JP4931430B2 - Tire temperature distribution prediction method and tire temperature distribution prediction calculation program - Google Patents

Description

  The present invention relates to a method for predicting a tire temperature distribution during traveling using a numerical analysis model of a tire by dividing a tire into a finite number of elements, and a tire temperature distribution prediction calculation program used for the method. .

Conventionally, as a method of simulating tire performance, the tire to be evaluated is approximated by a tire finite element model divided into a finite number of elements, and material properties such as density and elastic modulus are given to each finite element, The Finite Element Method is often used for numerical analysis of tire dynamics such as tire deformation and rolling resistance by applying boundary conditions such as internal pressure and load to the above model and calculating the deformation state of each element. (For example, see Patent Documents 1 and 2).
On the other hand, as one method for evaluating the durability of a tire, an evaluation method has been proposed that takes into account the temperature rise due to heat generated during rolling of a rubber material that is a viscoelastic body.
FIG. 7 is a diagram showing the flowchart, and FIG. 8 is a diagram showing an outline of a tire finite element model (tire model) 70 used in this evaluation method. In the tire model 70, the tire is divided into a finite number of elements 70S, rubber members such as the tread portion 71 and the side portion 72 are modeled as solid elements, and a reinforcing member such as the belt 73 is modeled as a membrane element. Therefore, when evaluating the durability, first, the tire model 70 is used to perform a static stress analysis or a dynamic analysis such as a rolling analysis to determine the stress of each element of the tire model 70. After the analysis (step S51), the stress σ and the strain ε when the tire is rotated once are obtained for each element obtained in the stress analysis, and the strain ε corresponds to the loss tangent of the rubber material. The heat generation energy of each element is calculated from the area of the hysteresis loop of the stress σ and the strain ε obtained by giving the phase delay δ (step S52). Determine the temperature distribution in the case of exothermic traveling by theta (step S53).
Next, a heat transfer analysis is performed in which the modeled tire travels for a predetermined time θ to dissipate heat to predict the temperature distribution of the tire (step S54), and the predicted breakage at the temperature of each element after heat dissipation. The tire safety factor is calculated from the strength and elongation at break (step S55), and the durability of the tire is evaluated (step S56). In the analysis at the time of heat generation, it is assumed that the tire only generates heat but does not dissipate heat, and in the analysis at the time of heat dissipation, the tire only calculates heat and does not generate heat.
In this way, after performing the heat generation analysis and the heat dissipation analysis separately, by matching the heat generation time and the heat dissipation time, the prediction calculation time of the temperature distribution can be greatly shortened (for example, patent document) 3).
JP 2003-118328 A JP 2005-186900 A JP 2005-138621 A

By the way, it is known that the viscoelastic coefficient and tan δ of the rubber member used when calculating the calorific value of each element of the tire model 70 show temperature dependency and strain amount dependency.
However, in the conventional temperature distribution prediction method, the numerical values given when performing the stress analysis are used as they are as the viscoelastic coefficient and tan δ, and the temperature dependence of the viscoelastic coefficient and tan δ is not considered. In addition, since the strain dependence is not considered, it is difficult to accurately predict the temperature distribution of the tire.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a method capable of accurately predicting the temperature distribution of a tire during traveling.

According to a first aspect of the present gun, as well as to create a stress analysis model comprising a three-dimensional tire model or 3D tire model and the road model, giving elasticity to the elements of each rubber member of the tire model After calculating the stress and strain amount of each part of the tire by performing load or rolling analysis, the heat generation distribution of the tire obtained by using the calculated stress and strain amount of each part of the tire and the loss tangent of the rubber member Is a tire temperature distribution prediction method for predicting the temperature distribution inside and outside the tire by performing thermal analysis calculation, and giving a loss tangent of a predetermined temperature to each rubber member element of the tire model. after predicting the temperature distribution of the tire Te, the load or rolling analysis using the new stress analysis model by replacing the elastic modulus of the elastic modulus of the elements of the rubber members of the tire model with the predicted temperature I calculated the stress and strain of the tire each portion again obtains the heat generation distribution of the tire with the loss tangent of the rubber member in which the calculated stress and strain amount and the upper Symbol predicted temperature Rutotomoni, Add one or both of the above-mentioned tire models to the tire model, the internal air model that divides the air inside the tire into finite elements, and the rim model that divides at least part of the wheel including the rim part into finite elements. and the thermal analysis model is created, have rows prediction temperature distribution of the tire by performing the thermal analysis calculations based on the heat generation distribution, and predicted temperature distribution in the new thermal analysis calculations, before thermal analysis The temperature distribution predicted by the calculation is compared to determine the convergence of the temperature distribution. If the temperature distribution does not converge, the new thermal analysis calculation is added to each rubber member element of the tire model. By Predict the tire temperature distribution by giving the elastic modulus and loss tangent at the predicted temperature, predicting the temperature distribution of the tire and determining the convergence of the temperature distribution until the temperature distribution converges. It is characterized by that.
The invention according to claim 2 is the tire temperature distribution prediction method according to claim 1, wherein each element of the rim model is given a thermal conductivity according to a wheel material as a physical property value, and the internal air Each element of the model is characterized in that the thermal conductivity of air is given as a physical property value.

