JP7439393B2 - Tire simulation method - Google Patents

Description

The present invention relates to a tire simulation method, and more particularly to a method for calculating the influence of a rotating tire on the surrounding fluid using a computer.

Patent Document 1 below proposes a simulation method for evaluating tire noise performance. In this method, a sound space region that models a space in which fluid flows is set around the tread portion of a tire model.

The sound space region includes a plurality of in-groove regions corresponding to the inner space of the tread groove of a tire, and other main regions. Each in-groove region and main region are defined by mutually independent elements. In the simulation process of Patent Document 1 below, while the main region is fixed as not changing, a plurality of in-groove regions are moved (slided) in the tire circumferential direction along the main region, thereby improving the stability of the rolling tire. It reproduces the sound space area. Complementary calculation is performed on the interface between each groove area and the main area to match the physical quantities calculated in each groove area and the main area.

Patent No. 4792049

In the method of Patent Document 1, it is necessary to move each groove region in accordance with the shape of the rolling tire model. Furthermore, in the method of Patent Document 1, since both the in-groove region and the main region are in contact with the tread portion of the tire model, the entire sound space region is adjusted according to the shape of the tire model during rolling. Needs to be redefined. For this reason, the method of Patent Document 1 has a problem in that the sound space region of a rolling tire cannot be easily defined.

The present invention was devised in view of the above-mentioned circumstances, and its main purpose is to provide a simulation method that can easily define the fluid around a rotating tire.

The present invention is a simulation method for calculating the influence of a rotating tire on the surrounding fluid using a computer, the computer using a finite number of elements to calculate a static region in which the tire rotates. inputting a background model defining the tire into the computer using a finite number of elements; inputting into the computer a tire model defining the tire using a finite number of elements; modeling the fluid into the computer using a finite number of elements; inputting a fluid model defined by a predetermined thickness from the surface of the tire and rotationally associated with the tire model; However, in the step of rotating the tire model within the background model with the fluid model and the background model superimposed on each other, the computer rotates the tire model in the region where the fluid model and the background model overlap. The method is characterized in that it includes a step of calculating physical quantities of the finite number of elements of the fluid model based on mutual physical quantities of the model and the background model.

In the tire simulation method according to the present invention, the background model includes a first boundary surface that defines an area occupied by the background model, and the rotating step includes bringing the tire model into contact with the first boundary surface. It may also include a step of rotating while rotating.

In the tire simulation method according to the present invention, in the rotating step, the fluid model includes a region that protrudes from the background model, and the step of calculating the physical quantity includes a step of excluding the protruding region from a calculation target. But that's fine.

In the tire simulation method according to the present invention, the tire has at least one recessed part recessed from the surface, and the fluid model includes a first model part located inside the recessed part, and a first model part located outside the recessed part. and a second model part in contact with the surface.

The present invention is a simulation method for calculating the influence of a rotating tire on the surrounding fluid using a computer, the computer using a finite number of elements to calculate a static region in which the tire rotates. inputting a background model defining the tire into the computer using a finite number of elements; inputting into the computer a tire model defining the tire using a finite number of elements; modeling the fluid into the computer using a finite number of elements; the fluid model is defined to include an outer peripheral surface having a predetermined radius from the center of rotation of the tire, and is associated with the tire model so as to rotate integrally with the tire model, and The model is placed inside the background model without being superimposed on the background model, the fluid model includes a second boundary surface that defines the outer peripheral surface of the fluid model, and the background model includes: a third boundary surface coincident with the second boundary surface such that the second boundary surface of the fluid model is fittable; rotating the tire model and the fluid model within the background model in a state where the tire model and the fluid model are in contact with a boundary surface; , calculating physical quantities of the finite number of elements of the fluid model based on mutual physical quantities of the fluid model and the background model.

A tire simulation method according to a first aspect of the invention includes the steps of: inputting into a computer a background model that defines a stationary area in which the tire rotates using a finite number of elements; The method includes a step of inputting a defined tire model and a step of inputting a fluid model in which the fluid is modeled with a finite number of elements. The fluid model is defined at a predetermined thickness from the surface of the tire and is associated with the tire model so as to rotate together with the tire model.

Since the fluid model of the first invention is associated with the tire model so as to rotate together with the tire model, as in the method of Patent Document 1, a plurality of in-groove regions are formed in accordance with the rotation of the tire model. There is no need to move each one. Therefore, the method of the first invention can easily define the fluid around the rotating tire.

The method of the first invention further includes the step of: the computer rotating the tire model within the background model with the fluid model and the background model superimposed on each other; In a region where the background model overlaps, the method includes a step of calculating physical quantities of the finite number of elements of the fluid model based on mutual physical quantities of the fluid model and the background model.

In the method of the first invention, since the background model is defined independently of the fluid model, there is no need to redefine the background model in accordance with the rotation of the tire model. Therefore, the method of the first invention can define the fluid around the rotating tire in a short time.

Furthermore, in the method of the first invention, since the fluid model and the background model are superimposed on each other, the elements of the fluid model are not crushed between the tire model and the background model. Therefore, since the method of the first invention can prevent abnormal termination due to element collapse, it is possible to stably calculate the physical quantities of the fluid model.

Further, in the method of the first invention, in a region where the fluid model and the background model overlap, mutual physical quantities of the fluid model and the background model are taken into consideration, so that the rotating tire is affected by the surrounding fluid. The influence can be calculated with high accuracy.

A tire simulation method according to a second aspect of the invention includes the steps of: inputting into a computer a background model that defines a stationary area in which the tire rotates using a finite number of elements; The method includes a step of inputting a defined tire model and a step of inputting a fluid model in which the fluid is modeled with a finite number of elements. The fluid model is defined to include an outer peripheral surface having a predetermined radius from the center of rotation of the tire, and is associated with the tire model so as to rotate together with the tire model.

Since the fluid model of the second invention is associated with the tire model so as to rotate together with the tire model, as in the method of Patent Document 1, a plurality of in-groove regions are controlled in accordance with the rotation of the tire model. There is no need to move each one. Therefore, the method of the second invention can easily define the fluid around the rotating tire.

The method of the second invention is further characterized in that the computer converts the tire model and the fluid model into the background model while the second boundary surface of the fluid model and the third boundary surface of the background model are in contact with each other. and in a region where the second boundary surface and the third boundary surface contact each other, the finite number of elements of the fluid model is rotated based on mutual physical quantities of the fluid model and the background model. and a step of calculating physical quantities.

In the method of the second invention, since the background model is defined independently of the fluid model, there is no need to redefine the background model in accordance with the rotation of the tire model. Therefore, the method of the second invention can define the fluid around the rotating tire in a short time.

Furthermore, in the method of the second invention, physical quantities of the fluid model and the background model are taken into consideration in a region where the second boundary surface and the third boundary surface contact each other, so that the rotating tire is The influence on the surrounding fluid can be calculated with high accuracy.

