JP6434705B2 - Tire vibration performance evaluation method and simulation apparatus - Google Patents

Description

  The present invention relates to a tire vibration performance evaluation method and a simulation apparatus capable of accurately evaluating tire vibration performance.

  Conventionally, a method has been used in which a tire is run on a cylindrical drum having a smooth road surface having a certain radius and a protrusion raised from the road surface, and the vibration performance of the tire over the protrusion is evaluated.

  In this type of evaluation method, the tire vibration performance is evaluated by frequency analysis of the tire vibration data from the time when the tire climbs over the protrusion until the next protrusion is reached (measurement section). .

JP 2012-137419 A

  In the above evaluation method, since the tire is traveling on the drum, the time until the tire gets over the next protrusion becomes shorter as the traveling speed increases. For this reason, in the said evaluation method, the quantity of the vibration data which can be acquired in a measurement area becomes small. As the amount of vibration data decreases, the resolution of frequency analysis increases and it is difficult to accurately evaluate the vibration performance of the tire.

  The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire vibration performance evaluation method and a simulation apparatus that can accurately evaluate the tire vibration performance.

The present invention is a method for evaluating, using a computer, the vibration performance of a tire that has overcome a protrusion protruding from a road surface, and a tire model obtained by modeling the tire with a finite number of elements is input to the computer. A step of inputting a road surface model in which the road surface is modeled by a finite number of elements to the computer, and the computer causes the tire model to roll to the road surface model so that a physical quantity relating to vibration of the tire is obtained. The road surface model includes a protrusion model obtained by modeling the protrusion, and the simulation step includes converting the road surface model into the protrusion after the tire model has overcome the protrusion model. and changes to the model without the road surface model, rolling the tire model on the road surface model without the projection model Characterized in that it comprises a make changing step.

  In the tire vibration performance evaluation method according to the present invention, the method includes a step of inputting, into the computer, a smooth road surface model obtained by modeling the road surface without the protrusion with a finite number of elements, and the changing step includes the protrusion model. It is desirable to switch the road surface model having the above to the smooth road surface model.

  In the tire vibration performance evaluation method according to the present invention, it is preferable that the changing step deletes the protrusion model.

  In the tire vibration performance evaluation method according to the present invention, the road surface is preferably formed on an outer peripheral surface of a cylindrical drum.

The present invention relates to a tire simulation apparatus having an arithmetic processing unit that evaluates the vibration performance of a tire that has overcome a protrusion protruding from a road surface, and the arithmetic processing unit is a tire in which the tire is modeled by a finite number of elements A tire model input unit to which a model is input; a road surface model input unit to which a road surface model obtained by modeling the road surface with a finite number of elements; and And the road surface model has a protrusion model that models the protrusion, and the road calculation unit is configured to convert the road surface model after the tire model has overcome the protrusion model. a, change in the projection model with no road model, the road surface to roll the tire model in the projection model with no road surface model change Characterized in that it comprises a part.

  The tire vibration performance evaluation method of the present invention includes a step of inputting a tire model obtained by modeling a tire into a computer, a step of inputting a road surface model obtained by modeling a road surface with a finite number of elements, and the computer comprising a tire model Rolling to the road surface model and calculating a physical quantity related to tire vibration. The road surface model has a projection model obtained by modeling a projection.

  The simulation process of the present invention includes a changing process of changing the road surface model to a road surface model without a protrusion model after the tire model has overcome the protrusion model. Thus, in the tire vibration performance evaluation method of the present invention, since the road model without projections can roll for a long time after the tire model has overcome the projection model, the tire model that rolls a smooth road model It is possible to increase the amount of physical quantity data related to vibrations. Therefore, in the tire vibration performance evaluation method of the present invention, the frequency resolution can be increased in the frequency analysis using the physical quantity related to vibration, and therefore the tire vibration performance can be accurately evaluated.

