JP2012025283A - Tire model preparation method, computer program for preparing tire model, tire simulation method, and device for preparing tire model - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce time for preparing an analysis model for evaluation of characteristics, performance, etc.SOLUTION: The tire model preparation method includes: a procedure (step S101) wherein a tire to be analyzed is divided into a plurality of elements and a first tire model is prepared; a procedure (step S102 to step S104) wherein the mass density and elastic modulus of the prepared first tire model are adjusted to set the natural frequency of the first tire model within a predetermined range; and a procedure (step S105) for preparing a second tire model wherein the tire to be analyzed is divided into a plurality of elements so that the circumferential division number may be larger than the first tire model to set mass density and elastic modulus to those when the natural frequency becomes within the predetermined range.

Description

  The present invention relates to a technique for creating a tire model used when executing tire vibration analysis using a computer.

  In order to shorten the tire development period and reduce the development cost, in recent years, a technique for evaluating the performance of the tire by simulation using a computer has been used. In this case, it is necessary to convert the tire into an analysis model that can be analyzed by a computer. Patent Document 1 describes a technique for modeling a composite formed by laminating a cord layer and a rubber layer by further reducing the number of elements and the number of nodes.

Japanese Patent No. 3892652

  It is important for the transient response and the vibration / noise performance to simulate the dynamic response of the tire caused by the input generated between the tire and the road surface due to the road surface unevenness and the tire pattern. At that time, in order to correctly calculate the input in the contact surface, an analysis model in which the number of divisions of the contact surface of the tire is made fine is necessary. When analyzing using such a model for analysis, preliminary analysis is performed and the physical property value of the material is set to an appropriate value. Preliminary analysis may be performed several times until a material property value of an appropriate value is obtained, but if the time required for one analysis is large, it takes time to set the material property value of the material, It took a lot of time to create an analysis model. The present invention has been made in view of such a problem, and an object thereof is to reduce the time for creating an analysis model for evaluating characteristics, performance, and the like.

  In order to solve the above-described problems and achieve the object, a tire model creation method according to the present invention includes a procedure in which a computer creates a first tire model by dividing a tire to be analyzed into a plurality of elements. The computer adjusts the mass density and elastic modulus of the first tire model to bring the natural frequency of the first tire model within a predetermined range, and the computer includes the first tire model. The tire is divided into a plurality of elements so that the number of divisions in the circumferential direction becomes larger, and the mass density and elastic modulus are determined when the natural frequency falls within the predetermined range. And a procedure for creating the second tire model.

  As a desirable mode of the present invention, when adjusting the mass density and the elastic modulus of the first tire model in a non-grounded state, the computer equalizes the division angles in the circumferential direction of the first tire model, and The number of divisions in the circumferential direction of the first tire model is preferably 6 times or more the highest order of the vibration mode.

  As a preferred aspect of the present invention, when the computer adjusts the mass density and the elastic modulus of the first tire model in a ground contact state, the computer calculates the number of divisions in the circumferential direction of the first tire model in the ground contact region. The absolute value of the difference in the division angle in the circumferential direction of the first tire model is within 10 degrees in the portion excluding the portion of the contact area, with the number of divisions in the circumferential direction of the second tire model being ½ or less. The ground contact area of the first tire model has a division number of 1 in the circumferential direction, and the total division number of the first tire model is at least six times the highest order of the vibration mode for adjusting mass density and elastic modulus. It is preferable to divide like this.

  As a preferred aspect of the present invention, the computer analyzes and models a meridional cross-sectional shape of the tire, a meridional cross-sectional shape of a cavity existing inside the tire, and a meridional cross-sectional shape of a rim to which the tire is attached. By developing the analysis model in the circumferential direction, the tire / the second tire model is attached to the rim model created from the rim, and the space surrounded by the second tire model and the rim model is an analysis model / It is preferable to create a rim assembly model.

  As a preferred aspect of the present invention, the computer may develop the second tire model by developing a meridional cross-sectional shape of the tire in a circumferential direction, and combine the second tire model with an analysis model of an elastic wheel. preferable.

  As a preferred aspect of the present invention, the computer analyzes the meridional cross-sectional shape of the tire and the shape of a cavity existing inside the tire, and develops the analytical model in the circumferential direction to thereby generate the second model. It is preferable to create a tire / cavity model having a tire model and the analytically modeled cavity, and to combine the tire / cavity model with an analytical model of an elastic wheel.

  In order to solve the above-described problems and achieve the object, a computer program for creating a tire model according to the present invention causes a computer to execute the tire model creating method.

  In order to solve the above-described problems and achieve the object, in the tire simulation method according to the present invention, a computer performs vibration analysis using the second tire model created by the tire model creation method. .

  In order to solve the above-described problems and achieve the object, a tire model creation device according to the present invention divides a tire to be analyzed into a plurality of elements to create a first tire model. And adjusting the mass density and elastic modulus of the first tire model to adjust the natural frequency of the first tire model within a predetermined range, and the circumferential direction more than the first tire model The tire is divided into a plurality of elements so as to increase the number of divisions in the second tire model, and a second tire model is created with the mass density and elastic modulus when the natural frequency falls within the predetermined range. And a model creation unit.

