JP2014141164A - Tire simulation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate durability of tread grooves etc. with good accuracy.SOLUTION: A tire simulation method is a tire simulation method for evaluating performance of a tire 2 having tread grooves 12. The tire simulation method includes: a step S2 for inputting a meridian cross section shape 14S of a non-load tire 14 in which the tire 2 is filled for an inner pressure and is not loaded; a step S3 for inputting a tire model 21 based on the meridian cross section shape 14S; a deformation step S6 for defining a loading condition specified in advance for the tire model 21 and calculating the tire model 21 having tread grooves 16 deformed; and a calculating step S7 for calculating physical quantities on the tread grooves 16 of the deformed tire model 21.

Description

  The present invention relates to a tire simulation method that can accurately evaluate durability and the like of a tread groove.

  In recent years, simulation methods for analyzing various performances of tires having tread grooves using a computer have been proposed. For example, in a simulation method for calculating a physical quantity related to a tread groove, a step of inputting a tire model composed of a finite number of elements to a computer based on the meridian cross-sectional shape of the tire before filling with internal pressure is first performed. In the tire model, a tread groove of a tire is set.

  Next, a step is performed in which the computer calculates the shape of the tire model after filling the internal pressure based on a predetermined internal pressure condition. Next, a step is performed in which the computer calculates the shape of the tire model after being loaded based on a predetermined load condition. Then, in the tire model after the internal pressure is filled and the load is applied, physical quantities such as the shape and strain of the tread groove are calculated. Based on these physical quantities, the durability of the tread groove is evaluated. Related literature includes:

JP 2006-175937 A

  As described above, in the conventional simulation method, since the tire model is set based on the tire before the internal pressure filling, the step of calculating the shape after the internal pressure filling of the tire model, and the shape of the tire model after being loaded Both steps of calculating are performed. For this reason, the shape of the tire model after being loaded is likely to be different from the actual shape of the tire filled with the internal pressure and loaded. Therefore, the conventional simulation method has a problem that errors in calculation of physical quantities such as strain around the tread groove are likely to occur, and durability of the tread groove cannot be accurately evaluated.

  The present invention has been devised in view of the actual situation as described above. When the meridian cross-sectional shape of the tread groove of the tire model is deformed to the meridian cross-sectional shape of the tread groove of the deformed tire loaded, a tread is obtained. The main object is to provide a tire simulation method capable of accurately evaluating the durability of a tread groove and the like based on the calculation of physical quantities related to the groove.

  The invention according to claim 1 of the present invention is a tire simulation method for evaluating the performance of a tire having a tread groove by using a computer, wherein the tire is filled with an internal pressure to be in a no-load state. Preparing a loaded tire; inputting to the computer a meridian cross-sectional shape of the unloaded tire including at least the tread groove based on the unloaded tire; into the computer, a meridian section of the unloaded tire A step of inputting a tire model composed of a finite number of elements based on the shape; a deformation in which the computer defines a predetermined load condition for the tire model and calculates the tire model in which the tread groove is deformed And the computer relates to the tread groove of the deformed tire model. Characterized in that it comprises a calculation step of calculating that the physical quantity.

  According to a second aspect of the present invention, there is provided a deformed tire obtained by deforming the tread groove by applying a load to the no-load tire, and the computer is provided with the tread groove based on the deformed tire. The method further includes the step of inputting at least a meridian cross-sectional shape of the deformed tire, wherein the deforming step matches a meridian cross-sectional shape of the tread groove of the tire model with a meridian cross-sectional shape of the tread groove of the deformed tire. Until the deformation calculation of the tire model is repeatedly performed, the calculation step includes the tread groove when the meridian cross-sectional shape of the tread groove of the tire model matches the meridian cross-sectional shape of the tread groove of the deformed tire. The tire simulation method according to claim 1, wherein the physical quantity relating to the tire is calculated.

  The invention according to claim 3 is the tire simulation method according to claim 1 or 2, wherein the physical quantity is strain or stress of an element around the tread groove.