It is a block diagram of the simulation apparatus with which the evaluation method of this embodiment is implemented. It is a side view showing the tire on which vibration performance is evaluated by the evaluation method of this embodiment, and the road surface on which the tire travels. It is sectional drawing of the tire of FIG. It is sectional drawing which expands and shows the protrusion provided in the road surface of FIG. It is a flowchart which shows an example of the specific process sequence of the evaluation method of this embodiment. It is a side view of the tire model and road surface model of this embodiment. It is sectional drawing of the tire model of FIG. It is a fragmentary perspective view of the road surface model of FIG. It is a fragmentary perspective view of a smooth road surface model. It is a flowchart which shows an example of the specific process sequence of the simulation process of this embodiment. It is a side view of a road surface model without a projection model and a tire model. It is a graph which shows the relationship between the vertical axial force of the tire model of an Example, and rolling time. It is a graph which shows the relationship between a vertical force power spectral density and a frequency. It is a perspective view which shows only a protrusion model. It is a graph which shows the relationship between the up-and-down axial force of the tire of a comparative example, and rolling time. It is the graph by which the up-and-down axial force after the 2nd time of the comparative example was changed to "0".

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The tire vibration performance evaluation method of the present embodiment (hereinafter sometimes simply referred to as “evaluation method”) is a method for evaluating the vibration performance of a tire to be analyzed using a computer. In this embodiment, the vibration performance of a tire that has climbed over a protrusion protruding from the road surface is evaluated.

  FIG. 1 is a block diagram of a simulation apparatus in which the evaluation method of this embodiment is implemented. FIG. 2 is a side view showing a tire whose vibration performance is evaluated by the evaluation method of the present embodiment and a road surface on which the tire travels. FIG. 3 is a cross-sectional view of a tire whose vibration performance is evaluated by the evaluation method of the present embodiment.

  As shown in FIG. 1, a computer 1 used in the evaluation method of the present embodiment includes an input unit 11 as an input device, an output unit 12 as an output device, and an arithmetic processing unit 13 that calculates a physical quantity of a tire and the like. Is configured as a simulation apparatus 1A.

  For the input unit 11, for example, a keyboard or a mouse is used. For example, a display device or a printer is used for the output unit 12. Furthermore, the arithmetic processing unit 13 includes a calculation unit (CPU) 13A that performs various calculations, a storage unit 13B that stores data, programs, and the like, and a work memory 13C.

  The storage unit 13B is a non-volatile information storage device made of, for example, a magnetic disk, an optical disk, or an SSD. The storage unit 13B is provided with a data unit 15 and a program unit 16.

  The data unit 15 includes an initial data unit 15A in which information (for example, CAD data and the like) related to a tire to be evaluated and a road surface is stored, and a tire model input unit 15B in which a tire model in which the tire is modeled is input. include. The data unit 15 further includes a road surface model input unit 15C to which a road surface model with a road surface modeled is input, a smooth road surface model input unit 15D to which a smooth road surface model with a road surface without protrusions is input, and A physical quantity input unit 15E to which a physical quantity related to vibration calculated by the calculation unit 13A is input is included.

  The program unit 16 is a program executed by the calculation unit 13A. The program unit 16 includes an internal pressure filling calculation unit 16A that calculates the shape of the tire model after the internal pressure filling, and a load load calculation unit 16B that defines a load in the tire model after the internal pressure filling. Further, the program unit 16 includes a travel calculation unit 16C that acquires a physical quantity related to tire vibration by running a tire model on a road surface model, and a vibration performance evaluation unit 16D that evaluates tire vibration performance. Yes.

  The travel calculation unit 16C includes a physical quantity calculation unit 17A that calculates a physical quantity related to the vibration of the tire model, and a road surface change unit 17B that changes to a road surface model without a projection model after the tire model has overcome the projection model. .

  As shown in FIG. 2, the tire 2 to be analyzed in the present embodiment is configured as a pneumatic tire for passenger cars, for example. As shown in FIGS. 2 and 3, the tire 2 includes, for example, a carcass 6 extending from the tread portion 2a through the sidewall portion 2b to the bead core 5 of the bead portion 2c, and the outer side of the carcass 6 in the tire radial direction and the tread portion. 2a, and a belt layer 7 disposed inside.