  According to the present invention, it is possible to reduce the time for creating an analysis model for evaluating characteristics, performance and the like in determining the vibration mode.

FIG. 1 is a meridional sectional view of a tire. FIG. 2 is an explanatory diagram showing a tire model creation device that executes the tire model creation method according to the present embodiment. FIG. 3 is a flowchart showing a procedure of a tire model creation method according to the present embodiment. FIG. 4 is a perspective view showing the first tire model. FIG. 5 is a cross-sectional view showing a meridional cross-sectional model for creating the first tire model. FIG. 6 is a schematic diagram showing division in the circumferential direction of the first tire model. FIG. 7 is a schematic diagram showing a state in which the first tire model is grounded. FIG. 8 is a schematic diagram showing a state in which the second tire model is grounded. FIG. 9 is a diagram showing a meridional section model of a rim. FIG. 10 is a diagram showing a meridional section model of a tire. FIG. 11 is a diagram illustrating a meridional section model of a cavity existing inside a tire to be analyzed. FIG. 12 is a diagram showing a tire / rim assembly model. FIG. 13 is a diagram showing a second tire model. FIG. 14 is a diagram showing an analytical model of a wheel. FIG. 15 is a diagram showing a tire / wheel assembly model. FIG. 16 is a diagram showing a tire / wheel / cavity model. FIG. 17 is a schematic diagram illustrating an example of a mode.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content of the form (henceforth embodiment) for implementing the invention demonstrated below. The following constituent elements include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

  FIG. 1 is a meridional sectional view of a tire. The tire 1 is an annular structure that rotates about a rotation axis (Y axis), and a meridional section having a similar shape is developed around the center axis in the circumferential direction. As shown in FIG. 1, a carcass 2, a belt 3, a belt cover 4, and a bead core 5 appear on the meridional section of the tire 1. The tire 1 is a composite material structure in which rubber as a base material is reinforced by a reinforcing cord such as a carcass 2, a belt 3 or a belt cover 4 as a reinforcing material. Here, the layer of the reinforcing cord made of a cord material such as metal fiber or organic fiber, such as the carcass 2, the belt 3, and the belt cover 4, is referred to as a cord layer.

  The carcass 2 is a strength member that serves as a pressure vessel when the tire 1 is filled with air. The carcass 2 supports a load by its internal pressure and withstands a dynamic load during traveling. The belt 3 is a layer of reinforcing cords in which rubberized cords arranged between the cap tread and the carcass 2 are bundled. In the case of a bias tire, it is called a breaker. In the radial tire, the belt 3 plays an important role as a shape retention and strength member.

  A belt cover 4 is disposed on the ground contact surface (tread) G side of the belt 3. The belt cover 4 is formed by arranging, for example, organic fiber materials in layers, and has a role as a protective layer for the belt 3 and a role as a reinforcing layer for the belt 3. The bead core 5 is a bundle of steel wires that supports the cord tension generated in the carcass 2 by internal pressure. The bead core 5 becomes a strength member of the tire 1 together with the carcass 2, the belt 3, the belt cover 4, and the tread. A groove 7 is formed on the ground surface G side of the cap tread 6. This improves drainage during rainy weather. The side portion of the tire 1 is called a sidewall 8 and connects between the bead core 5 and the cap tread 6. Further, a shoulder portion Sh is provided between the cap tread 6 and the sidewall 8. Next, an apparatus for executing the tire model creation method according to the present embodiment will be described.

  FIG. 2 is an explanatory diagram showing a tire model creation device that executes the tire model creation method according to the present embodiment. The tire model creation method according to the present embodiment can be realized by a tire model creation device (hereinafter referred to as a model creation device) 50 shown in FIG. The model creation device 50 is a computer and includes a processing unit 52 and a storage unit 54 as shown in FIG. In addition, an input / output device 51 is connected to the model creation device 50, and physical property values of rubber and reinforcing cords constituting a tire model as an analysis model by an input means 53 provided therein, or A boundary condition in vibration analysis, the number of vibration modes to be analyzed, and the like are input to the processing unit 52 and the storage unit 54.

  An input device such as a keyboard and a mouse can be used for the input means 53. The storage unit 54 stores a computer program that can realize the tire model creation method according to the present embodiment, other computer programs, a data table, a data map, and the like. The storage unit 54 is a hard disk device, a magneto-optical disk device, a non-volatile memory such as a flash memory (a storage medium that can be read only such as a CD-ROM), or a volatile memory such as a RAM (Random Access Memory). The memory can be configured by a combination of these, or a combination thereof.

  The tire model creation computer program capable of realizing the tire model creation method according to the present embodiment realizes the structure vibration mode discrimination method according to the present invention in combination with a computer program already recorded in the computer system. It may be possible. Also, the tire model creation computer program according to the present embodiment is recorded on a computer-readable recording medium, and the tire model creation computer program recorded on the recording medium is read into a computer system and executed. Thus, the tire model creation method according to the present invention may be realized. Here, the “computer system” includes hardware such as an OS (Operating System) and peripheral devices.

