JP2024034878A - Method for simulating tire - Google Patents

Abstract

To provide a method for simulating a tire capable of improving prediction accuracy for temperature of the tire while shortening a calculation time.SOLUTION: The present invention relates to a method for simulating a tire. The method comprises a step S1 of inputting into a computer a tire model and a road surface model in which tires and road surfaces are modeled using a finite number of elements. The computer executes: a step S2 of calculating centrifugal force acting on the tire model based on a predetermined running speed condition; a step S3 of applying a predetermined load, internal pressure, and centrifugal force to the tire model to calculate the deformation of the tire model that is statically grounded on the road surface model; a step S4 of calculating a heat generation amount and a heat radiation amount of the deformed tire model; and a step S5 of calculating a temperature of the elements of the tire model based on the heat generation amount and the heat radiation amount.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a tire simulation method.

Patent Document 1 listed below describes a simulation method for calculating physical quantities related to the temperature of a tire model. In this method, different heat transfer coefficients are defined for the first element that is in contact with the road surface and the second element that is not in contact with the road surface in the tread part model of the tire model, and physical quantities related to the temperature of the tire model during running are defined. is calculated.

JP2017-009482A

In the above method, a tire model rolling on a road surface model is calculated for each unit time of simulation. Such dynamic analysis has the problem of requiring a lot of time.

In order to shorten calculation time, it is also possible to perform static analysis without rolling the tire model. However, static analysis cannot adequately reproduce the conditions in which tires are running, so there is room for further improvement in the accuracy of tire temperature prediction.

The present disclosure has been devised in view of the above-mentioned circumstances, and its main purpose is to provide a tire simulation method that can improve tire temperature prediction accuracy while reducing calculation time.

The present disclosure is a tire simulation method that includes a step of inputting a tire model and a road surface model in which the tire and the road surface are modeled using a finite number of elements into a computer, and the computer a step of calculating a centrifugal force acting on the tire model based on conditions; and applying a predetermined load and internal pressure and the centrifugal force to the tire model to statically ground it on the road surface model. a step of calculating a deformation of the tire model, a step of calculating a calorific value and a heat dissipation amount of the deformed tire model, and a step of calculating a temperature of the element of the tire model based on the calorific value and the heat dissipation amount. This is a tire simulation method that performs the steps of:

By employing the above-described steps, the tire simulation method of the present disclosure can improve prediction accuracy of tire temperature while reducing calculation time.

FIG. 2 is a perspective view showing an example of a computer for executing a tire simulation method. 3 is a flowchart illustrating an example of a processing procedure of a tire simulation method. It is a perspective view showing an example of a tire model and a road surface model. It is a sectional view showing an example of a tire model. 7 is a flowchart illustrating an example of a processing procedure of a deformation calculation step. It is a graph which shows an example of the relationship between the heat transfer coefficient of the outer surface of a tire model, and a running speed condition. It is a flowchart explaining an example of the processing procedure of other embodiments of this indication. FIG. 3 is a side view of a tire model and a road surface model. It is a graph showing the relationship between the temperature of the elements of the tire model and the running speed. 3 is a graph showing temperature differences between elements of a tire model.

Hereinafter, one embodiment of the present disclosure will be described based on the drawings. It should be noted that the drawings are for the purpose of enhancing the understanding of the contents of the disclosure, and in addition to including exaggerated representations, it is previously pointed out that the scales and the like do not exactly match between the drawings.

[Tire simulation method (first embodiment)]
In the tire simulation method (hereinafter sometimes simply referred to as "simulation method") of the present embodiment, the temperature of the tire during running is predicted. A computer is used in the simulation method of this embodiment. FIG. 1 is a perspective view showing an example of a computer 1 for executing a simulation method.

[Computer]
The computer 1 includes, for example, a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with, for example, an arithmetic processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1 and 1a2. The storage device stores in advance software and the like for executing the simulation method of this embodiment. Therefore, the computer 1 is configured as a simulation device that predicts the temperature of tires during running.