  According to a fourth aspect of the present invention, the tire includes a tread rubber in which the tread groove is formed, and at least a part of the tread rubber is 24 in toluene at a temperature of 40 ° C. according to JIS K6258. The step of determining the swelling rate of the tread rubber by immersing for a time, the crack resistance of the tread groove of the tire or the tire from the strain of the tread groove calculated in the calculation step and the swelling rate of the tread rubber The tire simulation method according to claim 1, further comprising a step of evaluating the high speed stability of the tire.

  The tire simulation method of the present invention includes a step of preparing an unloaded tire in which the tire is filled with an internal pressure to be in an unloaded state, and a meridian section of the unloaded tire including at least a tread groove based on the unloaded tire in a computer. Inputting a shape, and inputting a tire model composed of a finite number of elements to a computer based on a meridian cross-sectional shape of the unloaded tire.

  Further, the simulation method includes a deformation step for calculating a tire model in which a tread groove is deformed by defining a predetermined load condition for the tire model, and a calculation step for calculating a physical quantity relating to the tread groove of the deformed tire model. Including.

  Thus, in the simulation method of the present invention, since the tire model is set based on the unloaded tire filled with the internal pressure, it is not necessary to calculate the shape of the tire model after filling with the internal pressure as in the conventional case. Thereby, in the simulation method of the present invention, the difference between the meridian cross-sectional shape of the tire model deformed based on the load condition and the meridian cross-sectional shape of the actual tire filled with the internal pressure and loaded is minimized. be able to. Therefore, in the simulation method of the present invention, the error of the physical quantity related to the tread groove can be reduced, and the durability of the tread groove can be accurately evaluated.

It is a perspective view of the computer which performs the simulation method of this embodiment. It is sectional drawing of the tire of analysis object. It is a flowchart which shows the simulation method of this embodiment. It is a diagram which visualizes and shows the meridian section shape of an unloaded tire. It is sectional drawing which visualizes and shows a tire model. It is sectional drawing of a deformation | transformation tire. It is a diagram which visualizes and shows the meridian cross-sectional shape of a modification tire. It is a flowchart which shows the calculation step of this embodiment. It is sectional drawing which visualizes and shows the tire model and road surface model which deform | transformed. It is sectional drawing which visualizes and shows the tread groove | channel of the tire model before a deformation | transformation. It is sectional drawing which visualizes and shows the tread groove | channel of the tire model after a deformation | transformation. It is a flowchart which shows the simulation method of other embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the tire simulation method of the present embodiment (hereinafter sometimes simply referred to as “simulation method”) is a method for evaluating the durability of a tread groove using a computer.

  As shown in FIG. 1, the computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a is provided with an arithmetic processing unit (CPU), a ROM, a working memory, a storage device such as a magnetic disk, and disk drive devices 1a1, 1a2. Note that a processing procedure (program) for executing the simulation method of the present embodiment is stored in the storage device in advance.

  As shown in FIG. 2, the analysis target tire 2 of the present embodiment is configured as a motorcycle tire. The tire 2 includes a carcass 6 extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and a belt layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2a. It has.

  In the tread portion 2a, the outer surface 2S between the tread ends 2t and 2t, which is the outer end in the tire axial direction, extends and curves in a convex arc shape outward in the tire radial direction. Further, in the tread portion 2a, the tread width TW, which is the distance in the tire axial direction between the tread ends 2t and 2t, forms the maximum tire width.

  Further, the tread portion 2a is provided with a tread surface 11 that comes in contact with the road surface and a plurality of tread grooves 12 that are recessed from the tread surface 11. The tread groove 12 includes a pair of center tread grooves 12a and 12a adjacent to each other with the tire equator C interposed therebetween, and a pair of shoulder tread grooves 12b and 12b disposed on the outer side in the tire axial direction of the center tread grooves 12a and 12a. These tread grooves 12a and 12b extend, for example, the tread portion 2a so as to be inclined with respect to the tire circumferential direction or the tire circumferential direction. Further, the groove depth D1 of the tread groove 12 is set to, for example, about 3.5 to 5.5 mm. Furthermore, the groove width W1 of the tread groove 12 is set to about 2 to 4 mm, for example.