  The carcass 6 is composed of at least one carcass ply 6A in this embodiment. The carcass ply 6A includes 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 a turn around the bead core 5 connected to the main body portion 6a from the inner side to the outer side in the tire axial direction. Part 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 of the carcass ply 6A. In the carcass ply 6A, for example, carcass cords arranged at an angle of 80 degrees to 90 degrees with respect to the tire equator C are overlapped so as to cross each other.

  The belt layer 7 includes at least two belt plies 7A and 7B that are overlapped in the tire radial direction in the present embodiment. The two belt plies 7A and 7B are arranged such that the belt cord is inclined at an angle of, for example, 10 degrees to 35 degrees with respect to the tire circumferential direction. Such belt plies 7A and 7B are overlapped so that the belt cords cross each other.

  As shown in FIG. 2, the road surface 31 on which the tire 2 of the present embodiment travels is formed on the outer peripheral surface 32 o of a cylindrical drum 32. The drum 32 has, for example, a support shaft 32s that forms the rotation center axis thereof. The support shaft 32s is pivotally supported across a pair of support columns 33, 33 fixed to the floor surface. Such a drum 32 is rotated by a driver (not shown) and braked by a brake device.

  The road surface 31 is formed as a smooth road surface having a certain radius. For example, the road surface 31 of the present embodiment has an outer diameter R1 of about 1200 to 1800 mm and a width in the drum axis direction of about 500 to 2000 mm.

  The road surface 31 is provided with at least one protrusion 35 that protrudes radially outward from the road surface 31, in this embodiment. The protrusion 35 of this embodiment is provided over the entire width of the road surface 31. The protrusion 35 may be provided on at least a part of the entire width of the road surface 31.

  FIG. 4 is an enlarged sectional view showing the protrusion 35. The protrusion 35 of the present embodiment includes side surfaces 35a and 35a extending along the normal direction of the road surface 31, and an upper surface 35b connecting the upper ends of the side surfaces 35a and 35a along the road surface 31, and is formed in a substantially rectangular cross section. ing. Chamfers 35c and 35c are formed at the side surface 35a, the upper surface 35b, and the protruding corner. A height H2 between the upper surface 35b of the protrusion 35 and the road surface 31 and a width W2 of the upper surface 35b of the protrusion 35 are set to about 3 mm to 7 mm, for example. The cross-sectional shape of the protrusion 35 is not limited to a substantially rectangular cross-section, and may be, for example, a triangular cross-section projecting outward in the radial direction of the drum 32 or a semicircular cross-section.

  FIG. 5 is a flowchart showing an example of a specific processing procedure of the evaluation method of the present embodiment. In the evaluation method of this embodiment, first, a tire model obtained by modeling the tire 2 shown in FIG. 2 is set in the computer 1 (step S1). FIG. 6 is a side view of the tire model and the road surface model of the present embodiment. FIG. 7 is a cross-sectional view of the tire model of the present embodiment.

  In step S1, first, as shown in FIG. 1, information about the tire 2 (shown in FIG. 3) stored in the initial data portion 15A (for example, contour data of the tire 2) is stored in the work memory 13C. Entered. As shown in FIG. 1 and FIG. 7, the calculation unit 13A (shown in FIG. 1) is based on information related to the tire 2 and can handle a finite number of elements Fi (i = 1, 2,...). ) To discretize. Thereby, a tire model 20 in which the tire 2 is modeled is set. The set tire model 20 is input to the tire model input unit 15B (shown in FIG. 1). As a 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.

  For example, a tetrahedral solid element, a pentahedral solid element, or a hexahedral solid element is preferably used as the element Fi. Each element Fi is provided with a plurality of nodes 27. For each such element Fi, numerical data such as an element number, the number of the node 27, the coordinate value of the node 27, and material characteristics (for example, density, Young's modulus and / or attenuation coefficient) are defined.

  The tire model 20 includes a rubber member model 21 in which the rubber portion 2g including the tread rubber shown in FIG. 3 is modeled, a carcass ply model 22 in which the carcass ply 6A is modeled, and belt plies 7A and 7B. A modeled belt ply model 23 is included.

  Next, in the evaluation method of the present embodiment, a road surface model obtained by modeling the road surface 31 shown in FIG. 2 is set in the computer 1 (step S2). FIG. 8 is a partial perspective view of the road surface model.

