JP5585436B2 - Tire simulation method - Google Patents

Description

  The present invention relates to a technique for analyzing a tire using a computer.

  Predicting various performances of tires or physical quantities related thereto by numerical analysis such as a finite element method by analysis using a computer is useful for improving performance and improving development efficiency. Among these, the simulation of the dynamic response of the tire caused by the input generated between the tire and the road surface due to the road surface unevenness and the tire tread pattern is important for the transient response and the vibration / noise performance. For example, Patent Document 1 describes a method in which a road surface and a tread pattern are modeled in detail and a rolling calculation is directly performed on a non-flat road. Further, Patent Document 2 describes a method in which a convex portion of a road surface is modeled as an aggregate of single protrusions, vibrations are obtained when the single protrusion is overcome, and each protrusion of the aggregate of road surface model protrusions is overcome. A method for synthesizing the vibrations of the two and calculating the total vibration is described. Patent Document 3 discloses a step of subdividing a convex portion on the road surface as an aggregate of a plurality of protrusions, a step of calculating an effect that the tire receives from the protrusion when the convex portion gets over the tire, and a calculated operation. Is added for each protrusion, and a method for analyzing the tire acting force is described. Further, a method for analyzing tire vibration and tire noise using the calculated acting force is also described.

Japanese Patent Laid-Open No. 11-201874 JP 2000-241308 A JP 2010-230641 A

  However, in the method of Patent Document 1, it is necessary to execute a travel analysis with a large model and a large calculation load in order to ensure accuracy, and a travel analysis is necessary again to calculate responses at different speeds. Therefore, there is a problem that calculation time increases.

  In addition, as described in Patent Document 2 and Patent Document 3, in the method of subdividing the road surface shape and separately calculating the aggregate of a plurality of protrusions, the calculation load can be reduced, but the calculation accuracy is improved. There is a limit. Even with the method of subdividing the surface shape and calculating separately as a collection of multiple protrusions, the calculation accuracy can be improved by subdividing the elements of the calculation model, but if the elements are subdivided, the number of elements The amount of calculation increases with the increase.

  The present invention has been made in view of the above, and an object of the present invention is to improve calculation accuracy while suppressing an increase in calculation time in a tire simulation using a computer.

  Means for solving the above-described problem is a tire simulation method, in which a computer sets a node on an analysis target tire and divides the tire into a plurality of elements, and a road surface model of a road surface in contact with the tire, A model creation step of creating a response analysis model including: an action force calculation step in which the computer calculates an action force acting on the tire model from the road surface model when the tire model and the road surface model are in contact with each other And the computer restrains the node of the ground contact end where at least the acting force exists in the ground contact surface where the tire model and the road surface model come into contact, and applies the acting force acting on the node of the ground contact end outside the ground contact region. An action force adjustment step for adding to unconstrained nodes, and the computer adjusts the action force adjustment step. Using the adjustment results, characterized in that it comprises a, an analysis step of analyzing the dynamic response of the tire model.

  Here, the nodes that are not restrained outside the contact area are preferably nodes that already have an acting force on the outer side in the tire circumferential direction than the nodes at the contact end.

  In addition, it is preferable that the node that is not restrained outside the grounding region is a node adjacent to the contact point of the grounding end.

  In the acting force adjustment step, it is preferable that an acting force obtained by multiplying an acting force acting on the ground contact end by a coefficient is added to a node that is not restrained outside the ground contact region.

  The coefficient is preferably a constant of 0.3 or more and 0.9 or less.

  Means for solving the above-described problem is a tire simulation method, in which a computer sets a node on an analysis target tire and divides the tire into a plurality of elements, and a road surface model of a road surface in contact with the tire, A model creation step of creating a response analysis model including: an action force calculation step in which the computer calculates an action force acting on the tire model from the road surface model when the tire model and the road surface model are in contact with each other And an acting force adjusting step that restrains at least some of the nodes in the contact surface where the tire model and the road surface model are in contact with each other, and does not restrain the nodes of the contact end where the acting force exists, and The computer uses the adjustment result adjusted in the action force adjustment step to determine the dynamic response of the tire model. Characterized in that it comprises an analysis step of analyzing, the.

  Moreover, it is preferable that the said analysis process analyzes the vibration or the noise which generate | occur | produces with the dynamic response as the said dynamic response which generate | occur | produces with the action force which acts on a tire from the said road surface.

  The present invention can improve calculation accuracy while suppressing an increase in calculation time in a tire simulation using a computer.

