment, an optimized tire cross-sectional shape having consistent characteristics in the tire cross-sectional shape exceeding the tire size can be determined. Moreover, this embodiment is applicable also when a tire cross-sectional shape differs in addition to a tire size. Two tires having different tire cross-sectional shapes often have different peripheral lengths of the entire tire outer peripheral surface or a part of the tire outer peripheral surface of the tire cross-sectional shape. Note that the difference in tire cross-sectional shape includes a difference in tire size.

More specifically, a reference tire model, which is a finite element model of a reference tire having a tire structure with a certain tire size, is created, and a tire cross-sectional shape in which the tire cross-sectional shape of the reference tire model is deformed from the reference tire model. A plurality of modified tire models, which are finite element models, are defined. Using this modified tire model, a trial tire model is created by a finite element method from an analysis target reference tire model having a tire cross-sectional shape different from that of the reference tire. At this time, a distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model is obtained. Further, in each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the shape difference is the peripheral length of the corresponding section of the created analysis target reference tire model. The corrected shape difference is obtained by expanding or compressing the peripheral length for each section in the distribution of the shape difference so as to match the above. A plurality of analysis target base tire models, which are finite element models, are created by deforming the analysis target reference tire model using the distribution of the corrected shape difference.
Finally, a trial tire model, which is a finite element model, is created by linearly adding the deformation amounts of the created base tire models to be analyzed. The trial tire model is used to optimize the tire cross-sectional shape.

(Tire cross-sectional shape determination device)
FIG. 1 is a block diagram illustrating a configuration of a tire cross-sectional shape determining apparatus according to the present embodiment. The tire cross-sectional shape determining device of the present embodiment includes the tire model creating device of the present embodiment, and executes a tire model creating method and a tire cross-sectional shape determining method.

A tire cross-sectional shape determining device (hereinafter simply referred to as a device) 10 according to the present embodiment is configured by a computer.
The device 10 is a computer having a CPU 12, a memory 14, an input / output unit 16, and a bus 17. The input / output unit 16 is connected to an input operation device 18 such as a mouse or a keyboard and an output device 20 such as a printer or a display. The memory 14 stores a program for executing the tire model creation method and the tire cross-sectional shape determination method of the present embodiment, and the apparatus 10 is constructed by calling and starting this program. The processing module 22 is formed in the apparatus 10 when the apparatus 10 calls and executes the program. Each part of the processing module 22 is a software module that causes the CPU 12 to perform substantial calculations. Therefore, the processing module 22 is a part functionally formed via the CPU 12, the memory 14, the input / output unit 16, and the bus 18.
The processing module 22 includes a model creation unit 24, a modified tire model setting unit 26, an analysis target base tire model creation unit 28, a trial tire model creation unit 30, an evaluation unit 32, and a determination unit 34.
A tire model creation device that creates a trial tire model includes a model creation unit 24, a modified tire model setting unit 26, an analysis target base tire model creation unit 28, and a trial tire model creation unit 30.

  The model creation unit 24 creates a reference tire model and an analysis target reference tire model, which are finite element models, reproducing a reference tire and an analysis target reference tire having different tire cross-sectional shapes. The difference in tire size, which is one form with different tire cross-sectional shapes, means that the length along the tire outer peripheral surface is different from the position of the center line on the tread surface to the bead tip position in the tire cross-sectional width direction. For example, when even one piece of information such as “225 / 60R15” such as tire width, flatness ratio, and rim diameter is different, the tire size is different. The analysis target reference tire model is a finite element model that can be simulated by a finite element method, including the position coordinates of nodes and elements, information on the nodes constituting the elements, and material constants of each element. . FIGS. 2A and 2B show tire cross-sectional shapes of an example of a reference tire model 40 and an analysis target reference tire model 42 that are created by the model creating unit 24 and have different tire cross-sectional shapes including tire sizes. It is shown. The created reference tire model 40 and analysis target reference tire model 42 are stored in the memory 14. Note that the reference tire model and the analysis target reference tire model may not be able to perform simulation calculation because the material constant of each element is not given. In this case, the material constant of each element is preferably given immediately before the simulation calculation.

  The modified tire model setting unit 26 determines a plurality of modified tire models having a tire deformed shape in which the tire cross-sectional shape of the reference tire model 40 is deformed from the reference tire model 40 which is a finite element model. The mesh division structure of the modified tire model is the same as the mesh division structure of the reference tire model 40. The tire deformed shape information is stored in the memory 14, and the deformed tire model setting unit 26 calls the tire deformed shape information from the memory 14 to create a deformed tire model. Alternatively, the reference tire model 40 is subjected to eigenvalue analysis of the reference tire model 40 when a material constant is given so that simulation calculation by the finite element method is possible, and there is a difference in deformation shape in the tire cross-sectional shape. A plurality of natural vibration mode deformation shapes can be used as tire deformation shapes. Such a deformed shape of the natural vibration mode is output to the output device 20. The operator may appropriately select the natural vibration mode from the plurality of output natural vibration modes. 3A and 3B show examples of cross-sectional shapes of the modified tire models 1 and 2 obtained from the reference tire model 40. FIG. The modified tire model 1 shown in FIG. 3A has a deformed shape having a larger tire maximum width than the reference tire model 40. The deformed tire model 2 shown in FIG. 3B has a deformed shape having a larger tread width than the reference tire model 40. Thus, the modified tire model setting unit 26 creates a plurality of modified tire models including the modified tire models 1 and 2. The created tire deformation tire model is stored in the memory 14. Hereinafter, a plurality of modified tire models including the modified tire models 1 and 2 are referred to as a modified tire model 44.