  In step S2, information (for example, road surface contour data) on the road surface 31 and the protrusion 35 (shown in FIG. 2) stored in the initial data portion 15A shown in FIG. 1 is first input to the work memory 13C. Is done. The computing unit 13A (shown in FIG. 1) is based on the information about the road surface 31 and the protrusion 35, and a finite number of elements Gi (i = 1, 2) that can be handled by a numerical analysis method (in this embodiment, a finite element method). , ...) to discretize. Thereby, in process S2, as shown in Drawing 6 and Drawing 8, cylindrical road surface model 41 is set up. The road surface model 41 has a protrusion model 42 that models the protrusion 35. The projection model 42 of this embodiment is modeled integrally with the road surface model 41.

  The elements Gi of the road surface model 41 and the protrusion model 42 are defined as rigid plane elements set so as not to be deformable. This element Gi is provided with a plurality of nodes 43. Furthermore, numerical data such as an element number and a coordinate value of the node 43 is defined for the element Gi. The road surface model 41 and the protrusion model 42 are input to the road surface model input unit 15C (shown in FIG. 1).

  Next, in the evaluation method of the present embodiment, a smooth road surface model obtained by modeling the road surface 31 (shown in FIG. 2) without the protrusion 35 is set in the computer 1 (step S3). FIG. 9 is a partial perspective view of the smooth road surface model.

  In step S3, first, information (for example, road surface contour data) related to the road surface 31 (shown in FIG. 3) stored in the initial data portion 15A shown in FIG. 1 is input to the work memory 13C. In this step S3, information relating to the protrusion 35 (shown in FIG. 2) is deleted from information relating to the road surface 31 (shown in FIG. 2).

  The calculation unit 13A (shown in FIG. 1) is based on information on the road surface 31 without the protrusion 35, and can handle a finite number of elements Gi (i = 1, i.e., finite element method in this embodiment). 2, ...) to discretize. Thereby, a smooth road surface model 45 in which the road surface 31 without the protrusion 35 is modeled is set. Such a smooth road surface model 45 is input to the smooth road surface model input unit 15D (shown in FIG. 1).

  Next, the computer 1 rolls the tire model 20 on the road surface model 41 to calculate a physical quantity related to the vibration of the tire 2 (simulation step S4). FIG. 10 is a flowchart showing an example of a specific processing procedure in the simulation step S4 of the present embodiment.

  In the simulation step S4, first, the shape after the internal pressure filling of the tire model 20 (shown in FIG. 7) is calculated (step S41). In step S41, as shown in FIG. 1, the tire model 20 input to the tire model input unit 15B is read into the work memory 13C. Further, the internal pressure filling calculation unit 16A is read into the work memory 13C. Then, the internal pressure filling calculation unit 16A is executed by the calculation unit 13A.

  In step S41, first, as shown in FIG. 7, the bead portions 29 and 29 of the tire model 20 are restrained by the rim model 30 in which the rim of the tire 2 is modeled. Further, the tire model 20 is deformed and calculated based on the uniform distribution load w corresponding to the internal pressure condition. Thereby, in process S41, tire model 20 after internal pressure filling is calculated. For example, in the standard system including the standard on which the tire 2 (shown in FIG. 2) is based, the internal pressure is preferably set to the air pressure defined by each standard for each tire.

  In the deformation calculation of the tire model 20, a mass matrix, a stiffness matrix, and a damping matrix of each element Fi are created based on the shape and material characteristics of each element. Furthermore, each of these matrices is combined to create a matrix for the entire system. Then, the computer 1 applies the above-described various conditions to create an equation of motion, and calculates the deformation of the tire model 20 for each minute time (unit time Tx (x = 0, 1,...)). Such deformation calculation of the tire model 20 can be calculated using commercially available finite element analysis application software such as LS-DYNA manufactured by LSTC. The unit time Tx can be set as appropriate depending on the required simulation accuracy.