FIG. 1 is a meridional sectional view of a tire. FIG. 2 is an explanatory diagram illustrating an analysis apparatus that executes the tire simulation method according to the present embodiment. FIG. 3 is a flowchart showing the procedure of the tire simulation method according to the present embodiment. FIG. 4 is a front view showing an example of a response analysis model. FIG. 5 is a partial cross-sectional view showing an example of a tire / wheel assembly model. FIG. 6 is an explanatory diagram illustrating an example of a method for adjusting the acting force. FIG. 7 is an explanatory diagram illustrating another example of the method for adjusting the acting force. FIG. 8 is an explanatory diagram illustrating another example of the method for adjusting the acting force. FIG. 9 is a perspective view illustrating an example of a response analysis model. FIG. 10 is a perspective view illustrating an example of a road surface model of the response analysis model. FIG. 11 is an explanatory diagram schematically showing a relationship between a road surface model and a tire model. FIG. 12 is a graph illustrating an example of the simulation result of the comparative example. FIG. 13 is a graph showing an example of the simulation result of this example. FIG. 14 is a graph showing the relationship between the position of the tire surface and vibration.

  DESCRIPTION OF EMBODIMENTS Hereinafter, modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content described in the following embodiment. 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. Furthermore, the constituent elements described in the following embodiments can be appropriately combined.

  FIG. 1 is a meridional sectional view of a tire. The tire 1 is an annular structure that rotates about a rotation axis (Y axis), and a meridional section having a similar shape is developed around the rotation axis in the circumferential direction. As shown in FIG. 1, a carcass 2, a belt 3, a belt cover 4, and a bead core 5 appear on the meridional section of the tire 1. 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. A layer of a reinforcing cord made of a cord material such as a metal fiber or an 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 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 serves as a protective layer for the belt 3 and serves 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. A groove 7 is formed on the tread surface G side of the cap tread 6. This improves drainage during rainy weather. 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. 2 is an explanatory diagram illustrating an analysis apparatus 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 analysis device 50 shown in FIG. The analysis device 50 is a computer and includes a processing unit 52 and a storage unit 54 as shown in FIG. In addition, an input / output device 51 is electrically connected to the analysis device 50. The input / output device 51 has input means 53. This input means 53 inputs physical property values of rubber constituting the tire, physical property values of reinforcing cords, boundary conditions used for grounding analysis, rolling analysis, vibration analysis, noise analysis, and the like to the processing unit 52 and the storage unit 54. To do.

  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 tire analysis (ground contact analysis, rolling analysis, vibration analysis, etc.) and a tire simulation method according to the present embodiment. 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 volatile memory such as a RAM (Random Access Memory). The memory can be configured by a combination of these, or a combination thereof.

  The computer program may be capable of realizing the ground contact analysis, the rolling analysis, or the tire simulation method according to the present embodiment, in combination with a computer program already recorded in the computer system. The “computer system” here includes hardware such as an OS (Operating System) and peripheral devices.

  The processing unit 52 includes a model creation unit 52a, an action force calculation unit 52b, an action force adjustment unit 52c, and an analysis unit 52d. The model creation unit 52 a includes a tire / wheel assembly model and a road surface model, creates a response analysis model for analysis, and stores the response analysis model in the storage unit 54. Here, the tire / wheel assembly model is created by dividing the tire / wheel assembly to be analyzed into a plurality of elements having a plurality of nodes. Here, the tire / wheel assembly model is obtained by attaching a wheel to a tire, and is created by fitting the tire model and the wheel model. The tire / wheel assembly model has a plurality of elements in which the inner region surrounded by the tire model and the rim surface of the wheel model, that is, the region filled with air when the tire is inflated also has a plurality of nodes. It may be divided into models.

  The acting force calculation unit 52b calculates a contact state between the tire model of the tire / wheel assembly model and the road surface model using the response analysis model created by the model creating unit 52a, and acts on the tire model from the road surface model. Is calculated. The acting force calculation unit 52b calculates the acting force for each node of the tire model. The acting force calculation unit 52 b stores the calculated acting force in the storage unit 54. Note that the acting force calculation unit 52b calculates the acting force acting on the tire model in each of a plurality of states in which the stress analysis model dynamically changes, for example, models corresponding to each time changing in time series. That is, the acting force calculation unit 52b obtains a history of force (acting force) acting on the response analysis model ground contact region using the analysis model of the tire to be analyzed, the response analysis model, and the like, and stores the predetermined region in the storage unit 54. To store.

  The acting force adjustment unit 52c adjusts the acting force calculated by the acting force calculation unit 52b. Specifically, among the nodes of the tire model, the acting force of the node at the end of the contact area in contact with the road surface model is adjusted. The adjustment method will be described later.

  The analysis unit 52d reads out the response analysis model created by the model creation unit 52a and the acting force acting on the tire / wheel assembly model adjusted by the acting force adjustment unit 52c from the storage unit 54, under a predetermined condition. Run the analysis with. The analysis unit 52d can perform analysis of various dynamic responses using the acting force. The analysis unit 52d executes, for example, vibration analysis of a tire / wheel assembly model and noise analysis generated during traveling.