FIG. 1 is a perspective view showing an example of a computer for executing the tire simulation method of the present invention. It is a sectional view showing an example of a tire. 3 is a flowchart illustrating an example of a processing procedure of a tire simulation method. FIG. 2 is a conceptual diagram showing an example of a tire model and a road surface model. It is a sectional view showing an example of a tire model. FIG. 3 is a cross-sectional view showing an example of a tire model, a background model, and a fluid model. It is a perspective view showing an example of a tire model and a background model. 8 is a sectional view taken along line AA in FIG. 7. FIG. FIG. 2 is a cross-sectional view showing an example of a tire model and a fluid model. 9 is a partially enlarged view of FIG. 9. FIG. FIG. 9 is a sectional view taken along line BB in FIG. 9; It is a flowchart which shows an example of the processing procedure of a 1st physical quantity calculation process. It is a flowchart which shows an example of the processing procedure of a 2nd physical quantity calculation process. It is a sectional view showing an example of a tire model, a background model, and a fluid model of other embodiments of the present invention. It is a sectional view showing an example of a tire model and a background model of other embodiments of the present invention. It is a flowchart which shows an example of the processing procedure of the 2nd physical quantity calculation process of other embodiments of this invention.

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

The tire simulation method (hereinafter sometimes simply referred to as the "method") of this embodiment uses a computer to simulate the influence that a rotating tire has on the surrounding fluid (hereinafter sometimes simply referred to as the "effect"). This is a method for calculation using . In the method of this embodiment, the fluid to be calculated is air, for example. Furthermore, examples of the effects to be calculated include aerodynamic performance and noise performance of rotating tires.

FIG. 1 is a perspective view showing an example of a computer for executing the tire simulation method of the present invention. 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, for example, a 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 tire simulation method of this embodiment.

FIG. 2 is a sectional view showing an example of a tire. The tire 2 of this embodiment is exemplified as a tire for a passenger car, but is not particularly limited. As shown in FIG. 2, the tire 2 of this embodiment includes a carcass 6 extending from a tread portion 2a through a sidewall portion 2b to a bead core 5 of a bead portion 2c, and a carcass 6 located outside the carcass 6 in the tire radial direction and located at the tread portion 2a. A belt layer 7 arranged inside is provided. Furthermore, the tire 2 is provided with bead apex rubber 8 extending outward in the tire radial direction from the bead core 5.

The carcass 6 includes at least one, in this embodiment, one carcass ply 6A. The belt layer 7 includes two belt plies 7A and 7B arranged on the inner side and the outer side in the tire radial direction.

The tire 2 of this embodiment has at least one recess 4 recessed from the surface 3 thereof. The recess 4 of this embodiment is configured as a groove 10 recessed from the tread surface 3a that contacts the road surface (not shown). The groove 10 of this embodiment includes a main groove 10A that extends continuously in the tire circumferential direction, and a lateral groove 10B that extends in a direction intersecting the main groove 10A. Note that the concave portion 4 is not limited to these grooves 10 (main groove 10A, lateral groove 10B), and may include, for example, dimples (not shown) provided on the buttress surface, sidewall surface, etc., or cooling fins. (not shown) may be a portion (not shown) in which unevenness is formed.

FIG. 3 is a flowchart showing an example of the processing procedure of the tire simulation method. In the method of this embodiment, first, a tire model is input to the computer 1 (step S1). FIG. 4 is a conceptual diagram showing an example of the tire model 12 and the road surface model 17. FIG. 5 is a sectional view showing an example of the tire model 12.

As shown in FIG. 5, in step S1, a finite number of elements F(i) (i=1, 2 ,...). In this embodiment, each tire constituent member such as the rubber member 2G including the tread rubber shown in FIG. ) is discretized by F(i). As a result, a tire model 12 that models the tire 2 is set.

Each element F(i) can be handled by numerical analysis. As the numerical analysis method, for example, a finite element method, a finite volume method, a finite difference method, a boundary element method, or the like can be appropriately employed. The finite element method is adopted as the numerical analysis method of this embodiment. Further, as each element F(i), it is preferable to use, for example, a tetrahedral solid element, a pentahedral solid element, a hexahedral solid element, or a polyhedral solid element having more than one surface. Each element F(i) is provided with a plurality of nodes 15. Numerical data such as the element number, the number of the node 15, the coordinate value of the node 15, and material properties (for example, density, Young's modulus, and/or damping coefficient, etc.) are defined for each of these elements F(i). .

The tire model 12 is provided with at least one recess 14 recessed from its surface 13. This recess 14 is a representation of the recess 4 (groove 10 in this embodiment) of the tire 2 based on the outline of the tire 2 shown in FIG. The recess 14 of this embodiment includes a main groove 14A set based on the main groove 10A of the tire 2 (shown in FIG. 2), and a lateral groove 14B set based on the lateral groove 10B of the tire 2 (shown in FIG. 2). (shown in FIGS. 4 and 6). The tire model 12 is input to the computer 1.

Next, in the method of this embodiment, the road surface model 17 (shown in FIG. 4) is input to the computer 1 (step S2). Although the road surface model 17 of this embodiment is exemplified as a model of a flat road (not shown), it is not limited to such an aspect. The road surface model 17 may be, for example, a model of the outer peripheral surface of a cylindrical drum testing machine (not shown). In step S2, a finite number of elements G(i) (i=1, 2,...). Thereby, in step S2, the road surface model 17 is set.

Although the outer surface of the road surface model 17 in this embodiment is set as a smooth road surface, it is not limited to such an aspect. Irregularities (not shown) may be set on the outer surface of the road surface model 17 based on, for example, a road surface used for a running noise test (ISO road surface) or an asphalt road surface. Further, as the finite number of elements (hereinafter sometimes simply referred to as "elements") G(i), rigid planar elements set to be non-deformable are employed. Each element G(i) is provided with a plurality of nodes 18. Numerical data such as an element number and coordinate values of the node 18 are defined for each of these elements G(i). The road surface model 17 is stored in the computer 1.

FIG. 6 is a cross-sectional view showing an example of the tire model 12, the background model 21, and the fluid model 22. FIG. 7 is a perspective view showing an example of the tire model 12 and the background model 21. FIG. 8 is a sectional view taken along line AA in FIG. In addition, in FIG. 6, each element of the tire model 12, the background model 21, and the fluid model 22 is omitted, and the area|region T7 which the tire model 12 and the fluid model 22 protrude is shown by coloring. Further, in FIG. 7, each element of the background model 21 is omitted. Moreover, in FIG. 8, each element of the tire model 12 and the background model 21 is omitted, and the tire model 12 is shown in color.

Next, in the method of this embodiment, a stationary region in which the tire 2 (shown in FIG. 2) rotates is defined in the computer 1 using a finite number of elements H(i) (i=1, 2, ...). The background model 21 that has been created is input (step S3). The stationary area (not shown) is a virtual space (area) that surrounds the rotating tire 2 and is stationary without being affected by the rotation of the tire 2. Although the shape of the stationary area (the background model 21 shown in FIG. 7) in this embodiment is defined as a cube, it is not limited to this form. The stationary region may be appropriately defined, for example, in a hemisphere, a semicircular cylinder, or in a shape that takes into consideration the shape of the vehicle.