  Next, in the simulation step S4, a load is defined on the tire model 20 after the internal pressure filling (step S42). In this step S42, first, as shown in FIG. 1, the road surface model 41 and the protrusion model 42 (shown in FIG. 8) input to the road surface model input unit 15C are read into the work memory 13C. Further, the load load calculation unit 16B is read into the work memory 13C. Then, the load load calculation unit 16B is executed by the calculation unit 13A.

  In step S42, first, as shown in FIG. 6, contact between the tire model 20 and the road surface model 41 after the internal pressure filling is set. At this time, the tire model 20 and the protrusion model 42 are not in contact with each other.

  Further, in step S42, a predetermined load T is set on the rotating shaft 20s of the tire model 20, and the deformation of the tire model 20 is calculated. Thereby, in step S42, the tire model 20 deformed by the load T is calculated. For example, in the standard system of the tire 2 (shown in FIG. 2), the load T is preferably set to a load determined by each standard for each tire.

  Next, a state in which the tire model 20 rolls on the road surface model 41 is calculated based on the predetermined traveling speed V (step S43). In this step S43, as shown in FIG. 1, the physical quantity calculation unit 17A of the travel calculation unit 16C is read into the work memory 13C. Then, the physical quantity calculation unit 17A is executed by the calculation unit 13A.

  In step S43, as shown in FIG. 6, boundary conditions for rolling the tire model 20 on the road surface model 41 and the projection model 42 are defined. The boundary conditions include, for example, the friction coefficient between the tire model 20 and the road surface model 41, the friction coefficient between the tire model 20 and the projection model 42, and the like.

  In the tire model 20, an angular velocity V1 corresponding to the traveling speed V is defined. Thus, the rotation of the tire model 20 around the rotation axis 20s is calculated. In the road surface model 41, an angular speed V2 corresponding to the traveling speed V is defined. Thereby, the road surface model 41 is calculated to rotate around the rotation axis 41s. Based on these conditions, the calculation unit 13A can calculate the tire model 20 that rolls on the road surface model 41.

  Further, in step S43, a physical quantity related to the vibration of the tire model 20 is calculated. Examples of the physical quantity related to vibration include the vertical axial force and the longitudinal axial force of the tire model 20. In the present embodiment, the longitudinal axial force of the tire model 20 is calculated. Further, in the present embodiment, while the tire model 20 rolls on the road surface model 41 or the protrusion model 42, the vertical axial force of the tire model 20 is calculated in minute time (unit time Tx) increments. The vertical axial force of the tire model 20 is input to the physical quantity input unit 15E (shown in FIG. 1). The vertical axial force of the tire model 20 is calculated by using the force acting on the tire model 20 transmitted through the rim model 30 on the rotary shaft 20s rigidly coupled to the rim model 30 shown in FIG. .

  Next, in the simulation step S4, it is determined whether or not the projection model 42 is provided on the road surface model 41 (step S44). In step S44, when it is determined that the projection model 42 is provided on the road surface model 41 (“Y” in step S44), the next step S45 is performed. On the other hand, when it is determined that the projection model 42 is not provided on the road surface model 41 (“N” in step S44), the next step S47 is performed.

  Next, in the simulation step S4, it is determined whether or not the tire model 20 has overcome the protrusion model 42 (step S45). The time from the start of rolling of the tire model 20 to overcoming the protrusion model 42 can be calculated based on the running speed V of the tire model 20 and the distance between the tire model 20 and the protrusion model 20 before rolling. . For this reason, in step S45, it is determined whether or not the tire model 20 has overcome the protrusion model 42 based on whether or not the time from the start of rolling until it has exceeded the protrusion model 42 has elapsed.

  In step S45, when it is determined that the tire model 20 has overcome the protrusion model 42 ("Y" in step S45), the next changing step S46 is performed. On the other hand, when it is determined that the tire model 20 does not get over the protrusion model 42 ("N" in step S45), the next step S47 is performed.

  Next, in the simulation step S4, the road surface model 41 is changed to a road surface model without the projection model 42 (change step S46). FIG. 11 is a side view of a road surface model without the tire model 20 and the protrusion model 42.