  The carcass 6 includes at least one carcass ply 6A and 6B in this embodiment. The carcass plies 6A and 6B include a main body portion 6a that extends from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and extends around the bead core 5 from the inner side to the outer side in the tire axial direction. And a folded portion 6b that is folded. Further, a bead apex 8 made of, for example, hard rubber is disposed between the main body portion 6a and the folded portion 6b of the carcass plies 6A and 6B.

  The belt layer 7 is composed of two belt plies 7A and 7B in which a belt cord is arranged with an inclination of, for example, 10 to 35 degrees with respect to the tire circumferential direction. These belt plies 7A and 7B are overlapped so that the belt cords cross each other.

FIG. 3 shows a specific processing procedure of the simulation method of the present embodiment.
In the present embodiment, first, a no-load tire is prepared in which the tire 2 shown in FIG. 2 is filled with the internal pressure and is in an unloaded state (step S1). In step S1 of this embodiment, the tire 2 is assembled to the rim 13 which is a normal rim, and the normal internal pressure is filled. In addition, about the internal pressure with which the tire 2 is filled, it is not necessarily limited to the above normal internal pressures, and can be appropriately set according to analysis conditions and the like.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire 2 is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, For ETRTO, use “Measuring Rim”.

  In addition, the “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire 2 is based. TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "Maximum value", ETRTO, "INFLATION PRESSURE".

  Next, the meridian cross-sectional shape of the unloaded tire 14 is input to the computer 1 based on the unloaded tire 14 (step S2). In step S <b> 2 of the present embodiment, first, CT scan imaging of the unloaded tire 14 is performed, and image data of a meridian section of the unloaded tire 14 is input to the computer 1. Then, the video data of the no-load tire 14 is converted into CAD data or the like. Thereby, as shown in FIG. 4, the meridian cross-sectional shape (contour shape) 14 </ b> S of the unloaded tire 14 including the tread groove 12 can be input to the computer 1.

  Next, a tire model composed of a finite number of elements is input to the computer 1 based on the meridian cross-sectional shape 14S of the unloaded tire 14 (step S3). In step S3 of the present embodiment, first, based on the meridian cross-sectional shape 14S of the unloaded tire 14, the tread rubber 2g in which the tread groove 12 shown in FIG. , The two-dimensional element Fi (i = 1, 2,...) Shown in FIG. As a result, a two-dimensional tire model 21 having a tread rubber model 17, a carcass model 18, a belt model 19 and the like in which the tread grooves 16 are formed is set. The tread groove 16 includes a center tread groove 16a that models the center tread groove 12a and a shoulder tread groove 16b that models the shoulder tread groove 12b.

  As the two-dimensional element Fi, for example, a quadrilateral element suitable for expressing a complex shape is preferable, but is not limited thereto. Each element Fi includes a plurality of nodes 22. Further, numerical data such as an element number, a node number 22, a coordinate value of the node 22, and material characteristics (for example, density, Young's modulus, attenuation coefficient, etc.) are defined for each element Fi. In addition, the distance L1 between the adjacent nodes 22 and 22 is preferably set to, for example, 0.2 to 0.8 mm from the viewpoint of preventing an increase in calculation time while maintaining simulation accuracy.

  In the tire model 21 of the present embodiment, the rim contact areas 21r and 21r of the tire model 21 are constrained so as not to be deformable. In the present embodiment, the constraint of the rim contact areas 21r and 21r is defined by defining the constraint condition at each node 22 in the element Fi constituting the rim contact areas 21r and 21r. The constraints on the rim contact areas 21r and 21r may be defined by setting a rim model (not shown) that models the rim 13, for example.

  Further, the tire model 21 is defined such that the tire radial distance Rs between the rim contact area 21r and the rotation shaft (not shown) is always equal to the rim radius. Further, an evenly distributed load w corresponding to the internal pressure condition of the no-load tire 14 is defined on the inner cavity surface of the tire model 21.

  Thus, in this embodiment, since the tire model 21 is modeled based on the unloaded tire 14 filled with the internal pressure, there is no need to perform deformation calculation of the tire model 21 accompanying the internal pressure filling. Therefore, in this embodiment, the calculation time of the tire model 21 can be shortened.

