JP2012006522A - Simulation model creating method, simulation method, simulation model creating device and simulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more easily create a simulation model used for analyzing a tire.SOLUTION: The method for creating a simulation model in a region around a pneumatic tire has: a first model creating step for creating an ununiform tire model in a tire circumferential direction, a road surface model and a wheel model, and setting boundary conditions; a tire shape calculating step for executing analysis of contact with the tire model created in the first model forming step to calculate the tire shape in a state of contact with the ground; a tire rolling shape creating step for converting the tire shape calculated in the tire shape calculating step to create a tire shape in a rolling state in time series; and a second model creating step for creating a model created by dividing a region including a region in contact with the tire shape in every time obtained in the tire rolling shape creating step into a mesh.

Description

  The present invention relates to a method for creating a simulation model used for tire analysis using a computer, a simulation method using the created simulation model, and an apparatus therefor.

  A method for evaluating various performances of a tire by analysis using a computer and designing a tire and further a vehicle on which the tire is mounted based on the performance has been proposed and put into practical use. For example, Patent Document 1 describes a simulation method for analyzing the behavior of an assembly of a tire and a wheel by a numerical analysis method such as a finite element method. Patent Document 2 describes a simulation method for analyzing the noise performance of a tire.

JP 2007-83925 A JP 2009-161115 A

  Here, in order to evaluate the performance of the tire, it is necessary to calculate the shape of the tire at each time corresponding to the condition as a simulation model. For example, in the simulation methods described in Patent Document 1 and Patent Document 2, an operation for rotating the tire with the tire model in contact with the road surface model is performed, that is, deformation calculation is repeatedly performed to calculate the shape of the tire.

  However, as in the simulation methods described in Patent Literature 1 and Patent Literature 2, the tire model and the road surface model are relatively rotated, that is, the tire shape at each time of the rolling tire model is calculated. If is repeated, more calculations are performed to calculate the tire shape. As the amount of calculation increases in this way, the time required for analysis becomes longer and the load on the computer increases. In particular, in the case of a pneumatic tire in which a lug groove or the like is formed and the shape changes in the circumferential direction, the calculation amount increases.

  The present invention has been made in view of the above, and provides a simulation model creation method, a simulation method, a simulation model creation device, and a simulation device that can more easily create a simulation model used for tire analysis. For the purpose.

  In order to solve the above-described problems and achieve the object, the present invention provides a simulation model creation method for a region around a pneumatic tire, which includes a tire model, a road surface model, and a wheel model that are uneven in the tire circumferential direction. A first model creating step for creating and setting boundary conditions, a tire shape calculating step for calculating a tire shape in a grounded state by performing a contact analysis of the tire model created in the first model forming step, and the tire The tire shape calculated in the shape calculation step is converted to create a rolling tire shape in time series, and the tire rolling shape creation step is in contact with the tire shape at each time obtained in the tire rolling shape creation step. A second model creation step of creating a model in which a region including the region is divided into meshes.

  Moreover, it is preferable that the wheel model has a closed space on the surface of the tire model opposite to the ground contact surface with the road surface model.

  Further, the tire shape calculating step further performs a ground contact analysis under a condition in which the tire model is rotated from the conditions formed in the first model creating step, calculates a tire shape in a grounded state, and the tire In the rolling shape creation step, it is preferable that the calculated tire shapes in a grounded state are converted to create rolling tire shapes in time series.

  The tire model has a shape in which a pattern having a constant rotation angle width is repeatedly arranged, and the tire shape calculation step preferably rotates the tire model at an angle smaller than the constant angle width of the pattern. .

  Moreover, it is preferable that the tire model has a shape in which patterns having a constant rotation angle width are repeatedly arranged.

  Further, in the tire rolling shape creation step, the information on the coordinates of the corresponding point and the circumferential rotation angle at the same position in the pattern is extracted for each pattern from the shape of the tire, and the extracted circumferential direction By converting the rotation angle into time, the relationship between the coordinates of the corresponding point and time is detected for each corresponding point, the relationship between the detected coordinate of the corresponding point and time is extracted for each time, and the tire shape in the rolling state Is preferably calculated in time series.

  Moreover, it is preferable that the said tire rolling shape creation step extracts the arbitrary points on the rolling track which connected the said corresponding points as said corresponding points from the shape of the said tire.

  In the second model creation step, the mesh is formed around the tire, and a first mesh region in which a mesh structure changes according to a time change of the tire shape, and an outer periphery of the first mesh region. It is preferable to include a second mesh region that is formed and does not change the mesh structure.

  In the second model creation step, it is preferable to create a model in which a region including a model obtained by combining the tire model and the wheel model with a model of at least a part of a vehicle on which the tire is mounted is divided into meshes.

  In order to solve the above-described problems and achieve the object, a simulation method according to the present invention is a tire of each time obtained in the tire rolling shape creation step by any of the simulation model creation methods described above. A model in which a region including a region in contact with a shape is divided into meshes is created, and fluid analysis is performed using the created model.

  In order to solve the above-described problems and achieve the object, the present invention is a simulation model creation device for a region around a pneumatic tire, and includes a tire model, a road surface model, and a wheel model that are uneven in the tire circumferential direction. A first model creation unit that creates and sets boundary conditions; a tire shape calculation unit that performs a contact analysis of the tire model created by the first model creation unit and calculates a tire shape in a grounded state; and the tire A tire rolling shape creation unit that converts the tire shape calculated by the shape calculation unit to create a rolling tire shape in time series, and a tire shape at each time obtained by the tire rolling shape creation unit And a second model creation unit that creates a model in which a region including the region is divided into meshes.

  Moreover, it is preferable that the wheel model has a closed space on the surface of the tire model opposite to the ground contact surface with the road surface model.

  In addition, the tire shape calculation unit further performs a ground contact analysis under the condition in which the tire model is rotated from the conditions formed by the first model creation unit, calculates a tire shape in a grounded state, and the tire It is preferable that the rolling shape creating unit creates the tire shape in the rolling state in time series by converting the calculated tire shape in the grounded state.