  The analysis target base tire model creation unit 28 obtains a distribution of shape differences representing the difference in shape between each of the modified tire models 44 and the reference tire model 40. The shape difference is obtained by subtracting the value of the position coordinate of the node on the tire outer peripheral surface of the reference tire model 40 from the value of the position coordinate of the node on the outer peripheral surface of the modified tire model 44 to obtain the movement distance between the nodes. The amount of deformation between corresponding nodes can be obtained. Further, the analysis target base tire model creation unit 28 determines that the peripheral length for each section used for the distribution of the obtained shape difference in each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape is the model creation unit 24. The corrected shape difference is obtained by expanding or compressing the peripheral length for each section in the distribution of the shape difference so as to coincide with the peripheral length of the corresponding section of the analysis target reference tire model 42 created in the above. The analysis target base tire model creation unit 28 further deforms the analysis target reference tire model 42 by using the obtained distribution of the corrected shape difference, so that the analysis target base tire model 46 (FIG. 3). (See (c) and (d)).

FIGS. 3C and 3D show tire cross-sectional shapes of base tire models 1 and 2 that are examples of the analysis target base tire model 46 created by the analysis target base tire model creation unit 28.
The base tire model 1 shown in FIG. 3 (c) is obtained from the modified tire model 1 shown in FIG. 3 (a), and the base tire model 2 shown in FIG. 3 (d) is shown in FIG. 3 (b). Is obtained from the modified tire model 2 shown in FIG.

  4 (a) to 4 (c) are diagrams for explaining the deformation of the tire, and (d) and (e) are diagrams showing an example of the distribution of the deformation amount with respect to the peripheral length on the outer peripheral surface of the tire model. . Specifically, FIG. 4A shows tire cross-sectional shapes of the reference tire model 40 and the modified tire model 44. The reference tire model 40 and the modified tire model 44 show an example in which the position in the tire radial direction of the point A2 that is the tire maximum width is the same, but the position in the tire cross-sectional width direction is different. When the shape difference, that is, the amount of deformation is given to the analysis target reference tire model 42 to create the analysis target base tire model 46, the peripheral length for each section of the plurality of sections in the distribution of the shape difference is set for each section. The modified shape difference is obtained by expanding or compressing the image. As a section, the region from the tire center line position C to the bead tip position C ′ is divided by a plurality of representative points on the tire outer peripheral surface that characterize a plurality of tire cross-sectional shapes. As shown in FIG. 4C, the representative points preferably include a point C2 having the maximum tire width and a point C1 at the end in the tire cross-sectional width direction in the arrangement region of the tread rubber. Note that the point C1 is also a point at which the sector mold and the side mold are divided. The point C2 having the maximum tire width and the point C1 at the end in the tire cross-sectional width direction in the arrangement region of the tread rubber play a large role in characterizing the tire cross-sectional shape. The point C1 at the end in the tire cross-sectional width direction in the tread rubber arrangement region is also the mold division position of the tread portion and the side portion. The point C1 at the end of the tread rubber arrangement region in the tire cross-sectional width direction determines the width of the tread portion and can further characterize the degree of curvature (curvature) of the tread portion. The point C2 having the maximum tire width can characterize the swelling of the side portion. The width of the tread, the degree of curvature (curvature) of the tread, or the bulge of the side are tire performance including rolling resistance, wear characteristics, belt durability, drainage, vibration ride comfort, noise, and steering stability. It has a big influence on.

  At this time, the analysis target base tire model creation unit 28 determines that the peripheral length for each section used for the distribution of the shape difference in each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape is the analysis target reference tire model. The corrected shape difference is obtained by expanding or compressing the peripheral length for each section in the distribution of shape differences so as to match the peripheral length of the corresponding section of 42. The squares in FIG. 4D indicate the distribution of the deformation amount, which is the distribution of the difference in shape between the reference tire model 40 and the modified tire model 44. Specifically, the amount of displacement in the tire cross-sectional width direction calculated from the position coordinates between corresponding nodes in the tire model is plotted on the graph along the peripheral length from the point A that is the center line position of the reference tire model 40. The distribution plotted in. In FIG. 4D, Δ indicates the bead tip position B ′ (FIG. 4B) from the center line point B (see FIG. 4B) without expanding or compressing the length of the peripheral for each section. The difference in shape obtained by compressing or expanding the distribution of the shape difference, that is, the distribution of the deformation amount, so that the peripheral length up to (see)) matches the length of the peripheral on the tire outer peripheral surface of the reference tire model 42 to be analyzed. The distribution of is shown. When such a shape difference is given to the analysis target reference tire model 42, as shown in FIG. 4B, the position in the tire radial direction of the point having the maximum tire width of the deformed tire cross-sectional shape is the analysis target reference tire. Compared with the position in the tire radial direction of the point having the maximum tire width of the model 42, the position in the tire radial direction does not match. In this case, the difference in the tire cross-sectional shape gives a difference in the tire characteristics, and the position in the tire radial direction at the point having the maximum tire width is the same as shown in FIG. Since the deformation | transformation from which the position of is not expressing is not preferable. For this reason, the analysis target base tire model creation unit 28 determines the peripheral length for each section in the distribution of the shape difference so that the peripheral length for each section matches the peripheral length for the corresponding section of the analysis target reference tire model 40. The length is expanded or compressed for each section to obtain a corrected shape difference.