  In the vibration analysis, the analysis unit 52d reads the set forced displacement input and the acting force input to each contact point of the tire model from the storage unit 54, and the response analysis corresponding to the contact area with the road surface of the tire. This is given to the model area (response analysis model ground contact area). More specifically, the analysis unit 52d inputs a corresponding displacement history as a forced displacement to a plurality of nodes existing in the response analysis model ground contact region, and inputs an action force history corresponding to the displacement history. . And the analysis part 52d calculates | requires the dynamic response of the said response analysis model by performing a vibration analysis with respect to the said response analysis model. Thereafter, the analysis unit 52 d stores the obtained dynamic response of the response analysis model in a predetermined area of the storage unit 54. The input of the action force may be, for example, the action force history itself or a value obtained by converting the action force history into a frequency. The input of the forced displacement may be, for example, the displacement history itself, or a value obtained by converting the displacement history into a frequency.

  The processing unit 52 includes, for example, a memory and a CPU (Central Processing Unit). At the time of analysis, based on the analysis model created by the model creation unit 52a, input data, and the like, the processing unit 52 reads the program into a memory incorporated in the processing unit 52 and performs computation. 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.

  The display means 55 is a display device such as a liquid crystal display device. The storage unit 54 may be in another device (for example, a database server). For example, the analysis 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 tire simulation method according to this embodiment will be described. The tire simulation method according to this embodiment can be realized by the analysis device 50 described above.

  FIG. 3 is a flowchart showing the procedure of the tire simulation method according to the present embodiment. FIG. 4 is a front view showing an example of a response analysis model. FIG. 5 is a partial cross-sectional view showing an example of a tire / wheel assembly model. The present embodiment will be described as a case where a tire vibration analysis is executed among dynamic response analyses. In executing the tire simulation method according to the present embodiment, in step S101, the model creation unit 52a of the analysis apparatus 50 shown in FIG. 2 creates a model (analysis model) of a tire to be analyzed (model creation step). ). The analysis model is a model used by a computer to perform vibration analysis or ground contact analysis using a numerical analysis method such as a finite element method (FEM) or a finite difference method (FDM). It can be analyzed with a computer. The analysis model includes a mathematical model and a mathematical discretization model. The analysis model created in step S101 is the response analysis model 10 shown in FIGS. The response analysis model 10 is subjected to vibration analysis in step S104 described later to obtain a dynamic response or the like. In this embodiment, since the finite element method is used for the analysis of the response analysis model 10, the response analysis model 10 is created based on the finite element method. The response analysis model 10 includes a tire / wheel assembly model 12 and a road surface model 14 on which the tire / wheel assembly model 12 is grounded. The tire / wheel assembly model 12 includes a tire model 16, a wheel model 18, and a space model 20 surrounded by the tire model 16 and the wheel model 18.

  An analysis method applicable to the analysis according to the present embodiment is not limited to the finite element method, and an analysis method such as a finite difference method or a boundary element method (BEM) can also 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. The finite element method is an analysis method suitable for structural analysis, and is particularly suitable for a structure such as a tire.

  For example, the model creation unit 52a creates the tire model 16 from CAD (Computer Aided Design) data of the tire to be analyzed. When the response analysis model 10 is created based on the finite element method, the model creation unit 52a divides the tire specified by the CAD data into a plurality of finite elements, as shown in FIGS. A tire model 16 as shown is created. Similarly, the model creation unit 52a creates the wheel model 18 from the analysis target wheel data. Furthermore, the model creation unit 52a performs contact calculation between the created tire model 16 and the wheel model 18, and calculates the deformation of the tire model 16 when the tire model 16 is fitted into the wheel model 18, thereby the tire model 16 Into the wheel model 18. The model creation unit 52a creates the space model 20 by dividing the space between the tire model 16 and the wheel model 18 into a plurality of finite elements. In addition, the model creation unit 52a creates the road surface model 14 from the data on the road surface with which the tire contacts. The road surface model 14 of the present embodiment is provided with a convex shape at least partially. In the present embodiment, the response analysis model 10 is an analysis model having a three-dimensional shape as shown in FIGS.

  The elements included in the response analysis model 10 include, for example, a solid element such as a tetrahedral solid element, a pentahedral solid element, and a hexahedral solid element, a shell element such as a triangular shell element, a quadrangle shell element, a surface element, and the like in a three-dimensional analysis model. It is desirable to use an element that can be handled by a computer. In the process of analysis, the elements divided in this way are identified one by one using three-dimensional coordinates and cylindrical coordinates in a three-dimensional analysis model. When the response analysis model 10 is created, the processing unit 52 executes the process of step S102.

  In step S102, the acting force calculator 52b of the analyzing apparatus 50 shown in FIG. 2 calculates the acting force. Specifically, the acting force calculation unit 52b is configured to reduce the force (acting force) acting on the tire model 16 (or the tire / wheel assembly model 12) from the road surface model 14 of the response analysis model 10 illustrated in FIGS. 4 and 5. Calculate the history. That is, the acting force calculation unit 52 b sets a history of forces acting on the tire model 16 from the road surface model 14 using the response analysis model 10 in which the tire model 16 is in contact with the road surface model 14. Store in a predetermined area.