  In the changing step S46 of the present embodiment, the smooth road surface model 45 (shown in FIG. 9) input to the smooth road surface model input unit 15D is read into the work memory 13C. Further, as shown in FIG. 1, the road surface changing unit 17B of the travel calculation unit 16C is read into the work memory 13C. Then, the road surface changing unit 17B is executed by the calculation unit 13A.

  In the changing step S46, first, boundary conditions and the like for rolling the tire model 20 (shown in FIG. 6) on the smooth road surface model 45 (shown in FIG. 9) are defined. The boundary condition includes, for example, a friction coefficient between the tire model 20 and the smooth road surface model 45 as shown in FIG. In the smooth road surface model 45, an angular velocity V2 corresponding to the traveling speed V is defined as in the road surface model 41 shown in FIG. Further, the coordinates of the rotation axis 41 s (shown in FIG. 6) of the road surface model 41 are defined as the coordinates of the rotation axis 45 s of the smooth road surface model 45.

  Next, in the changing step S46, the road surface model 41 (shown in FIG. 6) is returned to the road surface model input unit 15C. Thereby, the contact (rolling) between the tire model 20 and the road surface model 41 is released. Based on the above conditions defined in the smooth road surface model 45, contact between the tire model 20 and the smooth road surface model 45 is defined. Thereby, in simulation process S4, tire model 20 which rolls on smooth road surface model 45 can be calculated in process S43 which calculates rolling of tire model 20.

  In the change step S46 of the present embodiment, the tire model 20 is switched from the road surface model 41 to the smooth road surface model 45 after the tire model 20 gets over the projection model 42. Therefore, the physical quantity of the tire model 20 that rolls on the smooth road surface model 45 (for example, The contact pressure, the deformation amount, and the like) and the physical amount of the tire model 20 that has rolled the road surface model 41 coincide with each other. Thereby, in step S43 for calculating the rolling of the tire model 20, there is a difference between the physical quantity of the tire model 20 on the road surface model 41 and the physical quantity of the tire model 20 on the smooth road surface model 45 shown in FIG. Can be prevented.

  Next, it is determined whether or not a predetermined rolling end time has elapsed (step S47). In step S47, when it is determined that the rolling end time has elapsed ("Y" in step S47), the next step S5 is performed. On the other hand, when it is determined that the rolling end time has not elapsed ("N" in step S47), the unit time Tx is advanced by one (step S48), and each of steps S43 to S47 is performed again. The Thus, in the simulation step S4, the vertical axial force of the tire model 20 from the start of rolling to the end of rolling is stored in the physical quantity input unit 15E as time series data for each unit time Tx.

  FIG. 12 is a graph showing the relationship between the vertical axial force of the tire model 20 and the rolling time. As described above, in the simulation step S4 of the present embodiment, after the tire model 20 gets over the projection model 42, the road surface model 41 is changed to the smooth road surface model 45 without the projection model 42. Therefore, the tire model 20 can continue to travel on a smooth road surface model (in this embodiment, the smooth road surface model 45) until the predetermined rolling end without overcoming the protrusion model 42 again. For this reason, in the simulation step S4, the data amount of the physical quantity of the tire model 20 that rolls the smooth road surface model (smooth road surface model 45) after overcoming the protrusion model 42 can be increased. Note that the rolling end time can be appropriately set according to the simulation to be executed.

  Next, the computer 1 evaluates the vibration performance of the tire that has overcome the protrusion based on the physical quantity related to vibration (step S5). In step S5, first, as shown in FIG. 1, a physical quantity related to tire vibration (in this embodiment, vertical axial force) input to the physical quantity input unit 15E is read into the work memory 13C. Further, the vibration performance evaluation unit 16D is read into the work memory 13C. And vibration performance evaluation part 16D is performed by the calculating part 13A.

  In step S5 of the present embodiment, frequency analysis (FFT processing) is performed on the vertical axial force of the tire model 20 from the start of rolling of the tire model 20 to overcoming the protrusion model 42 until the end of rolling. Is done. Accordingly, as shown in FIG. 13, a graph showing the relationship between the vertical force power spectral density (the vertical axial force density) and the frequency can be obtained. In addition, the vertical force power spectral density of this embodiment is shown with the continuous line (Example).