The section is, for example, a section between a point C at the position of the tire center line and a point C1 at the end in the tire cross-section width direction in the tread rubber arrangement area, and a tire cross-section width in the tread rubber arrangement area. It is preferable to include a section between the point C1 at the end of the direction and the point C2 having the tire maximum width and a section between the point C2 having the tire maximum width and the bead tip position C ′. The problem that the position in the tire radial direction of the point having the maximum tire width as shown in FIG. 4B is shifted is that the distribution of the corrected shape difference is obtained by compressing or expanding the peripheral length for each section described above. It can be solved by seeking. For example, as shown in FIG. 4C, the position in the tire radial direction of the point C2 having the maximum tire width in the analysis target reference tire model 42 is the distribution of the corrected shape difference for each section, and the analysis target reference tire model. 42 corresponds to the position in the tire radial direction of the point C2 having the maximum tire width in the analysis target base tire model obtained by giving to 42. The circles in FIG. 4 (e) correspond to the section (point A to point A1, point A1 to point A2, point A2 to point A2) in the reference tire model 40 so as to correspond to the peripheral length for each section of the analysis target reference tire model 42. The distribution of the shape difference is corrected for each point A ′) to represent the distribution of the corrected shape difference. The square in FIG. 4E represents the distribution of the shape difference between the reference tire model 40 and the modified tire model 44, which is the same as the square in FIG. As described above, the distribution of the corrected shape difference represented by ◯ shown in FIG. 4E used in the present embodiment is different from the distribution shown by Δ in FIG. 4D. The analysis target base tire model creation unit 28 thus generates the tire cross-sectional shape of the analysis target base tire model 46 by giving the distribution of the corrected shape difference to the nodes on the outer peripheral surface of the analysis target reference tire model 42.
Note that the mesh division structure of the analysis target reference tire model 42 and the mesh division structure of the reference tire model 40 do not necessarily match, and the nodes on the tire outer peripheral surface of the analysis target reference tire model 42 are tires of the reference tire model 40. It may not always correspond to a node on the outer peripheral surface. In this case, the distribution of the obtained shape difference can be obtained once as a function by interpolating using linear approximation or curve approximation, and the correction difference distribution can be obtained using this function.

  When generating the tire cross-sectional shape of the analysis target base tire model 46, the analysis target base tire model creation unit 28 applies a forced displacement according to the distribution of the corrected shape difference to the nodes on the tire outer peripheral surface of the analysis target base tire model 46. It is preferable to generate the analysis target base tire model 46 by performing deformation calculation of the analysis target base tire model 46. Thereby, the information of the nodes inside the analysis target base tire model 46 and the nodes on the inner surface of the tire facing the tire cavity region can be obtained accurately. At this time, it is preferable that the Poisson's ratio of each element of the analysis target reference tire model 42 is set to a constant value of 0.1 or less, and constant values are given to the elastic constant and the mass density. In general, for example, 0.4999 is used as the Poisson's ratio of the element corresponding to the rubber in consideration of the incompressibility of the rubber. However, in the deformation calculation of the base tire model 46 to be analyzed, a deformation result is appropriately obtained. As described above, each element (all elements) of the analysis target reference tire model 42 is a compression element, and the Poisson's ratio is, for example, 0.01. Further, the elastic constant including Young's modulus and shear rigidity of each element (all elements) is set to, for example, 1/10 or less, preferably 1/100 or less, with respect to the values used in the simulation calculation of the tire performance. Similarly, the mass density is set to, for example, 1/100 or less, preferably 1/1000 or less. In this way, by performing the deformation calculation using the analysis target reference tire model 42 using the elastic physical constant that is softer than the elastic constant used when calculating the tire performance simulation and using the virtual physical property value having compressibility. The tire cross-sectional shape of the tire outer peripheral surface has a shape of the tire outer peripheral surface in which the distribution of the corrected shape difference is added to the tire cross-sectional shape of the analysis target reference tire model 42 without adversely affecting the mesh division inside the tire model. . Here, the adverse effect on the mesh division means that the aspect ratio and distortion of the elements increase, and the calculation is likely to fail and the calculation accuracy is reduced.

FIGS. 5A and 5B are diagrams for explaining the analysis-target base tire model of the present embodiment. FIG. 5A unifies each element (all elements) of the analysis target reference tire model 42 with the same physical property values. Specifically, it has a compressibility, is very soft, has a very low mass density, has a Poisson's ratio of 0.01, and uses elastic constants including Young's modulus and shear stiffness in simulation calculations of tire performance. The value (actual rubber member value) is set to 1 / 100th of the value, and the mass density is 100,000 times the value used for the tire performance simulation calculation (actual rubber, steel and other tire component values). The result after deformation | transformation calculation of the analysis object reference | standard tire model 42 when set to the value of 1 is shown. As shown in FIG. 5A, the nodes inside the tire model are arranged in an orderly manner without being disturbed. FIG. 5B shows the result after deformation calculation of the analysis target reference tire model 42 using the commonly used Poisson's ratio and material constant values. As shown in FIG.5 (b), the node inside a tire model is disordered and the element has an irregular shape. Thus, in the present embodiment, each element (all the analysis target reference tire model 42) is obtained in that the analysis target base tire model 46 generated by the deformation calculation of the analysis target reference tire model 42 is obtained as an appropriate tire model. It is preferable to set the Poisson's ratio of the element) to a constant value of 0.1 or less, and to give a constant value to the elastic constant and mass density of each element.
The deformation applied to the analysis target reference tire model 42 can also be obtained by performing a deformation calculation by applying a forced displacement to the nodes on the tire inner peripheral surface in addition to the nodes on the tire outer peripheral surface of the analysis target reference tire model 42. . In this case, the distribution of the corrected shape difference is also given as a forced displacement to the nodes on the tire inner peripheral surface.

