JP6393027B2 - Tire simulation method - Google Patents

Description

  The present invention relates to a method for simulating tire durability using a computer.

  Conventionally, in order to evaluate the durability of a tire, for example, a durability test in which a tire loaded with a load is run on a cylindrical drum is generally performed. In order to perform such a durability test, it is necessary to actually manufacture a tire. Therefore, expensive molds for manufacturing tires must be manufactured. Further, if the result of the durability test is not good, it is necessary to discard or remanufacture the mold. Therefore, much time and cost are required to evaluate the durability of the tire.

JP2013-108900A

  In order to solve such a problem, it is considered to simulate the durability of a tire using a computer. In this type of method, for example, a tire model obtained by discretizing a tire with a finite number of elements is used. Then, based on various conditions determined in advance, the deformation state of the tire model is calculated, and the physical quantity of the tire model is calculated. However, there is a problem that it is difficult to accurately simulate the durability of the tire simply by calculating the deformation state of the tire model.

  As a result of extensive research, the inventors have found that the durability of the tire can be accurately simulated by deforming the tire model more greatly than when the tire is deformed under the standard load.

  The present invention has been devised in view of the above circumstances, and has as its main object to provide a tire simulation method capable of accurately simulating the durability of a tire.

The present invention, the durability of the tire, a method for simulating with a computer, the tire, the step of inputting the modeled tire model a finite number of elements, the computer, step to enter the contact surface models a contact surface modeling in which the tire model is in contact, and said computer comprises a deformation step of calculating a deformation of the tire model in contact with the contact surface model, wherein the deforming step, the tire model, the tire is viewed contains a large deformation step of largely deformed as compared with the state deformed under the standard load, the tire model leads to a bead core of a bead portion through a sidewall portion from a tread portion of the tire The main body and the bead core connected to the main body are folded back from the inner side to the outer side in the tire axial direction. A carcass ply model obtained by modeling a carcass ply including a shoulder portion, further including a step of outputting a physical quantity of the tire model obtained by deformation calculation of the tire model, and the step of outputting the physical quantity includes the step of outputting the physical quantity Outputting a graph showing a relationship between the stress of the model and the position of the carcass ply model. The distance between the nodes of the elements arranged on the inside is “0”, and is a distance along the main body from the bead to the tread through the sidewall .

  The tire simulation method according to the present invention includes a step of defining, in the computer, a first boundary condition that prevents the tire model from slipping through the contact surface model, and the first boundary condition includes the tire It is desirable to define at least between a tread portion of the model and the contact surface model and between a sidewall portion extending inward in the tire radial direction from both ends of the tread portion and the contact surface model.

  In the tire simulation method according to the present invention, in the large deformation step, the tire model is pressed in a tire radial direction, and the tread portion of the tire model and at least a part of the sidewall portion are brought into contact with each other. The surface model may be contacted.

  In the tire simulation method according to the present invention, the large deformation step may press the tire model in a tire radial direction to bring the inner liner rubber models into contact with each other.

  In the tire simulation method according to the present invention, it is desirable that the large deformation step applies a load larger than the standard load to the tire model.

  In the tire simulation method according to the present invention, it is preferable that the contact surface model is defined to be undeformable, and in the large deformation step, the tire model is pressed and deformed toward the contact surface model side.

In the tire simulation method according to the present invention, at least a part of the element of the tire model is defined as an incompressible superelastic body whose volume does not change due to deformation and returns to its original shape when the load is removed. Is desirable .

  The tire simulation method of the present invention includes a step of inputting a tire model obtained by modeling a tire with a finite number of elements to a computer, a step of inputting a contact surface model that models a contact surface that the tire model contacts, and The computer includes a deformation step in which the deformation of the tire model in contact with the contact surface model is calculated.

  The deformation process of the present invention includes a large deformation process in which the tire model is deformed to be larger than a state in which the tire deforms under a standard load. Thereby, in this invention, durability of a tire can be simulated based on the physical quantity of the tire model which has deform | transformed greatly with high load. Therefore, in the present invention, for example, large deformation of the tire when riding on a curb or the like can be taken into consideration, and the durability of the tire can be accurately simulated.