[Tire model and road surface model input process]
FIG. 2 is a flowchart showing an example of the processing procedure of the tire simulation method. In the simulation method of this embodiment, first, a tire model and a road surface model in which tires and a road surface (not shown) are respectively modeled using a finite number of elements are input to the computer 1 (step S1). FIG. 3 is a perspective view showing an example of the tire model 2 and the road surface model 3. FIG. 4 is a sectional view showing an example of the tire model 2. As shown in FIG. Note that in FIG. 3, the tire model 2 is shown in a simplified manner, and the element F(i), tread pattern, etc. are omitted.

The tire model 2 is a model of a tire to be analyzed (not shown). There is no question as to whether or not the tire to be analyzed actually exists. In addition, although pneumatic tires for passenger cars are exemplified as tires to be analyzed, tires of other categories may be used, such as tires for heavy loads such as trucks and buses, and airless tires.

As shown in FIG. 4, in the tire model 2, for example, a tire to be analyzed (not shown) has a finite number of elements F(i) (i=1, 2,...) that can be handled by numerical analysis. It can be defined by modeling (discretization).

As the numerical analysis method, for example, a finite element method, a finite volume method, a finite difference method, or a boundary element method (in this embodiment, a finite element method) can be appropriately employed. For example, a three-dimensional tetrahedral solid element, a pentahedral solid element, or a hexahedral solid element is used as the element F(i). Each element F(i) is configured to include a plurality of nodes 5. Each element F(i) includes the element number, the number of node 5, the coordinate value of node 5, and material properties (for example, density, Young's modulus, damping coefficient, thermal conductivity, heat transfer coefficient, etc.). Numerical data is defined.

In step S1, a rubber portion including tire tread rubber (not shown), a carcass ply forming the frame of the tire, and a belt ply disposed outside the carcass ply in the tire radial direction are each discretized into elements F(i). (modeled). Thereby, a rubber member model (for example, a sidewall rubber model, etc.) 6, a carcass ply model 7, and a belt ply model 8 are set in the tire model 2.

As shown in FIG. 3, in step S1, based on information regarding the road surface (not shown), the road surface has a finite number of elements G(i ) (i=1, 2,...). As a result, in step S1, a road surface model 3 that models a road surface is set.

Element G(i) is defined as a rigid planar element defined to be non-deformable. A plurality of nodes 10 are provided in element G(i). Furthermore, numerical data such as an element number and coordinate values of the node 10 are defined for the element G(i).

In this embodiment, the road surface model 3 having a smooth surface is defined, but the road surface model 3 is not limited to such an aspect. For example, a road surface model 3 (not shown) may be defined that is provided with minute irregularities such as an asphalt road surface, irregular steps, depressions, undulations, or irregularities similar to an actual driving road surface such as ruts. The tire model 2 and road surface model 3 are input to the computer 1 shown in FIG.

[Centrifugal force calculation process]
Next, in the simulation method of this embodiment, the computer 1 (shown in FIG. 1) calculates the centrifugal force acting on the tire model 2 based on predetermined running speed conditions (step S2). The running speed condition is appropriately set (for example, 10 to 300 km/h) based on the running state of the tires (not shown) whose temperature is required to be predicted. Centrifugal force f(i) is calculated using the following formula (1).

ここで、
ｍ（ｉ）：要素Ｆ（ｉ）の質量
ｒ（ｉ）：要素Ｆ（ｉ）の半径
ｐ（ｉ）：要素Ｆ（ｉ）の密度
Ｖ（ｉ）：要素Ｆ（ｉ）の体積
ω：タイヤ角速度
ｖ：タイヤ周速度
Ｒ：タイヤ半径

here,
m(i): Mass of element F(i) r(i): Radius of element F(i) p(i): Density of element F(i) V(i): Volume of element F(i) ω: Tire angular velocity v: Tire circumferential velocity R: Tire radius

In the above formula (1), mass m(i) is the mass of each element F(i) of tire model 2. This mass m(i) is determined by the product of the density p(i) set for each element F(i) and the volume V(i).

In the above equation (1), the tire circumferential speed v is specified from the running speed condition (running speed). The tire radius R is specified by the distance (not shown) from the rotational axis of the tire to the outermost end of the tread portion in the tire radial direction in the normal state of the tire. Then, by dividing the tire circumferential speed v by the tire radius R, the tire angular speed ω is obtained.