  In this graph, since the vertical power spectrum density can be obtained for each frequency, it is possible to evaluate the vibration performance (vibration characteristics) of the tire over the protrusion. Such a graph is input to the physical quantity input unit 15E.

  As described above, in the evaluation method of the present embodiment, in the simulation step S4, the physical quantity (vertical axial force in the present embodiment) data of the tire model 20 that rolls on the smooth road surface model 45 after overcoming the projection model 42. The amount can be increased. That is, the vibration (vertical axial force) of the tire model that occurs when the bump model 42 is overcome can be attenuated over a longer period of time than before. Thereby, in the evaluation method of this embodiment, the frequency resolution of the vertical axial force can be increased as compared with the conventional method. Therefore, with the tire vibration performance evaluation method of the present invention, the tire vibration performance can be accurately evaluated.

  Moreover, in the evaluation method of the present embodiment, the vibration performance of the tire 2 (shown in FIG. 2) can be evaluated by simulation using the computer 1. Therefore, in the evaluation method of the present embodiment, since the vibration performance of the tire 2 over the protrusion 35 protruding from the road surface 31 can be evaluated without actually manufacturing the tire 2, the actual tire 2 was used. Compared with the conventional evaluation method, cost and time can be reduced. Further, since the road surface model 41 of the present embodiment is modeled based on the cylindrical drum 32 shown in FIG. 2, an evaluation method for the tire 2 using the drum 32 implemented at the tire design site is used. It can be easily implemented on the computer 1.

  Next, the computer 1 determines whether or not the vibration performance of the tire 2 is good (step S6). Whether or not the vibration performance is good is appropriately determined from the graph shown in FIG. 13 based on the category of the tire 2 (shown in FIG. 2) and the performance required for the tire 2. In step S6, when it is determined that the vibration performance of the tire 2 is good, the tire 2 is manufactured based on the tire model 20 (step S7). On the other hand, when it is determined that the vibration performance is not good, the structure of the tire 2 is redesigned (step S8), and steps S1 to S6 are executed again. Thereby, in this invention, the tire 2 which is excellent in vibration performance can be designed reliably.

  Further, when the vertical axial force when the evaluation target tire 2 shown in FIG. 2 gets over the protrusion 35 is measured, in step S6, the waveform of the vertical axial force of the tire 2 and the tire model 20 are the protrusion model. It is desirable to determine whether or not the waveform of the vertical axial force when overcoming 42 is the same. As a result, in step S6, it is possible to confirm whether or not the vertical axial force of the tire model 20 calculated by the computer 1 approximates the vertical axial force of the actual tire 2, so that the evaluation accuracy of vibration performance is increased. Can do.

  As shown in FIG. 8, the road surface model 41 of the present embodiment is modeled integrally with the protrusion model 42, but is not limited thereto. For example, the road surface model may be obtained by fixing a projection model 42 in which only the projection 35 (shown in FIG. 4) is independently modeled to the smooth road surface model 45 shown in FIGS. FIG. 14 is a perspective view showing only the protrusion model 42.

  When such a road surface model is used, in the changing step S46 for changing to a road surface model without the protrusion model 42, it is possible to switch to the smooth road surface model 45 simply by deleting the contact definition of the protrusion model 42. For this reason, in the change step S46 of this embodiment, unlike the change step S46 of the previous embodiment, it is not necessary to redefine the contact between the tire model 20 and the road surface model (smooth road surface model 45). It can be shortened.

  Moreover, in the evaluation method of this embodiment, it is not necessary to model the road surface model 41 shown in FIG. Therefore, in the evaluation method of this embodiment, the capacity of the data unit 15 (shown in FIG. 1) storing the road surface model 41 is reduced while omitting the step S2 of setting the road surface model 41 (shown in FIG. 8). can do.

  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.

  The tire vibration performance evaluation method using the tire model and the road surface model shown in FIG. 6 was implemented according to the processing procedure shown in FIGS. 5 and 10 (Example). In the changing process of the example, after the tire model got over the protrusion model only once, the road surface model having the protrusion model shown in FIG. 8 was switched to the smooth road surface model shown in FIG.