The invention according to claim 3 is the tire temperature distribution prediction method according to claim 1 or 2 , wherein the temperature distribution predicted by the new thermal analysis calculation and the temperature predicted by the previous thermal analysis calculation are used. The convergence is determined when the difference from the distribution is within 5%.
According to a fourth aspect of the present invention, in the tire temperature distribution prediction method according to any one of the first to third aspects, the relationship between the elastic modulus and loss tangent given to each of the rubber members and the temperature is experimentally determined in advance. It is what you want.
According to a fifth aspect of the present invention, in the tire temperature distribution prediction method according to any one of the first to fourth aspects, the load or rolling analysis is performed using the new stress analysis model. In addition to the predicted temperature distribution, the elastic modulus and the loss tangent used when calculating the heat generation distribution again are set based on the strain of each part of the tire determined by the previous load or rolling analysis. It is a thing.
According to a sixth aspect of the present invention, in the tire temperature distribution prediction method according to the fifth aspect , the relationship between the elastic modulus and loss tangent given to each rubber member and the amount of strain is obtained in advance by experiments. is there.

The invention described in 請 Motomeko 7 is the prediction temperature distribution method tire according to any one of claims 1 to 6, the thermal analysis calculations, using a two-dimensional tire model cut sample type or axisymmetric This is what we do.

The invention according to claim 8 is a calculation program for predicting and calculating the temperature distribution inside and outside the tire using an analysis model in which the tire is divided into finite elements.
A first step of previously determining the temperature dependence and strain dependence of the elastic modulus and loss tangent of each rubber member constituting the tire;
A second step of creating a stress analysis model comprising a three-dimensional tire model or a three-dimensional tire model and a road surface model;
A third step of giving an elastic modulus and a loss tangent at a predetermined temperature to elements of each rubber member of the tire model;
A fourth step of calculating a stress and a strain amount of each part of the tire by performing a load or rolling analysis using an analysis model given an elastic modulus;
A fifth step of obtaining a strain energy density distribution from the calculated stress and strain amount of each part of the tire and multiplying the density distribution by a loss tangent to obtain a heat generation distribution of the tire;
A part or all of the above three-dimensional tire model, or an internal air model in which the air inside the tire is divided into a finite number of elements in the cut sample type or axisymmetric two-dimensional tire model, and at least part of the wheel including the rim portion the create a thermal analysis model obtained by adding one or both of Rimumoderu divided into a finite number of elements, with the above thermal analysis model, by performing the thermal analysis calculations based on the heat generation distribution, surface and internal of the tire A sixth step for obtaining a temperature distribution of
Based on the temperature distribution, a three-dimensional analysis model for load analysis or rolling analysis in which an elastic modulus in the temperature and strain amount of each rubber member of the tire model is given as a new stress analysis model. And a seventh step of replacing the loss tangent used in obtaining the heat generation distribution with the loss tangent at the temperature of the element;
An eighth step of obtaining a new temperature distribution by repeating the fourth step to the sixth step using the new stress analysis model and the replaced loss tangent;
A ninth step of comparing the temperature distribution obtained in the eighth step and the temperature distribution obtained in the sixth step to determine the convergence of the temperature distribution;
If the convergence determination is not made in the ninth step, the process returns to the seventh step to create a new stress analysis model based on the temperature distribution obtained in the eighth step and The loss tangent of each element used for the determination is replaced with the loss tangent based on the temperature distribution, and the temperature distribution is predicted again to confirm the convergence of the temperature distribution .

According to the present invention, a stress analysis model composed of a three-dimensional tire model or a three-dimensional tire model and a road surface model is created, and a load or rolling analysis is performed to calculate the stress and strain amount of each part of the tire. After obtaining the heat distribution of the tire using the stress and strain amount of each part of the tire and the loss tangent of the rubber member, the thermal analysis calculation is performed using the thermal analysis model to predict the temperature distribution on the tire surface and inside When the tire temperature distribution of the tire model is predicted by giving an elastic modulus and a loss tangent of a predetermined temperature to each rubber member element of the tire model, The stress and strain are recalculated using the analysis model given the elastic modulus at the predicted temperature as a new stress analysis model, and the stress and strain and the loss tangent at the predicted temperature are used. New heat distribution After that, perform a thermal analysis calculation to predict the temperature distribution of the new tire, compare the temperature distribution predicted by the new thermal analysis calculation with the temperature distribution predicted by the previous thermal analysis calculation, and Since the temperature distribution of the tire is predicted by repeatedly performing the operation of determining the convergence of the temperature distribution until the difference is within 5%, for example, the temperature distribution of the tire at the time of rolling is accurately determined. Can be predicted.
At this time, as the thermal analysis model, an internal air model in which the air inside the tire is divided into a finite number of elements in the three-dimensional tire model, and at least a part or all of the wheel including the rim portion is converted into a finite number of elements. Since the thermal analysis model to which one or both of the divided rim models are added is used, the tire temperature distribution during rolling can be accurately predicted.
Further, in addition to the predicted temperature distribution, the elastic modulus used when performing the load or rolling analysis using the new stress analysis model and the loss tangent used when obtaining the new heat generation distribution, since so as to set based on the amount of distortion of the tire each part determined by the load or rolling analysis, the prediction accuracy of the temperature distribution can be further improved.
Further , since the tire is a rotating body , the calculation can be efficiently performed if the thermal analysis calculation is performed using a cut sample type or an axially symmetric two-dimensional analysis model.