  Next, in the simulation method of the present embodiment, a deformed tire in which a load is applied to the unloaded tire 14 is acquired (step S4). In step S4 of the present embodiment, the unloaded tire 14 shown in FIG. 2 is grounded to the road surface 25 at a camber angle of 0 degrees, and a normal load is applied. Thereby, as shown in FIG. 6, the unloaded tire 14 can be deformed by the loaded load, and a deformed tire 26 in which the tread groove 12 is deformed can be obtained.

  “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS AT for TRA” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” for ETRTO. In addition, when neither standard exists, a tire manufacturer's recommendation value is applied. In addition, about the load loaded on the no-load tire 14, it is not necessarily limited to the above normal loads, but can be suitably set according to analysis conditions.

  Furthermore, in the simulation method of the present embodiment, the meridian cross-sectional shape of the modified tire 26 is input to the computer based on the modified tire 26 (step S5). In step S <b> 5 of the present embodiment, as in step S <b> 2, the deformed tire 26 is CT-scanned and image data of a meridian section of the deformed tire 26 is input to the computer 1. Then, the video data of the modified tire 26 is converted into CAD data or the like. Thereby, as shown in FIG. 7, the meridian cross-sectional shape 26 </ b> S of the modified tire 26 including the tread groove 12 can be input to the computer 1.

  Next, the computer 1 defines a predetermined load condition for the tire model 21, and calculates the tire model 21 in which the tread groove 16 is deformed (deformation step S6). FIG. 8 shows a specific processing procedure of the modification step S6 of the present embodiment.

  In the modified step S6 of the present embodiment, first, a road surface model obtained by modeling the road surface 25 on which the tire 2 contacts is input to the computer 1 (step S61). As shown in FIG. 9, the road surface model 28 of the present embodiment is defined by a two-dimensional contour based on the surface shape of the road surface 25 (shown in FIG. 6). The road surface model 28 is defined as a rigid surface that does not deform.

  Next, the computer 1 calculates deformation of the tire model 21 based on a predetermined load condition (step S62). As shown in FIG. 9, in step S <b> 62 of the present embodiment, the tire model 21 is grounded to the road surface model 28, and a load in the vertical direction is defined on the rotation axis (not shown) of the tire model 21. Thereby, the tire model 21 in which the tread groove 16 is deformed by the load is calculated. The load applied to the tire model 21 is preferably the same as the load applied to the modified tire 26.

  In the deformation calculation of the tire model 21, a mass matrix, a stiffness matrix, and a damping matrix for each element Fi (shown in FIG. 5) are created based on the shape and material characteristics of each element. The matrix of the whole system is created by combining the matrices. The computer 1 applies various conditions to create an equation of motion, and calculates the deformation of the tire model 21 for each unit time Tx (x = 0, 1,...) (For example, every 1 μsec). Do. Such rolling calculation can be calculated using commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC.

  Next, the computer 1 determines whether the meridian cross-sectional shape 12S (shown in FIG. 7) of the tread groove 12 of the modified tire 26 matches the meridian cross-sectional shape 16S (shown in FIG. 9) of the tread groove 16 of the tire model 21. (Step S63).

  In step S63 of this embodiment, it is determined whether the meridian cross-sectional shape 12S of the center tread groove 12a of the modified tire 26 matches the meridian cross-sectional shape 16S of the center tread groove 16a of the tire model 21. If it is determined that the meridian cross-sectional shapes 16S and 12S coincide with each other, next, step S7 for calculating a physical quantity related to the tread groove 16 of the tire model 21 is executed. On the other hand, if it is determined that the meridian cross-sectional shapes 16S and 12S do not match, the unit time Tx is advanced by one (step S64), and step S62 is executed again.

  Thereby, in the deformation step S6 of the present embodiment, the deformation calculation of the tire model 21 is performed until the meridian cross-sectional shape 16S of the tread groove 16 of the tire model 21 matches the meridian cross-sectional shape 12S of the tread groove 12 of the modified tire 26. Repeatedly. Therefore, in the deformation step S6 of the present embodiment, the meridian cross-sectional shape 16S of the tread groove 16 of the tire model 21 can be reliably matched with the meridian cross-sectional shape 12S of the tread groove 12 of the modified tire 26. In addition, in order to make each meridian cross-sectional shape 16S and 12S correspond, various conditions, such as a load defined in the tire model 21, may be changed suitably.