In the above equation (1), the radius r(i) is set as the distance from the tire rotation axis to the center of gravity of the element F(i) for each element F(i) of the tire model 2. The radius r(i) of each element F(i) is multiplied by the mass m(i) of each element (i), and further multiplied by the square of the tire angular velocity ω ² . The centrifugal force is calculated respectively. Then, by finding the sum of the centrifugal forces of each element F(i), the centrifugal force f of the tire model 2 is found. The centrifugal force f is input to the computer 1.

The "regular state" is a state in which the tire is mounted on a regular rim (hereinafter sometimes simply referred to as "rim"), is filled with the regular internal pressure, and is under no load. Hereinafter, unless otherwise specified, the dimensions of each part of the tire are values measured under this normal condition.

A "regular rim" is a rim defined for each tire in a standard system that includes the standard on which the tire is based. For example, the regular rim is "Standard Rim" for JATMA, "Design Rim" for TRA, and "Measuring Rim" for ETRTO.

"Regular internal pressure" is the air pressure specified for each tire by each standard in a standard system including the standards on which tires are based. For example, the normal internal pressure is "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITSAT VARIOUSCOLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO.

[Deformation calculation process]
Next, in the simulation method of this embodiment, the computer 1 calculates the deformation of the tire model 2 statically in contact with the road surface model 3 based on the predetermined load and internal pressure, and the centrifugal force f ( Deformation calculation step S3). FIG. 5 is a flowchart showing an example of the processing procedure of the deformation calculation step S3.

In the deformation calculation step S3 of this embodiment, the tire model 2 after being filled with internal pressure is calculated (step S31). In step S31, first, as shown in FIG. 4, the bead portions 2c, 2c of the tire model 2 are restrained by a rim model 11 that models a tire rim (not shown). Furthermore, the deformation of the tire model 2 is calculated based on the uniformly distributed load w corresponding to the internal pressure condition. As a result, the tire model 2 after being filled with internal pressure is calculated. The internal pressure can be set as appropriate, and, for example, it is desirable to set the above-mentioned normal internal pressure.

Deformation calculation (including rolling calculation described later) of tire model 2 is based on the shape and material properties of each element F(i), and calculates the mass matrix, stiffness matrix, and damping of each element F(i). A matrix is created respectively. Furthermore, each of these matrices are combined to create the overall system matrix. Then, equations of motion are created by applying the various conditions described above, and these are calculated for every minute time (unit time T(x) (x=0, 1, . . . )). As a result, the deformation calculation of the tire model 2 is performed.

Commercially available finite element analysis application software, such as LS-DYNA manufactured by LSTC, is used to calculate the deformation of the tire model 2 (including the rolling calculation described later). Note that the unit time T(x) is appropriately set depending on the required simulation accuracy.

Next, in the deformation calculation step S3 of this embodiment, the tire model 2 after loading is calculated (step S32). In step S32, as shown in FIG. 3, the contact between the tire model 2 (indicated by a two-dot chain line) that has protruded outward in the tire radial direction due to the centrifugal force f shown in FIG. 4 and the road surface model 3 is calculated. . Then, a load L is set on the rotating shaft 12 of the tire model 2 while the road surface model 3 is immovably fixed. As a result, in the deformation calculation step S3 of this embodiment, the road surface model 3 is statically modified based on the load L and internal pressure (equally distributed load w shown in FIG. 4), and the centrifugal force f (shown in FIG. 4). A tire model 2 that is in contact with the ground is calculated.

The load L can be set as appropriate. It is desirable that the load L is set to, for example, a regular load defined for each tire by each standard in a standard system including the standards on which the tire is based. For example, the normal load is "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO.

Next, in the deformation calculation step S3 of this embodiment, the deformation of the tire model 2 is calculated based on the centrifugal force f (step S33). In step S33 of this embodiment, the centrifugal force f calculated in step S2 is defined for each element F(i) of the tire model 2 after the internal pressure has been filled. As a result, a tire model 2 (indicated by a two-dot chain line in FIG. 4) that protrudes outward in the tire radial direction due to the centrifugal force f is calculated.