Here, FIG. 6 is an explanatory diagram showing an example of a method for adjusting the acting force. FIG. 6 is an explanatory diagram showing an enlarged view of the periphery of the end portion of the contact area between the tire model 16 and the road surface model 14. As shown in FIG. 6, the road surface model 14 and the tire model 16 of the response analysis model 10 are divided into a ground area and a non-ground area by a ground boundary. The tire model 16 of the response analysis model 10 shown in FIG. 6 has a plurality of nodes 30a, 30b, 30c, 30d, 30e, and 30f, and is arranged in a line. Among the plurality of nodes, the nodes 30a, 30b, 30c, and 30d are inside the ground boundary, and the plurality of nodes 30e and 30f are outside the ground boundary. Therefore, the node 30d is a ground end node adjacent to the ground boundary that is closest to the ground boundary. In FIG. 6, only the nodes near the ground contact end region of the tire model 16 are shown, but the tire model 16 has discrete nodes in the entire region as described above. In step S102, the action force calculation unit 52b in the region illustrated in FIG. 6 calculates the action force history for each of the nodes 30a, 30b, 30c, 30d, 30e, and 30f of the tire model 16. In FIG. 6, an acting force F ₁ that is a force acting on the node 30c, an acting force F ₂ that is a force acting on the node 30d, an acting force F ₃ that is a force acting on the node 30e, and a node 30f. acting force F ₄ is the force acting is calculated. In the present embodiment, the plurality of nodes 30a, 30b, 30c, and 30d in the ground contact region are constrained by the road surface model 14 in the case of a dynamic response (vibration analysis).

  Next, the history of acting force will be described. In general, when a tire rolls on a road surface, a force caused by a tread pattern or a road surface unevenness (including protrusions) of the tire or a force caused by a vehicle such as steering is applied to a region including a ground contact region of the tire. Works. When the analysis device 50 obtains a dynamic response when the tire rolls on the road surface using the response analysis model 10, some form of force acting on the region including the contact area of the tire due to contact between the tire and the road surface is obtained. Therefore, it is necessary to give to the tire model 16 (tire / wheel assembly model 12). For this reason, in step S102, a history of forces (acting forces) acting on the tire model 16 from the road surface model 14 is set.

  The acting force calculation unit 52b can calculate the acting force acting on each node of the tire model 16 by various methods. For example, as described in Japanese Patent Application Laid-Open No. 2010-230461, the acting force calculation unit 52b calculates the area of the overlapping region between the uneven shape of the road surface model 14 and the tire model 16, and based on the overlapping amount of the areas. Thus, the acting force may be calculated. Specifically, the acting force calculator 52b divides the convex portion of the road surface model 14 into a plurality of protrusions, and the area between the nodes of the tire model 16 and the protrusions of the road surface model 14 overlaps. Based on the above, the acting force is calculated. Note that the analysis device 50 stores the relationship between the area where the tire model 16 area and the projection of the road surface model 14 that are calculated based on calculations and experiments in advance and the acting force are stored in the storage unit 54, thereby overlapping. The acting force can be calculated based on the area. Thereafter, the calculated acting force is assigned to two nodes adjacent to the overlap position based on the information on the overlap position between the tire model 16 and the protrusion. In addition, the acting force calculation unit 52b also calculates a force (acting force) at which a node in a region where the road surface model 14 does not have a convex portion acts. In addition, as the acting force of the node in the region where the road surface model 14 does not have a convex portion, there are an acting force caused by contact between the tire model 16 and the road surface and an acting force caused by the deformation of the tire model 16. The acting force calculation unit 52b may calculate the acting force on all the nodes of the tire model 16, but may calculate the acting force of a certain range of nodes including the contact area with the road surface model 14. Good. Thus, the amount of calculation can be reduced by setting the nodes for calculating the acting force to be a constant region. When the acting force is calculated by the acting force calculation unit 52b, the processing unit 52 executes the process of step S103.

In step S103, the acting force adjustment unit 52c of the analysis device 50 shown in FIG. 2 adjusts the acting force. Specifically, the acting force adjustment unit 52c adjusts the acting force of each node calculated by the acting force calculation unit 52b so that the dynamic response calculation accuracy can be further improved. Specifically, the action force adjustment portion 52c, of the acting force _{F 1,} F _2, F 3, _{F 4} shown in the upper side in FIG. 6, acting force acting force _{F 2} of the node 30d is a ground terminal node F ₂ ′ and added to the acting force of the node 30e in the non-contact area as shown in the lower side of FIG. That is, it is assumed that the acting force F ₃ + the acting force F ₂ ′ is applied to the node 30d. The acting force adjusting unit 52c performs the same processing, and applies the acting force of the grounding end node included in the acting force history calculated in step S102 to a node in the adjacent non-contact area, more specifically, the grounding end node. Is added to a node that is adjacent to and in the non-contact area. For example, when calculating the history of acting force in time series, the acting force of the ground contact node at each time is added to the node of the adjacent non-contact area. When the acting force is adjusted by the acting force adjusting unit 52c, the processing unit 52 executes the process of step S104.

