JP4466119B2 - Operation method of simulation apparatus - Google Patents

Description

The present invention relates to an operation method of a simulation apparatus for creating a tire model composed of a plurality of members and simulating tire characteristics.

  Various methods for predicting tire characteristics using a finite element model divided into a plurality of finite elements and designing a tire based on the tire characteristics have been proposed. Each of these methods creates a finite element model of the tire using a computer, reproduces the stationary state or rolling state of the tire using the created tire model, and the characteristic physical quantity acting on the model generated at this time Is used to evaluate the tire characteristics. By using this tire characteristic, a tire having excellent tire characteristics can be designed without actually manufacturing the tire.

As a method of creating a tire model used for such a tire simulation, a method of creating a finite element model of a tire with a tread pattern that can analyze the influence of a tread pattern has been proposed (for example, see Patent Document 1). .
In this Patent Document 1, a tire body part model and a tread pattern part model in a tire finite element model are created separately, and then a finite element model of a tire is created by combining the models with each other. . At that time, by making various changes to the tread pattern part model with respect to the tire body part model, the tread pattern is taken into account and the tire characteristics with high accuracy applicable to actual development can be obtained. It is said that simulation can be performed efficiently.
Japanese Patent No. 3314082

  By the way, an actual tire is manufactured by vulcanizing a green tire obtained by wrapping a tire constituent member cut to a predetermined length in a cylindrical shape into a predetermined shape. When a green tire is molded, the tire constituent members are not necessarily uniformly wound with the same cross-sectional shape, and the winding position also varies slightly in the tire circumferential direction. For this reason, it is known that in an actual tire, a subtle vibration component (uniformity component) is generated with the rolling of the tire, and this vibration component affects the tire characteristics.

  However, in patent document 1, since the tire body part in the finite element model of the tire is developed in the same cross-sectional shape with respect to the circumferential direction of the tire, in the tire circumferential direction of the model of each tire constituent member constituting the tire body part Fluctuations are not taken into account. For this reason, it was not possible to simulate tire characteristics including variations in the shape and arrangement position of the tire constituent members.

The present invention has been made in view of such problems, and an object thereof is to provide an operation method of a simulation apparatus capable of simulating tire characteristics including changes in cross-sectional shape and arrangement position in the tire circumferential direction. To do.

In order to achieve the above object, the present invention is an operation method of a simulation apparatus for simulating tire characteristics, comprising an input device, an output device, and a CPU , wherein the CPU constitutes a tire. A step of creating a cross-sectional shape model that reproduces a tire cross-sectional shape obtained by cutting a tire constituent member to be cut along a plane perpendicular to the tire circumferential direction, and developing the created cross-sectional shape model in the tire circumferential direction, A three-dimensional shape model of a tire component is created by changing the cross-sectional shape model within the tire cross-section based on the amount of change input from the input device by an operator according to the development angle in the tire circumferential direction. a method comprising the steps, by using the created three-dimensional shape model, to create a tire model of a three-dimensional shape, creating A step of calculating a tire characteristic by executing a simulation calculation based on a simulation condition input from an input device by an operator to the tire model, and a step of outputting the calculated tire characteristic by the output device The operation method of the simulation apparatus characterized by performing the above is provided.
Alternatively, the present invention is an operation method of a simulation apparatus for simulating tire characteristics, comprising an input device, an output device, and a CPU , wherein the CPU comprises a tire comprising a plurality of tire constituent members. A step of creating a cross-sectional shape model reproduced by a tire cross-sectional shape cut at a plane orthogonal to the tire circumferential direction, and developing the created cross-sectional shape model in the tire circumferential direction, and in the development, in the tire circumferential direction While varying at least one model of a plurality of tire constituent members included in the cross-sectional shape model within a tire cross section based on a variation amount input from the input device by an operator according to a development angle a step of creating a three-dimensional shape model of the plurality of tire components, wherein the plurality of tire this created By combining the three-dimensional shape model of the formation member, and creating a tire model of a three-dimensional shape, based on the simulation conditions input from the input device by an operator with respect to the tire model created simulation You may provide the operation method of the simulation apparatus characterized by performing the step which calculates a tire characteristic by performing a calculation, and the step which outputs the calculated tire characteristic by the said output device .
By having such steps, it is possible to operate a simulation device that can simulate tire characteristics including changes in cross-sectional shape and arrangement position in the tire circumferential direction.

