JP5183970B2 - Prediction method of cavity resonance of pneumatic tire - Google Patents

Description

  The present invention relates to a method for predicting cavity resonance of a pneumatic tire that predicts cavity resonance frequency, sound pressure, transfer function, etc. by modeling the pneumatic tire and a cavity region inside the tire using a finite element method (FEM). About.

  It is known that a pneumatic tire has a cavity resonance phenomenon due to the length of a circular pipe inside the tire due to its structure. In the case of a passenger car tire, the cavity resonance frequency exists around 200Hz to 270Hz from the tire circumference, and when it is transmitted to the axle due to the cavity resonance, it becomes a sharp peak unlike other bands and is uncomfortable in the vehicle. It contributes to noise.

  It has been conventionally known to simulate the vibration and noise of a pneumatic tire due to input to the tire from road surface unevenness using a technique such as FEM. For example, in Patent Document 1 below, input to the tire due to road surface unevenness is performed. There has been proposed a tire vibration / noise simulation method for quantitatively obtaining at least one of tire vibration and noise.

  Further, Patent Document 2 proposes a vehicle interior noise prediction method and apparatus for easily predicting road noise, including frequency response functions for all four wheels of a standard tire, and auto power spectrum and cross power spectrum of a noise prediction target tire. Is synthesized for four wheels, and the power spectrum of road noise is calculated.

  However, analysis using the FEM or the like has not been sufficiently performed for the cavity resonance of the tire, and there have been many problems when incorporated in the tire design step.

  Conventionally, when cavity resonance of a pneumatic tire is evaluated and incorporated in a tire design step, the following method is exemplified.

  Conventional method 1: Tires were actually manufactured, and cavity resonance frequencies were evaluated by experimental measurement. In this case, the number of man-hours and costs for tire manufacture, tire characteristics, vibration, and noise measurement are very large and the accuracy is low, and there are obstacles to incorporating the evaluation results into the tire design step.

  Conventional method 2: An approximate desktop calculation has been executed as a one-dimensional problem based on the pipe length of the cavity in the circumferential direction inside the tire. In this case, the tire design parameters, the tire deformation state, and external conditions (internal pressure, ground contact, etc.) are not taken into consideration, and this is also low in accuracy.

Conventionally, a tire structure is modeled as a finite element, and internal pressure filling, vibration is input to the load load, and performance predictions such as tire vibration and noise approximated to the running state have been performed. The calculation took a long time. Furthermore, the tire cavity resonance frequency has not been predicted by modeling the tire structure itself as a finite element model and simultaneously modeling the cavity region inside the tire.
JP 2000-241309 A Japanese Patent Laid-Open No. 11-6758

  The conventional method for evaluating the cavity resonance of a pneumatic tire has a large man-hour and cost in manufacturing and evaluating the tire, and has low accuracy.

  Therefore, the present invention predicts cavity resonance such as cavity resonance frequency in a short time and accurately by modeling the tire structure of a pneumatic tire and the cavity region inside the tire using a finite element method (FEM). An object of the present invention is to provide a method for predicting cavity resonance of a pneumatic tire.

  The present inventors have modeled not only the tire structure but also the air layer in the cavity region inside the tire, and analyzed the tire cavity resonance using a finite element model in which both are combined. A prediction of tire cavity resonance is obtained and is intended to be incorporated into the tire design step.

That is, the method for predicting the cavity resonance of a pneumatic tire according to the present invention calculates the deformation shape of the tire structure by a finite element method, and calculates the deformation shape of the tire cavity based on the deformation shape of the tire structure. A finite element model representing the tire structure and the deformed shape of the cavity by combining the deformed shape of the tire structure and the deformed shape of the tire cavity (tire structure + cavity) The tire cavity resonance frequency, sound pressure, and transfer function are obtained from the obtained natural frequency by executing the eigenvalue calculation by the finite element method as a coupled problem of the tire structure and the cavity, and the tire cavity resonance is obtained. It is characterized by prediction.