  Further, it is preferable that the tire model has a shape in which a pattern having a constant rotation angle width is repeatedly arranged, and the tire shape calculation unit rotates the tire model at an angle smaller than the constant angle width of the pattern. .

  Moreover, it is preferable that the tire model has a shape in which patterns having a constant rotation angle width are repeatedly arranged.

  Further, the tire rolling shape creation unit extracts, for each pattern, information on the coordinates of the corresponding points and the circumferential rotation angle at the same position in the pattern from the shape of the tire, and extracts the circumferential direction. By converting the rotation angle into time, the relationship between the coordinates of the corresponding point and time is detected for each corresponding point, the relationship between the detected coordinate of the corresponding point and time is extracted for each time, and the tire shape in the rolling state Is preferably calculated in time series.

  Moreover, it is preferable that the said tire rolling shape preparation part extracts the arbitrary points on the rolling track | truck which connected the said corresponding points as said corresponding points from the shape of the said tire.

  In addition, the second model creation unit may form the mesh on the outer periphery of the first mesh region formed around the tire, and the mesh structure may change in accordance with the time change of the tire shape. It is preferable to include a second mesh region that is formed and does not change the mesh structure.

  Further, it is preferable that the second model creation unit creates a model in which a region including a model obtained by combining at least a part of a model of a vehicle on which the tire is mounted on the tire model and the wheel model is divided into meshes.

  In order to solve the above-described problems and achieve the object, a simulation device according to the present invention is a tire of each time obtained in the tire rolling shape creation step by the simulation model creation device described above. A model in which a region including a region in contact with a shape is divided into meshes is created, and fluid analysis is performed using the created model.

  The simulation model creation method, simulation method, simulation model creation device, and simulation device of the present invention can create a simulation model used for tire analysis more easily, reduce the amount of calculation, and evaluate in a shorter time. It can be carried out.

FIG. 1 is a perspective view of a tire. FIG. 2 is a meridional sectional view of the tire shown in FIG. FIG. 3 is a front view illustrating a schematic configuration of a tread surface of the tire illustrated in FIG. 1. FIG. 4 is an explanatory diagram showing a simulation device that executes the tire simulation method according to the present embodiment. FIG. 5 is a flowchart showing the procedure of the tire simulation method according to the present embodiment. FIG. 6A is a cross-sectional view illustrating an example of a tire model. FIG. 6B is a partially enlarged view showing an example of the tire model shown in FIG. FIG. 7A is a graph illustrating an example in which the position of the corresponding point is calculated based on the ground contact analysis. FIG. 7B is a graph illustrating an example in which the position of the corresponding point is converted into a function of time. FIG. 8 is a perspective view showing a schematic configuration of a model around the tire. FIG. 9 is a graph showing another example in which the position of the corresponding point is converted into a function of time. FIG. 10A is a partially enlarged view illustrating an example of a tire model. 10-2 is a partially enlarged view showing a state where the tire model shown in FIG. 10-1 is rotated. FIG. 10C is a graph illustrating an example in which the position of the corresponding point is calculated based on the ground contact analysis. FIG. 11A is a partially enlarged view illustrating an example of a tire model. FIG. 11B is a graph illustrating an example in which the position of the corresponding point is calculated based on the ground contact analysis. FIG. 12 is a front view showing a schematic configuration of another example of a model around the tire. FIG. 13A is an enlarged front view showing a part of the model shown in FIG. 12 in an enlarged manner. FIG. 13-2 is an enlarged front view showing a part of the model shown in FIG. 12 in an enlarged manner. FIG. 14 is a perspective view showing a schematic configuration of a model around the tire.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content of the form (henceforth embodiment) for implementing the following invention. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same.

  In the following description, the tire width direction means a direction parallel to the tire rotation axis, the inner side in the tire width direction means the side toward the tire equatorial plane in the tire width direction, and the outer side in the tire width direction means in the tire width direction. It means the side away from the tire equatorial plane. The tire radial direction means a direction orthogonal to the rotational axis of the pneumatic tire, the tire radial inner side is the side toward the rotational axis in the tire radial direction, and the tire radial outer side is from the rotational axis in the tire radial direction. It means the side that leaves. The tire circumferential direction means a circumferential direction with the rotation axis as the central axis. The tire equator plane means a plane perpendicular to the rotation axis of the pneumatic tire and passing through the center of the tire width of the pneumatic tire.

  1 is a perspective view of the tire, FIG. 2 is a meridional sectional view of the tire shown in FIG. 1, and FIG. 3 is a front view showing a schematic configuration of the tread surface of the tire shown in FIG. As shown in FIG. 1, the tire 1 is an annular structure that rotates about a rotation axis. As shown in FIG. 2, a carcass 2, a belt 3, a belt cover 4, and a bead core 5 appear on the meridional section of the tire 1. A cap tread 6 is disposed on the outer side in the tire radial direction of the tire 1 (on the contact surface side with the road surface). The tire 1 is a composite material structure in which rubber as a base material is reinforced by a reinforcing cord such as a carcass 2, a belt 3 or a belt cover 4 as a reinforcing material. Here, the layer of the reinforcing cord made of a cord material such as metal fiber or organic fiber, such as the carcass 2, the belt 3, and the belt cover 4, is referred to as a cord layer.

  The carcass 2 is a strength member that serves as a pressure vessel when the tire 1 is filled with air. The carcass 2 supports a load by its internal pressure and withstands a dynamic load during traveling. The belt 3 is a layer of reinforcing cords in which rubberized cords arranged between the cap tread 6 and the carcass 2 are bundled. In the case of a bias tire, it is called a breaker. In the radial tire, the belt 3 plays an important role as a shape retention and strength member.

  A belt cover 4 is disposed on the tread surface G side of the belt 3. The belt cover 4 is formed by arranging, for example, organic fiber materials in layers, and has a role as a protective layer for the belt 3 and a role as a reinforcing layer for the belt 3. The bead core 5 is a bundle of steel wires that supports the cord tension generated in the carcass 2 by internal pressure. The bead core 5 becomes a strength member of the tire 1 together with the carcass 2, the belt 3, the belt cover 4, and the tread.