  Note that, as shown in FIG. 10, the above determination is based on the average separation distance D2 between the meridian cross-sectional shape 16S of the tread groove 16 of the tire model 21 and the meridian cross-sectional shape 12S of the tread groove 12 of the modified tire 26. , 0.5 to 1.0 mm, it is determined that they match. The average separation distance D2 is calculated at each node 22 of the element Fi constituting the surface 30 of the tread groove 16 of the tire model 21.

  Next, the computer 1 calculates a physical quantity related to the tread groove 16 of the tire model 21 after deformation (step S7). In the present embodiment, the strain Si of the element Fi around the tread groove 16 is calculated as a physical quantity related to the tread groove 16.

The strain Si of each element Fi around the tread groove 16 is obtained by the following formula (1) in the element Fi constituting the surface 30 of the tread groove 16.
Si = (Mi-Li) / Li (1)
here,
Li: distance between adjacent nodes 22 and 22 on the surface 30 in the element Fi of the tire model 21 before deformation (shown in FIG. 10)
Mi: distance between adjacent nodes 22 and 22 on the surface 30 in the element Fi of the tire model 21 after deformation (shown in FIG. 11)

  Furthermore, in the present embodiment, among the elements Fi constituting the surface 30 of the tread groove 12, an element 31 having the largest strain Si (hereinafter, simply referred to as “strain maximum element”) 31 is specified. Such a strain maximum element 31 can be regarded as a portion that is most likely to be the starting point of a crack in the tread groove 16.

  Next, it is determined whether the physical quantity related to the tread groove 16 of the tire model 21 is within an allowable range (evaluation step S8).

  In the evaluation step S8 of the present embodiment, it is determined whether the strain Si of the maximum strain element 31 is within an allowable range. As described above, the maximum strain element 31 can be regarded as the most likely location of crack initiation in the tread groove 16. For this reason, it is possible to evaluate the durability (crack resistance) of the tread groove 12 of the tire 2 by determining whether the strain Si of the maximum strain element 31 is within an allowable range.

  Note that the allowable range of the strain Si of the maximum strain element 31 can be appropriately set according to the tire 2 to be analyzed. The allowable range of strain Si of the maximum strain element 31 of the present embodiment is desirably set to 0.15 to 0.26.

  In the evaluation step S8, when it is determined that the physical quantity is within the allowable range, the tire 2 is commercialized (step S9). On the other hand, if it is determined that the physical quantity is not within the allowable range, the tire 2 is redesigned (step S10), and simulation is performed again (steps S1 to S8). In the simulation method of the present embodiment, the tire 2 is redesigned until the physical quantity related to the tread groove 16 of the tire model 21 falls within the allowable range. Therefore, the tire 2 having excellent durability of the tread groove 12 is efficiently designed. be able to.

  As described above, in the simulation method of the present invention, the tire model 21 is set based on the unloaded tire 14 (shown in FIG. 2) filled with the internal pressure in step S3. There is no need to calculate the shape after filling the inner pressure. Thereby, in the simulation method of the present invention, the difference between the meridian cross-sectional shape of the tire model 21 deformed based on the load condition and the meridian cross-sectional shape 26S (shown in FIG. 7) of the deformed tire 26 can be minimized. it can. Therefore, in the simulation method of the present invention, the error of the physical quantity related to the tread groove 16 can be reduced, and the durability of the tread groove 16 can be accurately evaluated.

  Furthermore, in the simulation method of the present embodiment, the meridian cross-sectional shape 16S of the tread groove 16 of the tire model 21 after deformation is matched with the meridian cross-sectional shape 12S of the tread groove 12 of the actual deformed tire 26, so that the tread groove 16 is related. The physical quantity is calculated. As a result, in the simulation method of the present invention, errors in the physical quantities between the tire model 21 and the deformed tire 26 can be further reduced, so that the durability of the tread groove 12 of the tire 2 can be evaluated more accurately.

  In the present embodiment, the strain Si of the element Fi around the tread groove 16 is calculated as a physical quantity related to the tread groove 16, but the present invention is not limited to this. For example, the stress Ti of the element Fi around the tread groove 16 may be calculated.