A method for predicting cavity resonance of a pneumatic tire according to the present invention includes a first step of creating a tire finite element model by approximating a tire structure into a finite element model obtained by dividing a tire structure into a finite number of elements, and the tire. tread constituting the structure, the belt, the Young's modulus representing the material properties of the members, such as carcass, a second step of defining a Poisson's ratio and specific gravity in the tire finite element model, with respect to the tire finite element model, evaluation define the pressure and load a condition, and a third step of calculating a deformed shape of the tire structure by a finite element is approximated modeled by finite element model by dividing a tire internal cavity on a number of factors tire to define a fourth step of creating a cavity finite element model, the bulk modulus and mass density representing the air material properties with respect to the tire cavity finite element model A fifth step, based on the deformation shape of the tire structure according to the calculation of the third step, a sixth step of calculating a deformed shape of the tire cavity finite element model by a finite element method, and the third step 6 A finite element model ( tire structure + cavity ) that represents the deformation shape of the tire structure and the cavity by combining the deformation shape of the tire structure calculated in the step and the deformation shape of the tire cavity. an eighth step of performing eigenvalue calculation by the finite element method as interaction problem of tire structure and the cavity portion and a seventh step of creating, for finite element model created in the seventh step, the eighth It is preferable to have a ninth step of acquiring the cavity resonance frequency, sound pressure, and transfer function of the tire from the natural frequency acquired in the step.

  According to the present invention, the FEM is used to calculate the deformation shape of the tire structure and the deformation shape of the tire cavity, and the tire + cavity is formed by combining the tire structure and the deformation shape of the cavity to form a finite element model. Steps to design pneumatic tire cavity resonance in a short time with high accuracy by obtaining tire cavity resonance frequency, sound pressure, and transfer function from natural frequency by FEM The built-in vehicle noise can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a flow of a tire cavity resonance prediction method according to the embodiment, which can be implemented using a computer. More specifically, a cavity resonance prediction method according to the present embodiment can be implemented by creating a program for causing a computer to execute the following first to ninth steps and using a computer that inputs this program.

  In the present embodiment, first, in the first step (S1), an initial FEM model is created by approximating an finite element model obtained by dividing a tire structure into a finite number of elements for a tire to be analyzed. More specifically, the tire cross-sectional shape is set as a reference shape, and this reference shape is modeled by a finite element method (FEM) to represent the tire cross-sectional shape including the internal structure and the tire divided into a plurality of finite elements by mesh division. Create an FEM model. FIG. 2 shows an example of the FEM model. As shown in FIG. 2, the tire cross section is divided into a plurality of finite elements and a plurality of tire circumferential directions. In the example of FIG. 2, the tire is divided at an equal angle in the tire circumferential direction. However, the division is not limited to such an equal division, and for example, the ground contact surface side may be finely divided into meshes.

  In the next second step (S2), material property values are defined and their initial values are given. Material property values are defined for each rubber material and reinforcing material such as tread rubber, sidewall rubber, belt layer, carcass layer, and bead core, and the Young's modulus and Poisson representing the material properties of each member as their initial values. The ratio, specific gravity, etc. are specified and assigned to the FEM model. In this case, the usage amount and thickness of the rubber material, the cross-sectional area of the cord material, the arrangement interval, the angle, and the like are taken into consideration.

  In the next third step (S3), a tire FEM model is mounted and coupled to a virtual rim having a rim size corresponding to the actual use state, and an internal pressure and a vertical load are applied to the center of the rim as evaluation conditions corresponding to the actual use state. The tire is deformed and the deformed shape of the tire is calculated by FEM.

  By S1 to S3, the tire deformation shape in the actual use state in the tire structure alone is obtained by FEM analysis (see FIG. 2). For the FEM analysis, a commercially available FEM analysis software program such as a structural analysis program “ABAQUS” may be used.

  In the next fourth step (S4), an approximate model is formed by a tire cavity FEM model in which the tire cavity, that is, the air layer inside the tire is divided into a number of elements. More specifically, the tire cross-section inner surface shape is set as a reference shape, and this reference shape is modeled by FEM to represent the cross-sectional shape of the internal cavity, and the FEM model of the tire internal cavity divided into a plurality of finite elements by mesh division Create FIG. 3 shows an example of the FEM model of the tire internal cavity. As shown in FIG. 3, the cavity section is divided into a plurality of finite elements and divided into a plurality of tire circumferential directions.

  In the next fifth step (S5), a volume elastic modulus and a mass density representing air material characteristics are defined and given to the FEM model with respect to the tire internal cavity FEM model. Then, in a sixth step (S6), the deformation shape of the cavity FEM model is calculated by FEM based on the deformation shape of the single tire structure obtained by the calculation of S3.

  Through S4 to S6, a deformed shape in the tire internal cavity is obtained by FEM analysis (see FIG. 3).

  In the next seventh step (S7), referring to the displacement results of S3 and S6, the tire structure and the deformed shape of the cavity are combined, and the FEM modeled tire structure + inside as shown in FIG. An FEM model in which cavities are combined is created.