  On the tread surface G side (tread surface) of the cap tread 6, as shown in FIGS. 2 and 3, four grooves 7a, 7b, 7c, 7d extending in the tire circumferential direction are formed. This improves drainage during rainy weather. Further, by forming the four grooves 7a, 7b, 7c, and 7d, the cap tread 6 has a land portion 11a on the outer side in the tire width direction from the groove 7a and a land portion between the grooves 7a and 7b. 11b, a land portion 11c between the groove 7b and the groove 7c, a land portion 11d between the groove 7c and the groove 7d, and a land portion 11e outside the groove 7d in the tire width direction are formed. The land portion 11c is formed at a position passing through the tire equator plane C. The land portion 11c is provided with a decorative groove 12 having a narrower groove width and a shallower groove depth than the grooves 7a, 7b, 7c, and 7d. Furthermore, a plurality of lug grooves 14 extending in the tire width direction and extending from the grooves 7a to the grooves 7b are formed in the land portion 11b at regular intervals in the tire circumferential direction. Thus, the land portion 11b has a shape in which a plurality of blocks 16 surrounded by the main groove 7a, the main groove 7b, and the lug groove 14 are arranged on the row. In addition, a plurality of lug grooves 14 extending in the tire width direction and extending from the groove 7c to the groove 7d are also formed in the land portion 11d at regular intervals in the tire circumferential direction. Thereby, the land portion 11d has a shape in which a plurality of blocks 16 surrounded by the main groove 7c, the main groove 7d, and the lug groove 14 are arranged on the row. Thus, in the tire 1, lug grooves 14 are formed in the land portions 11b and 11d at regular intervals in the circumferential direction. For this reason, the tire 1 has a non-uniform shape in the circumferential direction, that is, a shape in which irregularities are formed in the tire circumferential direction. In the tire 1, lug grooves 14 and blocks 16 are alternately formed at regular intervals in the tire circumferential direction. As described above, the tire 1 has a shape in which the same shape is repeated for each pitch P in the tire circumferential direction. That is, the tire 1 has a shape of a certain angle corresponding to the pitch P around the rotation axis as a repeating unit, and a plurality of shapes arranged in the circumferential direction of the shape corresponding to the pitch P.

  The side portion of the tire 1 is called a sidewall 8 and connects between the bead core 5 and the cap tread 6. Further, a shoulder portion Sh is provided between the cap tread 6 and the sidewall 8.

  Next, an apparatus for executing the tire simulation method according to the present embodiment will be described. FIG. 4 is an explanatory diagram showing a simulation device that executes the tire simulation method according to the present embodiment. The tire simulation method according to the present embodiment can be realized by the simulation device 50 shown in FIG. As shown in FIG. 4, the simulation apparatus 50 includes a processing unit 52 and a storage unit 54. In addition, an input / output device 51 is electrically connected to the simulation device 50, and the physical property value of the rubber constituting the tire model, the physical property value of the reinforcing cord, or the deformation analysis by the input means 53 provided therein. Is input to the processing unit 52 and the storage unit 54. In addition, the simulation device 50 displays various information such as calculation results and input results on the display means 55 of the input / output device 51.

  Here, an input device such as a keyboard and a mouse can be used for the input means 53. The storage unit 54 stores a computer program including a tire deformation analysis and a tire simulation method according to the present embodiment. Here, the storage unit 54 is a hard disk device, a magneto-optical disk device, a non-volatile memory such as a flash memory (a storage medium that can be read only such as a CD-ROM), or a RAM (Random Access Memory). Such a volatile memory or a combination thereof can be used.

  The computer program may be capable of realizing various tire simulation methods in combination with a computer program already recorded in the computer system. Further, the computer program for realizing the function of the processing unit 52 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by the computer system and executed to deform the structure. Analysis and a tire simulation method according to the present embodiment may be executed. Here, the “computer system” includes hardware such as an OS (Operating System) and peripheral devices.

  The processing unit 52 includes a first model creation unit 52a, a ground analysis unit 52b, an analysis result conversion unit 52c, a second model creation 52d, a fluid analysis unit 52e, and an evaluation unit 52f. The first model creation unit 52 a creates an analysis model for use in contact analysis (deformation analysis) and stores the analysis model in the storage unit 54. As an analysis model, a tire model, a road surface model, and a wheel model are created. Also, a boundary condition setting process is performed. Note that these models and boundary conditions are created and set based on numerical values input from the input means 53 by the user. The ground analysis unit 52b reads the model created by the first model creation unit 52a from the storage unit 54, and executes the ground analysis under the set conditions. The analysis result conversion unit 52c extracts the corresponding points from the tire shape acquired by the ground contact analysis by the ground contact analysis unit 52b, and the result of the ground contact analysis using the position, rotation angle information, and speed information of the corresponding points Convert to time-series data of the tire shape in the state. The second model creation unit 52d models the periphery of the tire shape at each time using the time-series data of the rolling tire shape converted by the analysis result conversion unit 52c. In the present embodiment, a model in which a fluid mesh is created around the tire shape is created. The fluid analysis unit 52e performs a fluid analysis on the model created by the second model creation unit 52d under the set conditions. The conditions used for the analysis in the fluid analysis unit 52e can also be created and set based on the numerical values and the like input from the input means 53 by the user. The evaluation unit 52f evaluates the performance of the tire based on the result analyzed by the fluid analysis unit 52e. Here, evaluation targets include air flow around the tire, tire air resistance, tire sound, tire noise, and the like.

  The processing unit 52 includes, for example, a memory and a CPU (Central Processing Unit). At the time of contact analysis and fluid analysis, the processing unit 52 incorporates the program into the processing unit 52 based on the analysis model created by the first model creation unit 52a, the second model creation unit 52d, input data, and the like. Read into memory and perform calculations. At that time, the processing unit 52 appropriately stores a numerical value in the middle of the calculation in the storage unit 54, and extracts the numerical value stored in the storage unit 54 and advances the calculation. The processing unit 52 may realize the function by dedicated hardware instead of the computer program.