  In step S104, the analysis unit 52d of the analysis device 50 illustrated in FIG. 2 obtains a dynamic response. That is, the dynamic response analysis (vibration analysis in this embodiment) of the response analysis model 10 is executed based on the history of the acting force adjusted in step S103 and other various conditions. In addition, as the analysis performed by the analysis unit 52d, various analyzes can be used in which the analysis is performed using the acting force acting on each node of the tire model 16 from the road surface model 14. The dynamic response analysis includes a transient response analysis based on a time calendar and a frequency response analysis on the frequency axis. The analysis device 50 displays the analysis result on the display means 55 when the analysis of the dynamic response is executed.

As described above, the analysis device 50 can perform the analysis of the dynamic response with higher accuracy by adjusting the action force by the action force adjusting unit 52c. Specifically, of the acting force _{F 1, F 2, F 3} , F 4 calculated as shown in the upper side in FIG. 6, the acting force _F 1, _{F 2} in the ground area, the nodes 30c, 30d are restrained Is done. For this reason, if a dynamic response is executed with the applied forces F ₁ , F ₂ , F ₃ , and F _{4 applied} to the nodes as they are as shown in the upper side of FIG. 6, the dynamic response is analyzed. The acting forces F ₁ and F ₂ are invalid and are not reflected in the analysis of the dynamic response. On the other hand, as shown in the lower side of FIG. 6, the analysis device 50 of the present embodiment applies the acting force F2 of the grounding end node to the node 30d adjacent to the grounding end contact by the acting force adjusting unit 52c. For this reason, the analysis apparatus according to the present embodiment can perform vibration analysis in a state where the acting force F ₂ ′ + the acting force F ₃ is applied to the node 30d, and takes into account the acting force applied to the ground contact node. Dynamic response analysis can be performed. In addition, since it is possible to analyze the dynamic response in consideration of the acting force applied to the contact end node, it is possible to analyze the vicinity of the contact end without making each element of the tire model 16 of the response analysis model 10 to be analyzed fine. It can be analyzed using the applied force. That is, by making each element of the tire model 16 finer, the acting force in the vicinity of the ground contact end can be calculated with high accuracy. However, by using the simulation method of the present embodiment, each element of the tire model 16 is constant. Even when the size is large, an analysis result equivalent to the case where each element of the tire model 16 is calculated in detail can be obtained. Thereby, it is possible to improve the analysis accuracy while reducing the calculation amount.

  Further, by adding the acting force of the grounding end node to the other nodes, the acting force of the grounding end node can be set as the analysis target force while maintaining the restrained state of the grounding end node. As a result, the dynamic response characteristics (vibration transmission characteristics) due to the tire ground restraint state are not changed (that is, the dynamic response characteristics in the vicinity of the ground end are not changed by changing the boundary conditions), and the ground contact is made. The acting force of the end node can be used as the force to be analyzed, and the accuracy of the analysis can be increased.

  It should be noted that the node to which the action force of the grounding end contact is added may be any node that is not constrained outside the grounding region, but is preferably a node around the grounding region, and from the grounding center in the circumferential direction. It is preferable that the node is within a range of ± 30 ° (−30 ° to 30 °). Thus, the dynamic response can be analyzed with higher accuracy by setting the addition destination node as a node around the ground contact area. For example, if the positional relationship between the grounding end node and the addition destination node satisfies the above relationship, the angular difference between the grounding end node and the addition destination node increases, and the radial input acts as the circumferential input. Can be suppressed, and the accuracy can be improved.

  Moreover, it is preferable that the node to which the action force of the ground contact is added is a node where the action force already exists on the outer side in the tire circumferential direction than the ground contact. By making the addition destination node outside in the tire circumferential direction, the direction in which the input added in the tire circumferential direction acts on the tire can be made the same. That is, the direction with respect to the center of the ground contact region can be the same, and the direction of the acting force with respect to the tire center can be made the same. In addition, by making the node of the addition destination a node that already has an acting force, it is possible to input only from within the range where the road surface protrusion and the tire interfere with each other. Analysis can be performed.

  The node to which the addition is made is a node that is adjacent to the grounding end node and outside the grounding end node in the tire circumferential direction, as in this embodiment, in the non-grounding region (in the direction away from the grounding center). Is more preferable. By making the node of the addition destination a node that satisfies the above conditions, the above effects can be obtained more suitably in terms of the similarity of the vibration transfer characteristics (dynamic response characteristics), and the accuracy can be increased. Can do. In addition, it is preferable that the node of the addition destination is a node whose position in the width direction is the same as that of the ground contact node. By making the position in the width direction of the addition destination node and the grounding end node the same position, the excitation component (dynamic response characteristic) in the left-right direction (around the front-rear axis) can be made equal. In addition, since the above effect can be obtained more effectively, it is preferable to set the position in the width direction of the addition destination node and the grounding end node to the same position, but the same applies to the node having the closest position in the width direction. The effect of can be obtained.