The background model 21 can be defined in the same way as the sound space region of Patent Document 1 above. In the background model 21 of this embodiment, a stationary region (not shown) is divided (discrete) using a finite number of elements (hereinafter simply referred to as "elements") H(i) shown in FIG. It is composed of Eulerian meshes (Euler elements). Physical quantities such as the flow velocity and pressure of fluid (air) are assigned to each element H(i) in this embodiment. Each element H(i) is provided with a plurality of nodes 23. At each node 23, physical quantities in the stationary region (background model 21) are calculated.

As a method for discretization, for example, a finite volume method is used. The size of each element H(i) can be set as appropriate. For example, when the physical quantity to be evaluated is sound (noise), it is desirable that the size of each element H(i) is set to a size that can sufficiently express pressure fluctuations depending on the frequency of the noise.

As shown in FIGS. 7 and 8, the area T1 occupied by the background model 21 of this embodiment is determined by subtracting the area T3 occupied by the tire model 12 from the area T2 occupied by the cube surrounding the tire model 12. . Note that the region T3 occupied by the tire model 12 may be set based on the tire model 12 filled with internal pressure and in which a load L (shown in FIG. 4) is defined in a state in which the tire model 12 is in contact with the road surface model 17.

The background model 21 includes a boundary surface 24 for defining a region T1 occupied by the background model 21. The boundary surface 24 of this embodiment includes a front wall surface 24f, a rear wall surface 24r, and a side wall surface 24s extending between the front wall surface 24f and the rear wall surface 24r. Furthermore, the boundary surface 24 of this embodiment includes a first boundary surface 31 and a third boundary surface 33.

The first boundary surface 31 of this embodiment is for bringing the rotating tire model 12 into contact. The first boundary surface 31 is defined by one side wall surface 24s. The first boundary surface 31 (side wall surface 24s) of this embodiment is desirably set to match the shape of the road surface model 17 (shown in FIG. 4).

As shown in FIG. 8, the third boundary surface 33 of this embodiment matches the surface 13 of the tire model 12 and the recess 14 so that the surface 13 of the tire model 12 can be fitted therein. The third boundary surface 33 is conditioned to be movable relative to the surface 13 of the tire model 12 (for example, a boundary condition such as a sliding surface). Thereby, the tire model 12 can rotate with respect to the background model 21.

These boundary surfaces 24 (namely, the front wall surface 24f, the rear wall surface 24r, the side wall surface 24s, the first boundary surface 31, and the third boundary surface 33) are defined so that the fluid cannot pass through them. This limits the calculation range of the background model 21, which helps reduce calculation time.

The background model 21 may define the inflow of air from the front wall surface 24f at a speed close to the running speed of the tire 2, and may also define the free outflow of air from the rear wall surface 24r. Thereby, the background model 21 can reproduce the air flow when the actual vehicle is running. Note that the inflow and outflow of air may be defined by swapping the front wall surface 24f and the rear wall surface 24r, for example, or the inflow and outflow of air from the vertical direction or diagonal direction with respect to the tire may be defined. good.

As shown in FIG. 7, the width L1w of one side of the background model 21, the length L1d in the front-rear direction, and the height L1h can be set as appropriate. If the width L1w, length L1d, and height L1h are large, the calculation range of the background model 21 becomes large, which may increase the calculation time. Conversely, if the width L1w, length L1d, and height L1h are small, the calculation range of the background model 21 becomes small, and there is a possibility that the influence of the rotating tire 2 on the fluid cannot be calculated with high accuracy. Therefore, the width L1w is preferably about 3 to 10 times the diameter (width) L2 (shown in FIG. 8) of the tire model 12. The length L1d is preferably about 3 to 20 times the diameter (width) L2 of the tire model 12. The height L1h is preferably about 0.5 to 10 times the diameter (width) L2 of the tire model 12. The lower limit of the height L1h is set to 0.5 times the diameter (width) L2, for example, based on the fact that the reduction in noise generation is near the road surface. This is because it includes an aspect of analysis using the background model 21 set to . The background model 21 is input to the computer 1.

FIG. 9 is a sectional view showing an example of the tire model 12 and the fluid model 22. FIG. 10 is a partially enlarged view of FIG. 9. In addition, in FIG. 9, each element of the tire model 12 and the fluid model 22 is omitted, and the tire model 12 is shown in color. Further, in FIG. 10, elements of the tire model 12 are omitted, and the edges of the tire model 12 are shown in color.

Next, in the method of the present embodiment, the computer 1 transmits the fluid (not shown) around the rotating tire 2 (shown in FIG. 2) to the finite number of elements J(i) (i= 1, 2,...) is input (step S4). As mentioned above, the fluid in this embodiment is air. Further, the fluid around the rotating tire 2 is defined as air existing in a region T4 having a predetermined thickness W1 from the surface 3 of the tire 2 (surface 13 of the tire model 12) shown in FIG.

As shown in FIG. 9, the fluid model 22 includes an outer peripheral surface 28 having a predetermined thickness W1 from the surface 13 of the tire model 12 (the surface 3 of the tire 2 shown in FIG. 2). This outer peripheral surface 28 has a predetermined radius L3 from the rotation center 16 of the tire model 12 (the rotation center of the tire 2 shown in FIG. 2). The fluid model 22 is defined independently of the background model 21 shown in FIGS. 7 and 8. The fluid model 22 of this embodiment is different from the background model 21 which is defined in a stationary state, and is associated with the tire model 12 so as to rotate together (boundary conditions are set).

In the fluid model 22 of this embodiment, the fluid (not shown) around the rotating tire 2 (shown in FIG. 2) is composed of a finite number of elements (hereinafter simply referred to as "elements") shown in FIG. .) It is composed of Euler meshes (Euler elements) that are divided (discretized) using J(i). Physical quantities such as the flow velocity and pressure of fluid (air) are assigned to each element J(i) in this embodiment. Each element J(i) is provided with a plurality of nodes 27. At each node 27, a physical quantity of fluid (not shown) around the rotating tire 2 is calculated. As for the discretization method, the same method as the background model 21 (shown in FIG. 8) is adopted. Further, the size of each element J(i) is preferably set to be the same as the size of the element H(i) of the background model 21 (shown in FIG. 8).

Each element J(i) of the fluid model 22 of this embodiment is defined as an overset mesh (chimera mesh) that allows overlap with each element H(i) of the background model 21 shown in FIG. Thereby, as shown in FIG. 6, the fluid model 22 can move relative to the background model 21 (rotate together with the tire model 12) while being superimposed on the background model 21.

As shown in FIG. 9, the region T4 occupied by the fluid model 22 of this embodiment is determined by subtracting the region T3 occupied by the tire model 12 from the region T5 surrounded by the outer peripheral surface 28 of the fluid model 22. Note that the area T3 occupied by the tire model 12 may be set based on the tire model 12 filled with internal pressure and after the load L (shown in FIG. 4) is defined in a state in which the tire model 12 is in contact with the road surface model 17. good.