Next, in the simulation method of this embodiment, the computer 1 calculates the amount of heat generated and the amount of heat released from the deformed tire model 2 (step S4). In step S4 of this embodiment, a static analysis is performed based on the tire model 2 that is statically in contact with the road surface model 3.

In static analysis, the strain that tire model 2 receives when it is in static contact (grounding) with road model 3 is substantially equal to the dynamic strain that the tire receives at a moment when it is rolling under load. The dynamic strain history is obtained from the static calculation results. Such a static analysis can reduce the calculation time, compared to, for example, a dynamic analysis in which the tire model 2 is rolled on the road surface model 3. For such static analysis, for example, the above-mentioned finite element analysis application software can be used.

The calorific value is calculated based on the amount of variation in strain and stress in the tire circumferential direction of the tire model 2 and the loss coefficient of each element F(i) of the tire model 2, as in the conventional case. On the other hand, the amount of heat radiation is based on the heat transfer coefficient set for the outer surface 2o and inner surface 2i (shown in FIG. 4) of the tire model 2, the temperature of the outside air, and the thermal conductivity of each element F(i). Calculated. Such calculation of the amount of heat generated and the amount of heat dissipation can be performed based on, for example, a patent document (Japanese Patent Laid-Open No. 2017-9482).

Note that the amount of heat dissipated from the outer surface of an actual tire (not shown) tends to increase in proportion to the amount of air that comes into contact with the outer surface. The air volume increases in proportion to the tire running speed (running speed condition). Therefore, the heat transfer coefficient of the outer surface 2o of the tire model 2 may be set to be large depending on the traveling speed. This makes it possible to calculate the heat radiation amount of the tire model 2 with high accuracy. Note that it is desirable that the relationship between the heat transfer coefficient of the outer surface 2o and the running speed be obtained in advance through an experiment using an actual tire, a fluid simulation, or the like. FIG. 6 is a graph showing an example of the relationship between the heat transfer coefficient of the outer surface 2o of the tire model 2 and the running speed condition. In FIG. 6, the heat transfer coefficient of the outer surface of the sidewall is representatively shown.

The amount of heat generated and the amount of heat radiation of the tire model 2 are calculated for each element F(i). The amount of heat generated and the amount of heat dissipated are input into the computer 1.

[Process of calculating tire model temperature]
Next, in the simulation method of this embodiment, the computer 1 calculates the temperature of the element F(i) of the tire model 2 based on the amount of heat generated and the amount of heat radiation (step S5). In step S5, the heat balance between the amount of heat generated and the amount of heat dissipated in each element F(i) of the tire model 2 is calculated. Thereby, in step S5, the temperature of each element F(i) when the tire model 2 is running is calculated.

In the simulation method of this embodiment, if the temperature of each element F(i) of the tire model 2 has not converged, the temperature of each element F(i) is updated and the deformation calculation steps S3 to S5 are performed again. may be done. This makes it possible to predict the steady state temperature of tires (not shown) that are running under the running speed conditions.

In this embodiment, the deformation of the tire model 2 statically in contact with the road surface model 3 is calculated based on the centrifugal force f calculated from the running speed condition (tire circumferential speed v). A tire model 2 that reproduces the condition can be calculated. As a result, in this embodiment, the calorific value of each element F(i) of the tire model 2 can be calculated with high accuracy without performing a dynamic analysis to calculate the tire model 2 rolling on the road surface model 3. be able to. Therefore, the simulation method of this embodiment can improve the prediction accuracy of the tire temperature while shortening the calculation time.

[Judgment process]
Next, in the simulation method of this embodiment, it is determined whether the temperature of the tire model 2 is within an allowable range (step S6). The allowable range can be set as appropriate depending on the performance required of the tire (not shown). The allowable range may be set for each component model (such as a sidewall rubber model) of the tire model 2, or may be set for each element F(i) of the tire model 2, for example.