  In the next eighth step (S8), an eigenvalue calculation by FEM is performed on the FEM model of S7 as a coupled problem of the tire structure / cavity, and the actual use state of the tire loaded with internal pressure and vertical load Get the natural frequency at. Then, based on the natural frequency obtained from the FEM analysis result, the tire cavity resonance frequency, sound pressure, and transfer function are acquired (9th step), and the result is evaluated to finish.

  FIG. 5 illustrates a transfer function of cavity resonance in the rim center portion obtained as described above.

  The cavity resonance prediction method according to the present invention obtains a natural frequency by modeling a tire structure and a tire cavity individually, obtaining a deformed shape, and combining them to obtain a natural frequency. The peak of the resonance frequency appears.

  The feature of the method for predicting cavity resonance according to the present invention is that only the tire structure is conventionally modeled, but the cavity resonance can be predicted by modeling the cavity inside the tire. By reducing the analysis size, individual calculation efficiency is improved, and by analyzing the FEM model obtained by combining the results, FEM analysis can be performed in a short time.

  For two pneumatic radial tires (control tire and trial tire) having a tire size of 205 / 50R17 and different tire structures, a cavity resonance frequency is predicted according to the analysis method of the present embodiment, and a conventional tire is used. Table 1 shows the time required for the actual manufacturing and experimental measurement method, and Table 2 shows the FEM analysis values of the cavity resonance frequencies of the two tires and the actual measurement values obtained by the conventional method.

  The rim size was 17 × 6.5JJ, the air pressure was 220 kPa, and the load was 5000N. The cavity resonance frequency was measured by adding a hammer in the Z direction (vertical direction) to the center of the tread on the tire outer surface when the tire was filled with air to a predetermined air pressure and a load was applied. The response in the Z direction generated on the shaft at that time was measured at the vibration transmission level.

  As shown in the table, compared with the conventional method, in the method according to the embodiment of the present invention, the analysis time is shortened to 1/10, and the FEM analysis result close to the actual measurement value is obtained for both tires. It was confirmed that the resonance can be predicted with high accuracy.

  The present invention can predict tire cavity resonance with high accuracy and can therefore be used in tire development and design steps.

It is a block diagram which shows the flow of the tire cavity resonance prediction method which concerns on one Embodiment of this invention. It is a figure of the FEM model which divided | segmented the tire into the several finite element. It is a figure of the FEM model which divided the tire cavity part into a plurality of finite elements. It is a figure of the FEM model which combined the tire and the tire cavity. It is a graph which shows the transfer function of cavity resonance obtained by FEM analysis.

Claims (2)

Calculate the deformation shape of the tire structure by the finite element method,
Based on the deformed shape of the tire structure, calculating a deformed shape of the tire cavity,
A finite element model (tire structure + cavity) representing a finite element model representing the tire structure and the deformed shape of the cavity by combining the deformed shape of the tire structure and the deformed shape of the tire cavity. make,
Execute the eigenvalue calculation by the finite element method as a coupled problem of the tire structure and the cavity, and obtain the cavity resonance frequency, sound pressure, and transfer function of the tire from the acquired natural frequency to predict the cavity resonance of the tire A method for predicting cavity resonance of a pneumatic tire. A first step of creating a tire finite element model by approximating the tire structure with a finite element model obtained by dividing a tire structure into a finite number of elements;
A second step of defining, in the tire finite element model, a Young's modulus, Poisson's ratio and specific gravity representing material characteristics of each member such as a tread, a belt and a carcass constituting the tire structure;
For the tire finite element model, a third step of defining internal pressure and load as evaluation conditions, and calculating a deformation shape of the tire structure by a finite element;
A fourth step of creating a tire cavity finite element model approximated modeled by finite element model by dividing a tire internal cavity on a number of factors,
A fifth step of defining a bulk modulus and mass density representing air material properties for the tire cavity finite element model;
Based on the deformed shape of the tire structure according to the calculation of the third step, a sixth step of calculating a deformed shape of the tire cavity finite element model by a finite element method,
The deformed shape of the tire structure calculated in the third step and the sixth step and the deformed shape of the tire cavity are combined to form a finite element model representing the deformed shape of the tire structure and the cavity ( tire structure + A seventh step of creating a finite element model of the cavity ) ;
An eighth step of performing eigenvalue calculation by the finite element method as interaction problem of tire structure and the cavity portion for finite element model created in the seventh step,
The prediction of cavity resonance of a pneumatic tire according to claim 1, further comprising a ninth step of acquiring a cavity resonance frequency, sound pressure, and transfer function of the tire from the natural frequency acquired in the eighth step. Method.

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