  The processing unit 52 includes a first model creation unit 52a, a material property adjustment unit 52b, a second model creation unit 52c, an analysis unit 52d, and a third model creation unit 52e. The first model creation unit 52 a divides the analysis target tire (for example, the tire 1 shown in FIG. 1) into a plurality of elements, creates a first tire model, and stores the first tire model in the storage unit 54. The first tire model is an analysis model that can be variously analyzed by being handled by a computer. The analysis model includes a mathematical model and a mathematical discretization model (the same applies to the following examples). The material property adjusting unit 52b adjusts the mass density and elastic modulus of the first tire model created by the first model creating unit 52a, thereby bringing the natural frequency of the first tire model within a predetermined range. The material property adjusting unit 52b stores the mass density and elastic modulus of the first tire model when the natural frequency of the first tire model is within a predetermined range in the storage unit 54.

  The second model creation unit 52c creates an analysis model by dividing the analysis target tire into a plurality of elements so that the number of divisions in the circumferential direction is larger than that of the first tire model created by the first model creation unit 52a. To do. And the 2nd model preparation part 52c shows mass density and an elasticity modulus when the natural frequency of a 1st tire model becomes in a predetermined range among the material physical property values of the created analysis model. And Through such processing, the second model creation unit 52c creates a second tire model. The second model creation unit 52 c stores the created second tire model in the storage unit 54. Similar to the first tire model, the second tire model is an analysis model that can be variously analyzed by being handled by a computer.

  The analysis unit 52d performs vibration analysis such as vibration response analysis when adjusting the mass density and elastic modulus of the first tire model. The third model creation unit 52e creates at least one of a rim analysis model combined with the second tire model, a wheel analysis model, and a cavity analysis model existing inside the tire. Then, the third model creation unit 52e creates an assembly model by combining the second tire model and the analysis model of the rim or the analysis model of the wheel. Similar to the first tire model and the second tire model, the rim analysis model, the wheel analysis model, and the cavity analysis model are analysis models that can be variously analyzed by being handled by a computer. The analysis unit 52d executes a dynamic response simulation using the assembly model described above having the second tire model. As described above, the model creation device 50 has a function of creating a second tire model and an assembly model, and executing a dynamic response simulation using these models.

  The processing unit 52 includes, for example, a CPU (Central Processing Unit) and a memory. Based on the first tire model created by the first tire model or the second tire model created by the second model creation unit 52c and the input data, the processing unit 52 executes the tire model creation program. The calculation is performed by reading into the memory incorporated in the processing unit 52. At that time, the processing unit 52 appropriately stores a numerical value in the middle of the calculation in the storage unit 54, and reads the numerical value stored in the storage unit 54 to advance the calculation. The processing unit 52 may realize the function by dedicated hardware instead of the tire model creation computer program.

  As the display means 55, for example, a liquid crystal display device can be used. The determination result can also be output to a printer provided as necessary. The storage unit 54 in which the above-described mass density, elastic modulus, second tire model, and the like are stored may be in another device (for example, a database server). For example, the model creation device 50 may access the processing unit 52 and the storage unit 54 by communication from a terminal device including the input / output device 51. Next, a method for creating a tire model according to the present embodiment will be described.

  FIG. 3 is a flowchart showing a procedure of a tire model creation method according to the present embodiment. FIG. 4 is a perspective view showing the first tire model. FIG. 5 is a cross-sectional view showing a meridional cross-sectional model for creating the first tire model. FIG. 6 is a schematic diagram showing division in the circumferential direction of the first tire model. In executing the tire model creation method according to the present embodiment, in step S101, the first model creation unit 52a of the model creation device 50 shown in FIG. 2 creates the first tire model 10 shown in FIG. The first tire model 10 is a three-dimensional analysis model having a plurality of elements E11, E12,. Each element E11, E12,... E1n has a plurality of nodes. The Y axis is a rotation axis of the first tire model 10, and the Z axis is an axis orthogonal to the rotation axis (Y axis) and the road surface on which the first tire model 10 contacts the ground. The X axis is an axis orthogonal to the Y axis and the Z axis.

  The first tire model 10 is a model used for performing vibration analysis using a numerical analysis method such as a finite element method or a finite difference method. In the present embodiment, a finite element method (FEM) is used for vibration analysis of the first tire model 10. The analysis method applicable to the tire model creation method according to the present embodiment is not limited to the finite element method, and a finite difference method (FDM), a boundary element method (BEM), or the like can also be used. Further, the most appropriate analysis method can be selected according to the boundary condition or the like, or a plurality of analysis methods can be used in combination. Since the finite element method is an analysis method suitable for structural analysis, it can be suitably applied particularly to a structure such as a tire.

  The elements E11, E12,... E1n of the first tire model 10 are solid elements such as tetrahedral solid elements, pentahedral solid elements, hexahedral solid elements, etc. It is desirable to use an element that can be handled by a computer such as a shell element or a surface element. In the process of analysis, the elements thus divided are identified one by one using the two-dimensional coordinate in the two-dimensional model and using the three-dimensional coordinate in the three-dimensional model.