The fluid model 22 includes a boundary surface 29 for defining a region T4 occupied by the fluid model 22. The boundary surface 29 includes a second boundary surface 32 that defines the outer peripheral surface 28 of the fluid model 22, and an inner wall surface that matches the surface 13 of the tire model 12 and the recess 14 so that the surface 13 of the tire model 12 can be fitted therein. 29i. These boundary surfaces 29 (second boundary surface 32, inner wall surface 29i) are defined so that fluid (not shown) cannot pass through them. This limits the calculation range of the fluid model 22 (that is, the influence that the rotating tire 2 has on the surrounding fluid), which helps to shorten the calculation time.

The fluid model 22 of this embodiment has a first model part 34 located inside the recess 14 of the tire model 12 and a second model part 35 that is in contact with the surface 13 of the tire model 12 outside the recess 14. It is composed of: FIG. 11 is a sectional view taken along line BB in FIG. In FIG. 11, each element of the tire model 12 and the fluid model 22 is omitted, and the edges of the tire model 12 are shown in color.

The first model part 34 of this embodiment includes a main groove model part 34A located in the main groove 14A of the tire model 12 shown in FIG. 11, and a main groove model part 34A located in the lateral groove 14B of the tire model 12 shown in FIG. The horizontal groove model part 34B is configured to include a horizontal groove model part 34B.

It is desirable that the element J(i) (not shown) of the main groove model portion 34A and the element J(i) of the lateral groove model portion 34B shown in FIG. 10 share nodes 27, 27 with each other. As a result, in step S4, the main groove model portion 34A and the lateral groove model portion 34B can be integrated and discretized (modeled) using the element J(i), so that the model creation time and calculation time can be shortened. . Note that when the nodes 27 and 27 are not shared, a constraint condition is defined at the boundary between element J(i) of the main groove model part 34A and element J(i) of the lateral groove model part 34B. is desirable.

As shown in FIG. 10, each element J(i) of the first model portion 34 is defined by dividing (discretizing) the area occupied by the recess 14 into layers along the contour of the wall surface 14s of the recess 14. It is desirable to Such a first model section 34 can independently calculate the flow of fluid (not shown) on the wall surface 14s side of the recess 14 and the flow of fluid inside the recess 14, so that the physical quantity of the fluid (not shown) can be calculated independently. The calculation accuracy can be improved.

As shown in FIG. 9, the second model portion 35 of this embodiment is defined as a cylinder that continues in the tire circumferential direction. As shown in FIG. 10, each element J(i) of the second model section 35 covers the area between the surface 13 and the outer peripheral surface 28 (shown in FIG. 9) of the tire model 12. It is preferable to divide (discretize) into layers and define them along the contour of 13. Such a second model section 35 independently controls the flow of fluid (not shown) on the side of the surface 13 of the tire model 12 and the flow of fluid on the side of the outer peripheral surface 28 (shown in FIG. 9) of the fluid model 22. Since the calculation can be performed, the calculation accuracy of the physical quantity of the fluid can be improved.

The thickness W1 of the second model portion 35 shown in FIG. 9 (the thickness from the surface 3 of the tire 2 shown in FIG. 2) can be set as appropriate, for example, based on the required calculation accuracy, etc. . The thickness W1 of this embodiment is such that the second model section 35 is placed at a position where the influence of the rotating tire 2 on the fluid is evaluated (for example, at the position of the sound collection microphone when noise performance is evaluated). It is set as follows. Note that if the thickness W1 of the second model section 35 is large, the calculation range of the fluid model 22 (second model section 35) becomes large, which may increase the calculation time. From this point of view, the thickness W1 of the second model portion 35 is desirably 1 to 15 cm.

As shown in FIG. 10, it is desirable that the element J(i) of the second model part 35 and the element J(i) of the first model part 34 share nodes 27, 27 with each other. As a result, in step S4, the first model section 34 and the second model section 35 can be integrated and discretized (modeled) using the element J(i), so that the model creation time and calculation time can be shortened. can. Note that when the nodes 27 and 27 are not shared, a constraint condition is defined at the boundary between the element J(i) of the first model part 34 and the element J(i) of the second model part 35. is desirable. Fluid model 22 is stored in computer 1.

Next, in the method of this embodiment, physical quantities of the rotating tire model 12 are calculated (first physical quantity calculation step S5). In the first physical quantity calculation step S5 of the present embodiment, the tire model 12 shown in FIG. 4 is rotated (rolled) on the road surface model 17, and the physical quantities of the tire model 12 are calculated. Note that in the first physical quantity calculation step S5 of this embodiment, the background model 21 (shown in FIG. 8) and the fluid model 22 (shown in FIG. 9) are not used. Thereby, in the first physical quantity calculation step S5, the background model 21 and the fluid model 22 can be set to be excluded from calculation targets, so that the calculation time for the physical quantities of the tire model 12 can be shortened. FIG. 12 is a flowchart showing an example of the processing procedure of the first physical quantity calculation step S5.

In the first physical quantity calculation step S5 of the present embodiment, first, boundary conditions for causing the tire model 12 shown in FIG. 4 to rotate (roll) on the road surface model 17 are input to the computer 1 (step S51). In step S51, first, boundary conditions for bringing the tire model 12 into contact with the road surface model 17 are input. Examples of this boundary condition include the contact condition between the tire model 12 and the road surface model 17, the internal pressure condition of the tire model 12, the rim condition, the load condition (load L), the camber angle, or the tire model 12 and the road surface model. 17, etc. are included. The internal pressure conditions and load conditions can be set as appropriate. As the internal pressure conditions and load conditions of this embodiment, the air pressure and load defined for each tire 2 by each standard in a standard system including the standard on which the tire 2 (shown in FIG. 2) is based are set.

Furthermore, in step S51, boundary conditions for causing the tire model 12 to rotate (roll) on the road surface model 17 are input. The boundary conditions include, for example, the slip angle of the tire model 12, the running speed V, the angular velocity Va of the tire model 12 corresponding to the running speed V, the translational speed Vb of the road surface model 17 corresponding to the running speed V, or the tire model 12. The dynamic friction coefficient between the road model 17 and the road model 17 is included. These boundary conditions are input to the computer 1.

Next, in the first physical quantity calculation step S5 of the present embodiment, the computer 1 calculates the tire model 12 after the internal pressure has been filled (step S52). In step S52, first, as shown in FIG. 5, the bead portions 12c, 12c of the tire model 12 are restrained by a rim model 40 that models the rim 39 of the tire 2 (shown in FIG. 2). The rim model 40 is discretized into a finite number of elements (not shown) that can be handled by a numerical analysis method (in this embodiment, a finite element method) based on information (contour data, etc.) regarding the rim 39, for example. Set by. It is desirable that the elements constituting the rim model 40 be defined, for example, as rigid planar elements (not shown) that are set to be non-deformable.

Furthermore, in step S52, the deformation of the tire model 12 is calculated based on the uniformly distributed load w corresponding to the internal pressure condition input as the boundary condition. Thereby, in step S52, the tire model 12 after being filled with internal pressure is calculated.