It is a perspective view of the computer which performs the simulation method of the tire of this embodiment. It is sectional drawing which shows an example of the tire by which durability is simulated. It is a flowchart which shows the specific process sequence of the simulation method of this embodiment. It is sectional drawing which visualizes and shows the tire model of this embodiment. It is a perspective view which visualizes and shows a tire model and a contact surface model. It is a flowchart which shows the specific process sequence of the condition input process of this embodiment. It is a flowchart which shows the specific process sequence of the deformation | transformation process of this embodiment. (A) is a side view showing a tire model in a state in which a standard load is applied, and (b) is a side view showing a tire model that is greatly deformed. It is a fragmentary sectional view of the tire model of Drawing 8 (b). It is a graph which shows the relationship between the stress of a carcass ply model, and the position of a carcass ply model. It is a fragmentary sectional view of the tire model in which the camber angle was set.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The tire simulation method of the present embodiment (hereinafter sometimes simply referred to as “simulation method”) is a method for simulating tire durability using a computer.

  FIG. 1 is a perspective view of a computer that executes the simulation method of the present embodiment. The computer 1 includes a main body 1a, a keyboard 1b, a mouse 1c, and a display device 1d. The main body 1a includes an arithmetic processing unit (CPU), a ROM, a working memory, disk drive devices 1a1 and 1a2 that can read a recording medium such as a CD-ROM and a flexible disk, and a storage device such as a magnetic disk (illustrated). Are omitted). A processing procedure (program) of the simulation method of the present embodiment is stored in advance in the storage device.

  FIG. 2 is a cross-sectional view showing an example of a tire whose durability is simulated according to the present invention. The tire 2 of the present embodiment is configured as a passenger car tire, for example. The tire 2 includes a carcass 6 that extends 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 that is disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2a. It has been. Further, the tire 2 of the present embodiment is provided with an inner liner 9 that forms the inner cavity surface 2 i of the tire 2.

  The carcass 6 is composed of at least one carcass ply 6A, in this embodiment, one carcass ply 6A. The carcass ply 6A has a main body portion 6a extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and the bead core 5 connected to the main body portion 6a is folded back from the inner side in the tire axial direction. And a folded portion 6b. A bead apex rubber 8 extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b. Further, the carcass ply 6A has a carcass cord arranged with respect to the tire equator C at an angle of, for example, 75 to 90 degrees.

  The belt layer 7 is composed of two outer belt plies 7A and 7B, in which a belt cord is arranged at an angle 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.

  The inner liner 9 is disposed on almost the entire area of the lumen surface 2i across the bead cores 5 and 5 in a toroidal shape. The inner liner 9 is made of, for example, butyl rubber or air-impermeable rubber containing 50 parts by weight or more of halogenated butyl in the rubber. Such an inner liner 9 is useful for maintaining the internal pressure of the tire 2.

FIG. 3 is a flowchart showing a specific processing procedure of the simulation method of the present embodiment.
In the present embodiment, first, a tire model obtained by modeling the tire 2 shown in FIG. 2 is input to the computer 1 (step S1).

  FIG. 4 is a cross-sectional view showing the tire model 11 visualized. The tire model 11 is set by modeling (discretizing) the tire 2 shown in FIG. 2 with a finite number of elements Fi (i = 1, 2,...) That can be handled by a numerical analysis method. As this numerical analysis method, for example, a finite element method, a finite volume method, a difference method, or a boundary element method can be adopted as appropriate, but in this embodiment, a finite element method is adopted.

  Further, as the element Fi, for example, a tetrahedral solid element suitable for expressing a complex shape is preferable, but a pentahedral solid element or a hexahedral solid element may be used in addition to this. Each element Fi is set with a plurality of nodes 12 and sides 13 connecting the nodes.

  Further, each element Fi includes an element number, a node 12 number, a coordinate value of the node 12 in the global coordinate system xyz, and material properties (such as density, Young's modulus and / or attenuation coefficient). Numeric data is defined.