  A meridional section model 10C shown in FIG. 5 is an analysis model of the meridional section of a tire to be analyzed (for example, the tire 1 shown in FIG. 1). The meridional section model 10C is a two-dimensional analysis model having a plurality of elements E1, E2,. Each element E1, E2,... En has a plurality of nodes. Elements E1, E2,... En included in the meridional section model 10C are trigonal elements, quadrilateral elements, and the like. In the present embodiment, the first model creation unit 52a moves the meridional section model 10C around the axis that serves as the rotation axis (Y axis) of the first tire model 10 in the circumferential direction (the direction indicated by the arrow C in FIG. 6). The first tire model 10 shown in FIG. 4 and FIG. 6 is created by developing one round (360 degrees or 2 × π) toward.

  The first tire model 10 is divided into a plurality of parts (circumferential division parts) SA by a plane CSP corresponding to the meridional section model 10C. A portion (circumferential division portion) SA surrounded by the planes CSP corresponding to the adjacent meridional cross-section models 10C represents the size of (one) element in the first tire model 10 in the circumferential direction. In the first tire model 10, the number of elements existing in the circumferential direction, that is, the number of plane CSPs existing in the circumferential direction is the number of divisions in the circumferential direction of the first tire model 10. The number of divisions in the circumferential direction of the first tire model 10 is smaller than the number of divisions in the circumferential direction of the second tire model described later. The interval (division interval) between adjacent plane CSPs is represented by center angles θ1, θ2, etc. with the Y axis as the center. An angle at which the first tire model 10 is divided in the circumferential direction is referred to as a division angle, and the central angles θ1, θ2, and the like correspond to the division angles.

  When the first tire model 10 is created, the natural frequency of the first tire model 10 is obtained in step S102. In obtaining the natural frequency of the first tire model 10, the analysis unit 52 d included in the model creation device 50 illustrated in FIG. 2 performs vibration analysis of the first tire model 10 to obtain the natural frequency of the first tire model 10. Ask. When the analysis unit 52 d executes the vibration analysis, an analysis condition is input from the input unit 53 to the model creation device 50. The analysis unit 52d performs vibration analysis on the first tire model 10 using the input analysis conditions. Then, the analysis unit 52d obtains the natural frequency of the first tire model 10 and stores the mass density and elastic modulus of the first tire model 10 when the natural frequency is obtained in the storage unit 54. The mass density and elastic modulus of the first tire model 10 are the mass density and elastic modulus of materials constituting the first tire model, such as rubber and reinforcing fibers. As the initial values of the mass density and elastic modulus of the first tire model 10, the material constituting the tire to be analyzed, for example, the mass density and elastic modulus of rubber, reinforcing fibers, etc. are used.

  When the natural frequency is obtained, the processing of the tire model creation method proceeds to step S103. In step S103, the material property adjusting unit 52b of the model creation device 50 shown in FIG. 2 determines that the natural frequency of the first tire model 10 obtained in step S102 is not within a predetermined allowable range (step S103, No). ) The process of the tire model creation method proceeds to step S104. In addition, when the natural frequency of the first tire model 10 obtained in step S102 is within a predetermined allowable range (step S103, Yes), the material physical property adjustment unit 52b performs processing of the tire model creation method. Proceed to step S105.

  In the present embodiment, for example, a predetermined range centered on a natural frequency (experimental value) obtained by conducting a vibration experiment on a tire to be evaluated or a tire similar thereto is set as an allowable value. In the present embodiment, for example, an allowable value is within ± 5% of the experimental value. Therefore, when the natural frequency of the first tire model 10 obtained in step S102 is experimental value × 0.95 or more and experimental value × 1.05 or less, it is within the allowable range. The point where the predetermined range centered on the experimental value is the allowable value is not limited to this, and the predetermined range centered on the result (simulation value) of the computer-executed vibration analysis for the tire to be evaluated It may be an allowable value. Moreover, the magnitude | size of the predetermined range can be made into an appropriate value as needed.

  In step S104, the material property adjusting unit 52b adjusts the mass density and elastic modulus of the first tire model. Specifically, the material physical property adjusting unit 52b determines whether the value in step S103, that is, the natural frequency of the first tire model 10 is within a predetermined allowable range, for the mass density and the elastic modulus. It is set to a value different from that when it is set, and stored in the storage unit 54. When the mass density and the elastic modulus are set to the different values, for example, the material physical property adjusting unit 52 b acquires new values of the mass density and the elastic modulus input from the input unit 53 and stores them in the storage unit 54. Further, the material property adjusting unit 52b may add or subtract a predetermined value to the mass density and the elastic modulus in step S103, and store the obtained value in the storage unit 54 as a new mass density and elastic modulus.