In calculating the deformation of the tire model 12, a mass matrix, a stiffness matrix, and a damping matrix of each element F(i) are created based on the shape and material properties of each element F(i). Furthermore, each of these matrices are combined to create the overall system matrix. Then, an equation of motion is created by applying the various conditions described above, and a deformation calculation of the tire model 12 is performed using these equations at every minute time (unit time Tx (x=0, 1, . . . )). Such a deformation calculation of the tire model 12 can be performed using commercially available finite element analysis application software such as Abaqus manufactured by Dassault Systems, LS-DYNA manufactured by LSTC, or NASTRAN manufactured by MSC. Note that the unit time Tx can be set as appropriate depending on the required simulation accuracy.

Next, in the first physical quantity calculation step S5 of the present embodiment, the computer 1 calculates the tire model 12 in which the load conditions are defined (step S53). In step S53, first, as shown in FIG. 4, contact between the tire model 12 after internal pressure filling and the road surface model 17 is set. Next, in step S53, a load condition (load L) input as a boundary condition is set on the rotating shaft 12s of the tire model 12. Thereby, in step S53, the tire model 12 deformed under the load conditions is calculated.

Next, in the first physical quantity calculation step S5 of the present embodiment, the computer 1 calculates the tire model 12 rotating (rolling) on the road surface model 17 based on the predetermined running speed V (step S54 ). In step S54, the angular velocity Va input as a boundary condition is defined on the rotation axis 12s of the tire model 12. Furthermore, the translational speed Vb input as a boundary condition is defined in the road surface model 17. Thereby, in step S54, the tire model 12 rotating (rolling) on the road surface model 17 at the traveling speed V can be calculated for each unit time Tx.

In step S54, the deformation of the tire model 12 is calculated by rotation calculation (rolling calculation) of the tire model 12. Furthermore, in step S54, the physical quantity (for example, wear energy, etc.) of the element F(i) of the tire model 12 is calculated for each unit time Tx. These physical quantities are stored in the computer 1.

Next, in the first physical quantity calculation step S5 of the present embodiment, coordinate data of the node 15 (shown in FIG. 5) on the surface 13 of the tire model 12 is input to the computer 1 (step S55). In this embodiment, the surface 13 of the tire model 12 into which the coordinate data is input is the outer surface continuous from the tread portion 12a of the tire model 12 to the bead portion 12c via the sidewall portion 12b. Such coordinate data of the node 15 is useful for specifying the shape of the surface 13 of the tire model 12 during rotation (rolling), including the surface 13 and the recess 14, for each unit time Tx. The coordinate data is stored in the computer 1.

Next, in the first physical quantity calculation step S5 of the present embodiment, the computer 1 determines whether a predetermined end time has elapsed (step S56). The end time can be set as appropriate, for example, depending on the physical quantity to be acquired by the tire model 12 or the physical quantity to be acquired by the fluid model 22 in the second physical quantity calculation step S6, which will be described later.

In step S56, if it is determined that the end time has elapsed ("Y" in step S56), the next second physical quantity calculation step S6 (shown in FIG. 3) is performed. On the other hand, if it is determined in step S56 that the end time has not elapsed ("N" in step S56), the unit time Tx is advanced by one (step S57), and steps S54 to S56 are performed again. Ru. Thereby, in the first physical quantity calculation step S5, the coordinate data of the tire model 12 from the start of rotation to the end of rotation can be acquired as time series data for each unit time Tx.

Next, in the method of this embodiment, as shown in FIG. 6, the computer 1 rotates the tire model 12 and calculates the physical quantity of the element J(i) (shown in FIG. 10) of the fluid model 22. (Second physical quantity calculation step S6). In the second physical quantity calculation step S6, physical quantities of the fluid model 22 are calculated using the tire model 12, the background model 21, and the fluid model 22. The series of processes in the second physical quantity calculation step S6 can be performed using, for example, commercially available application software for fluid analysis such as STAR-CD manufactured by CD-adapco or FLUNET manufactured by ANSYS. FIG. 13 is a flowchart illustrating an example of the processing procedure of the second physical quantity calculation step S6.

In the second physical quantity calculation step S6 of this embodiment, first, as shown in FIG. 6, the fluid model 22 (shown in FIG. 8) and the background model 21 (shown in FIG. 9) are superimposed on each other (step S61). In step S61, first, as shown in FIG. 8, the tire model 12 is placed on the background model 21. In this embodiment, the surface 13 of the tire model 12 is brought into contact with the first boundary surface 31 of the background model 21 . Furthermore, in this embodiment, the third boundary surface 33 of the background model 21 is brought into contact with the surface 13 of the tire model 12. As described above, the third boundary surface 33 of the background model 21 is conditioned to be movable relative to the surface 13 of the tire model 12, so as shown in FIG. 21.

Next, in step S61, the fluid model 22 is placed on the background model 21, as shown in FIG. In this embodiment, the inner wall surface 29i of the fluid model 22 is brought into contact with the surface 13 of the tire model 12. Element J(i) of the fluid model 22 shown in FIG. 10 is defined as an overset mesh (chimera mesh), so as shown in FIG. duplicates) are allowed.

As mentioned above, the fluid model 22 is associated with the tire model 12 so as to rotate therewith. Therefore, in the second physical quantity calculation step S6, as shown in FIG. 6, the fluid model 22 can be rotated together with the tire model 12 in step S63, which will be described later.

In this embodiment, the tire model 12 is brought into contact with the first boundary surface 31 of the background model 21. Therefore, the fluid model 22 includes a region T7 that protrudes from the background model 21 (hereinafter sometimes simply referred to as a "protruding region"). As described above, the first boundary surface 31 with which the tire model 12 comes into contact is set based on the road surface model 17 (shown in FIG. 4). Therefore, the protruding region T7 of the fluid model 22 corresponds to the region inside the road surface (not shown) on which the tire 2 (shown in FIG. 2) rolls, and in reality, the fluid (air) around the tire 2 does not exist. Therefore, in step S64 of calculating the physical quantities of the fluid model 22, which will be described later, it is desirable to exclude the protruding region T7 from the object of calculating the physical quantities of each element J(i) of the fluid model 22. As a result, in the method of the present embodiment, for example, the fluid model 22 with a complicated shape is defined so that the protruding region T7 is not formed, and the thickness W1 is adjusted between the tire model 12 and the first boundary surface 31. There is no need to define a fluid model 22 that is partially small. Therefore, in the method of this embodiment, the fluid (fluid model 22) around the rotating tire 2 can be easily defined.

Next, in the second physical quantity calculation step S6 of this embodiment, the shape of the surface 13 of the rotating tire model 12 is acquired (step S62). The acquired shape of the surface 13 of the tire model 12 is used to rotate the tire model 12 in step S63, which will be described later.