Further, in the present invention, the development of the cross-sectional shape model in the tire circumferential direction is performed once in the tire circumferential direction, and the cross-sectional shape models match at the deployment start position and the deployment end position in the tire circumferential direction. Thus, it is preferable to vary the cross-sectional shape model. By doing in this way, it can prevent that the boundary part of a deployment start position and a deployment end position becomes discontinuous.
Further, in the present invention, the variation according to the development angle in the tire circumferential direction of the cross-sectional shape model is based on a variation represented by a periodic function having at least one basic cycle with one cycle in the tire circumferential direction as a basic cycle. It is preferable. By doing so, the shape change of the three-dimensional shape model can be approximated smoothly, and element division is facilitated when the three-dimensional shape model is divided by a plurality of finite elements. Further, in the present invention, the periodic function is preferably a trigonometric function.

Further, in the present invention, the periodic function representing the amount of variation includes a high-order periodic function in which one cycle in the tire circumferential direction is two or more cycles, and a three-dimensional shape tire model is obtained using the three-dimensional shape model. The creating step further includes a step of dividing the three-dimensional shape model into a plurality of finite elements, and at least the tire casing portion of the three-dimensional shape model has a finite number of six times or more of the maximum order of the periodic function. It is preferable to generate a finite element by equally dividing the number of elements.
By doing so, periodicity can be maintained in one round of the tire, and interference between the element division period and the shape change period can be suppressed, so that accurate tire characteristics can be obtained when the simulation is executed. be able to. An example of such a higher-order periodic function is a Fourier series.

According to the present invention, when the cross-sectional shape model is developed in the tire circumferential direction and the three-dimensional shape model is created, the cross-sectional shape model is changed within the tire cross-section, It is possible to provide a method of operating a simulation apparatus that can simulate tire characteristics including fluctuations.

  In the present invention, when a three-dimensional shape model is created by developing a cross-sectional shape model of a tire constituent member at a tire circumferential position, the shape and position of the cross-sectional shape model are changed according to the tire circumferential position. Since the model is created, it is possible to perform a simulation calculation of tire characteristics in consideration of tire uniformity components.

Hereinafter, the operation method of the simulation apparatus of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

FIG. 1 is a schematic diagram showing an outline of a simulation apparatus that performs the tire model creation method of the present invention and further executes simulation of tire characteristics.
The simulation apparatus 1 includes a central processing unit (CPU) 2 that controls functions of each part (processing unit) and controls processing of the entire apparatus, and a RAM that temporarily stores calculation results obtained in each part. And a memory 3 such as a ROM for storing various control information for executing processing of each part, and an input / output port 4. The simulation apparatus 1 includes an input device 5 such as a keyboard and a mouse for inputting various conditions such as a model creation condition, a processing condition, or a characteristic calculation condition via an input / output port 4, and an input result or tire by the input device 5. It is connected to an output device 6 such as a display or a printer for displaying a simulation result of characteristics and an external storage device 7 such as a hard disk or a magneto-optical disk.

Such a simulation apparatus 1 creates a tire finite element method analysis model (hereinafter referred to as a tire model) in accordance with an operator input, sets simulation conditions, executes a simulation, and calculates tire characteristics.
FIG. 2 shows the flow of the tire characteristic simulation process executed by the simulation apparatus 1.