  The stress Ti of the element Fi around the tread groove 16 is calculated by the computer 1 in step S62 for calculating the deformation of the tire model 21. Such stress Ti is shown by a stress contour diagram as shown in FIG. 11, for example. Furthermore, among the stresses Ti of the elements Fi around the tread groove 16, an element 32 having the largest stress Ti (hereinafter, simply referred to as “stress maximum element”) 32 is identified. Such a stress maximum element 32 can be regarded as a point most likely to be the starting point of a crack because stress is locally concentrated in the tread groove 16.

  In the evaluation step S8, it is determined whether the stress Ti of the stress maximum element 32 is within an allowable range. As described above, the stress maximum element 32 can be regarded as a location that is likely to be a starting point of a crack in the tread groove 12. Therefore, the durability (crack resistance) of the tread groove 12 of the tire 2 can be evaluated by determining whether the stress Ti of the stress maximum element 32 is within the allowable range. It is desirable that the allowable range of the stress Ti of the maximum stress element 32 is appropriately set for each tire 2 to be analyzed.

  Next, a simulation method according to another embodiment of the present invention will be described. The simulation method of this embodiment is the same as the simulation of the above embodiment except for the configuration described below. FIG. 12 shows a specific processing procedure of the simulation method of this embodiment.

  In the simulation method of this embodiment, the swelling ratio of the tread rubber 2g of the tire 2 shown in FIG. 2 is acquired (step S11). The swelling rate of 2 g of tread rubber is determined according to JIS K6258. In this step S10, first, at least a part of the tread rubber 2g is immersed in toluene at a temperature of 40 ° C. for 24 hours. And the swelling rate of 2 g of tread rubber is calculated | required from the volume change rate (%) of 2 g of tread rubber. Such a swelling rate of the tread rubber 2g is useful for evaluating the rigidity and heat resistance of the tread rubber 2g.

  Further, in the evaluation step S8 of the present embodiment, it is determined whether the swelling rate of the tread rubber 2g (shown in FIG. 2) is within an allowable range in addition to the physical quantity related to the tread groove 16 of the tire model 21 described above. If the swelling rate of the tread rubber 2g is reduced, the flexibility of the tread rubber 2g is reduced, and even if the physical quantity related to the tread groove 16 of the tire model 21 (shown in FIG. 9) is within an allowable range, the tread groove 12 There is a risk of cracking. On the other hand, even if the swelling rate of the tread rubber 2g is large, the rigidity of the tread rubber 2g may be reduced, and the high-speed stability of the tire 2 may not be maintained.

  Thus, in the simulation method of this embodiment, it is determined whether both the physical quantity related to the tread groove 12 and the swelling ratio of the tread rubber 2g are within the allowable range, whereby the durability (resistance resistance) of the tread groove 12 is determined. (Crackability) and high-speed stability of the tire 2 can be more effectively evaluated.

  In addition, the allowable range of the swelling rate of the tread rubber 2g can be appropriately set according to the tire 2 to be analyzed. The allowable range of the swelling rate in this embodiment is set to 200 to 350%.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  Tires having the basic structure shown in FIG. 2 and different tread rubber swelling rates were produced. These motorcycle tires were modeled with a finite number of elements, and the tire model shown in FIG. 5 was created.

  Then, according to the processing procedure shown in FIG. 3, the meridian cross-sectional shape of the tread groove of the tire model was matched with the meridian cross-sectional shape of the tread groove of the modified tire, and the physical quantity (strain Si) related to the tread groove was calculated. Further, the durability (crack resistance) of the tread groove and the high-speed stability of the tire 2 were evaluated from the strain Si of the tread rubber and the swelling rate of the tread rubber. And the presence or absence of correlation with these evaluations and the test result using an actual tire was confirmed.