In step S62, first, the shape of the surface 13 of the tire model 12 in unit time Tx is acquired based on the coordinate data input in the first physical quantity calculation step S5 (shown in FIG. 12). In step S62, the shape of the surface 13 of the rotating tire model 12 changes over a unit time from the start of rotation to the end of rotation of the tire model 12 by repeatedly performing the process until the end determination in step S65 described below is satisfied. Obtained for each Tx.

Next, in the second physical quantity calculation step S6 of this embodiment, the tire model 12 is rotated within the background model 21 (step S63). In step S63, the tire model 12 is rotated within the background model 21 with the fluid model 22 and the background model 21 superimposed on each other.

In this embodiment, the rotation of the tire model 12 is calculated based on the shape of the surface 13 of the tire model 12 specified in step S62. In step S63, the tire model 12 is moved in the tire circumferential direction within the background model 21 so as to match the shape of the surface 13 of the tire model 12 identified in step S62. As a result, in the second physical quantity calculation step S6, the tire model 12 rotated (rolling) after the unit time Tx can be calculated without calculating the tire model 12 rotating (rolling) on the road surface model 17. , it is possible to prevent the calculation in the second physical quantity calculation step S6 (calculation of the physical quantity of the fluid model 22) from becoming complicated.

As mentioned above, the fluid model 22 is associated with the tire model 12 so as to rotate therewith. Therefore, in step S63, the fluid model 22 can be rotated together with the tire model 12 within the background model 21. Accordingly, in this embodiment, the first model part 34 (main groove model part 34A and lateral groove model part 34B) of the fluid model 22 is positioned in the recessed part 14 (main groove 14A and lateral groove 14B) of the tire model 12. be able to.

As described above, in the method of the present embodiment, as in the method of Patent Document 1, a plurality of in-groove regions (the first model portion 34 shown in FIGS. 9 and 10) are There is no need to move the corresponding parts in the circumferential direction of the tire. Therefore, with the method of this embodiment, the fluid around the rotating tire 2 can be easily defined.

Furthermore, in the method of this embodiment, since the background model 21 and the fluid model 22 are defined independently, the background model 21 is redefined (for example, by remeshing, deformation calculation, etc.) according to the rotation of the tire model 12. ) There is no need to do so. Therefore, the method of this embodiment can define the fluid around the rotating tire 2 in a short time.

Furthermore, in the method of this embodiment, since the fluid model 22 and the background model 21 are superimposed on each other, the element J(i) of the fluid model 22 is not crushed between the tire model 12 and the background model 21. . Therefore, since the method of this embodiment can prevent abnormal termination due to element collapse, it is possible to stably calculate the physical quantities of the fluid model 22 in step S64, which will be described later.

In addition, when the surface 13 and the recessed part 14 of the tire model 12 shown in FIG. It is desirable to deform each element J(i) of the 2-model portion 35. Thereby, in this embodiment, the shapes of the first model part 34 and the second model part 35 can be made to match the shapes of the surface 13 and the recess 14 of the tire model 12.

The method of deforming each element J(i) can be selected as appropriate. As a method of deforming each element J(i), for example, so-called morphing, in which the element J(i) is deformed by moving its node 27, can be adopted. Morphing can be easily performed using the above-mentioned finite element analysis application software.

In the present embodiment, a mode in which the fluid model 22 is moved integrally with the tire model 12 in the tire circumferential direction is exemplified, but the present invention is not limited to such a mode. For example, by redefining (remeshing) the fluid model 22 based on the shapes of the surface 13 and recesses 14 of the tire model 12 after rotation, and the thickness W1 (shown in FIG. 9), the fluid model 22 is integrated with the tire model 12. A fluid model 22 may be defined that rotates at . As a result, this method does not require movement of the fluid model 22 or calculation of deformation of each element J(i) of the first model section 34 and second model section 35 of the fluid model 22. can be easily defined.

Next, in the second physical quantity calculation step S6 of this embodiment, the physical quantities of each element J(i) of the fluid model 22 shown in FIG. 10 are calculated (step S64). In step S64, the physical quantity of each element J(i) of the fluid model 22 is calculated at at least one observation point (not shown) set in advance, similarly to the simulation method of Patent Document 1 above.

In step S64, the physical quantities of each element J(i) of the fluid model 22 shown in FIG. 10 and the physical quantities of each element H(i) of the background model 21 shown in FIG. 8 are calculated. When the fluid is defined as air as in this embodiment, the motion of the fluid (air) is expressed by, for example, the Navier-Stokes equation. This Navier-Stokes equation is calculated by converting it into an approximate equation that can be calculated by the computer 1, for example, to calculate the motion of the air, that is, each element J(i) of the fluid model 22, and the background model 21. The pressure, velocity, etc. at each element H(i) are calculated. The physical quantities of each element J(i) of the fluid model 22 and each element H(i) of the background model 21 can be calculated using the above fluid analysis application software.

In each element J(i) of the fluid model 22, the flow of fluid (air) around the tire model affected by the rotation of the tire model 12 is calculated. In this embodiment, the protruding region T7 is excluded from the calculation target of the physical quantity of each element J(i) of the fluid model 22. As a result, in the second physical quantity calculation step S6, physical quantities are calculated in a region where no fluid exists during actual rotation of the tire 2 (i.e., a region inside the road surface (not shown) on which the tire 2 rolls). You can prevent this from happening.

On the other hand, in each element H(i) of the background model 21, only the inflow of air having a speed approximate to the running speed of the tire 2 is calculated without being affected by the rotation of the tire model 12.

As shown in FIG. 6, in a region T8 where the fluid model 22 and the background model 21 overlap (hereinafter sometimes simply referred to as an "overlapping region"), based on the mutual physical quantities of the fluid model 22 and the background model 21, , the physical quantities of each element J(i) of the fluid model 22 are calculated. In the overlapping region T8, the physical quantities of the fluid model 22 and the physical quantities of the background model 21 are associated (data mapping). Thereby, in step S64, the behavior of the fluid model 22 with respect to the background model 21 can be matched.

As described above, in the method of the present embodiment, the physical quantities of the fluid model 22 are calculated taking into account the physical quantities of the fluid model 22 and the background model 21, so that the rotating tire 2 is ) can be calculated with high accuracy. Furthermore, in the method of the present embodiment, the calculation range of the influence of the rotating tire 2 on the surrounding fluid is determined by the fluid model 22 defined by a predetermined thickness W1 (shown in FIG. 9) from the surface 3 of the tire 2. Since the calculation time is limited to , the calculation time can be shortened.

The physical quantities of the fluid model 22 include, for example, air pressure fluctuations, flow velocity, or air pressure distribution in each part of the fluid model 22 at any given time. In this embodiment, the main groove 10A (shown in FIG. 2) of the tire 2 shown in FIG. A physical quantity that reproduces the resonance noise caused by the air column is calculated. Moreover, the physical quantity that reproduces the pumping noise can be calculated using the main groove model part 34A and the lateral groove model part 34B (shown in FIG. 9) provided in the main groove 14A and the lateral groove 14B of the tire model 12. The physical quantities of the fluid model 22 are stored in the computer 1.