  In the above-described embodiment, the acting force of the grounding end node is added to the addition destination node as it is, but a value obtained by multiplying the acting force of the grounding end node by a coefficient H may be added to the addition destination node as an acting force. preferable. That is, it is preferable to add F × H obtained by multiplying the acting force F by the coefficient H to the addition destination node.

Hereinafter, a description will be given with reference to FIG. Here, FIG. 7 is an explanatory diagram showing another example of the method for adjusting the acting force. The road surface model 14 and the tire model 16 of the response analysis model 10 shown in FIG. 7 have basically the same configuration as the response analysis model 10 shown in FIG. The tire model 16 of the response analysis model 10 shown in FIG. 7 has a plurality of nodes 30a, 30b, 30c, 30d, 30e, and 30f, and is arranged in a line. Among the plurality of nodes, the nodes 30a, 30b, 30c, and 30d are inside the ground boundary, and the plurality of nodes 30e and 30f are outside the ground boundary.
In the example shown in FIG. 7, the force acting on the node 30c is calculated as the acting force Fa, the force acting on the node 30d is calculated as the acting force Fb, and the force acting on the node 30e is calculated as the acting force Fc. The force acting on the node 30f is calculated as the acting force Fd.

  In this state, the acting force adjusting unit 52c calculates a value obtained by multiplying the acting force Fb of the node 30d, which is the ground contact node, by the coefficient H among the acting forces Fa, Fb, Fc, and Fd shown in the upper side of FIG. ′ (Fb ′ = Fb × H) is added to the acting force of the node 30e in the non-contact area as shown in the lower side of FIG. That is, it is assumed that the acting force Fc + the acting force Fb ′ is applied to the node 30d.

  In this way, the dynamic response characteristics (difference in the level of vibration transfer characteristics) that change depending on the position and conditions can be obtained by multiplying the acting force of the grounding end node by the coefficient H and adding it to the destination node. The applied force can be added. Thereby, the precision of the analysis of a dynamic response can be improved. Note that various values can be used as the coefficient H, and a function of frequency or a complex number can also be used. The coefficient H is preferably set to a value less than 1. Since the level of the dynamic response characteristic (the level of the transfer characteristic) becomes smaller as it is closer to the grounding end, the coefficient H is set to a value in accordance with the change in the level of the dynamic response characteristic by making the coefficient H less than 1. It can be.

  The coefficient H is preferably a constant, and the value of the constant is more preferably from 0.3 to 0.9. Since dynamic response characteristics such as vibration and noise have similar transfer characteristics, analysis can be performed with high accuracy even as the coefficient H. Moreover, the calculation amount at the time of an analysis can be reduced by making the coefficient H into a constant. In addition, by setting the value of the constant to be 0.3 or more and 0.9 or less, the component of the acting force of the ground contact node can be appropriately added when analyzing the dynamic response.

(Modification)
Here, in the above-described embodiment, the acting force at the end of the ground contact is added to other nodes, but the present invention is not limited to this. The analysis device 50 may be in a state in which the ground contact node is not restrained by the acting force adjusting unit 50c. In this way, even when the grounding end portion is not restrained, the dynamic response can be analyzed in consideration of the acting force of the grounding end node.

Hereinafter, a description will be given with reference to FIG. Here, FIG. 8 is an explanatory diagram showing another example of the method for adjusting the acting force. The road surface model 14 and the tire model 16 of the response analysis model 10 shown in FIG. 8 have basically the same configuration as the response analysis model 10 shown in FIG. The tire model 16 of the response analysis model 10 shown in FIG. 8 has a plurality of nodes 30a, 30b, 30c, 30d, 30e, and 30f, and is arranged in a line. Among the plurality of nodes, the nodes 30a, 30b, 30c, and 30d are inside the ground boundary, and the plurality of nodes 30e and 30f are outside the ground boundary.
Further, in the example shown in FIG. 8, the force acting on the node 30c is calculated and the working force F _1, the force acting on the node 30d is calculated as applied force F _2, the force acting on the node 30e is acting force F ₃ It is calculated as the force acting on the node 30f is calculated action force F _4.

In this state, the acting force adjustment unit 52c does not constrain the node 30d, which is a grounding end node, as shown on the lower side in FIG. That is, the restraint state of the node 30d in contact with the road surface model 14 is released. In this way, by a state of not constraining the contacts 30d, the action force F ₂ is effective when the analysis of the dynamic response. In this case as well, the nodes in the grounding region other than the grounding end nodes are in a restrained state when the dynamic response is analyzed.

  The analysis device 50 can also set the acting force of the grounding end node as an analysis target by releasing the restraint of the grounding end node. As described above, the analysis can be performed with higher accuracy by analyzing the dynamic response using the acting force of the contact end node as an analysis target. In addition, as described above, since the analysis can be executed with high accuracy even if the number of elements of the tire model is reduced, the analysis accuracy can be improved while reducing the calculation load.