As a process for executing the simulation, a tire model is created using a method described later (step S101).
The created tire model is composed of models (member models) of a plurality of tire constituent members (hereinafter referred to as members), and the elements constituting each member model are three-dimensional models.
3A and 3B are a perspective view and a front view of an example of a tire model of a passenger car tire.
The tire model 10 is mainly divided into a tread pattern part model 12 and a tire body part model 14, and these models are created separately, and then the tread pattern part model 12 and the tire body part model 14 are joined. . In this case, the models are created by combining the nodes of the joint portion or by giving a predetermined constraint condition to the nodes of the joint portion. Each model is constituted by a large number of finite elements, for example, a hexahedral solid element, a pentahedral solid element, a tetrahedral solid element, a shell element, or a membrane element. Thus, after the tread pattern part model 12 and the tire body part model 14 are created separately, the tire characteristics are simulated by changing the tread pattern part model 12 without changing the tire body part model 14. Because.

FIG. 4A is a perspective view of the tire body part model 14.
The tire body portion model 14 is a model obtained by removing the tread pattern portion model 12 from the tire model 10 and has a substantially toroidal shape. In FIG. 4 (a), the tire circumferential direction is the A direction, the tire width direction is the B direction, the tire cross-sectional direction is the plane direction when cut along a plane that passes through the tire rotation axis and is orthogonal to the tire circumferential direction. To express. FIG. 4B is a cross-sectional view of the right half of the tire body part model 14 when cut in the tire cross-sectional direction of the tire body part model 14.
The tire body part model 14 mainly includes a belt member model 14a reproducing a belt member, a tread base member model 14b reproducing a tread base member, a carcass member model 14c reproducing a carcass member, and a side member reproducing a side member. A model 14d, a bead filler member model 14e reproducing the bead filler member, a bead member model 14f reproducing the bead member, and the like are configured.

FIG. 5 is a perspective view of the tread pattern portion model 12.
The tread pattern part model 12 is a model that reproduces the tread pattern of the tire, and is composed of finite elements that are finer than the tire body part model 14.
Such a tire model 10 is created by the tire model creation method of the present invention described later.

Simulation conditions are set for the created tire model 10 (step S102).
Boundary conditions and test conditions are set as simulation conditions. The boundary condition includes a dynamic boundary condition and a geometric boundary condition. The mechanical boundary condition is a condition related to a so-called external force, and the geometric boundary condition is a condition related to a constraint condition or a forced displacement.

  The test conditions are the use conditions when the tire is used (various conditions such as load, internal pressure, travel speed, road surface condition, etc.). For example, when simulating the tire characteristics in the running state, the condition for performing the internal pressure filling process on the tire model and setting the grounded state is set as the test condition. In other words, the internal pressure filling is reproduced by attaching a rim model created separately to the tire model and applying a certain load to the inner peripheral surface of the tire model. After the internal pressure filling process, the tire model is set to a rigid road surface model and grounded with a load, and a grounded tire model is created.

Next, a simulation calculation is executed, and the calculation result is output to the output device (step S103).
For example, when simulating the tire characteristics in the running state, a translation calculation speed and a rotation angular speed are given to the tire model set in the ground contact state, and a simulation calculation is performed in a state where the tire runs on the road surface. The simulation calculation is performed using a known finite element solver or the like.

Simulation calculations include, for example, dry performance during cornering with camber angle and slip angle, braking / driving performance when braking torque or driving torque is applied to the tire rotation axis, and a fluid model that reproduces the wet road surface. A simulation calculation of wet performance such as hydroplaning performance on the road surface is given, and the calculation is performed using the above test conditions.
A predetermined characteristic physical quantity acting on the tire model 10 is calculated as a calculation result, and the calculated characteristic physical quantity is displayed on the display as an index of tire characteristics. Alternatively, it is output to a printer.
Such tire characteristics affect the uniformity component that accompanies the rolling of the tire. In the present invention, the tire characteristics can be simulated in consideration of this uniformity.