Next, in the second physical quantity calculation step S6 of the present embodiment, it is determined whether all the shapes of the surface 13 of the tire model 12 (from the start of rotation to the end of rotation in the first physical quantity calculation step S5) have been acquired. (Step S65). In step S65, if it is determined that the shape of the surface 13 of the tire model 12 has been acquired from the start of rotation to the end of rotation in the first physical quantity calculation step S5 ("Y" in step S65), the second physical quantity calculation step S6 The series of processing ends. On the other hand, in step S65, if it is determined that the shape of the surface 13 of the tire model 12 has not been acquired from the start of rotation to the end of rotation, the shape of the surface 13 of the tire model 12 for the next unit time Tx is acquired ( Step S62) and steps S63 to S65 are performed again. Thereby, in the second physical quantity calculation step S6, the physical quantities of the fluid model 22 can be calculated by rotating the tire model 12 every unit time Tx from the start of rotation to the end of rotation.

Next, in the method of this embodiment, it is determined whether the physical quantity of element J(i) (shown in FIG. 10) of the fluid model 22 is within an allowable range (step S7). The allowable range of the physical quantities of the fluid model 22 can be set as appropriate depending on the performance (for example, aerodynamic performance, noise performance, etc.) required of the tire 2 (shown in FIG. 2).

In step S7, if the physical quantity of element J(i) (shown in FIG. 10) of the fluid model 22 is within the allowable range ("Y" in step S7), the tire 2 (see FIG. ) is manufactured (step S8). On the other hand, in step S7, if the physical quantity of the fluid model 22 is outside the allowable range ("N" in step S7), the design factors of the tire 2 are changed (step S9), and steps S1 to S7 are performed again. be done. Therefore, in the method of the present embodiment, the design factors of the tire 2 are changed until the physical quantities of the fluid model 22 fall within the allowable range, so that a tire with high performance can be efficiently designed.

In the method of this embodiment, as shown in FIG. 6, the tire model 12 is rotated within the background model with the fluid model 22 and the background model 21 superimposed on each other, but the method is not limited to this. . The fluid model 22 may be placed inside the background model 21 without being superimposed on the background model 21.

FIG. 14 is a sectional view showing an example of a tire model 12, a background model 21, and a fluid model 22 according to another embodiment of the present invention. FIG. 15 is a cross-sectional view of a tire model 12 and a background model 21 according to another embodiment of the present invention. In FIG. 14, each element of the tire model 12, background model 21, and fluid model 22 is omitted, and the region T7 where the tire model 12 and fluid model 22 protrude is shown in color. Moreover, in FIG. 15, each element of the tire model 12 and the background model 21 is omitted, and the tire model 12 and the background model 21 are shown in colors. Note that in this embodiment, the same components as those in the previous embodiment are given the same reference numerals, and the explanation may be omitted.

In step S3 (shown in FIG. 3) of inputting the background model 21 of this embodiment, the third boundary surface 33 of the background model 21 is set to the second boundary surface so that the second boundary surface 32 of the fluid model 22 can be fitted into the third boundary surface 33 of the background model 21. It is set to match the surface 32. The third boundary surface 33 is conditioned to be movable relative to the second boundary surface 32 (for example, a boundary condition such as a sliding surface). This allows the fluid model 22 to rotate with respect to the background model 21.

FIG. 16 is a flowchart showing an example of the processing procedure of the second physical quantity calculation step S6 according to another embodiment of the present invention. In the second physical quantity calculation step S6 of this embodiment, as shown in FIG. 14, first, the fluid model 22 is placed inside the background model 21 (step S67). In step S67, unlike the method of the previous embodiment, the fluid model 22 is placed inside the background model 21 without being superimposed on the background model 21.

In step S67 of this embodiment, first, as in step S61 of the previous embodiment, the tire model 12 is placed on the background model 21, as shown in FIG. Next, in step S67, the fluid model 22 is placed on the background model 21, as shown in FIG. In this embodiment, the second boundary surface 32 of the fluid model 22 and the third boundary surface 33 of the background model 21 are brought into contact.

In the rotating step S63 of the second physical quantity calculation step S6 of this embodiment, the tire model 12 and the fluid The model 22 is rotated within the background model 21. The rotations of the tire model 12 and fluid model 22 are calculated based on the same procedure as in the previous embodiment.

With the method of this embodiment, the fluid around the rotating tire 2 can be easily defined, similar to the method of the previous embodiment. Furthermore, in the method of this embodiment, as in the method of the previous embodiment, there is no need to redefine the background model 21 (for example, remeshing or deformation calculation) in accordance with the rotation of the tire model 12. The fluid around the tire 2 (fluid model 22) can be defined in a short time.

In the second physical quantity calculation step S6 of this embodiment, in the step S64 of calculating the physical quantity of the fluid model 22, the area where the second boundary surface 32 and the third boundary surface 33 contact (hereinafter simply referred to as "contact area") ) At T9, the physical quantities of each element J(i) of the fluid model 22 are calculated based on the physical quantities of the fluid model 22 and the background model 21. In the contact region T9, the physical quantities of the fluid model 22 and the physical quantities of the background model 21 are associated (data mapping). Thereby, in step S64, the behavior of the fluid model 22 with respect to the background model 21 can be matched.

As described above, in the method of this embodiment, as in the method of the previous embodiment, the physical quantities of the fluid model 22 are calculated taking into account the physical quantities of the fluid model 22 and the background model 21, so that the rotating tire 2 on the surrounding fluid (not shown) can be calculated with high accuracy. Furthermore, in this embodiment, compared to the previous embodiment, the association (data mapping) between the physical quantities of the fluid model 22 and the physical quantities of the background model 21 is limited to the contact area T9, so that calculation time can be reduced. I can do it.

In the embodiments so far, a case has been described in which air is used as the fluid to be calculated, but the present invention is not limited to such an aspect. The fluid to be calculated may be entirely or partially liquid (water), for example. Thereby, the method of the present invention can calculate, for example, the influence (drainage performance, etc.) that a rotating tire has on a water film on a road surface. Furthermore, the fluid to be calculated may be, for example, wholly or partially snow, sand, mud, or the like. This makes it possible to analyze tires running on soft roads such as snow.

In addition, in the second physical quantity calculation step S6 shown in FIGS. 13 and 16, the tire model 12 is simply rotated without performing the step S62 of acquiring the shape of the surface 13 of the rotating tire model 12. Physical quantities of the model 22 may be calculated. In such a method, the first physical quantity calculation step S5 (shown in FIGS. 3 and 12) for calculating the deformation of the tire model 12 can be omitted, so that calculation costs can be further reduced.

In the methods of the previous embodiments, it is assumed that the tire 2 is not deformed by the force of the fluid (air), and prior to calculating the physical quantities of the fluid model 22 (second physical quantity calculation step S6), the rotating tire model 12 is Although the coordinate data of the surface 13 of is acquired in advance (first physical quantity calculation step S5), the present invention is not limited to such an embodiment. For example, the calculation of the shape of the surface 13 of the rotating tire model 12 and the calculation of the physical quantity of the fluid model 22 may be performed simultaneously every unit time Tx. With this method, it is possible to calculate the tire model 12 that is deformed by the force of fluid (for example, water, snow, etc.), so the accuracy of calculation of the influence that a rotating tire has on the surrounding fluid can be improved. It can be further increased.