  Further, in the simulation process of the example, the vertical axial force of the tire model that got over the protrusion model only once was calculated from the start of rolling to the end of rolling. The relationship between the vertical axial force and the rolling time of the tire model of the example is as shown in the graph of FIG. In step S5 of the example, the vertical axial force of the tire model was subjected to frequency analysis, and the relationship between the vertical force power spectral density (the vertical axial force density) indicated by the solid line in FIG. 13 and the frequency was determined.

  For comparison, a tire vibration performance evaluation method having no changing process was performed using the tire model and road surface model shown in FIG. 6 (comparative example). In the simulation process of the comparative example, the vertical axial force of the tire model that repeatedly climbed over the protrusion model from the start of rolling to the end of rolling was calculated. The relationship between the vertical axial force and the rolling time of the tire model of the example is shown in the graph of FIG. As shown in FIG. 15, the tire model of the comparative example gets over the protrusion model three times between the start of rolling and the end of rolling.

Next, in the comparative example, the vertical axial force after the second time was changed to “0” in order to perform frequency analysis while ignoring the vertical axial force of the tire model 20 that got over the protrusion model after the second time (see FIG. 16). In the comparative example, the vertical axial force shown in FIG. 16 was subjected to frequency analysis, and the relationship between the vertical force power spectral density indicated by the broken line in FIG. 13 and the frequency was obtained. The common specifications are as follows.
tire:
Tire size: 205 / 60R16
Rim size: 16 × 6J
Internal pressure: 220 kPa
Load T: 4510N
Traveling speed V: 100km / h
Road surface (drum):
Outer diameter R1: 1500mm
Protrusion:
Height H2: 5mm
Width W2: 5mm
Rolling time: 0.5 seconds Frequency analysis:
Window function: Rectangle Frame size: 1024
Number of display lines: 400
Sampling time: 0.0005 seconds

  As a result of the test, the example shows a vertical force power spectral density over a wide range as compared with the comparative example. Therefore, in the example, it was confirmed that the resolution of the frequency analysis can be reduced as compared with the comparative example, and the vibration performance of the tire can be accurately evaluated.

2 Tire 20 Tire model 31 Road surface 35 Projection 41 Road surface model 42 Projection model

Claims (5)

A method for evaluating, using a computer, the vibration performance of a tire that has overcome a protrusion protruding from a road surface,
Inputting to the computer a tire model obtained by modeling the tire with a finite number of elements;
Inputting to the computer a road surface model obtained by modeling the road surface with a finite number of elements;
A simulation step in which the computer rolls the tire model to the road surface model and calculates a physical quantity related to vibration of the tire;
The road surface model has a protrusion model that models the protrusion,
In the simulation step, after the tire model gets over the protrusion model, the road surface model is changed to a road surface model without the protrusion model, and the tire model is rolled to a road surface model without the protrusion model. A tire vibration performance evaluation method comprising a step.
Inputting to the computer a smooth road surface model obtained by modeling the road surface without the protrusions with a finite number of elements;
The tire vibration performance evaluation method according to claim 1, wherein the changing step switches a road surface model having the protrusion model to the smooth road surface model.   The tire vibration performance evaluation method according to claim 1, wherein in the changing step, the protrusion model is deleted.   The tire road performance evaluation method according to any one of claims 1 to 3, wherein the road surface is formed on an outer peripheral surface of a cylindrical drum. A tire simulation apparatus having an arithmetic processing unit that evaluates the vibration performance of a tire overcoming a protrusion protruding from a road surface,
The arithmetic processing unit includes a tire model input unit that inputs a tire model obtained by modeling the tire with a finite number of elements;
A road surface model input unit to which a road surface model obtained by modeling the road surface with a finite number of elements is input;
A traveling calculation unit that travels the tire model with the road surface model and calculates a physical quantity related to the vibration of the tire,
The road surface model has a protrusion model that models the protrusion,
The running calculation unit, after the tire model gets over the projection model, the road surface model, and change the projection model with no road model, to roll the tire model on the road model without the projection model A tire simulation apparatus including a road surface changing unit.

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