  In this way, the analysis target base tire model creation unit 28 analyzes the distribution of the corrected shape difference determined according to the modified tire model 44 for the type of the modified tire model 44 set by the modified tire model setting unit 26. The analysis target base tire model 46 is created. The created analysis target base tire model 46 is stored in the memory 14. At this time, the base tire model 46 to be analyzed is based on the position information of the nodes, the information of the elements constituted by the nodes, the Poisson's ratio of the tire constituent members, the elastic constants of the tire constituent members, the information on the mass density of the tire constituent members, etc. Since it is configured, these pieces of information are stored in the memory 14.

The trial tire model creation unit 30 calls a plurality of analysis target base tire models 46 stored in the memory 14 and linearly adds deformation amounts for each analysis target base tire model 46, so that the trial tire is a finite element model. Create a model. FIG. 6 is a diagram for explaining a method of creating a trial tire model from the analysis target base tire model of the present embodiment.
As shown in FIG. 6, when the analysis target base tire models 1 to N are generated, the trial tire model generation unit 30 determines the deformation amount of each model, that is, the analysis target reference of each analysis target base tire model 46. The trial tire model is obtained by multiplying the deformation amount from the tire model 42 by weighting coefficients α _{1 to} α _N , adding the multiplication results, and giving the deformation amount obtained by the addition to the analysis target reference tire model 42. create.
Note that set values are used as the weighting coefficients α _{1 to} α _N. For the weighting coefficients α _{1 to} α _N , for example, the levels may be assigned according to an experimental design such as Monte Carlo method, Latin hypersquare method, or quasi-random method, or the levels may be changed using orthogonal tables in the experimental design method. Also good. The values of the weighting coefficients α _{1 to} α _N are determined by the determination unit 34. It is preferable that the total sum of the values of the weighting coefficients alpha ₁ to? _N is always set to be 1.
In the trial tire model creation unit 30 of the present embodiment, the trial tire model is created by linearly adding the deformation amount for each analysis target base tire model 46. However, the position information of each node for each analysis base tire model 46 The trial tire model may be created by multiplying the value of the position coordinates by the weighting coefficients α _{1 to} α _N and accumulating them. In this case, it is preferable that the total sum of the values of the weighting coefficients alpha ₁ to? _N is always set to be 1.

The evaluation unit 32 evaluates the tire performance with respect to the tire cross-sectional shape of the trial tire model by performing a simulation calculation of the tire performance using the trial tire model created by the trial tire model creation unit 30. Tire performance includes, for example, tire rolling resistance, tread wear life, tread uneven wear, vibration ride performance, tire noise, belt durability, tire lateral spring constant (lateral stiffness) or longitudinal spring constant (longitudinal stiffness). ) And other tire characteristic values.
In addition, when the value of the virtual physical property is used for the element at the time of calculating the base tire model, the value of the actual tire constituent member such as rubber or steel is set as the material physical property of the element at the time of tire performance evaluation.

  The evaluation unit 32 has characteristic values in the tire performance preset by the input operation device 18, for example, natural frequency, longitudinal spring constant, transverse spring constant, front and rear spring constant, rolling resistance, interlaminar shear strain between belts, and predicted wear value. Alternatively, the value of the contact pressure when the tire contacts the ground is calculated by numerical calculation. These specific calculations are well-known methods and will not be described.

The determination unit 34 causes the evaluation unit 32 to evaluate the tire performance using the trial tire model created by changing the weighting coefficients α _{1 to} α _N used for the weighted addition performed in the trial tire model creation unit 30. The values of the weighting coefficients α _{1 to} α _N may be changed continuously within a predetermined domain or may be changed discretely.
The determination unit 34 assigns levels to the weighting coefficients α _{1 to} α _{N in} accordance with a known experimental design method, and assigns this value to each of the analysis target base tire models 46, so that the trial tire model creation unit 30 has the trial tire model. To create.

The determination unit 34 determines the tire cross-sectional shape design space as a response surface function using a curved surface approximation function based on the tire characteristic value obtained by the evaluation unit 32 for each created trial tire model. This response surface function uses the weighting coefficient as a design variable. That is, the response surface function is a tire characteristic value expressed using a curved surface approximation function with weighting coefficients α _{1 to} α _N used for weighted addition of deformation amounts as design variables. For example, by defining six weighting factors, one tire cross section is determined, and one evaluation value is obtained by a curved surface approximation function. Here, examples of the curved surface approximation function include Chebyshev's orthogonal polynomial, n-order polynomial, radial basis function method (RBF), Kriging method, and the like. Then, based on the obtained curved surface approximation function, for example, a heuristic method such as a multi-purpose genetic algorithm or a mathematical programming method such as a gradient method is used to optimize the tire cross-sectional shape, that is, a tire satisfying a set condition. A tire cross-sectional shape of a trial tire model having a characteristic value is searched.
The determining unit 34 performs a simulation calculation for obtaining a tire characteristic value using a plurality of trial tire models, so that at least one tire characteristic value satisfies a preset condition. Find the shape.

  The determination unit 30 thus determines a tire cross-sectional shape in which the tire characteristic value meets the preset condition. The preset condition is, for example, a range of tire characteristic values, a minimum value of tire characteristic values, or a maximum value of tire characteristic values.

In decision section 34, because it determines the optimal tire cross section by changing the weighting coefficients alpha ₁ to? _N, by extracting the weighting coefficients alpha ₁ to? _N of characteristic values of the tire satisfies the condition, optimization The tire cross-sectional shape can be easily obtained.

  The obtained information on the optimized tire cross-sectional shape is output to the output device 20, and is also sent to a CAD system or the like that creates a tire vulcanization mold (not shown). Alternatively, the optimum tire cross-sectional shape obtained is stored in the memory 14 as information on the tire cross-sectional shape at the time of tire deflation or as information on the cross-sectional shape of the in-mold tire, and is further stored in a hard disk or recording medium (not shown). To be recorded.