  In the present embodiment, first, the rubber portion 2g including the tread rubber shown in FIG. 2, the carcass ply 6A, the belt plies 7A and 7B, the bead apex rubber 8, and the inner liner 9 are modeled by a plurality of elements Fi. Is done. As a result, the rubber member model 15, the carcass ply model 16, the belt ply model 17, the bead apex model 18, and the inner liner model 19 are set in the tire model 11, respectively. Then, the numerical data of each element Fi constituting the tire model 11 is stored in the computer 1.

  Next, a contact surface model obtained by modeling the contact surface with which the tire model 11 contacts is input to the computer 1 (step S2). FIG. 5 is a perspective view of the tire model 11 and the contact surface model 21 visualized.

  The contact surface model 21 of the present embodiment is modeled by, for example, a rigid surface element G constituting a single plane. Thereby, the contact surface model 21 is defined so as not to be deformed even when an external force is applied. Then, the numerical data of the element G constituting the contact surface model 21 is stored in the computer 1.

  The contact surface model 21 may be formed on a cylindrical surface like a drum testing machine, for example. Further, the contact surface model 21 may be provided with a step, a depression, a swell, a crease, or the like as necessary.

  Next, the conditions of the tire model 11 and the contact surface model 21 are input to the computer 1 (condition input step S3). FIG. 6 is a flowchart showing a specific processing procedure of the condition input step S3 of the present embodiment.

  In the condition input process S3, first, the rim condition, the internal pressure condition, and the load condition of the tire model 11 are input (process S31). The rim condition of this embodiment is set based on a regular rim, for example. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim".

  Moreover, as an internal pressure condition of this embodiment, the normal internal pressure of the tire 2 is defined, for example. “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. “JATMA” is “highest air pressure”, TRA is “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” if ETRTO, but 180 kPa if tire 2 is for passenger cars.

  Furthermore, as a load condition of the present embodiment, for example, a standard load (normal load) of the tire 2 is defined. “Standard load (regular load)” is the load specified by the standard for each tire. If it is JATMA, it is the maximum load capacity. If it is the maximum value, ETRTO, it is "LOAD CAPACITY". These conditions are stored in the computer 1.

  Next, a first boundary condition is defined in the computer 1 (step S32). As shown in FIG. 5, the first boundary condition is a condition for preventing the tire model 11 from slipping through the contact surface model 21. The first boundary condition of the present embodiment is defined between the outer surface of the tread portion 11 a of the tire model 11 and the contact surface model 21. Further, the first boundary condition is defined between the outer surface of the sidewall portion 11 b extending from the both ends of the tread portion 11 a inward in the tire radial direction and the contact surface model 21. Thereby, it is possible to prevent the tire model 11 from slipping through the contact surface model 21. The first boundary condition may also be defined between the bead portion 11c of the tire model 11 and the contact surface model 21. The first boundary condition is stored in the computer 1.

  Next, a second boundary condition is defined in the computer 1 (step S33). As shown in FIG. 4, the second boundary condition is a condition for preventing the lumen surfaces 11 i of the inner liner model 19 from slipping through each other. The second boundary condition of the present embodiment is defined for the entire lumen surface 11 i of the inner liner model 19. Such a second boundary condition is stored in the computer 1.

  Next, the computer 1 calculates the deformation of the tire model 11 in contact with the contact surface model 21 (deformation step S4). In the deformation step S4 of the present embodiment, as shown in FIG. 5, a grounding simulation for statically grounding the contact surface model 21 without rolling the tire model 11 is performed based on the set conditions. Is called. The physical quantity of the tire model 11 in this contact simulation is calculated at each node 12 (shown in FIG. 4) of each element Fi. FIG. 7 is a flowchart showing a specific processing procedure of the deformation step S4 of the present embodiment.