  The natural frequency increases as the elastic modulus increases, and decreases as the mass density increases. When adjusting the mass density and the elastic modulus, when adding or subtracting the predetermined values of the mass density and the elastic modulus in step S103, the material property adjusting unit 52b has a center value (experimental value) within the predetermined range of the natural frequency. Or the simulation value) is larger than the current value and / or the elastic modulus is made smaller than the current value. The material property adjusting unit 52b stores the values thus obtained in the storage unit 54 as new mass density and elastic modulus. When the natural frequency is smaller than the center value (experimental value or simulation value) of the predetermined range described above, the material physical property adjusting unit 52b makes the mass density smaller than the current value and the elastic modulus from the current value. At least one of increasing the size. The material property adjusting unit 52b stores the values thus obtained in the storage unit 54 as new mass density and elastic modulus.

  When step S104 is completed, the processing of the tire model creation method proceeds to step S102, and the model creation device 50 is used until the natural frequency of the first tire model 10 falls within a predetermined allowable range (step S103, Yes). Repeat step S102, step S103, and step S104. When the material property adjusting unit 52b detects that the natural frequency of the first tire model 10 falls within a predetermined allowable range (step S103, Yes), the material used for the second tire model in step S105. Determine physical properties. Specifically, the material property adjusting unit 52b determines the mass density and elastic modulus of the first tire model 10 when the natural frequency of the first tire model 10 falls within a predetermined allowable range. The mass density and elastic modulus of the model are determined and stored in the storage unit 54.

  The processing of the tire model creation method proceeds to step S106, and the second model creation unit 52c of the model creation device 50 illustrated in FIG. 2 creates the second tire model and stores it in the storage unit 54. The second tire model is an analysis model for evaluating the characteristics and performance of a tire to be analyzed, and is used for vibration analysis, dynamic response analysis, and the like. The second tire model is created in the same manner as the first tire model 10. In other words, the second tire model is created by expanding the analysis model of the meridional section of the tire to be analyzed around one axis (360 degrees or 2 × π) around the axis that is the rotation axis of the second tire model. The In the present embodiment, the second tire model is created from the meridional section model 10C (see FIG. 5) used when creating the first tire model 10. That is, the second model creation unit 52c creates the meridional section model 10C by developing it around the axis that is the rotation axis of the second tire model, and stores it in the storage unit 54.

  The second tire model has a greater number of circumferential divisions than the first tire model 10. If vibration analysis is performed using such a 2nd tire model, the fall of analysis accuracy can be controlled. When the second tire model is created, the process proceeds to step S107, and the analysis unit 52d reads the second tire model from the storage unit 54 and executes vibration analysis and dynamic response analysis.

  If the number of divisions in the circumference is small, the amount of calculation can be reduced, so that the effects of shortening the calculation time and reducing the load of hardware resources can be obtained. Further, as the number of divisions in the circumferential direction is increased, higher-order vibration modes can be expressed, and higher-order natural frequencies also coincide. For this reason, this embodiment uses the first tire model having a smaller number of divisions in the circumferential direction than the second tire model used for evaluating characteristics, performance, and the like, and is used for vibration analysis, dynamic response analysis, and the like. Physical properties, more specifically, mass density and elastic modulus are adjusted. And this embodiment uses the 2nd tire model larger than the division | segmentation number 1st tire model in the circumferential direction for the analysis for evaluating a characteristic, performance, etc., and a mass density and an elasticity modulus are 1st tires. The one adjusted using the model is used. As described above, this embodiment reduces the amount of calculation using the first tire model and adjusts the mass density and the elastic modulus, which are expected to be processed multiple times, for performance evaluation that requires accuracy. The second tire model is used for the analysis. As a result, this embodiment can greatly reduce the amount of calculation required for mass density and elastic modulus and shorten the time required for adjustment, so that an analysis model used for analysis for evaluating characteristics, performance, etc. The time for creating a two-tire model can be reduced.

  In the present embodiment, the first tire model and the second tire model are created from meridional section models having the same shape. By doing so, the natural vibration mode in the width direction (direction parallel to the rotation axis) can be accurately expressed, and therefore the accuracy of the natural frequency can be ensured in the analysis using the second tire model. . The range of the natural frequency when adjusting the mass density and the elastic modulus in the first tire model may be 200 Hz or less. If the mass density and the elastic modulus are adjusted at a natural frequency of 200 Hz or lower, the natural frequency of 200 Hz or higher can be accurately expressed by increasing the number of divisions in the circumferential direction of the second tire model.

  In step S102 to step S104, when the first tire model 10 is not grounded, that is, when the mass density and the elastic modulus are adjusted in a non-grounded state, the division angle θ1 in the circumferential direction of the first tire model 10 shown in FIG. , Θ2 are made equal, and the number of divisions in the circumferential direction of the first tire model 10 is 6 times or more the highest order of the vibration mode. In the non-grounding state, the difference in rigidity in the circumferential direction of the first tire model 10 can be suppressed by equalizing the division angles in the circumferential direction of the first tire model 10, so that the calculation accuracy of the natural frequency is improved.