In the present embodiment, the trial tire model creation unit 30 creates a plurality of trial tire models using the weighting coefficients α _{1 to} α _N determined by the determination unit 34, but the determination unit 34 obtains the evaluation unit 32. Trial tire models can be created one by one while changing the weighting coefficients α _{1 to} α _N in accordance with the characteristic values of the obtained tires. That is, the trial tire model creation unit 30 creates one trial tire model by changing the weighting coefficients α _{1 to} α _N , and the evaluation unit 32 obtains a tire evaluation value for the created trial tire model. Depending on the value, the determination unit 34 can also change the previously determined weighting coefficients α _{1 to} α _N. Accordingly, while constantly change the weighting coefficients alpha ₁ to? _N, the preset condition can be found by searching the weighting coefficients alpha ₁ to? _N, such as characteristic values of the tire satisfactory.

(Tire cross-sectional shape determination method)
FIG. 7 is a diagram illustrating the flow of the tire cross-sectional shape determination method of the present embodiment.
First, the model creation unit 24 creates a reference tire model 40 that is a finite element model that reproduces the reference tire, and the modified tire model setting unit 26 has a finite shape having a tire cross-sectional shape obtained by deforming the tire cross-sectional shape of the reference tire. A modified tire model 44, which is an element model, is set (step S10). The reference tire model 40 is a tire model that can be simulated by a finite element method. In the case where the eigenvalue analysis shown below is not performed, a tire model that does not include the material constants of each element and that simply defines a mesh division structure may be used. The tire model may be created by the model creation unit 24 based on information input and set by the operator using the input operation device 18, or by combining each information stored in the memory 14, the model creation unit 24 may be created.
The modified tire model setting unit 26 sets a plurality of types of modified tire models 44 having different tire cross-sectional shapes. The modified tire model 44 is set by calling the tire sectional shape stored in the memory 14 as the tire sectional shape of the modified tire model and creating a tire model having this tire sectional shape. Alternatively, the eigenvalue analysis of the reference tire model 40 is performed, the tire cross-sectional shape of the natural vibration mode having a different deformed shape is set as the tire cross-sectional shape of the deformed tire model 44, and the tire model having the tire cross-sectional shape is created. A tire model can be set. In this case, the material constant of the reference tire model 40 is set to a constant small value without distinction between a portion made of metal such as a belt constituent member or a bead core and a portion made of rubber material such as tread rubber or side rubber. It is preferable to do. The created modified tire model 44 is given the material constants of the actual tire components. Alternatively, a plurality of tire models that are finite element models having different tire cross-sectional shapes stored in the memory 14 can be called and set as the modified tire model 44.

  Further, the model creation unit 24 creates an analysis target reference tire model 42 (step S12). The analysis target reference tire model 42 is a finite element tire model obtained by modeling an analysis target reference tire having a tire cross-sectional shape different from that of the reference tire. Similar to the reference tire model 40, the analysis target reference tire model 42 is a tire model that can be simulated by a finite element method. The mesh division structure of the analysis target reference tire model 42 may not match the mesh division structure of the reference tire model 40. Matching mesh division structure means that the position coordinates of the nodes may be different, but the elements constituted by the nodes correspond to each other. Each information of the created analysis target reference tire model 42 is stored in the memory 14.

Next, the analysis target base tire model creation unit 28 creates a plurality of analysis target base tire models 46 (step S16).
Specifically, the analysis target base tire model creation unit 28 first obtains a distribution of shape differences representing the shape difference between each of the modified tire models 44 created in step S10 and the reference tire model 40. FIG. 4E shows an example of the distribution of the shape difference by the symbol ◯. The section includes a region extending from the position of the tire center line (the position of point C in the example of FIG. 4C) to the bead tip position (the position of point C ′ in the example of FIG. 4C). It is preferable that the tire is sectioned by representative points on the tire outer peripheral surface that characterize the tire cross-sectional shape. More specifically, the representative point is a point having the maximum tire width (point C2 in the example of FIG. 4C) and a point at the end in the tire cross-sectional width direction in the arrangement region of the tread rubber (see FIG. In the example of 4 (c), it is preferable to include the point C1).
Next, the analysis target base tire model creation unit 28 determines that the peripheral length for each section used for the distribution of the obtained shape difference in each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape is the analysis target criterion. The corrected shape difference is obtained by expanding or compressing the peripheral length for each section in the distribution of the shape difference so as to coincide with the peripheral length of the corresponding section of the tire model 42.
Further, the analysis target base tire model creation unit 28 creates a plurality of analysis target base tire models 46, which are finite element models, by deforming the analysis target reference tire model 42 using the obtained distribution of the corrected shape difference. To do.
At this time, the deformation applied to the analysis target reference tire model 42 applies a forced displacement to the nodes on the tire outer peripheral surface of the analysis target reference tire model 42, or the nodes on the tire outer peripheral surface and the nodes on the tire inner peripheral surface. It is preferable to obtain a tire model efficiently by applying a forced displacement to the tire and performing deformation calculation.
Further, when the deformation calculation is performed, the Poisson's ratio of each element of the analysis target reference tire model 42 is set to a constant value of 0.1 or less, and constant values are given to the elastic constant and the mass density as shown in FIG. ) Is preferable in that the positions of the nodes inside the tire model are arranged orderly without being disturbed. The created plurality of analysis target base tire models 46 are stored in the memory 14.