FIG. 6 is a flowchart for explaining the flow of the tire model creation method of the present invention.
First, a cross-sectional shape model in which the tire constituent member is cut in the tire cross-sectional direction to reproduce the cross-sectional shape of the tire constituent member is created (step S201).
Fig.7 (a) is a perspective view of the belt member which is an example of a tire structural member. The belt member 100 is a state in which a steel wire 102 in which a plurality of steel strands are twisted is inclined in a predetermined angle with respect to the tire circumferential direction (A direction in FIG. 7A) and arranged in parallel at a constant interval. A sheet-like laminated member having a rubber member and a steel wire coated with a coating rubber member. This laminated member is reproduced by a belt member model 14a represented by a shell element shown in FIG.
FIG. 7B is a diagram in which the belt member 100 is cut in the tire cross-sectional direction to reproduce the cross-sectional shape of the tire constituent member. That is, the belt member cross-sectional shape model 104 is created by expressing the shape when the belt member 100 is cut along a plane perpendicular to the tire circumferential direction by a curved element.

Next, the created cross-sectional shape model is developed in the tire circumferential direction (step S202).
During this development, the shape of the cross-sectional shape model is changed in the tire cross-section according to the position in the tire circumferential direction, and a three-dimensional shape model of the tire constituent member is created (step S203).
In the example of the cross-sectional shape model 104 of the belt member 100 shown in FIG. 7B, the cross-sectional shape model 104 is developed once in the tire circumferential direction around the tire rotation axis to form a rotating body shape. At that time, the shape and position of the cross-sectional shape model 104 are changed according to the position of the cross-sectional shape model 104 in the tire circumferential direction. This variation is given so that the cross-sectional shape model 104 matches at the development start position and the development end position in the tire circumferential direction of the cross-sectional shape model 104. For example, a fluctuation amount expressed by using a periodic function such as a trigonometric function having at least one basic period as a basic period is defined as one cycle in the tire circumferential direction. For example, the periodic function includes a high-order periodic function in which one turn in the tire circumferential direction is two or more periods. That is, the fluctuation amount is given by a fluctuation amount expressed by series expansion such as Fourier series expansion.

FIG. 8A is created by changing the cross-sectional shape model 104 in the tire circumferential direction by giving a predetermined amount of fluctuation according to the position in the tire width direction (angle θ in FIG. 8A). It is a perspective view which shows the example of another 3D shape model. Here, in the regions R ₁ and R ₂ , the end of the cross-sectional shape model 104 is rapidly changed due to the fluctuation. Such a change reflects the deviation of the joining position when the green tire is formed by winding the belt member once in the actual tire forming stage as shown in FIG. 8B. That is, the regions R ₁ and R ₂ correspond to the positional deviation of the joining position of the belt member 100 that is approximated by a broken line as shown in the enlarged view in FIG.
As shown in FIG. 8C, such fluctuation amount is expressed as a sum expressed by a high-order periodic function with respect to the angle θ representing the tire circumferential position using a trigonometric function such as sin or cos. can do. In particular, since the periodic function smoothly connects the cross-sectional shape models in the tire circumferential direction, it is possible to perform simulation calculation of tire characteristics with high accuracy.
Next, mesh division is performed on the created three-dimensional shape model (step S204). The mesh division may be performed using a known automatic division mesh module, or may be performed according to an instruction from the operator. FIG. 8D shows a belt member model 104a that is divided into meshes and includes finite elements (shell elements).

The three-dimensional finite element model of the tire constituent member thus divided is combined with the three-dimensional finite element models of other tire constituent members similarly created through steps S205 and S206. (Step S207).
The model can be connected by either sharing the joints of the joints of both models or by displacing the joint of one model located at the joint interface with the joint of the other model. This is done by giving a restraint condition that restrains a physical quantity such as force.
Next, a material constant is given to the determined finite element, and the tire model is completed (step S208).

  Thus, in the present invention, when the cross-sectional model representing the cross-sectional shape of the tire constituent member is developed in the tire circumferential direction, the tire cross-sectional shape is changed in the tire circumferential direction by changing the shape and position of the cross-sectional model. A changed tire model can be created. Thereby, in the tire simulation calculation, it is possible to obtain the tire characteristics in consideration of the tire uniformity caused by the tire cross-sectional shape becoming non-uniform.