  In the deformation step S4 of the present embodiment, first, an inflated tire model is calculated (step S41). In step S41, as shown in FIG. 4, in the bead portion 11c, regions (hereinafter, simply referred to as “rim contact regions”) 11r and 11r that are in contact with the rim are restrained so as not to be deformed. Next, based on the rim conditions, the bead portion 11c of the tire model 11 is forcibly displaced so that the width W becomes equal to the rim width. Then, the tire radial direction distance Rs between the rotating shaft 11s (shown in FIG. 5) of the tire model 11 and the rim contact area 11r is defined to be always equal to the rim radius.

  Further, in step S41, an evenly distributed load w corresponding to the internal pressure condition is set on the whole lumen surface 11i of the tire model 11. Under these conditions, the computer 1 performs a balance calculation of the tire model 11. As a result, the expansion and extension of the rubber member model 15, the carcass ply model 16 and the belt ply model 17 of the tire model 11 are calculated, and the tire model 11 after expansion and deformation is calculated.

  Next, the tire model 11 in a state where a standard load is applied is calculated (step S42). FIG. 8 is a side view of a tire model loaded with a load. In this step S42, first, as shown in FIGS. 5 and 8A, the tire model 11 is moved to the contact surface model 21 side, and the tread portion 11a of the tire model 11 is brought into contact with the contact surface model 21. Let Next, the standard load Ls is set on the rotating shaft 11 s of the tire model 11 toward the contact surface model 21. Thus, in step S42, the tire model 11 in a state where the tire model 11 is pressed in the tire radial direction toward the contact surface model 21 and a standard load is applied is calculated. In the present embodiment, the tire model 11 is moved to the contact surface model 21 side. However, the contact surface model 21 may be moved to the tire model 11 side.

  Next, the tire model 11 is deformed larger than the state in which the tire 2 is deformed under the standard load Ls (large deformation step S43). In the large deformation step S43 of the present embodiment, as shown in FIG. 8B, a load L larger than the standard load Ls is applied to the rotating shaft 11s of the tire model 11. Thereby, in large deformation process S43, the tire model 11 is strongly pressed toward the contact surface model 21 side, and the tire model 11 can be largely deformed.

  In the large deformation step S43 of this embodiment, the physical quantity of the tire model 11 is stored in the computer 1. As physical quantities, for example, in the tread portion 11a of the tire model 11, the sidewall portion 11b of the tire model 11, the carcass ply model 16, the belt ply model 17, the bead apex model 18, and the inner liner model 19 shown in FIG. , Stress and strain calculated at each node 12 of each element Fi. These physical quantities may be calculated for all the above-mentioned members, but may be calculated only for the analysis target. Such a simulation in the deformation step S4 can be calculated by using commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC.

  FIG. 9 is a partial cross-sectional view of the tire model in the large deformation step S43. In the large deformation step S43 of the present embodiment, it is desirable that the tire model 11 is pressed so that at least a part of the tread portion 11a and the sidewall portion 11b of the tire model 11 is brought into contact with the contact surface model 21. . Furthermore, in the large deformation step S43 of the present embodiment, it is desirable that the tire model 11 is pressed so that the inner liner models 19 are brought into contact with each other. Thereby, in the large deformation step S43, for example, the physical quantity of the tire model 11 can be acquired by effectively reproducing the large deformation of the tire when riding on a curbstone or the tire at the time of puncture.

  In the present embodiment, since the first boundary condition and the second boundary condition are preset, the tire model 11 slips through the contact surface model 21 due to the large deformation of the tire model 11 as described above. The lumen surfaces 11i of the inner liner model 19 do not slip through each other. For this reason, in the large deformation step S43, the large deformation of the tire model 11 as described above can be stably calculated. The maximum load Lm (shown in FIG. 8B) set in the large deformation step S43 is preferably 1.5 to 10 times the standard load Ls (shown in FIG. 8A).

  In the large deformation step S43, the load L set on the tire model 11 is gradually increased from the standard load Ls to the maximum load Lm (in this embodiment, 5.0 kN, 7.5 kN, 10.0 kN, and 12.5 kN), it is desirable to calculate deformation. Thereby, in large deformation process S43, the physical quantity of the tire model 11 can be acquired sequentially, for example for every load L until a tire breaks, for example from the state where the standard load was loaded. Note that the load L is preferably gradually increased, for example, every 1.5 kN to 3.5 kN.