Next, the trial tire model creation unit 30 creates a trial tire model using the plurality of analysis target base tire models 46 (step S16). Specifically, the trial tire model creation unit 30 calls a plurality of analysis target base tire models 46 stored in the memory 14, and linearly adds the deformation amount for each analysis target base tire model 46, thereby providing a finite element. Create a trial tire model that is a model. As shown in FIG. 6, when the analysis target base tire models 1 to N are generated, the trial tire model creation unit 30 determines the deformation amount of each model, that is, the deformation amount from the analysis target reference tire model 42, Is multiplied by weighting coefficients α _{1 to} α _N , the multiplication results are added, and the deformation amount obtained by the addition is added to the analysis target reference tire model 42 to create a trial tire model. As the weighting coefficients α _{1 to} α _N , set values are used. For the weighting coefficients α _{1 to} α _N , for example, the levels may be assigned according to an experimental design such as a Monte Carlo method, a Latin hypersquare method, or a quasi-random number method, or may be assigned using an orthogonal table. The values of the weighting coefficients α _{1 to} α _N are determined by the determination unit 34 and sent to the trial tire model creation unit 30.
While analyzed base tire model is fixed, since the weighting factor alpha ₁ to? _N attempts tire model is created by varying the pair is a set of trial tire model and the weighting factor alpha ₁ to? _N Corresponding to one.

  Next, the evaluation unit 32 performs a tire simulation calculation using the created trial tire model to evaluate the tire performance (step S18). The evaluation unit 32 is a characteristic value in a preset tire performance, such as a natural frequency, a longitudinal spring constant, a transverse spring constant, a longitudinal spring constant, a rolling resistance, an interlaminar shear strain between belts, a predicted wear value, or a tire The value of contact pressure when touching the ground is calculated by numerical calculation. The calculation result is stored in the memory 14. The evaluation unit 32 determines whether or not simulation calculation has been performed for all the created trial tire models (step S20). When the result of the determination is negative (when it is No), the evaluation unit 32 returns to Step S18 and performs simulation calculation of a trial tire model that has not yet been calculated by simulation. Thus, steps S18 and S20 are repeated until all of the created trial tire models are calculated by simulation and tire characteristic values are obtained.

Next, the determination unit 34 retrieves the tire characteristic values of the trial tire model from the memory 14, and uses these tire characteristic values to search for weighting coefficients α _{1 to} α _N that satisfy the conditions of the tire characteristic values. To do. Thereby, the determination part 34 extracts the optimized tire cross-sectional shape that a tire characteristic value satisfies conditions (step S22).
The determination unit 34 determines the tire cross-sectional shape design space as a response surface function using a curved surface approximation function based on the tire characteristic value obtained by the evaluation unit 32 for each created trial tire model. This response surface function uses the weighting coefficients α _{1 to} α _N as design variables. For example, by defining six weighting factors α _{1 to} α _N , one tire cross section is determined, and one evaluation value of tire performance is obtained by a curved surface approximation function. Based on this defined curved surface approximation function, for example, using an evolutionary calculation method such as a multi-objective genetic algorithm or a mathematical programming method such as a gradient method, the tire cross-sectional shape optimized, that is, the characteristics of a tire that satisfies the set conditions A tire cross-sectional shape of a trial tire model having a value is searched.
Note that the determination unit 34 determines the tire characteristics obtained using one trial tire model instead of the method of extracting the optimized tire cross-sectional shape using the response surface function created using a plurality of trial tire models. Based on the values, optimization is performed while successively creating trial tire models with tire cross-sectional shapes improved using evolutionary calculation methods such as multi-purpose genetic algorithms so that the tire characteristic values satisfy the set conditions The tire cross-sectional shape can also be extracted.
That is, the determination unit 34 creates a response curved surface from the tire characteristic value of the trial tire model and a method of extracting the optimized tire cross-section shape while sequentially creating the trial tire model having the improved tire cross-section shape, Both methods of extracting the modified tire cross-sectional shape are provided. The operator can select one of two methods using the input operation device 18 in advance. The extracted optimized tire cross-sectional shape is not limited to one. For example, when there are a plurality of target characteristics, all or a part of the Pareto solution may be extracted.

Thus, the determination unit 34 can extract the optimized tire cross-sectional shape, but it is preferable to display the search process for the optimized tire cross-sectional shape on the output device 20. That is, it is preferable that the determination unit 34 visualizes and displays the correspondence relationship between the parameter characterizing the tire cross-sectional shape obtained when finding the optimized tire cross-sectional shape and the characteristic value of the tire. The above parameters include weighting coefficients α _{1 to} α _N , a point having the maximum tire width, and a point of a division position of the sector mold and the side mold, for example, on the tire outer peripheral surface in the arrangement region of the tread rubber. It is preferable to include dimensional information characterizing the shape, such as the end point in the tire cross-sectional width direction, the tire outer diameter, and the radius of curvature of the tread center portion.
FIGS. 8A and 8B are diagrams showing the relationship between the values of the weighting coefficients α ₁ and α ₂ and the tire characteristic values. Such sets of weighting coefficients α ₁ and α ₂ and tire characteristic values are obtained in the process of searching for an optimized tire cross-sectional shape. In FIG. 8 (a), regardless of the value of the weighting factor alpha _1, changes in the characteristic values of the tire is shown to be smaller, in FIG. 8 (b), as the value of the weighting coefficient alpha ₂ is large, the characteristics of the tire The value is shown to decrease. From this, the operator who sees the screen display, whether the value of the weighting coefficient α ₂ that satisfies the predetermined condition of the tire is larger is more desirable, smaller is more desirable, or a certain predetermined value. You can see the trend of the better the closer you are. Thus, the screen display allows the operator to know which parameter affects the characteristic value among the parameters characterizing the tire cross-sectional shape, and uses this knowledge as a guideline for tire design. be able to.