  Moreover, the 1st tire model 10 should just adjust mass density and an elasticity modulus in the natural frequency of the vibration mode of each direction which appears in the range below 200 Hz. The highest order of the vibration mode appearing at 200 Hz or less varies depending on the rigidity and boundary conditions of the first tire model 10 created based on the tire to be analyzed, but at least the third or higher order vibration mode can be adjusted. preferable. Therefore, when adjusting up to the third order, the number of divisions in the circumferential direction of the first tire model 10 is 18 divisions or more, more preferably 30 divisions or more, and further less than half of the second tire model. By doing in this way, calculation time can be shortened, ensuring the precision at the time of calculating | requiring the natural frequency of the 1st tire model 10. FIG.

  FIG. 7 is a schematic diagram showing a state in which the first tire model is grounded. FIG. 8 is a schematic diagram showing a state in which the second tire model is grounded. In step S102 to step S104, when the first tire model is grounded, that is, when the mass density and the elastic modulus are adjusted in the grounded state, the following is preferable. First, in the ground contact area 19a of the first tire model 10a, the number of divisions in the circumferential direction of the first tire model 10a is 1 as the number of divisions in the circumferential direction of the second tire model 20 in the ground contact area 29 of the second tire model 20. / 2 or less. And in the part except the part of the contact area | region 19a of the 1st tire model 10, the absolute value of the difference of the division | segmentation angle in the circumferential direction of a 1st tire model shall be 10 degrees or less. Further, the ground contact area 19a of the first tire model 10a regards the number of divisions in the circumferential direction as 1, and the division number of the entire first tire model 10a is the highest order 6 of the vibration mode for adjusting the mass density and the elastic modulus. Try to be more than double.

  If the division angle in the circumferential direction of the first tire model 10a is different, a difference in rigidity in the circumferential direction occurs, and there is a possibility that an accurate natural frequency cannot be calculated. For this reason, as for the 1st tire model 10a, it is preferred that the field except ground contact field 19a is made equal. In this way, the calculation time can be shortened while ensuring the accuracy in obtaining the natural frequency of the first tire model 10a. And in the part except the part of the contact area 19a of the first tire model 10a, the absolute value (for example, | θ1-θ2 |) of the difference in the division angle θcs in the circumferential direction of the first tire model is within 10 degrees, The accuracy when obtaining the natural frequency can be further improved by setting the angle within 5 degrees.

  When calculating the natural frequency of the first tire model 10a, if the ground contact area 19a is appropriately restrained, it is not necessary to increase the number of divisions of the ground contact area 19a. For this reason, the division | segmentation number in the circumferential direction of the contact area 19a of the 1st tire model 10a may be 1/2 or less of the division | segmentation number in the circumferential direction of the contact area 29 of the 2nd tire model 20. Further, if the division angle θcs in the ground contact area 19a of the first tire model 10a is too large, there is a possibility that the vibration mode related to the deformation of the ground contact surface of the first tire model 10a may not be appropriately expressed. For this reason, it is preferable that the division angle θcs in the ground contact region 19a of the first tire model 10a is 5 degrees or less. In this way, since the vibration mode related to the deformation of the ground contact surface of the first tire model 10a can be appropriately expressed, the natural frequency of the first tire model 10a can be accurately obtained.

  The ground contact area 19a of the first tire model 10a is centered on an axis (Z axis) whose center angle θc about the rotation axis (Y axis) is orthogonal to the road surface model 30 to be grounded of the first tire model 10a. It is preferable to be in the range of ± 20 degrees or more and ± 30 degrees or less. That is, the center angle θc is preferably 40 degrees or more and 60 degrees or less. In this way, even if the grounding area 19a is not obtained by grounding analysis or the like, the approximate grounding area 19a can be obtained, so that the calculation load can be reduced.

  Moreover, when determining the contact area 19a of the first tire model 10a, it is preferable to do the following. That is, using the second tire model 20, a ground contact analysis is performed in which the second tire model 20 is brought into contact with the road surface model 30 to be grounded. 19a. In this way, the contact area obtained using the second tire model 20 having a larger number of divisions in the circumferential direction than the first tire model 10a is defined as the contact area 19a of the first tire model 10a. More accurately determined. As a result, the natural frequency can be obtained more accurately.

  As described above, the number of divisions of the entire first tire model 10a is set to be six times or more the highest order of the vibration mode for adjusting the mass density and the elastic modulus. At this time, the number of divisions in the circumferential direction is regarded as 1 in the grounding region 19a. Therefore, the number of divisions in the entire circumferential direction of the first tire model 10a is a value obtained by adding 1 to the number of divisions other than the contact area 19a. In the ground contact area 19a, the number of divisions in the circumferential direction may be regarded as 1. If the ground contact area 19a is appropriately restrained when calculating the natural frequency of the first tire model 10a, This is because it is not necessary to increase the number of divisions, and the number of divisions in the ground region 19a may be regarded as 1 on condition that the ground region 19a is constrained.