In the above description, the case in which the belt member is used as the tire constituent member and the tire member changes in the tire width direction has been described. However, in the present invention, not only the tire width direction change but also the tire radial direction (the tire circumferential direction and the tire width direction). In a direction orthogonal to the both), or a combination of changes in the tire width direction and the tire radial direction.
For example, as shown in FIG. 9A, a belt member arranged at an angle φ with respect to the tire center line CL may be reproduced. In addition to the belt member, a three-dimensional shape model may be created by changing a cross-sectional shape model such as a tread base member, a carcass member, a side member, a bead filler member, or a bead member in the tire circumferential direction.
FIG. 9B shows the thickness distribution w ₁ (θ) eccentric to the tire center axis O when the cross-sectional model of the tread base member made of a rubber member is developed in the tire circumferential direction. This is a given three-dimensional shape model.
FIG. 9C shows a three-dimensional model in which the thickness distribution w ₂ (θ) is given as a variation amount in the tire radial direction when the cross-sectional shape model of the tread base member is developed around the tire central axis O in the tire circumferential direction. It is a shape model.
Furthermore, in the present invention, a cross-sectional shape model representing a cross-section of the tire body portion is created by reproducing the cross-sectional shape of the outer shell of the tire and the arrangement of the tire constituent members in this cross-sectional shape, and the created cross-sectional shape By deploying the model in the tire circumferential direction, by changing the arrangement position of the tire constituent member in the cross-sectional shape model in the tire cross section using a predetermined variation amount in accordance with the position in the tire circumferential direction A three-dimensional tire model may be created. Thereby, the arrangement position and shape of the tire constituent member can be changed at least in the tire circumferential direction position.

  In the present invention, when the periodic function representing the amount of variation given to the cross-sectional shape model is a function including a high-order periodic function in which one cycle in the tire circumferential direction is two or more cycles, at least the tire body of the tire model It is preferable that the part model has a length of one-sixth or less of the period in the periodic function of the maximum order and is divided in the tire circumferential direction to generate a finite element. The uniformity component can be calculated with high accuracy by setting the length of the finite element in the tire circumferential direction to 1/6 or less of the period in the periodic function of the maximum order with respect to the above-described variation in the tire circumferential direction. Highly accurate tire characteristics can be calculated.

Uniformity test for passenger car tires prototyped by shifting the belt member connecting part in the 5mm tire width direction when the belt member is wound around the tire circumferential direction and both ends are connected to form a green tire Went. Uniformity test is a vibration component of force acting in the vertical direction, front-rear direction and left-right direction generated on a tire when the tire is pressed against a cylindrical drum road surface with a predetermined load and rolled at a predetermined speed. Mitty component). The measured vibration component in the left-right direction (lateral force variation (LFV)) was used as a reference (index 100).
On the other hand, a tire simulation model in which the prototype tire is reproduced with a finite element and the belt member is displaced by 5 mm at the connection portion is created by the above-described method (models 1 to 4), and the simulation calculation reproducing the tire uniformity test is performed. went.
The variation of the belt member model given to the tire model was given in the form of Fourier series expansion. Table 1 shows the relationship between the employed order (maximum order) of the Fourier series expansion and the number of divisions in the circumferential direction of the tire model at this time and the simulation calculation result of the lateral force variation (LFV).

According to Table 1, when the finite element is equally divided by four times the maximum order (model 1) and 4.8 times the maximum order (model 2) in the Fourier series expansion, the results of the uniformity test (experiment) An error of 7 to 8% occurs.
In addition, when a finite element is divided in the tire circumferential direction by a number that is six times the maximum order in the Fourier series expansion, the LFV value causes an error of 10% with respect to the experimental result due to non-uniform division. However, even division (model 4) reduces the LFV to an error of 2% with respect to the experimental result. This is considered to be because the period of the element division of the finite element interferes with the period of the fluctuation amount. That is, the number of element divisions in the tire circumferential direction of the finite element needs to create a model according to the shape change in the tire circumferential direction, and in order to obtain the simulation result corresponding to the experimental result, the finite element in the tire circumferential direction is limited. The number of element divisions of elements is preferably a division number (model 4) that is six times or more the maximum order of the periodic function that gives the fluctuation amount.
Further, if the element division in the tire circumferential direction is unequal (model 3), it can be predicted that a variation due to an element division of an order lower than the division number will occur, and the accuracy deteriorates. Therefore, it is preferable to divide the element of the finite element into elements equal to or more than 6 times the maximum order of the Fourier series and equally divide.