  Here, a liquid crystal display device, a CRT (Cathode Ray Tube) or the like can be used as the display means 55. In addition, since the simulation results, simulation conditions, and the like can be output to a recording medium such as paper by a printing machine provided as necessary, a printing machine may be used as the display means 55. Here, the memory | storage part 54 may exist in another apparatus (for example, database server). For example, the simulation device 50 may access the processing unit 52 and the storage unit 54 by communication from a terminal device including the input / output device 51.

  Next, a simulation model creation method and a tire simulation method according to this embodiment will be described. The tire simulation method according to the present embodiment can be realized by the above-described simulation apparatus. FIG. 5 is a flowchart showing the procedure of the tire simulation method according to the present embodiment. The tire simulation method according to this embodiment creates a simulation model by the simulation model creation method according to this embodiment. FIG. 6A is a cross-sectional view illustrating an example of a tire model. FIG. 6B is a partially enlarged view showing an example of the tire model shown in FIG. FIG. 6A shows a cross section of the tire model cut along a plane parallel to the tire circumferential direction. FIG. 7A is a graph illustrating an example in which the position of the corresponding point is calculated based on the ground contact analysis, and FIG. 7B is a graph illustrating an example in which the position of the corresponding point is converted into a function of time. . Further, FIG. 8 is a perspective view showing a schematic configuration of a model around the tire.

  In executing the tire simulation method according to the present embodiment, in step S12, the model creation unit 52a of the simulation apparatus 50 shown in FIG. 4 creates tire, road surface, and wheel models. Specifically, as shown in FIG. 6A, a tire analysis model (hereinafter referred to as a tire model) 60, a wheel analysis model (hereinafter referred to as a wheel model) 64 attached to the tire model 60, and a tire model 60 are provided. An analysis model (hereinafter referred to as a road surface model) 66 of a road surface to be contacted is created. The model creation unit 52a also sets boundary conditions used for analysis. Here, the analysis model is a model that can be numerically analyzed using a computer, and includes a mathematical model and a mathematical discretization model. Further, the tire model 60 used in the present embodiment has the same shape as the tire shown in FIGS. 1 to 3 and has a shape in which lug grooves extending in the tire width direction at regular intervals in the tire circumferential direction are formed. The plurality of blocks 62 are arranged in a row in the tire circumferential direction. That is, the tire model 60 is a model having a non-uniform shape in the circumferential direction.

  The tire model 60 is a model used for performing a ground contact analysis using a numerical analysis method such as a finite element method or a finite difference method. For example, in the present embodiment, since the finite element method (FEM) is used for the ground contact analysis of the tire model 60, the tire model 60 is created based on the finite element method. The analysis method applicable to the ground analysis according to the present embodiment is not limited to the finite element method, and a finite difference method (FDM), a boundary element method (BEM), or the like can be used. Further, the most appropriate analysis method can be selected according to the boundary condition or the like, or a plurality of analysis methods can be used in combination. Since the finite element method is an analysis method suitable for structural analysis, it can be suitably applied particularly to a structure such as a tire.

  In step S12, the model creation unit 52a divides a tire that is an annular structure into a plurality of finite elements, and creates a tire model 60 as shown in FIGS. 6-1 and 6-2. Each of the plurality of elements includes a plurality of nodes. In the present embodiment, the tire model 60 is a three-dimensional analysis model.

  The elements constituting the tire model 60 are, for example, solid elements such as tetrahedral solid elements, pentahedral solid elements and hexahedral solid elements in a three-dimensional body, shell elements such as triangular shell elements, rectangular shell elements, surface elements, etc. It is desirable to make it an element that can be handled with. In the process of analysis, the elements divided in this way are identified one by one using three-dimensional coordinates and cylindrical coordinates in the three-dimensional model.

  When the processing unit 52 creates the tire model 60 in step S12, the process proceeds to step S14. As step S14, the ground contact analysis unit 52b included in the processing unit 52 of the simulation apparatus 50 performs the ground contact analysis of the tire model 60 created in step S12. The grounding analysis is performed based on the set analysis conditions. For example, the analysis condition is input via the input unit 53 of the input / output device 51 shown in FIG. 4 and stored in the storage unit 54. When the analysis conditions are set, the ground contact analysis unit 52b performs a ground contact analysis of the tire model 60 and calculates the shape of the tire model 60 in a state of being in contact with the road surface model 66.

  The processing unit 52 proceeds to step S16 after performing the grounding analysis in step S14. The analysis result conversion part 52c with which the process part 52 of the simulation apparatus 50 is provided extracts the position of each corresponding point of a tire as step S16. Specifically, the analysis result conversion unit 52c calculates the relationship between the tire circumferential direction angle and coordinates of each node on the tire surface at the time of contact. Thereafter, the analysis result conversion unit 52c extracts information on the same point of adjacent pitches as information on corresponding points from the relationship between the calculated tire circumferential direction angle of each node and the coordinates. That is, in this embodiment, the position of one point in the block 62 is specified as a corresponding point, the corresponding point is detected in each block 62, and the relationship between the tire circumferential direction angle and the coordinate of the corresponding point is extracted. In FIG. 6B, information on a specific position of the block 62 is extracted as information on the corresponding point 70. Here, in FIG. 6B, in order to clarify the relationship between the block 62 and the corresponding point 70, the corresponding point 70 is displayed inside the block 62, but the corresponding point 70 is displayed on the surface of the block 62. It is a point (node). In this way, by detecting the relationship between the tire circumferential angle and the coordinates of a number of corresponding points extending in the circumferential direction, the relationship as shown in FIG. 7-1 can be calculated. Here, in FIG. 7A, the vertical axis is the radial coordinate [mm], and the horizontal axis is the angle [°]. It should be noted that the points at angles of 0 ° and 360 ° are the points farthest from the road surface model 66, the points in the 12 o'clock direction of the clock in FIG. 6A, and the points at an angle of 180 ° are closest to the road surface model 66. The point is a point in the 6 o'clock direction of the clock in FIG. Further, the radial coordinate is a coordinate in a direction perpendicular to the contact surface, and the rotation center of the tire model 60 is set as a reference (0 mm). From the relationship shown in FIG. 7A, it is possible to calculate at which position one point of the tire block 62 is located at each angle of the tire circumferential angle. In FIG. 7A, the relationship between the radial coordinate and the circumferential angle is shown, but the direction parallel to the road surface model 66 and orthogonal to the tire width direction, the coordinate in the left-right direction and the circumferential direction in FIG. The relationship with the angle can be calculated in the same manner. In addition, the analysis result conversion part 52c extracts a corresponding point in each point of the surface of the tire model 60 as step S16. That is, the tire model 60 extracts corresponding points for each surface point (node) within one pitch.