  The element Fi (shown in FIG. 4) of the tire model 11 can be set as appropriate. However, if the element Fi is defined by a normal elastic body model, the tire model 11 may be crushed due to large deformation of the tire model 11. Such an element collapse interrupts the deformation calculation of the tire model 11. For this reason, it is desirable that at least a part of the element Fi of the tire model 11 is defined as an incompressible superelastic body model. The incompressible superelastic body model is an element whose volume does not change due to deformation and returns to its original shape when the load is removed. Since such an element Fi can prevent the element from being crushed, the large deformation of the tire model 11 can be reliably calculated.

  The incompressible superelastic body model is preferably defined for all rubber members constituting the tire model 11, for example. As the incompressible superelastic body model, for example, Mooney-rivlin material or Ogden material can be used.

  Next, the computer 1 outputs the physical quantity of the tire model 11 obtained by the deformation calculation (step S5). In this step S5, each physical quantity of the tire model 11 at each load L from the standard load Ls to the maximum load Lm (in this embodiment, 5.0 kN, 7.5 kN, 10.0 kN, and 12.5 kN) Is output to the display device 1d (shown in FIG. 1) or the like.

  In the simulation method of the present embodiment, the design of the tire model 11 is changed until the physical quantity falls within the allowable range at each load L. Therefore, in the simulation method of the present embodiment, the tire 2 excellent in durability can be efficiently designed. In addition, in the simulation method of the present embodiment, it is not necessary to discard or remanufacture the mold used for making the tire 2 as a prototype, and therefore it is possible to prevent time and cost from increasing.

  In the simulation method of the present embodiment, due to the large deformation of the tire model 11, it is possible to take into account the large deformation of the tire when riding on a curb or the like and the tire during puncture. Therefore, with the simulation method of the present embodiment, the durability of the tire can be simulated more accurately. Furthermore, in the simulation method of the present embodiment, the physical quantity of the tire model 11 is calculated while gradually increasing the load L, so that the durability of the tire 2 from the state where the standard load is applied until the tire breaks is sequentially simulated. can do.

  In step S5, for example, for each member such as the carcass ply model 16, it is desirable to output a graph indicating a physical quantity such as stress, or visible information (contour diagram) obtained by visualizing the physical quantity with color information. The contour diagram can be obtained using, for example, a general-purpose post processor (such as Ls-PrePost manufactured by LSTC).

  FIG. 10 is a graph showing the relationship between the stress of the carcass ply model 16 and the position of the carcass ply model 16. In this graph, the stress of the carcass ply model 16 is shown for each load L (in the present embodiment, 5.0 kN, 7.5 kN, 10.0 kN, and 12.5 kN). Further, the position of the carcass ply model 16 that is the horizontal axis of the graph indicates that the distance of the innermost node 12s (shown in FIG. 4) in the tire radial direction of the main body portion 16a of the carcass ply model 16 is “0” in the tire meridian cross section. As shown, the distance along the main body portion 16a from the bead portion 11c to the tread portion 11a through the sidewall portion 11b is shown.

  As is clear from this graph, it can be confirmed that the stress of the sidewall portion 11b and the tread portion 11a is significantly increased as the load L is increased. Therefore, such a graph is useful for grasping a portion that is easily broken due to a large deformation of the tire when riding on a curb or the like. As shown in FIG. 8B, the graph shows the contact surface 22 between the tread portion 11a and the contact surface model 21 at the center position 22c in the tire circumferential direction of the contact surface 22 (FIG. 8B). It is preferably calculated in the meridian section of the tire model 11 passing through (shown). Thereby, in this embodiment, since the physical quantity of the tire model 11 can be acquired in the vicinity of the ground contact center where the deformation of the tire model 11 is the largest, the durability of the tire 2 can be effectively simulated.