In step S6, if the temperature of the tire model is within the allowable range ("Y" in step S6), a tire (not shown) is manufactured based on the tire design factors used to create tire model 2. (Step S7). On the other hand, if the temperature of the tire model 2 is not within the allowable range ("N" in step S6), the design factor is changed (step S8), and steps S1 to S6 are performed again. In this way, in the simulation method of the present embodiment, the design factors of the tire are changed until the temperature of the tire model 2 falls within the allowable range. can be designed efficiently.

[Tire simulation method (second embodiment)]
In the embodiments so far, the same centrifugal force is defined for each element F(i) of the tire model 2, but the invention is not limited to such an aspect. FIG. 7 is a flowchart illustrating an example of a processing procedure according to another embodiment of the present disclosure. FIG. 8 is a side view of the tire model 2 and the road surface model 3. In this embodiment, the same components as those in the previous embodiments are given the same reference numerals, and the explanation may be omitted.

In the simulation method of this embodiment, the computer 1 divides the area of the tire model 2 in the tire circumferential direction into a ground contact area 13 that contacts the road surface model 3 and an other non-ground contact area 14, as shown in FIG. (Step S9). Step S9 of this embodiment is performed prior to step S2 of calculating centrifugal force.

In step S9 of this embodiment, first, the tire model 2 after internal pressure filling (shown in FIG. 4) is calculated based on the same procedure as step S31 of the deformation calculation step S3 shown in FIG. Next, in step S9, the contact between the tire model 2 and the road surface model 3 after the internal pressure has been filled is calculated, and a load L is set on the rotating shaft 12 of the tire model 2. As a result, the tire model 2 after loading is calculated. Note that the centrifugal force f (shown in FIG. 4) is not defined in the tire model 2 after the load is applied in step S9.

Next, in step S9 of this embodiment, based on the tire model 2 after load application, the area of the tire circumferential direction of the tire model 2 is divided into a ground contact area 13 that contacts the road surface model 3 and a non-ground contact area other than that. It is divided into 14.

The ground contact area 13 and the non-ground contact area 14 may be set as appropriate. The ground contact area 13 of the present embodiment is defined as a region of the ground contact surface 15 of the tire model 2 that is divided by dividing lines 17, 17 connecting the outermost ends 16, 16 in the tire circumferential direction and the rotation axis 12. Ru. On the other hand, the non-ground area 14 is defined as an area other than the ground area 13.

Since the actual ground contact area (not shown) of the tire can be considered to move in parallel along the road surface when the tire rolls, centrifugal force does not act on it. However, in actual tires, the non-contact area that is deformed by the centrifugal force generated by tire rolling collides with the road surface with inertia force (receives impact force from the road surface) and becomes the non-contact area. Compared to the ground contact area, the ground contact area is recessed (crumpled) inward in the tire radial direction. Therefore, in order to calculate a tire model 2 that more accurately reproduces the tire running condition, it is important to calculate the deformation of the ground contact area 13 in consideration of the dents caused by the impact force from the road surface.

In this embodiment, different centrifugal forces f ₁ and f ₂ are calculated for the ground contact area 13 and the non-ground contact area 14 in order to calculate the deformation of the ground contact area 13 considering the dent caused by the impact force from the road surface. .

The ground contact area 13 is compressed (pressed) inward in the tire radial direction by the road surface model (road surface) 3. Therefore, the radius r ₁ of each element F(i) of the ground contact area 13 is smaller than the radius r 2 of each element F(i) of the non-ground contact area 14 that is not compressed by the road surface model ₃ . Therefore, the radius r ₁ (i) of each element F(i) of the ground contact area 13 is substituted into the above equation (1), and the centrifugal force f ₁ (indicated by the two-dot chain line) of the ground contact area 13 and the non-ground contact area 14 The radius r ₂ (i) of each element F(i) can be made different from the centrifugal force f ₂ (indicated by a chain double-dashed line) of the non-ground area 14 substituted into the above equation (1).

In the simulation method of this embodiment, in the next step S2 (FIG.), different centrifugal forces f ₁ and f ₂ are calculated in the ground contact area 13 and the non-ground contact area 14. By calculating such centrifugal forces f ₁ and f ₂ , in the deformation calculation step S3, deformation calculation taking into account the dent in the contact area 13 and deformation calculation taking into account the centrifugal force in the non-contact area 14 are performed. becomes possible. Therefore, in the simulation method of this embodiment, since the tire model 2 is calculated that further reproduces the conditions during tire running, the prediction accuracy of the temperature of the tire (not shown) is further improved while reducing the calculation time. It becomes possible to do so.