  The processing unit 52 proceeds to step S18 after extracting the position of each corresponding point in step S16. In step S18, the analysis result conversion unit 52c included in the processing unit 52 of the simulation apparatus 50 converts the circumferential angle of each corresponding point into time. Specifically, the analysis result conversion unit 52c converts the tire circumferential angle into time using the tire rolling speed condition. That is, based on the tire rolling speed, the time for one corresponding point to make one rotation is calculated, and the rotation angle at each time is calculated, and extracted in step S16 at the position corresponding to the rotation angle. The position information of the corresponding point is set as the position of the corresponding point at that time. Thereby, the relationship between the angle and the radial coordinate of an arbitrary corresponding point shown in FIG. 7A can be converted into the relationship between the time and the radial coordinate of one corresponding point shown in FIG. 7B. Here, in FIG. 7-2, the vertical axis is the radial coordinate [mm], and the horizontal axis is the time [s]. For example, when the time for one rotation of the tire is 1 s, the corresponding point at the angle 0 ° at the time 0 s moves to the position of the angle 180 ° at the time 0.5 s, and the angle 360 ° at the time 1 s. Move to position. Thereby, the position of each corresponding point at each time can be calculated from the result of grounding analysis. In step S18, the analysis result conversion unit 52c converts the relationship between the coordinates and the rotation angle into the relationship between the coordinates and time for each corresponding point on the surface of the tire model 60. Thereby, the tire model 60 can calculate at which coordinates each point is at an arbitrary time. Note that the relationship between the coordinates of each point of the tire model 60 and the time is based on the condition of the initial position (initial angle), in which corresponding points are extracted for each point (node) on the surface within one pitch. Thus, it can be calculated by shifting the time axis for each corresponding point in each pitch.

  The processing unit 52 proceeds to step S20 after converting the circumferential angle of each corresponding point to time in step S18. The analysis result conversion unit 52c included in the processing unit 52 of the simulation apparatus 50 creates time-series data of the surface shape as step S20. Specifically, the surface shape of the tire model at each time is calculated using the relationship between the coordinates of the corresponding points calculated at step S18 and the time. That is, by extracting the coordinates (position information) of each corresponding point at the same time from the relationship between the coordinates of each corresponding point and time, the surface shape of the tire at one time can be created. Thereby, the time series data of the tire surface shape can be obtained by repeating the creation of the tire surface shape in one time. In this embodiment, since the circumferential angle is converted to time as a state in which the tire is rotated at a predetermined rotation speed, the time-series data of the surface shape at the time of rolling of the tire is obtained.

  When the processing unit 52 creates time-series data of the tire surface shape in step S20, the processing unit 52 proceeds to step S22. The second model creation unit 52d included in the processing unit 52 of the simulation apparatus 50 creates a fluid analysis model as step S22. Specifically, a fluid mesh is created around the tire shape at each time using the time series data of the tire surface shape calculated in step S20. Thereby, as shown in FIG. 8, a fluid mesh 80 can be formed around the tire model 60. In the model for fluid analysis, a space inside the tire model 60 and a space outside the tire model 60 are separated (separated) by a wheel model 64. The tire model 60 is grounded to the road surface model 66.

  After creating the fluid analysis model in step S22, the processing unit 52 proceeds to step S24. The fluid analysis unit 52e included in the processing unit 52 of the simulation apparatus 50 performs fluid analysis as step S24. Specifically, the fluid flowing in the tire peripheral region is analyzed based on the fluid analysis model created in step S22 and various conditions. Note that fluid analysis includes air flow analysis, air resistance analysis, sound echo analysis, and fluid noise analysis such as air column resonance.

  When the fluid analysis is completed in step S24, the processing unit 52 proceeds to step S26. The evaluation part 52f with which the process part 52 of the simulation apparatus 50 is provided evaluates the analysis result of step S24 as step S26. Specifically, the evaluation unit 52f determines whether the result of the fluid analysis matches a condition or satisfies an allowable value, and evaluates the performance of the tire. The evaluation unit 52f can calculate the evaluation result of the tire with a numerical value or can be calculated by evaluation such as pass or fail. When the processing unit 52 evaluates the tire, the processing ends.

  Thus, in the simulation model creation method and the simulation method of the present embodiment, it is assumed that the tire surface shape is the same in the ground contact state and the rolling state, and the tire surface shape calculated in the ground contact state is changed. It is converted into the surface shape of a moving tire. Thereby, a simulation model used for tire fluid analysis can be created from quasi-static contact analysis. Thus, using the ground contact analysis to predict and create the tire surface shape of the rolling analysis, the amount of calculation can be reduced compared to calculating the tire surface shape by rolling analysis of the tire. it can. Thus, the analysis time can be shortened by reducing the amount of calculation. It should be noted that, as in the present embodiment, even if a simulation model is created based on a quasi-static grounding analysis, a result equivalent to the case where a simulation model is created by rolling analysis can be obtained. That is, according to this embodiment, the fluid analysis using the created simulation model can obtain the same result as the fluid analysis using the simulation model created by rolling analysis of the tire. That is, the amount of calculation can be reduced while maintaining the accuracy of the simulation. Thereby, a simulation can be performed efficiently. Note that when fluid analysis around a tire is performed as in the present embodiment, the surface shape of the tire may be acquired as time-series data, and information such as internal stress distribution does not have to be calculated. The surface shape of the tire is information on coordinates of nodes (corresponding points) on the surface of the tire.

  Note that the fluid mesh created around the tire in step S22 can be made into various meshes by the fluid analysis to be executed. Specifically, a mesh used for the difference method can be created, or a mesh used for the finite element method can be created. In the present embodiment, the mesh is created. However, the mesh is not limited to the mesh as long as a model used for fluid analysis around the tire can be created.