  Here, in the above embodiment, since the calculation load can be reduced, all the nodes of the grounding region (except for the grounding end node in the example shown in FIG. 8) are constrained, but the present invention is not limited to this. If the nodes in the grounding area are not constrained at all, the vibration characteristics will change due to the difference in boundary conditions and the analysis accuracy will deteriorate, but at least some of the nodes in the grounding area will be constrained. Just keep it. In this case, the acting force may be invalidated by not applying the acting force to the nodes in the ground contact area that is not restrained. It should be noted that the acting force acting on the nodes in the ground contact area other than the ground contact has little influence on the overall working force (that is, analysis of dynamic response) due to the tire envelope characteristics (characteristics that wrap the protrusions). Therefore, even if the acting force is invalidated by restraining the nodes in the ground contact area or not applying the acting force, the analysis can be executed with high accuracy.

  Further, the dynamic response analysis by the analysis unit 52d may be performed on the time axis, but may be performed by Fourier transform on the frequency axis. The analysis of the dynamic response is preferably performed by linear perturbation analysis. By executing the linear perturbation analysis in this way, the calculation efficiency can be improved as compared with the nonlinear calculation.

  In addition, since the analysis apparatus and simulation method of the present embodiment can more accurately consider the distribution of the acting force, the dynamic response analysis of the tire when overcoming a small unevenness on the road surface as in road noise analysis. The accuracy can be improved more effectively. In particular, a more remarkable improvement effect can be obtained in a frequency band of 150 Hz or higher when frequency response analysis is performed.

  Further, as the response analysis model 10, it is preferable to use a tire / wheel assembly model in which the wheel and the air inside are also modeled, as in the present embodiment. In the frequency region of 150 Hz or higher where the improvement effect is large, there is an influence of wheel vibration characteristics and cavity resonance. Therefore, the accuracy of analysis can be further improved by using the tire / wheel assembly model. In addition, since the said effect can be acquired, although it is preferable to use a tire and wheel assembly model for the response analysis model 10, you may comprise a response analysis model only with a road surface model and a tire model. Even when the dynamic response analysis with the road surface model is performed using only the tire model, the above effect can be obtained by executing the analysis in consideration of the acting force of the ground contact node as in the above embodiment.

  Further, it is preferable to consider rolling effects such as centrifugal force and Coriolis force in the analysis of the dynamic response. Thereby, analysis accuracy can be improved more.

  Further, in the division (division into elements) in the circumferential direction of the tire model, it is preferable that the vicinity of the grounding end (including the non-grounding area near the grounding end) be finer than the non-grounding area of the outer periphery. Moreover, it is preferable to divide the vicinity of the ground contact end of the tire model in such a size that the angle in the circumferential direction of each element is 3 ° or less. Thus, the analysis accuracy can be improved by dividing the circumferential angle of each element by 3 ° or less. Moreover, it is preferable to divide the angle in the circumferential direction of the element by 0.5 ° or more near the ground contact end of the tire model. Thus, the calculation load can be reduced by dividing the circumferential angle of each element by 0.5 ° or more. That is, it can be suppressed that the elements constituting the model become too fine, the model size (number of elements) increases, and the calculation efficiency deteriorates.

(Evaluation example)
Here, FIG. 9 to FIG. 11 are response analysis models used in this embodiment. FIG. 9 is a perspective view illustrating an example of a response analysis model, FIG. 10 is a perspective view illustrating an example of a road surface model of the response analysis model, and FIG. 11 schematically illustrates a relationship between the road surface model and the tire model. It is explanatory drawing shown in. In the present embodiment, the tire simulation method according to the present embodiment is executed using the response analysis model 10 shown in FIGS. Here, as the tire / wheel assembly model 12, a tire / wheel assembly in which a steel wheel of 14 × 5 1/2 is incorporated in a tire of size 175 / 70R14 and an air pressure of 210 kPa and a load of 3.9 kN is applied is modeled. What was made into was used. Each element of the tire / wheel assembly model was divided as shown in FIGS. Next, a drum-type model was used as the road surface model 14 in accordance with a running experiment.

  When the tire / wheel assembly model 12 travels on the road surface model 14 at a speed of 40 km / h using the response analysis model 10, the tire / wheel assembly model 12 is hemispherical with a radius of 5 mm provided on the road surface 60. The frequency spectrum of the vertical axial force when overriding the convex part 62 was analyzed. The acting force acting on the tire / wheel assembly model 12 from the road surface model 14 was calculated by a calculation method disclosed in Japanese Patent Application Laid-Open No. 2010-230641. In this embodiment, the coefficient H is set to 0.7. For comparison, the frequency spectrum of the vertical axial force calculated in the same manner was also calculated except that the acting force of the ground contact node was not applied to other nodes. Furthermore, a running experiment was performed under the same conditions, and the frequency spectrum of the vertical axial force was also measured.