As described above, the radius r ₁ (i) of the ground contact area 13 is smaller than the radius r ₂ (i) of the non-ground contact area 14 . On the other hand, the density p(i), the volume V(i), and the tire angular velocity ω of the element F(i) are not distinguished between the ground contact area 13 and the non-ground contact area 14 (that is, they are the same). Therefore, by simply making the radius r ₁ (i) of the ground contact area 13 smaller than the radius r ₂ (i) of the non-ground contact area 14, the centrifugal force f _{2 of the non-ground contact area 14 can be made smaller than the centrifugal force f 2} of the ground contact area 13. f ₁ can be calculated to be small. As a result, in the deformation calculation step S3, it is possible to calculate the tire model 2 that more accurately reproduces the state of the tire while it is running, and it is possible to further improve the prediction accuracy of the tire temperature while reducing the calculation time. becomes.

The centrifugal force f ₁ of the grounding area 13 and the centrifugal force f ₂ of the non-grounding area 14 can be calculated as appropriate. In this embodiment, at the tire equator C (shown in FIG. 4), the radius (shortest radius) r ₁ from the rotation axis 12 of the tire model 2 to the ground contact surface 15 is set to the radius r in the above equation (1). Ru. Thereby, in step S2, the centrifugal force f ₁ can be calculated with high accuracy, which enables calculation of the deformation of the ground contact area 13 in consideration of dents due to impact force from the road surface.

In this embodiment, at the tire equator C, the radius (maximum radius) r ₂ from the rotation axis 12 of the tire model 2 to the outermost end of the tread portion 2a (non-ground contact area 14) in the tire radial direction is determined by the above formula (1). ) is set to the radius r. Thereby, in step S2, the centrifugal force f ₂ in the non-ground contact area 14 where the rise toward the outside in the tire radial direction is relatively large can be calculated with high accuracy.

As described above, since centrifugal force does not act on the ground contact area 13, the centrifugal force f ₁ of the ground contact area 13 may be set to zero. Thereby, the centrifugal force f ₁ in the grounding area 13 can be set smaller than the centrifugal force f ₂ in the non-grounding area 14 . In addition, in the tire model (rolling tire) under dynamic analysis, the non-contact area 14 that protrudes due to the centrifugal force f collides with the road surface model 3 and becomes the contact area 13. The reaction force (load) from the road surface model 3 and the centrifugal force cancel each other out. Therefore, in order to take into account such canceled forces, the centrifugal force f ₁ of the ground contact area 13 is preferably calculated as described above. The centrifugal force f ₁ in the ground area 13 and the centrifugal force f ₂ in the non-ground area 14 are input to the computer 1 .

[Tire simulation method (third embodiment)]
In the embodiments described above, the centrifugal force f acting on the tire model 2 is set to be the centrifugal force specified from the running speed condition (tire circumferential speed v), but the present invention is not limited to such an embodiment. In this embodiment, the same components as those in the previous embodiments are given the same reference numerals, and the explanation may be omitted.

By the way, in an actual tire that is rolling, an inertial force generated by the rolling acts on the tire, so that when the tread comes into contact with the road surface, the tread receives an impact force. Due to this impact force, the tread portion of the actual ground contact area 13 tends to be depressed inward in the tire radius, compared to the tire model 2 which protrudes outward in the tire radial direction due to the centrifugal force f of the previous embodiments. Therefore, with the centrifugal force f specified from the above-mentioned running speed condition (tire circumferential speed v), the temperature of the tire model 2 calculated in step S5 deviates from the experimental value of the temperature of the tire (not shown). There are cases.