  In the tire simulation method according to the present embodiment, in the ground contact analysis in step S14, the wheel model to be attached to the tire is taken into account, and even if the ground contact analysis is performed, the wheel model is not taken into account, that is, the tire model and the road surface model. And may be used for grounding analysis.

  Further, the wheel model may be a model that can separate the region inside the tire (fluid region) and the region outside the tire (fluid region) during the fluid analysis in step S24. Therefore, when the wheel model is most simplified, the wheel model can be formed in a cylindrical shape connecting the end portions on the center side of the rotation axis of the tire. In addition, what is necessary is just to set a shape for a wheel model as needed, and it can also be set as the model of a detailed shape.

  Here, in the above embodiment, the shape of the surface of the tire is calculated using the corresponding points, but it may be further approximated and interpolated based on the positional relationship of the corresponding points. Thereby, the position information of the corresponding point at an arbitrary time can be acquired. That is, even if there is no corresponding point information at the corresponding time (circumferential angle), the position information of the corresponding point can be acquired. For example, as shown in FIG. 9, the position information of the triangular point can also be acquired by performing approximate interpolation based on the information of the circular point. FIG. 9 is a graph showing another example in which the position of the corresponding point is converted into a function of time. For approximate interpolation, linear interpolation, quadratic interpolation, spline function interpolation, or the like can be used.

  Next, another example of a method for creating time-series data of the surface shape of the tire will be described with reference to FIGS. 10-1 to 10-3. Here, FIG. 10-1 is a partially enlarged view showing an example of the tire model, and FIG. 10-2 is a partially enlarged view showing a state where the tire model shown in FIG. 10-1 is rotated. -3 is a graph showing an example in which the position of the corresponding point is calculated based on the ground contact analysis.

  In the simulation method shown in FIGS. 10-1 to 10-3, the tire ground contact analysis is performed twice, and the time series data of the tire surface shape is created based on the results of the two ground contact analyses. First, the processing unit 52 performs tire ground contact analysis using the tire model 60 shown in FIG. Thereafter, the processing unit 52 extracts information on the coordinates of the corresponding point 70a of the block 62a of the tire model 60 and the circumferential rotation angle, and information on the coordinates of the corresponding point 70b of the block 62b and the circumferential rotation angle. The processing unit 52 further extracts information on the coordinates of the corresponding points of all the blocks of the tire model 60 and the circumferential rotation angle. As described above, the corresponding point is a point having the same position in the block, and is a point (basically a node) on the surface of the tire model.

  Thereafter, the processing unit 52 rotates the tire model 60 by an angle α around the rotation axis from the state shown in FIG. 10-1 to obtain the state shown in FIG. 10-2. Note that the angle α is an angle shorter than the circumferential rotation angle of one pitch of the circumferential pattern of the tire. Thereafter, the processing unit 52 performs tire ground contact analysis using the tire model 60 shown in FIG. Thereafter, the processing unit 52 associates the coordinates of the corresponding point 72a of the block 62a of the tire model 60 and information on the circumferential rotation angle, the information of the coordinate of the corresponding point 72b of the block 62b and the circumferential rotation angle, and the correspondence of the block 62c. Information on the coordinates of the point 72c and the circumferential rotation angle is extracted. The processing unit 52 further extracts information on the coordinates of the corresponding points of all the blocks of the tire model 60 and the circumferential rotation angle. Here, since the angle α obtained by rotating the tire model 60 is narrower than the rotation angle corresponding to one pitch of the pattern, the corresponding points in the two ground contact analyzes are different circumferential rotation angles. In the present embodiment, when the tire model 60 of FIG. 10-1 and the tire model 60 of FIG. 10-2 are overlapped, the corresponding point 70a is located between the corresponding point 72a and the corresponding point 70b in the circumferential direction. The corresponding point 62b is sandwiched between the corresponding point 72b and the corresponding point 72c.

  The processing unit 52 includes the coordinates of the corresponding points and the circumferential rotation angle calculated by the tire model 60 shown in FIG. 10-1, and the coordinates and the circumferential rotation angles of the corresponding points calculated by the tire model 60 shown in FIG. 10-2. By combining both of these relationships, the relationship between the coordinates of corresponding points and the circumferential rotation angle shown in FIG. 10-3 is extracted. As described above, by extracting the relationship between the coordinates of the corresponding points and the circumferential rotation angle by using the ground contact analysis twice, as shown in FIG. )can do. In addition, since the rotation angle of the tire model is narrower than the rotation angle for one pitch of the pattern, the coordinates of the corresponding point in the rotation angle between the corresponding point calculated based on one analysis and the corresponding point are Information can be acquired.

  Thus, the position of the corresponding point can be calculated with higher accuracy by performing the installation analysis a plurality of times while shifting the tire model in the rotation direction. In addition, the approximation with respect to corresponding points can be performed with higher accuracy. In this case as well, since the position of the entire circumference can be extracted by simply shifting one corresponding point within an area of one pitch, position information with high accuracy can be obtained with a small amount of calculation. As described above, since the relationship between the coordinates of the corresponding point and the circumferential rotation angle can be calculated with higher accuracy, time-series data of the tire surface shape can also be acquired with high accuracy. Thereby, it is possible to create a simulation model capable of fluid analysis with higher accuracy.

  In the above embodiment, the rotation angle of the tire model is narrower than the rotation angle for one pitch of the pattern. However, the rotation angle is not limited to this, and is a rotation angle other than an integral multiple of the rotation angle for one pitch. Thus, the circumferential rotation angles of the corresponding points can be prevented from overlapping, and the calculated information of the corresponding points can be used effectively.

  Next, another example of a method for creating time-series data of the tire surface shape will be described with reference to FIGS. 11A and 11B. FIG. 11A is a partially enlarged view illustrating an example of the tire model, and FIG. 11B is a graph illustrating an example of calculating the position of the corresponding point based on the ground contact analysis. In the simulation method shown in FIGS. 11A and 11B, it is preferable to extract an arbitrary point on the rolling locus as a corresponding point (additional corresponding point). For example, as shown in FIG. 11A, a point 90 on a rolling track that passes through a corresponding point of the tire pattern (the same point on an adjacent pitch) is also included in the corresponding point. In addition, a rolling track | orbit is a track | truck at the time of rolling of the corresponding point of a tire pattern.