  In the large deformation step S43 of the present embodiment, the camber angle of the tire model 11 may be further set. FIG. 11 is a front view of the tire model 11 in which the camber angle θ1 is set. Such a camber angle θ1 can increase the deformation of the sidewall portion 11b on the one side T1 where the tire model 11 is inclined as compared with the sidewall portion 11b on the other side T2. Therefore, the setting of the camber angle θ1 is useful for more effectively deforming the sidewall portion 11b on the one side T1 of the tire model 11. The camber angle θ1 is preferably about 1 to 10 degrees, for example.

  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.

  According to the procedure shown in FIG. 3, the physical quantity (stress of the carcass ply model) of the tire model shown in FIG. 5 was calculated, and the durability of the tire was simulated (Example). In the tire model of the example, an incompressible superelastic body model (Mooney-rivlin model) was defined for each element of all rubber member models. Further, in the example, a graph showing the relationship between the stress of the carcass ply model shown in FIG. 10 and the position of the carcass ply model was created. For comparison, tire durability was simulated using a tire model in which each element of all rubber member models was defined only by an elastic body model (comparative example).

The common specifications of the examples and comparative examples are as follows.
Tire size: 195 / 55R16
Rim size: 16 × 6J
Internal pressure: 230 kPa
Standard load: 3.60kN
Load: 5kN, 7.5kN, 10kN, 12.5kN

  As a result of the test, it was confirmed that the tire model of the example can accurately and stably simulate the durability of the tire without causing element collapse at all the loads described above.

  On the other hand, in the comparative example, element collapse occurred at a load larger than the standard load, and the deformation calculation was interrupted. Therefore, in the comparative example, it was confirmed that the tire model could not be deformed more than the state deformed under the standard load, and the durability of the tire could not be sufficiently simulated.

2 Tire 11 Tire model 21 Contact surface model

Claims (7)

A method for simulating tire durability using a computer,
The computer, the step of inputting a tire model of the tires, were modeled with a finite number of elements,
The computer, step inputs the contact surface models a contact surface modeling in which the tire model is in contact, and said computer comprises a deformation step of calculating a deformation of the tire model in contact with the contact surface model,
The deforming step, the tire model, the tire is viewed contains a large deformation step of largely deformed as compared with the state deformed under the standard load,
The tire model includes a main body portion that extends from the tread portion of the tire through a sidewall portion to a bead core of the bead portion, and a folded portion that is connected to the main body portion and is turned around from the inner side in the tire axial direction around the bead core. Includes carcass ply models that model carcass plies,
A step of outputting a physical quantity of the tire model obtained by the deformation calculation of the tire model,
The step of outputting the physical quantity includes a step of outputting a graph showing a relationship between the stress of the carcass ply model and the position of the carcass ply model,
The position of the carcass ply model is defined as a distance from the bead portion to the side wall with a distance of a node of the element arranged at the innermost side in the tire radial direction of the main body portion of the carcass ply model in the tire meridian cross section being “0”. A tire simulation method, characterized by being a distance along the main body portion through the portion to the tread portion . Defining, in the computer, a first boundary condition that prevents the tire model from slipping through the contact surface model;
The first boundary condition is at least between the tread portion of the tire model and the contact surface model and between the sidewall portion extending inward in the tire radial direction from both ends of the tread portion and the contact surface model. The tire simulation method according to claim 1 defined.   The said large deformation process presses the said tire model to a tire radial direction, The said tread part of the said tire model and at least one part of the said sidewall part are made to contact the said contact surface model. Tire simulation method.   4. The tire simulation method according to claim 1, wherein the large deformation step presses the tire model in a tire radial direction to bring the inner liner rubber models into contact with each other. 5.   5. The tire simulation method according to claim 1, wherein in the large deformation step, a load larger than the standard load is applied to the tire model. The contact surface model is defined as non-deformable,
The tire simulation method according to claim 1, wherein in the large deformation step, the tire model is pressed and deformed toward the contact surface model side. At least a part of the elements of the tire model is defined as an incompressible superelastic body model whose volume does not change due to deformation and returns to its original shape when the load is removed. The tire simulation method described.

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