  FIG. 9 is a diagram showing a meridional section model of a rim. FIG. 10 is a diagram showing a meridional section model of a tire. FIG. 11 is a diagram illustrating a meridional section model of a cavity existing inside a tire to be analyzed. FIG. 12 is a diagram showing a tire / rim assembly model. In step S106, the second model creation unit 52c may create a tire / rim assembly model including the second tire model as follows. First, the second model creation unit 52c converts the meridional cross-sectional shape of the tire to be analyzed into an analysis model. Further, the third model creation unit 52e of the model creation device 50 shown in FIG. 2 includes a meridional cross-sectional shape of a cavity existing inside the tire to be analyzed and a meridional section of a rim (rigid rim) to which the tire to be analyzed is attached. Analyze shape and shape. By this process, a meridional section rim model 31C, a meridional section tire model 20C, and a meridional section cavity model 32C shown in FIG. 9 are obtained. These are all analytical models. The meridional section tire model 20C is an analysis model for creating the second tire model, and is the same as the meridional section model 10C shown in FIG. The meridional cavity model 32C is an analytical model of gas (for example, air) existing in the cavity.

  Next, the second model creation unit 52c assembles the meridional section tire model 20C into the meridional section rim model 31C, and arranges the meridional section cavity model 32C in the cavity existing inside the meridional section tire model 20C. Create a model. Then, the second model creation unit 52c develops the assembly model around the axis that serves as the rotation axis of the second tire model in the circumferential direction, so that the three-dimensional tire / rim shown in FIG. An assembly model 100 is created. In the tire / rim assembly model 100, the second tire model 20 is attached to the rim model 31 created from the meridional section rim model 31C, and the space surrounded by the second tire model 20 and the rim model 31 is an analysis model as a hollow model 32. It has become.

  Even if gas exists in the first tire model 10, the natural frequency is not affected. For this reason, when adjusting the mass density and the elastic modulus using the first tire model 10, the gas inside the first tire model 10 is not converted into an analytical model, but the second tire model 20 (in this example, tire / When creating the rim assembly model 100), the gas is converted into an analytical model. In this way, it is possible to reduce the labor required for creating the analysis model, and it is possible to reduce the calculation time for obtaining the natural frequency.

  FIG. 13 is a diagram showing a second tire model. FIG. 14 is a diagram showing an analytical model of a wheel. FIG. 15 is a diagram showing a tire / wheel assembly model. In step S106, the second model creation unit 52c may create the tire / wheel assembly model 100a including the second tire model 20 as follows. First, the second model creation unit 52c creates the second tire model 20 by developing the meridional section tire model 20C shown in FIG. 10 in the circumferential direction. Then, the second model creation unit 52c creates the tire / wheel assembly model 100a shown in FIG. 15 by combining the second tire model 20 with the wheel model 33 that is an analysis model of the elastic wheel. The wheel model 33 is created by the third model creation unit 52e.

  Since the rigidity of the elastic wheel is higher than that of the tire, the influence of the natural frequency of the elastic wheel is ignored when the natural frequency when the mass density and elastic modulus are adjusted in the first tire model 10 is about 200 Hz. it can. For this reason, the influence of the elastic wheel appearing on the high frequency side can also be expressed by adding the analysis model of the elastic wheel only when the analysis unit 52d analyzes using the second tire model 20. .

  In general, since the wheel has a design on the disk surface, if a two-dimensional meridional cross-sectional shape is developed in three dimensions, the rigidity and mass of the disk surface cannot be accurately modeled. For this reason, in order to improve the accuracy of the analysis, the elastic wheel is converted into an analysis model in three dimensions, the meridional section tire model 20C is developed, and the three-dimensional second tire model 20 is created. The model 20 and the wheel model 33 are combined. If analysis is performed using the tire / wheel assembly model 100a thus obtained, the analysis accuracy can be improved.

  FIG. 16 is a diagram showing a tire / wheel / cavity model. In step S106, the second model creation unit 52c may create the tire / wheel / cavity model 100b including the second tire model 20 as follows. First, the second model creation unit 52c combines the meridional section tire model 20C shown in FIG. 10 and the meridional section cavity model 32C shown in FIG. 11, and becomes the rotation axis of the second tire model 20 in a state where both are combined. A tire / cavity model is created that includes a second tire model 20 that extends circumferentially about the axis. The meridional cavity model 32C is created by the third tire model creation unit 52e.

  Next, the second model creation unit 52c creates a tire / wheel / cavity model 100b by combining the tire / cavity model with a wheel model 33 (see FIG. 15) that is an analysis model of an elastic wheel. The tire / wheel / cavity model 100b is a combination of the above-described tire / wheel assembly model 100a and a cavity model 32 obtained by analytically modeling the gas inside the tire. If such a tire / wheel / cavity model 100b is used, the analysis accuracy can be further improved. When the analysis is performed using the tire / wheel / cavity model 100b, the second tire model 20, the wheel model 33, and the cavity model 32 are combined, but the nodes fixed in the meridional section tire model 20C are not fixed.

[Evaluation example]
The first tire model (material adjustment model) is divided into 32 in the circumferential direction and the second tire model (production model) is divided into 100 in the circumferential direction. The natural frequency in mode 11 was determined. The mode means a vibration mode (the same applies hereinafter). The results are shown in Table 1. The error in Table 1 is an error in the natural frequency of the first tire model when the natural frequency obtained in the second tire model is used as a reference. The details of each mode are as shown in FIG. 17 which is a schematic diagram showing an example of the mode. As can be seen from the results in Table 1, the error of the natural frequency obtained using the first tire model with respect to the natural frequency obtained using the second tire model is at most −1.3%, Most modes were below 1%. As described above, when the first tire model was used, it was possible to obtain the same natural frequency as that obtained when the second tire model with the number of divisions in the circumferential direction was about three times. That is, it can be said that the natural frequency obtained using the first tire model has the same accuracy as the natural frequency obtained using the second tire model.