  In this way, in addition to the corresponding points that are basically only one point in the pattern, the points on the rolling trajectory are also extracted as corresponding points, and the relationship between the coordinates and the circumferential rotation angle is created. As shown in FIG. 2, additional corresponding points 90 other than corresponding points of the same point in the pattern can also be extracted. As a result, more points can be used when converting the relationship between the coordinates of the corresponding points and the time. The additional corresponding point can be an arbitrary point passing on the rolling track, but is preferably a point in contact with the surface of the tire. Note that the additional corresponding points need not be nodes.

  In addition, the fluid analysis model includes a first fluid mesh region in which a fluid mesh is formed around a tire (tire model), and the mesh structure changes according to a time change of the tire shape (tire surface shape); It is preferable to include a second mesh region that is formed on the outer periphery of the one fluid mesh region and in which the mesh structure does not change. Here, FIG. 12 is a front view showing a schematic configuration of another example of a model around the tire. 13-1 is an enlarged front view showing a part of the model shown in FIG. 12 in an enlarged manner, and FIG. 13-2 is an enlarged front view showing a part of the model shown in FIG. is there. A fluid mesh 101 shown in FIG. 12 includes a first fluid mesh region (first mesh region) 102 and a second fluid mesh region (second mesh region) 104. The fluid mesh 101 is formed around the tire model 60. In addition, this model is also provided with a wheel model 64 and a road surface model 66.

  The first fluid mesh region 102 is provided in the entire outer periphery of the tire model 60. The second fluid mesh region 104 is provided outside the first fluid mesh region 102, that is, in a region farther from the tire model 60 than the first fluid mesh region 102.

  Here, in the first fluid mesh region 102, the shape of the fluid mesh changes according to the shape of the tire model 60. Specifically, when the tire model 60 shown in FIG. 13-1 rotates by an angle narrower than the rotation angle corresponding to one pitch and reaches the position of the tire model 60 shown in FIG. The shape of the mesh changes from the first fluid mesh region 102 to the first fluid mesh region 102a in accordance with the shape conversion. That is, the first fluid mesh region 102a shown in FIG. 13-2 has a different shape from the first fluid mesh region 102 shown in FIG. 13-1.

  On the other hand, the second fluid mesh region 104 is a constant mesh regardless of the shape of the tire model. That is, the second mesh fluid region 104 shown in FIG. 13-2 has the same shape as the second mesh fluid region 104 shown in FIG.

  As described above, the fluid mesh is formed around the tire, the first fluid mesh region where the mesh structure changes according to the time change of the tire shape, and the outer periphery of the first fluid mesh region. By dividing into the second fluid mesh region that does not change, the region in which the mesh is re-formed can be reduced according to the shape of the tire. This eliminates the need to re-form the entire mesh when creating a model for fluid analysis, thereby reducing the burden of forming the mesh.

  Further, by fixing the mesh formation position with respect to the tire shape, that is, by rotating the first fluid mesh region 102 together with the tire, the relationship between the tire shape and the mesh can be made constant. In addition, by making the boundary between the first fluid mesh region and the second fluid mesh region constant regardless of the rotation of the first mesh, a model can be created without creating a mesh for each time series.

  At the time of analysis, a physical quantity is exchanged between the first fluid mesh area and the second fluid mesh area. Further, in the present embodiment, the boundary of the first fluid mesh region and the boundary of the second fluid mesh region are matched, but the boundary of the first fluid mesh region and the boundary of the second fluid mesh region are matched. It does not have to be. That is, the first fluid mesh region and the boundary of the second fluid mesh region may partially overlap.

  Moreover, in the said embodiment, although the fluid analysis of the space around a tire model, a wheel model, and a road surface model was performed, you may make it provide the model of another object in the circumference | surroundings. For example, a simulation model in which a vehicle on which tires are mounted or a part of the vehicle is modeled and a fluid mesh is created in the space may be created. Further, fluid analysis may be performed using the model.

  FIG. 14 is a perspective view showing a schematic configuration of a model around the tire. In this embodiment, the space model 210 is created using the object surface area obtained by using the object surface information of the objects (tire house, tire tester, etc.) existing around the tire model 60. That is, in addition to the tire boundary region and the contact surface region obtained from the surface information of the road surface model 66, one or more boundaries are further provided.

  The hemispherical region 220 described above is a virtual boundary, but when the tire is actually rolled, members such as a wheel house and a suspension arm of the vehicle body are provided in the vicinity of the tire. Further, when testing a tire, a test apparatus is arranged in the vicinity of the tire. A member, a test apparatus, or the like included in the vehicle body reflects or absorbs radiated sound generated by the tire. In addition, a member, a test apparatus, or the like that the vehicle body has affects the air flow around the tire. Therefore, a state closer to an actual event can be reproduced by adding the member, the test apparatus, or the like as a boundary of the space model 210.

  In the space model 210 shown in FIG. 14, a tire house model 224 is installed as an object in the tire peripheral space 222, and an object surface area as a boundary is provided on the surface of the tire house model 224. In this way, a simulation model is created by forming a fluid mesh in the space model 210 in which the tire house model 224 having boundary conditions set on the surface is provided.

  In this way, by arranging and modeling a member that the vehicle body has in the tire peripheral space 222 and that exists in the vicinity of the tire, and setting the object surface area on the surface, the flow of air around the tire Sound analysis can be performed under conditions closer to the actual state. A plurality of other models may be provided. For example, an axle model or a suspension arm model may be added in addition to the tire house model.

  In each of the above embodiments, a fluid analysis simulation is performed after creating a simulation model. However, the present invention is not limited to this, and the created simulation model may be used for another simulation. Further, the fluid analysis simulation may be performed by another device. Moreover, in the said embodiment, although the analysis result was evaluated, the evaluation by an evaluation part does not need to be performed.

  As described above, the simulation model creation method, the simulation method, the simulation model creation apparatus, and the simulation apparatus according to the present invention are suitable for use in the determination of tire performance using a computer.