(program)
The tire cross-sectional shape determination method can be realized by starting a program with a computer. Such a program includes the following procedures. That is, a computer-readable program that causes a computer to execute the following procedure,
(A) A procedure for determining a plurality of modified tire models 44 having a tire deformation shape in which the tire cross-sectional shape of the reference tire model 40 is deformed from the reference tire model 40 which is a finite element model;
(B) a procedure of creating a reference tire model 42 to be analyzed, which is a finite element model, in which the tire cross-sectional shape of the reference tire model 40 is different from the tire cross-sectional shape;
(C) a procedure for obtaining a distribution of shape differences representing a difference in shape between each of the modified tire models 44 and the reference tire model 40;
(D) In each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the obtained shape difference is the peripheral length of the section corresponding to the analysis target reference tire model The peripheral length of each section in the distribution of shape differences is expanded or compressed for each section to obtain a corrected shape difference, and the analysis target reference tire model 42 is used using the obtained distribution of the corrected shape difference. A procedure for creating a plurality of analysis target base tire models 46, which are finite element models, by giving deformation to
(E) A procedure for creating a trial tire model, which is a finite element model, by linearly adding deformation amounts for each created base tire model 46 to be analyzed.

further,
(F) A plurality of trial tire models are created by causing the computer to linearly add the deformation amounts of the plurality of analysis target base tire models created in steps (A) to (E) while changing the weighting coefficient. Procedure and
(G) Optimization in which at least one tire characteristic value satisfies a preset condition by causing a computer to perform simulation calculation for obtaining the tire characteristic value using a plurality of trial tire models Preferably having a computer to find the tire cross-sectional shape.

  In the tire model creation method according to the present embodiment, the distribution of the shape difference between the reference tire model 40 and the modified tire model 44 is determined so that the peripheral length in each section of the plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape is as follows. Then, a corrected shape difference is obtained by expansion or compression so as to match the peripheral length of the corresponding section of the analysis target reference tire model, and the analysis target base tire model 46 is created using the distribution of the corrected shape difference. . For this reason, even if the tire cross-sectional shape is different, an optimized tire cross-sectional shape having consistent characteristics in the tire cross-sectional shape beyond the tire cross-sectional shape can be obtained. Therefore, the optimized tire cross-sectional shape obtained in this embodiment can balance the same tire characteristics among tire sizes, so that it is made into a series that is sold under one product name beyond the tire size. It is used suitably for the used tire.

  In addition, as a plurality of sections characterizing the tire cross-sectional shape, the sections from the tire center line position to the bead tip position are divided by representative points on the tire outer peripheral surface that characterize the plurality of tire cross-sectional shapes. Thus, an optimized tire cross-sectional shape that satisfies the conditions set by the tire characteristic values can be effectively obtained. In particular, the representative points include the point C2 having the maximum tire width and the point C1 at the end in the tire cross-sectional width direction on the tire outer peripheral surface in the arrangement region of the tread rubber. Can be obtained effectively.

In the present embodiment, in order to obtain the analysis target base tire model 46, a forced displacement is applied to the nodes on the tire outer peripheral surface of the analysis target reference tire model 42, or the nodes on the tire outer peripheral surface and the tire inner periphery It is preferable to apply a forced displacement to the nodes on the surface and perform the deformation calculation from the viewpoint of easily obtaining the tire cross-sectional shape reflecting the distribution of the corrected shape difference.
Further, when the deformation calculation of the analysis target reference tire model 42 is performed, the Poisson's ratio of each element of the analysis target reference tire model 42 is set to a constant value of 0.1 or less, and the elastic constant and the mass density of each element are fixed values. Is preferable in that the position of the node inside the tire model is not disturbed.

  Further, a plurality of trial tire models are created by linearly adding the deformation amounts of the analysis target base tire models 46 while changing the weighting coefficients, and tire characteristic values are obtained using the plurality of trial tire models. By performing the simulation calculation, an optimized tire cross-sectional shape in which at least one or more tire characteristic values satisfy a preset condition can be efficiently found by a computer.

  The tire model creation method, tire cross-section shape determination method, tire model creation device, tire cross-section shape determination device, and program according to the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and Various improvements and changes may be made without departing from the spirit of the invention.

10 Tire cross-sectional shape determining device 12 CPU
14 Memory 16 Input / output unit 17 Bus 18 Input operation device 20 Output device 22 Processing module 24 Model creation unit 26 Modified tire model setting unit 28 Analysis target base tire model creation unit 30 Trial tire model creation unit 32 Evaluation unit 34 Determination unit 40 Standard Tire model 42 Analysis target reference tire model 44 Deformed tire model 46 Analysis target base tire model

Claims (11)