  The tire model creation method according to the present invention has been described in detail above. However, the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. You may go.

It is the schematic of a simulation apparatus. It is a figure which shows the processing flow in the simulation of a tire characteristic. It is the perspective view and front view of an example of the tire model of the tire for passenger cars. It is a figure which shows a tire body part model. It is a perspective view of a tread pattern part model. It is a flowchart explaining the flow of the tire model creation method. It is a figure which shows the cross-sectional shape of the belt member which is an example of a tire structural member, and a belt member model. It is a figure for demonstrating expansion | deployment in the tire circumferential direction of a cross-sectional shape model. It is a figure which shows the modification in the case of expand | deploying the cross-sectional shape model changed to the circumferential direction.

Explanation of symbols

1 Simulation device 2 Central processing unit (CPU)
3 Memory 4 Input / Output Port 5 Input Device 6 Output Device 7 External Storage Device

Claims (6)

An input device;
An output device;
CPU,
With a method of operating a simulation apparatus for simulating tire characteristic,
The CPU is
Creating a cross-sectional shape model that reproduces a tire cross-sectional shape obtained by cutting a tire constituent member constituting a tire at a plane orthogonal to the tire circumferential direction;
The created cross-sectional shape model is developed in the tire circumferential direction, and at the time of the development , the cross-sectional shape model is based on the amount of variation input from the input device by the operator according to the development angle in the tire circumferential direction. Creating a three-dimensional shape model of the tire component by varying the tire cross section within the tire cross section,
Using the created three-dimensional shape model to create a three-dimensional tire model;
Based on the simulation conditions input from the input device by the operator for the created tire model, performing simulation calculation to calculate tire characteristics;
Outputting the calculated tire characteristics by the output device;
The operation method of the simulation apparatus characterized by performing this . An input device;
An output device;
CPU,
With a method of operating a simulation apparatus for simulating tire characteristic,
The CPU is
Creating a cross-sectional shape model reproduced by a tire cross-sectional shape obtained by cutting a tire composed of a plurality of tire constituent members at a plane orthogonal to the tire circumferential direction;
The created cross-sectional shape model is developed in the tire circumferential direction, and at the time of the development , the cross-sectional shape model is based on the amount of variation input from the input device by the operator according to the development angle in the tire circumferential direction. Creating a three-dimensional shape model of the plurality of tire components while varying at least one of the models of the tire components included in the tire cross section,
A step of creating a three-dimensional tire model by combining the created three-dimensional shape models of the plurality of tire constituent members ;
Based on the simulation conditions input from the input device by the operator for the created tire model, performing simulation calculation to calculate tire characteristics;
Outputting the calculated tire characteristics by the output device;
The operation method of the simulation apparatus characterized by performing this . The development of the cross-sectional shape model in the tire circumferential direction is performed once in the tire circumferential direction, and the cross-sectional shape model is matched so that the cross-sectional shape model matches at the deployment start position and the deployment end position in the tire circumferential direction. The operation method of the simulation apparatus according to claim 1, wherein the simulation apparatus is varied. The variation according to the development angle in the tire circumferential direction of the cross-sectional shape model is based on a variation amount represented by a periodic function having at least one basic cycle as a basic cycle. An operation method of the described simulation apparatus . The operation method of the simulation apparatus according to claim 4, wherein the periodic function is a trigonometric function. The periodic function representing the amount of variation includes a high-order periodic function in which one cycle in the tire circumferential direction is two or more cycles,
The step of creating a three-dimensional shape tire model using the three-dimensional shape model further includes a step of dividing the three-dimensional shape model into a plurality of finite elements, and at least a tire casing portion of the three-dimensional shape model. 6. The operation method of the simulation apparatus according to claim 4 or 5, wherein a finite element is generated by equally dividing a number of six times or more of the maximum order of the periodic function as a finite element division number.

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