For comparison, a tire model was created based on the meridian cross-sectional shape of the tire before filling with the internal pressure shown in FIG. Next, a step of calculating the shape of the tire model after filling the internal pressure based on a predetermined internal pressure condition, and a shape of the tire model after being loaded based on a predetermined load condition are calculated. A step was performed, and a physical quantity (for example, an area change amount) related to the tread groove was calculated. And the presence or absence of correlation with the durability (crack resistance) of the tread groove evaluated from the calculated physical quantity and the test result using an actual tire was confirmed. The common specifications are as follows.
Tire (front wheel):
Tire size: 120 / 70ZR18M / C
Rim size:
Internal pressure: 235 kPa
Load: 2.86kN
Tread groove (center tread groove):
Groove width W1: 7.2 mm
Groove depth D1: 4.6 mm
Distance between nodes L1: 0.5 mm
Strain Si tolerance: 0.15 to 0.26
Swelling rate tolerance: 200-350%
The test method using actual tires is as follows.

<Durability of tread grooves (existence of cracks)>
Each test tire was assembled on the rim, filled with the internal pressure, and left in a greenhouse at a room temperature of 35 ° C. for 3 hours. Thereafter, each test tire was run (running speed of 80 km / h) on a drum testing machine (outer diameter of about 1700 mm) according to the following conditions (first stage to fourth stage). Then, it was visually confirmed whether or not a crack occurred in the tread groove (center tread groove) of each test tire in which the traveling from the first stage to the fourth stage was completed.
First stage:
Load: 100% of the above load
Travel time: 4 hours Second stage:
Load: 108% of the above load
Travel time: 6 hours Third stage:
Load: 117% of the above load
Travel time: 24 hours Stage 4:
Load: 117% of the above load
Travel time: 12 hours

<High-speed stability>
Each test tire was assembled on the rim, filled with the internal pressure, and mounted on the front wheel of a motorcycle with a displacement of 750 cc. Then, the driving stability (turning performance, transient characteristics, etc.) when the test course on the dry asphalt road surface was rotated at a speed of 200 km / h was evaluated by a ten-point method by sensory evaluation by the driver. A numerical value of 7 or more is good.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the simulation method of the example had a high correlation between the evaluation result and the test result using the actual tire, and that the durability and high-speed stability of the tread groove could be evaluated with high accuracy. On the other hand, in the comparative example, it was confirmed that the durability of the tread groove could not be accurately evaluated. Moreover, in the comparative example, high-speed stability could not be evaluated.

2 Tire 14 No-load tire 16 Tread groove 21 Tire model 26 Deformed tire

Claims (4)

A tire simulation method for evaluating the performance of a tire having a tread groove using a computer,
Preparing an unloaded tire filled with an internal pressure into the tire and brought into an unloaded state
Inputting the meridian cross-sectional shape of the unloaded tire including at least the tread groove to the computer based on the unloaded tire;
Inputting a tire model composed of a finite number of elements to the computer based on the meridian cross-sectional shape of the unloaded tire;
A deformation step in which the computer defines a predetermined load condition for the tire model and calculates the tire model in which the tread groove is deformed;
The tire simulation method, wherein the computer includes a calculation step of calculating a physical quantity related to the tread groove of the tire model that has been deformed. Obtaining a deformed tire obtained by deforming the tread groove by applying a load to the unloaded tire; and
The computer further includes a step of inputting a meridian cross-sectional shape of the deformed tire including at least the tread groove based on the deformed tire;
In the deformation step, the deformation calculation of the tire model is repeatedly performed until the meridian cross-sectional shape of the tread groove of the tire model matches the meridian cross-sectional shape of the tread groove of the deformed tire,
2. The tire according to claim 1, wherein the calculating step calculates a physical quantity related to the tread groove when a meridian cross-sectional shape of the tread groove of the tire model matches a meridian cross-sectional shape of the tread groove of the deformed tire. Simulation method.   The tire simulation method according to claim 1, wherein the physical quantity is strain or stress of an element around the tread groove. The tire includes a tread rubber in which the tread groove is formed,
In accordance with JIS K6258, at least a part of the tread rubber is immersed in toluene at a temperature of 40 ° C. for 24 hours to determine the swelling rate of the tread rubber;
4. The method according to claim 1, further comprising a step of evaluating crack resistance of the tire tread groove or high-speed stability of the tire from the strain of the tread groove calculated in the calculation step and the swelling rate of the tread rubber. The tire simulation method according to any one of the above.