A step of determining a plurality of modified tire models having a tire deformed shape obtained by deforming a tire cross-sectional shape of the reference tire model from a reference tire model that is a finite element model reproducing the reference tire;
Creating an analysis target reference tire model, which is a finite element model that reproduces an analysis target reference tire having a tire cross-sectional shape different from that of the reference tire;
Obtaining a shape difference distribution representing a difference in shape between each of the modified tire models and the reference tire model;
In each section of the plurality of sections on the outer circumferential surface of the tire characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the shape difference matches the peripheral length of the corresponding section of the reference tire model to be analyzed As described above, the peripheral length of each section in the distribution of the shape difference is expanded or compressed for each section to obtain a corrected shape difference, and the analysis target reference tire model is obtained using the distribution of the corrected shape difference. Creating a plurality of analysis target base tire models, which are finite element models, by giving deformation to
Creating a trial tire model that is a finite element model by linearly adding a deformation amount from the analysis target reference tire model for each of the generated analysis target base tire models,
A step of determining a plurality of the modified tire models, a step of generating the analysis target reference tire model, a step of obtaining a distribution of the shape difference, a step of generating a plurality of analysis target base tire models, and the trial tire model. A tire model creating method characterized by executing the creating step .   The plurality of sections characterizing the tire cross-sectional shape are sections divided by a plurality of representative points on the tire outer peripheral surface, characterized by a tire cross-sectional shape, in a region between a tire center line position and a bead tip position. The tire model creation method according to claim 1, wherein:   The tire model creation method according to claim 2, wherein the representative points include at least a point having a maximum tire width and a point at an end portion in a tire cross-sectional width direction on the tire outer peripheral surface in a tread rubber arrangement region. . The analysis target base tire model is obtained by applying a forced displacement to a node on a tire outer peripheral surface of the analysis target reference tire model, and the computer performs deformation calculation according to any one of claims 1 to 3. The tire model creation method described. The analyzed base tire model, the computer, deformation calculation gives forced displacement the analyzed reference tire model nodes on the circumference surface tire, or to a node on the node and the tire outer peripheral surface on the inner circumferential surface of the tire The tire model creation method according to any one of claims 1 to 3, which is obtained by performing the steps.   When the deformation calculation of the analysis target reference tire model is performed, the Poisson's ratio of each element of the analysis target reference tire model is set to a constant value of 0.1 or less, and the elastic constant and mass density of each element are fixed values. The tire model creation method according to claim 4 or 5, wherein a virtual physical property value is given. The amount of deformation from the analysis target reference tire model of each of the analysis target base tire models created by the tire model creation method according to any one of claims 1 to 6 is linearly added by changing a weighting coefficient. Creating a plurality of trial tire models,
A step of finding an optimized tire cross-sectional shape in which at least one tire characteristic value satisfies a preset condition by performing a simulation calculation to obtain a tire characteristic value using the plurality of trial tire models and, the possess,
A tire cross-sectional shape determination method , wherein a computer executes the steps of creating the plurality of trial tire models and finding the optimized tire cross-sectional shape . Furthermore, the computer, and parameters characterizing the tire cross-sectional shape obtained when finding the optimization tire cross-sectional shape, having a step, which causes the screen display to visualize the relationship between the characteristic values of the tire, in claim 7 The tire cross-sectional shape determination method described. A model creating unit that creates a reference tire model that is a finite element model that reproduces a reference tire, and a reference tire model that is a finite element model that reproduces a reference tire that has a cross-sectional shape different from that of the reference tire.
From the reference tire model, a modified tire model setting unit for determining a plurality of modified tire models having a tire deformed shape in which a tire cross-sectional shape of the reference tire model is deformed,
A distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model is obtained, and the distribution of the shape differences in each of a plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape. The peripheral length for each section in the distribution of the shape difference is set for each section so that the peripheral length for each section used for the same matches the peripheral length of the corresponding section of the reference tire model to be analyzed. Analyzing object to create a plurality of analysis target base tire models, which are finite element models, by obtaining a corrected shape difference by stretching or compressing, and using the distribution of the corrected shape difference to deform the analysis target reference tire model A base tire model creation unit;
A tire model creation device comprising: a trial tire model creation unit that creates a trial tire model that is a finite element model by linearly adding deformation amounts of the created base tire models to be analyzed. A model creating unit that creates a reference tire model that is a finite element model that reproduces a reference tire, and a reference tire model that is a finite element model that reproduces an analysis target reference tire having a tire cross-sectional shape different from the reference tire;
From the reference tire model, a modified tire model setting unit for determining a plurality of modified tire models having a tire deformed shape in which a tire cross-sectional shape of the reference tire model is deformed,
A distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model is obtained, and the distribution of the shape differences in each of a plurality of sections on the tire outer peripheral surface characterizing the tire cross-sectional shape. The peripheral length for each section in the distribution of the shape difference is set for each section so that the peripheral length for each section used for the same matches the peripheral length of the corresponding section of the reference tire model to be analyzed. Analyzing object to create a plurality of analysis target base tire models, which are finite element models, by obtaining a corrected shape difference by stretching or compressing, and using the distribution of the corrected shape difference to deform the analysis target reference tire model A base tire model creation unit;
Trial tires that create a plurality of trial tire models by linearly adding the amount of deformation from the reference tire model to be analyzed of each of the plurality of base tire models to be analyzed using a computer while changing the weighting coefficient A model creation unit;
By performing a simulation calculation for obtaining a tire characteristic value using the plurality of trial tire models, an optimized tire cross-sectional shape in which at least one tire characteristic value satisfies a preset condition is found. And a tire cross-sectional shape determining device. A computer-readable program that causes a computer to execute a tire model creation method,
From a reference tire model that is a finite element model reproducing the reference tire, a procedure for determining a plurality of modified tire models having a tire deformation shape in which a tire cross-sectional shape of the reference tire model is deformed,
A procedure for creating an analysis target reference tire model, which is a finite element model reproducing an analysis target reference tire having a tire cross-sectional shape different from that of the reference tire,
A procedure for obtaining a distribution of shape differences representing a difference in shape between each of the modified tire models and the reference tire model;
In each section of the plurality of sections on the outer circumferential surface of the tire characterizing the tire cross-sectional shape, the peripheral length for each section used for the distribution of the shape difference matches the peripheral length of the corresponding section of the reference tire model to be analyzed As described above, the peripheral length of each section in the distribution of the shape difference is expanded or compressed for each section to obtain a corrected shape difference, and the analysis target reference tire model is obtained using the distribution of the corrected shape difference. By creating multiple analysis target base tire models, which are finite element models, by giving deformation to
Creating a trial tire model, which is a finite element model, by linearly adding deformation amounts from the analysis target reference tire model for each of the generated analysis target base tire models, and the procedure is performed by a computer. A program to be executed using.

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