In step S2 of calculating the centrifugal force of this embodiment, the centrifugal force f acting on the tire model 2 is greater than the centrifugal force specified from the running speed condition (tire circumferential speed v). calculated to be small. In this embodiment, the tire circumferential speed v in the above equation (1) is set to a value smaller than the predetermined traveling speed condition. Thereby, the centrifugal force f acting on the tire model 2 is calculated to be small. By calculating the tire model 2 deformed by such a small centrifugal force f, the temperature of the tire model 2 calculated in step S5 is prevented from deviating from the experimental value of the temperature of the tire (not shown). Can be done. Therefore, with the simulation method of this embodiment, it is possible to further improve the prediction accuracy of tire temperature while shortening the calculation time.

The value set for the tire circumferential speed v in the above equation (1) can be set appropriately as long as the centrifugal force f can be calculated to be small. It is desirable that the tire circumferential speed v in this embodiment is set to a value of 1% to 5% of a predetermined running speed condition (actual speed). Similarly to the radius r, the tire circumferential speed v may be different between the ground contact area 13 and the non-ground contact area 14. In this case, the tire circumferential speed v of the ground contact area 13 is set to the tire circumferential speed v of the non-ground contact area _{14 so that the centrifugal force f 1 of} the ground contact area 13 is calculated to be smaller than the centrifugal force f 2 of the non-ground contact area 14. It may be set smaller than .

Although particularly preferred embodiments of the present disclosure have been described above in detail, the present disclosure is not limited to the illustrated embodiments, and can be modified and implemented in various ways.

The temperatures of the elements of the tire model were calculated based on the processing procedure shown in FIG. 2 (Examples 1 to 3). In Examples 1 to 3, the centrifugal force acting on the tire model was calculated based on the following running speed conditions. Centrifugal force was calculated for each running speed condition.

In Example 1, the centrifugal force specified by the running speed condition was uniformly defined for all elements of the tire model based on the processing procedure shown in FIG.

In Examples 2 and 3, a step of dividing the region of the tire model in the tire circumferential direction into a ground contact region and a non-ground contact region was implemented based on the processing procedure shown in FIG. In Example 2, centrifugal force was defined in the non-ground contact area, but the centrifugal force in the ground contact area was set to zero. In Example 3, the centrifugal force in the ground contact area was set to be smaller (5% of the running speed condition) than the centrifugal force in the non-ground contact area.

In Examples 1 to 3, the deformation of a tire model statically in contact with a road surface model was calculated under each running speed condition. Then, based on the amount of heat generated and the amount of heat dissipated from the deformed tire model, the temperature of the elements of the tire model was calculated for each traveling speed condition.

For comparison, the deformation of a tire model that was statically in contact with a road surface model was calculated without considering centrifugal force (centrifugal force is zero) (Comparative Example 1). In Comparative Example 1, the temperatures of the elements of the tire model under each running speed condition were calculated based on the amount of heat generated and the amount of heat released from the deformed tire model. Furthermore, the temperature of the elements of the tire model under each running speed condition was calculated based on a dynamic analysis in which the tire model was rolled on the road surface model (Comparative Example 2).

In order to evaluate the prediction accuracy of tire temperature, tires having the same configuration as the tire models of Examples 1 to 3 and Comparative Examples 1 to 2 were manufactured (experimental example). The tire was run on a drum tester (diameter: 1708 mm), and the temperature was measured under each running speed condition. Then, the temperature of the tire of the experimental example was compared with the temperature of the tire models of Examples 1 to 3 and Comparative Examples 1 to 2, and the prediction accuracy of the tire temperature was evaluated. The common specifications are as follows. The magnitude of centrifugal force is as shown in Table 1.
Tire size: 330/710R18
Rim size: 18 x 13J
Internal pressure: 160kPa
Load: 7.5kN
Traveling speed conditions: 150km/h, 250km/h
Camber angle: 2 degrees Room temperature: 25℃

As a result of the test, the calculation time of Examples 1 to 3 was able to be reduced to 10% to 20% of the calculation time of Comparative Example 2 in which dynamic analysis was performed. Therefore, it was confirmed that Examples 1 to 3 can reduce the calculation time compared to Comparative Example 2.