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

According to the processing procedure shown in FIG. 3, the influence (noise performance) of a rotating tire on the surrounding fluid was calculated using a computer (Example 1, Example 2). In Examples 1 and 2, a fluid model having a thickness W1 from the tire surface was defined. This fluid model was linked to rotate integrally with the tire model. In Example 1 and Example 2, the same tire model was used.

In Example 1, according to the steps shown in FIGS. 12 and 13, the step of rotating the tire model within the background model overlaps with the fluid model and the background model, with the fluid model and the background model superimposed on each other. In the region, a step of calculating the physical quantities of the elements of the fluid model based on the mutual physical quantities of the fluid model and the background model was performed.

On the other hand, in Example 2, a background model including a third boundary surface that coincides with the second boundary surface is defined so that the second boundary surface of the fluid model can be fitted. As a result, unlike the fluid model of Example 1, the fluid model of Example 2 was placed inside the background model without being superimposed on the background model. In Example 2, according to the procedure shown in FIGS. 12 and 16, the tire model and the fluid model are placed in the background with the second boundary surface of the fluid model and the third boundary surface of the background model in contact with each other. A step of rotating within the model, and a step of calculating physical quantities of elements of the fluid model based on mutual physical quantities of the fluid model and the background model in the region where the second boundary surface and the third boundary surface contact each other. It was done.

In Examples 1 and 2, the fluid model creation time, the fluid model rotation definition time, the fluid model physical quantity calculation time, and the total analysis time that is the sum of these times were measured.

Further, for comparison, the influence (noise performance) of a rotating tire on the surrounding fluid was calculated using a computer according to the procedure described in Patent Document 1 (comparative example). In the comparative example, the same tire model as in Examples 1 and 2 was used. Furthermore, in the comparative example, a sound space region modeled as a space in which fluid flows was set around the tread portion of the tire model. The sound space region includes a plurality of in-groove regions corresponding to the inner space of the tread groove of a tire, and other main regions.

In the comparative example, the sound space area is fixed as the main area does not change, but by moving (sliding) multiple groove areas in the tire circumferential direction along the main area, the sound of the rolling tire can be adjusted. It reproduces the spatial domain. In the comparative example, complementary calculations are performed at the interface between each groove area and the main area to match the physical quantities calculated for each groove area and the main area, and the physical quantities of the sound space area are calculated. In the comparative example, the creation time of the sound space region, the rotation (movement) definition time of the sound space region, the physical quantity calculation time of the sound space region, and the total analysis time that is the sum of these times were measured. The common specifications are as follows.
Tire size: 195/65R15
First physical quantity calculation process (rolling simulation):
Unit time for tire model deformation calculation (initial value): 5×10 ^-5 seconds
Road model: flat road
Load L: 4kN
Internal pressure: 220kPa
Traveling speed V: 80km/h
Fluid model thickness W1: 10cm
The test results are shown in Table 1.

As a result of the test, the methods of Examples 1 and 2 were able to significantly shorten the fluid model creation time, fluid model rotation definition time, and physical quantity calculation time compared to the comparative example method. Therefore, in Examples 1 and 2, the fluid around the rotating tire could be defined more easily than in the comparative example.

Furthermore, in Example 2, compared to Example 1, the amount of calculation for associating the physical quantities of the fluid model with the physical quantities of the background model (data mapping) could be reduced, and the physical quantity calculation time could be reduced.

Further, in Examples 1 and 2, unlike the comparative example, the elements (mesh) were not crushed into a wedge shape between the tire and the road surface, and thus the calculation accuracy of physical quantities could be improved.

S63 Step of rotating the tire model within the background model S64 Step of calculating physical quantities of the fluid model

Claims (5)

A simulation method for calculating the influence of a rotating tire on the surrounding fluid using a computer, the method comprising:
inputting into the computer a background model that defines a stationary region in which the tire rotates using a finite number of elements;
inputting into the computer a tire model that defines the tire using a finite number of elements;
inputting into the computer a fluid model in which the fluid is modeled with a finite number of elements;
The fluid model is defined at a predetermined thickness from the surface of the tire and is associated with the tire model so as to rotate integrally with the tire model,
The method further includes:
the computer rotating the tire model and calculating the shape of the surface of the tire model during rotation;
the computer rotating the tire model within the background model with the fluid model and the background model superimposed on each other based on the shape of the surface of the tire model;
the computer, in a region where the fluid model and the background model overlap, calculating physical quantities of the finite number of elements of the fluid model based on mutual physical quantities of the fluid model and the background model; fruit,
The step of calculating the shape of the surface, the step of rotating the surface, and the step of calculating the physical quantity are calculated simultaneously every unit time.
Method.
the background model includes a first boundary surface defining an area occupied by the background model;
2. The method of claim 1, wherein the step of rotating includes rotating the tire model while contacting the first interface. In the rotating step, the fluid model includes an area protruding from the background model,
3. The method according to claim 2, wherein the step of calculating the physical quantity includes the step of excluding the protruding area from calculation targets. The tire has at least one recess recessed from the surface,
The method according to any of claims 1 to 3, wherein the fluid model includes a first model part located within the recess and a second model part in contact with the surface outside the recess. . A simulation method for calculating the influence of a rotating tire on the surrounding fluid using a computer, the method comprising:
inputting into the computer a background model that defines a stationary region in which the tire rotates using a finite number of elements;
inputting into the computer a tire model that defines the tire using a finite number of elements;
inputting into the computer a fluid model in which the fluid is modeled with a finite number of elements;
The fluid model is defined to include an outer peripheral surface having a predetermined radius from the rotation center of the tire, and is associated with the tire model so as to rotate together with the tire model,
The fluid model is placed inside the background model without being superimposed on the background model,
The fluid model includes a second boundary surface defining the outer peripheral surface of the fluid model,
The background model includes a first boundary surface that defines an area occupied by the background model, and a third boundary surface that coincides with the second boundary surface so that the second boundary surface of the fluid model can be fitted into the background model. including,
The method further includes:
the computer rotating the tire model and calculating the shape of the surface of the tire model during rotation;
Based on the shape of the surface of the tire model, the computer may cause the tire model to contact the first boundary surface while the second boundary surface and the third boundary surface are in contact with each other. rotating a tire model and the fluid model within the background model;
In a region where the second boundary surface and the third boundary surface are in contact, the computer calculates physical quantities of the finite number of elements of the fluid model based on mutual physical quantities of the fluid model and the background model. and a step of
In the rotating step, the fluid model includes an area protruding from the background model,
The step of calculating the physical quantity includes the step of excluding the protruding area from the calculation target,
The step of calculating the shape of the surface, the step of rotating the surface, and the step of calculating the physical quantity are calculated simultaneously every unit time.
Method.

Images