DESCRIPTION OF SYMBOLS 1 Tire 50 Simulation apparatus 51 Input / output device 52 Processing part 52a 1st model creation part 52b Grounding analysis part 52c Analysis result conversion part 52d 2nd model creation part 52e Fluid analysis part 52f Evaluation part 53 Input means 54 Storage part 55 Display means 60 Tire model 62 Block 70 Corresponding point 102 First fluid mesh region 104 Second fluid mesh region

Claims (20)

A simulation model creation method for an area around a pneumatic tire,
A first model creating step for creating a tire model, a road surface model, and a wheel model that are non-uniform in the tire circumferential direction and setting boundary conditions;
A tire shape calculation step of performing a ground contact analysis of the tire model created in the first model forming step and calculating a tire shape in a grounded state;
A tire rolling shape creating step for creating a rolling tire shape in a time series by converting the tire shape calculated in the tire shape calculating step,
A simulation model creation method, comprising: a second model creation step for creating a model obtained by dividing a region including a region in contact with a tire shape at each time obtained in the tire rolling shape creation step into meshes.   The simulation model creation method according to claim 1, wherein the wheel model is a closed space on a surface of the tire model opposite to a contact surface with the road surface model. The tire shape calculating step further performs a ground contact analysis under the condition of rotating the tire model from the conditions formed in the first model creating step, and calculates a tire shape in a grounded state,
The simulation model according to claim 1 or 2, wherein the tire rolling shape creation step creates the rolling tire shape in time series by converting the calculated tire shape in contact with the ground. How to make. The tire model has a shape in which a pattern with a constant rotation angle width is repeatedly arranged,
The simulation model creation method according to claim 3, wherein the tire shape calculation step rotates the tire model at an angle smaller than a certain angle width of the pattern.   The simulation model creation method according to claim 1, wherein the tire model has a shape in which patterns having a constant rotation angle width are repeatedly arranged. In the tire rolling shape creation step, from the shape of the tire, the information of the coordinates of the corresponding points and the circumferential rotation angle at the same position in the pattern is extracted for each pattern,
The extracted circumferential rotation angle is converted to time, and the relationship between the coordinates of the corresponding point and time is detected for each corresponding point.
6. The simulation model creation method according to claim 4, wherein the relationship between the coordinates of the detected corresponding points and time is extracted for each time, and the rolling tire shape is calculated in time series.   The simulation model according to claim 6, wherein the tire rolling shape creation step extracts an arbitrary point on a rolling track connecting the corresponding points as the corresponding points from the shape of the tire. How to make.   In the second model creating step, the mesh is formed around the tire, and is formed on the outer periphery of the first mesh region, and a first mesh region in which the mesh structure changes according to the time change of the tire shape. The simulation model creating method according to claim 1, further comprising: a second mesh region in which the mesh structure does not change.   The second model creating step creates a model in which a region including a model obtained by combining at least a part of a model of a vehicle on which the tire is mounted on the tire model and the wheel model is divided into meshes. Item 9. The simulation model creation method according to any one of Items 1 to 8. A model obtained by dividing a region including a region in contact with a tire shape at each time obtained in the tire rolling shape creation step into a mesh by the simulation model creation method according to any one of claims 1 to 9. make,
A simulation method characterized by performing fluid analysis using a created model. A simulation model creation device for a region around a pneumatic tire,
A first model creation unit that creates tire models, road surface models, wheel models that are non-uniform in the tire circumferential direction, and sets boundary conditions;
Carrying out contact analysis of the tire model created by the first model creation unit, a tire shape calculation unit for calculating a tire shape in a grounded state,
A tire rolling shape creation unit that converts the tire shape calculated by the tire shape calculation unit to create a rolling tire shape in time series, and
A simulation model creation device, comprising: a second model creation unit that creates a model obtained by dividing a region including a region in contact with a tire shape at each time obtained by the tire rolling shape creation unit into a mesh.   12. The simulation model creating apparatus according to claim 11, wherein the wheel model is a space in which a surface of the tire model opposite to a contact surface with the road surface model is closed. The tire shape calculation unit further performs a ground contact analysis under the condition of rotating the tire model from the conditions formed by the first model creation unit, and calculates a tire shape in a grounded state,
The simulation model according to claim 11 or 12, wherein the tire rolling shape creation unit creates a tire shape in a rolling state in a time series by converting the calculated tire shape in a grounded state. Creation device. The tire model has a shape in which a pattern with a constant rotation angle width is repeatedly arranged,
The simulation model creation device according to claim 13, wherein the tire shape calculation unit rotates the tire model at an angle smaller than a certain angular width of the pattern.   The simulation model creation device according to claim 11 or 12, wherein the tire model has a shape in which patterns having a constant rotation angle width are repeatedly arranged. The tire rolling shape creation unit extracts, for each pattern, information on the coordinates of the corresponding points and the circumferential rotation angle at the same position in the pattern from the shape of the tire,
The extracted circumferential rotation angle is converted to time, and the relationship between the coordinates of the corresponding point and time is detected for each corresponding point.
The simulation model creating apparatus according to claim 14 or 15, wherein the relationship between the detected coordinates of corresponding points and time is extracted for each time, and the rolling tire shape is calculated in time series.   The simulation model according to claim 16, wherein the tire rolling shape creation unit extracts an arbitrary point on a rolling track connecting the corresponding points as the corresponding points from the shape of the tire. Creation device.   The second model creation unit is formed on the outer periphery of the first mesh region and the first mesh region in which the mesh is formed around the tire and the mesh structure changes according to the time change of the tire shape. The simulation model creation device according to claim 11, further comprising: a second mesh region in which the mesh structure does not change.   The second model creation unit creates a model in which a region including a model obtained by combining at least a part of a model of a vehicle on which the tire is mounted on the tire model and the wheel model is divided into meshes. Item 19. The simulation model creation device according to any one of Items 11 to 18. A model in which a region including a region in contact with a tire shape at each time obtained in the tire rolling shape creation step is divided into meshes by the simulation model creation device according to any one of claims 11 to 19. make,
A simulation apparatus that performs fluid analysis using a created model.