  Assuming that the calculation time when the natural frequency is obtained using the second tire model is 100, it is 21 when the natural frequency of the same mode is obtained using the first tire model. Thus, when obtaining the natural frequency of the same mode, the calculation time of the first tire model was reduced by 79% compared to the second tire model. The tire model creation method according to the present embodiment repeats vibration analysis while adjusting the mass density and elastic modulus until the natural frequency falls within a predetermined range. From the above calculation time results, if the vibration analysis is repeated the same number of times in adjusting the mass density and the elastic modulus, the calculation time is longer when the first tire model is used than when the second tire model is used. It can be said that it can be shortened by 79%.

  As described above, the tire model creation method, the tire model creation computer program, the tire simulation method, and the tire model creation apparatus according to the present invention are useful for reducing the time for creating a model for analysis. It is.

1 tire 10, 10a first tire model 10C meridional section model 19a, 29 contact area 20 second tire model 20C meridional section tire model 30 road surface model 31 rim model 31C meridional section rim model 32 cavity model 32C meridional section cavity model 33 wheel model 50 model Creation device (tire model creation device)
51 I / O Device 52 Processing Unit 52a First Model Creation Unit 52c Second Model Creation Unit 52e Third Model Creation Unit 52d Analysis Unit 50d Analysis Unit 52b Material Property Adjustment Unit 53 Input Unit 54 Storage Unit 55 Display Unit 100 Tire / Rim Group Solid assembly model 100a Tire / wheel assembly model 100b Tire / wheel / cavity model

Claims (9)

A computer that divides a tire to be analyzed into a plurality of elements to create a first tire model;
The computer adjusts the mass density and elastic modulus of the first tire model to bring the natural frequency of the first tire model within a predetermined range;
The computer divides the tire into a plurality of elements so that the number of divisions in the circumferential direction is larger than that of the first tire model, and the mass density and elastic modulus are within the predetermined range. A procedure for creating a second tire model with a mass density and an elastic modulus when
A method for creating a tire model, comprising: The computer
When adjusting the mass density and elastic modulus of the first tire model in a non-grounded state, the division angle in the circumferential direction of the first tire model is made equal, and the number of divisions in the circumferential direction of the first tire model The tire model creating method according to claim 1, wherein the tire model is at least six times the highest order of the vibration mode. The computer
When adjusting the mass density and elastic modulus of the first tire model in the ground contact state,
In the contact area, the number of divisions in the circumferential direction of the first tire model is ½ or less of the number of divisions in the circumferential direction of the second tire model,
In the portion excluding the portion of the ground contact region, the absolute value of the difference in the split angle in the circumferential direction of the first tire model is within 10 degrees,
The ground contact area of the first tire model has a division number of 1 in the circumferential direction, and the total division number of the first tire model is at least six times the highest order of the vibration mode for adjusting mass density and elastic modulus. The tire model creation method according to claim 1, wherein the tire model is divided as follows. The computer
By analyzing the meridional cross-sectional shape of the tire, the meridional cross-sectional shape of the cavity existing inside the tire, and the meridional cross-sectional shape of the rim to which the tire is attached, by developing this analytical model in the circumferential direction, 3. The tire / rim assembly model in which the second tire model is attached to a rim model created from the rim and a space surrounded by the second tire model and the rim model is analytically modeled. 3. A method for creating the tire model according to 3. The computer
The meridional cross-sectional shape of the tire is developed in the circumferential direction to create the second tire model,
The tire model creation method according to claim 2 or 3, wherein the second tire model is combined with an analysis model of an elastic wheel. The computer
Analyzing the meridional cross-sectional shape of the tire and the shape of the cavity existing inside the tire, and developing the analytical model in the circumferential direction, the second tire model and the analytically modeled cavity Tire / cavity model with
4. The tire model creation method according to claim 2, wherein the tire / cavity model is combined with an elastic wheel analysis model.   A computer program for creating a tire model, which causes a computer to execute the method for creating a tire model according to any one of claims 1 to 6.   A tire simulation method in which a computer executes vibration analysis using the second tire model created by the tire model creation method according to any one of claims 1 to 6. A first model creation unit that creates a first tire model by dividing a tire to be analyzed into a plurality of elements;
A material property adjusting unit that adjusts the natural density of the first tire model within a predetermined range by adjusting a mass density and an elastic modulus of the first tire model;
The tire is divided into a plurality of elements so that the number of divisions in the circumferential direction is larger than that of the first tire model, and the mass density and elastic modulus are obtained when the natural frequency falls within the predetermined range. A second model creation unit for creating a second tire model;
An apparatus for creating a tire model, comprising:

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