  The calculation results are shown in FIGS. Here, FIG. 12 is a graph showing an example of the simulation result of the comparative example. FIG. 13 is a graph showing an example of the simulation result of this example. In both FIG. 12 and FIG. 13, the horizontal axis is the frequency [Hz] and the vertical axis is the vertical axial force [dB]. In this evaluation example, the vertical axial force is 1 N is 0 dB. FIG. 12 shows the calculation result of the comparative example (model in FIG. 12) and the measurement result of the experiment, and FIG. 13 shows the calculation result of the present example (model in FIG. 13) and the measurement result of the experiment. . As shown in FIGS. 12 and 13, the result of the present example was closer to the experimental result than the comparative example. In particular, a calculation result (simulation result) closer to the experimental result could be obtained in the frequency range of 150 Hz or higher. From the above, it can be seen that the dynamic response can be analyzed with higher accuracy by using the analysis device 50 and the simulation method of the present embodiment.

Next, the vibration transmission characteristics up to the wheel center were measured by changing the excitation position in the circumferential direction of the tire. In this measurement, the tire shaft is movable, each position of the tread is hit with an impulse hammer to detect the excitation force, and the vibration (acceleration) of the wheel center (tire axis) at that time is detected to transmit vibration. Characteristics were measured. Specifically, the center of the ground contact area of the tire is 0 °, and the tread is vibrated in the vertical direction at positions of 24 °, 27 °, and 30 ° in the circumferential direction, and the vertical acceleration at the wheel center is input. We measured and compared the transfer characteristics (inertance) with the response. The measurement results are shown in FIG. Here, the horizontal axis represents the frequency [Hz], and the vertical axis represents the inertance [dB] in which 0 dB is 1 (m / s ² ) / N. As shown in FIG. 14, the transfer characteristics with circumferential angles of 24 °, 27 °, and 30 ° have different levels (the levels are lower as they are closer to the grounding end as indicated by arrow 102), but the waveform is Similar shape. From the above, at least at positions where the circumferential angle is 24 °, 27 °, and 30 °, that is, in the vicinity of the ground contact end of the tire, the transfer characteristics are similar depending on the circumferential position. Therefore, even if the coefficient H is a constant, the analysis can be performed with high accuracy.

  As described above, the tire simulation method, the tire analysis computer program, and the analysis apparatus according to the present invention are useful for tire analysis using a computer, and increase the calculation accuracy while suppressing an increase in calculation time. Suitable for improvement.

DESCRIPTION OF SYMBOLS 1 Tire 10 Response analysis model 12 Tire / wheel assembly model 14 Road surface model 16 Tire model 18 Wheel model 20 Spatial model 30a, 30b, 30c, 30b, 30e, 30f Node 50 Analysis device 51 Input / output device 52 Processing part 52a Model creation Part 52b action force calculation part 52c action force adjustment part 52d analysis part 54 storage part 60 road surface 62 convex part 102 arrow

Claims (7)

A model creation step in which a computer creates a response analysis model including a tire model in which nodes are set in an analysis target tire and divided into a plurality of elements and a road surface model of a road surface in contact with the tire;
An acting force calculating step of calculating an acting force acting on the tire model from the road surface model when the computer contacts the tire model and the road surface model;
The computer restrains the node of the ground contact edge where at least the acting force exists in the ground contact surface where the tire model and the road surface model contact, and restrains the acting force acting on the node of the ground contact end outside the ground contact area. A force adjustment step to add to the nodes that are not,
An analysis step in which the computer analyzes the dynamic response of the tire model using the adjustment result adjusted in the acting force adjustment step;
A tire simulation method comprising:   2. The tire simulation method according to claim 1, wherein the nodes that are not restrained outside the contact area are nodes that already have an acting force on the outer side in the tire circumferential direction than the nodes at the contact end.   The tire simulation method according to claim 2, wherein the nodes that are not restrained outside the ground contact area are nodes adjacent to the contact point of the ground contact end.   4. The acting force adjusting step according to claim 1, wherein the acting force obtained by multiplying the acting force acting on the ground contact end by a coefficient is added to a node that is not constrained outside the ground contact region. The tire simulation method according to one item.   The tire simulation method according to claim 4, wherein the coefficient is a constant not less than 0.3 and not more than 0.9. A model creation step in which a computer creates a response analysis model including a tire model in which nodes are set in an analysis target tire and divided into a plurality of elements and a road surface model of a road surface in contact with the tire;
An acting force calculating step of calculating an acting force acting on the tire model from the road surface model when the computer contacts the tire model and the road surface model;
An action force adjusting step in which the computer restrains at least some of the nodes in the contact surface where the tire model and the road surface model are in contact with each other, and does not restrict the nodes of the contact end where the action force exists;
An analysis step in which the computer analyzes the dynamic response of the tire model using the adjustment result adjusted in the acting force adjustment step;
A tire simulation method comprising:   7. The analysis according to claim 1, wherein the analysis step analyzes, as the dynamic response, tire vibration or noise generated by an acting force acting on the tire from the road surface. 8. Tire simulation method.

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