FIG. 9 is a graph showing the relationship between the temperature of the tire model elements and the running speed. FIG. 10 is a graph showing temperature differences between elements of a tire model. In FIG. 10, the difference (absolute value) between the temperature at 150 km/h and the temperature at 250 km/h is shown. In FIGS. 9 and 10, the temperature of one element disposed on the outer side in the axial direction of the tire among the elements constituting the tread portion is shown as a representative.

As shown in FIG. 9, the temperatures of the tire models of Examples 1 to 3 were able to approximate the temperature of the tire of the experimental example compared to the temperature of the tire model of comparative example 1. As shown in FIG. 10, with respect to the temperature difference (gradient of temperature rise) under different running speed conditions, Examples 1 to 3 were able to suppress deviation from the experimental example compared to Comparative Example 1. Therefore, Examples 1 to 3 were able to improve the prediction accuracy of tire temperature compared to Comparative Example 1. In Examples 2 and 3, different centrifugal forces are calculated in the ground contact area and non-ground contact area, so the prediction accuracy of tire temperature is improved compared to Example 1, in which the same centrifugal force is calculated. I was able to improve it.

Furthermore, in Example 3, the centrifugal force in the ground contact area was calculated based on a speed (5%) smaller than the running speed condition, so compared to Example 2, in which the centrifugal force in the ground contact area was set to zero, It was possible to effectively prevent the temperature of the tire model from deviating from the temperature of the tire in the experimental example.

[Additional notes]
The present disclosure includes the following aspects.

[This disclosure 1]
A tire simulation method,
Including a step of inputting into a computer a tire model and a road surface model in which the tires and the road surface are modeled using a finite number of elements, respectively,
The computer includes:
calculating a centrifugal force acting on the tire model based on a predetermined running speed condition;
applying a predetermined load and internal pressure and the centrifugal force to the tire model to calculate the deformation of the tire model that is statically in contact with the road surface model;
calculating the amount of heat generated and the amount of heat released from the deformed tire model;
calculating the temperature of the element of the tire model based on the calorific value and the heat radiation amount;
How to simulate tires.
[This disclosure 2]
further comprising the step of dividing the region of the tire model in the tire circumferential direction into a ground contact region that contacts the road model and a non-ground contact region,
The tire simulation method according to the present disclosure 1, wherein the step of calculating the centrifugal force calculates different centrifugal forces in the ground contact area and the non-ground contact area.
[Disclosure 3]
The tire simulation method according to the present disclosure 2, wherein the centrifugal force in the ground contact area is smaller than the centrifugal force in the non-ground contact area.
[Disclosure 4]
The tire simulation method according to any one of the present disclosures 1 to 3, wherein the step of calculating the centrifugal force calculates the centrifugal force acting on the tire model to be smaller than the centrifugal force specified from the traveling speed condition. .

S1 Step of inputting the tire model and road surface model S2 Step of calculating centrifugal force S3 Step of calculating the deformation of the tire model that is statically in contact with the road surface model S4 Step of calculating the heat generation amount and heat radiation amount of the tire model S5 Tire The process of calculating the temperature of the elements of the model

Claims (4)

A tire simulation method,
Including a step of inputting into a computer a tire model and a road surface model in which the tires and the road surface are modeled using a finite number of elements, respectively,
The computer includes:
calculating a centrifugal force acting on the tire model based on a predetermined running speed condition;
applying a predetermined load and internal pressure and the centrifugal force to the tire model to calculate the deformation of the tire model that is statically in contact with the road surface model;
calculating the amount of heat generated and the amount of heat released from the deformed tire model;
calculating the temperature of the element of the tire model based on the calorific value and the heat radiation amount;
How to simulate tires. further comprising the step of dividing the region of the tire model in the tire circumferential direction into a ground contact region that contacts the road model and a non-ground contact region,
The tire simulation method according to claim 1, wherein in the step of calculating the centrifugal force, different centrifugal forces are calculated in the ground contact area and the non-ground contact area. The tire simulation method according to claim 2, wherein the centrifugal force in the ground contact area is smaller than the centrifugal force in the non-ground contact area. The tire according to any one of claims 1 to 3, wherein the step of calculating the centrifugal force calculates a centrifugal force acting on the tire model to be smaller than a centrifugal force specified from the traveling speed condition. Simulation method.

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