The best mode of the present invention will be described below with reference to the flowchart of FIG.
First, as advance preparations for tire temperature prediction simulation, the temperature dependence and strain dependence of the elastic modulus / dynamic elastic modulus and loss tangent (tan δ) of each rubber member constituting the tire are measured (step S10). In detail, a vulcanized test piece of each rubber, preferably a test piece taken from a new tire or a running tire is measured and obtained based on the standard in JIS K6394 / ISO4664. In addition, as a measurement range of temperature and strain amount, the strain is the use strain range of each rubber member obtained by prediction calculation, and the temperature is a range obtained by actual measurement of temperature (about 40 ° C to 120 ° C). It was.
Next, an initial model M (0) of a numerical analysis model (hereinafter referred to as a stress analysis model) M (k) for performing stress analysis of the tire such as load analysis or rolling analysis is created (step S11). As shown in FIGS. 2A and 2B, the stress analysis model M (k) includes a tire model 10, a rim model 20, and a road surface model 30, and the tire model 10 includes a tread portion 11 and a side surface. The rubber member such as the portion 12 and the bead wire 13 are modeled by solid elements, the reinforcing members such as the belt 14 and the carcass ply 15 are modeled by shell elements, membrane elements, and river elements, and the rim model 20 is modeled by solid elements. Yes. On the other hand, the road surface is modeled by a flat rigid shell element, but actual road surface irregularities can also be modeled (note that the rim model 20 is omitted in FIG. 2A). Further, the road surface model 30 may be omitted, and boundary conditions may be given to the tire model 10.
Material properties such as density and elastic modulus are given as initial characteristics to the elements of the models 10 to 30, respectively. In this example, first, it is assumed that the temperature of each element of the tire model 10 is uniform, and the tire model Of the elastic modulus / dynamic elastic modulus and tan δ measured in step S10, the elastic modulus / dynamic elastic modulus and tan δ at the initial set temperature (for example, 40 ° C.) are set as initial values for the ten rubber members. (Step S12).
The initial stress analysis model M (0) is subjected to the load or rolling analysis by giving the initial value of the elastic modulus / dynamic elastic modulus set in step S12, and the stress σ and the amount of strain acting on each part of the tire are analyzed. ε is calculated (step S13).

Here, as a method of rolling the tire, set a boundary condition so that the tire and wheel rotate freely around the axle, create a model such as using joint elements, and either the road surface or the axle Can be analyzed by moving the other side in the longitudinal direction of the tire. Furthermore, it is possible to give the tire a slip angle or a camber angle, or to move the road surface so that the tire has a slip angle or a camber angle. Instead of the above rolling analysis, a flat push calculation (load analysis) of the tire model 10 may be performed.
After the calculation of the stress σ and the strain amount ε of each part of the tire is completed, the strain energy for one rotation of the tire of each element is calculated, and this is multiplied by tan δ at the initial set temperature of each element given in step S12 above. Then, the strain energy loss of each element is calculated to obtain the heat generation distribution P (0) of the tire (step S14).
Then, a thermal analysis model is created based on the obtained heat generation distribution P (0), and thermal analysis calculation is performed using this thermal analysis model to obtain the temperature distribution F (0) on the tire surface and inside ( Step S15). FIG. 3 is a diagram showing an example of a thermal analysis model. In this example, as a thermal analysis model G (k), a numerical analysis model including a tire model 40 and a rim model 50 is further added to a gas ( Here, a three-dimensional model to which an internal air model 60 in which air is divided into finite elements is added, or a cut sample type or an axisymmetric two-dimensional analysis model is used, and the shape of the tire model 40 is The shape of the rim model 50 is set to the shape at the time of internal pressure, and the thermal conductivity according to the material of the wheel is set for each element of the rim model 50, and the thermal conductivity of air is set as the physical property value for the internal air model 60.
That is, in step S15, a thermal analysis model G (0) having the heat generation distribution P (0) obtained in step S14 is created, and thermal analysis calculation is performed using the thermal analysis model G (0). The temperature distribution F (0) under the set conditions is obtained.
As shown in FIG. 4, by adopting a model obtained by adding the internal air model 60 to the tire model 40 and the rim model 50 as the thermal analysis model G (k) as in this example, as shown in FIG. In addition to the flow of heat released from the portion 41 and the side portion 42, the flow of heat released from the bead portion 46 to the outside air via the flange portion 51 of the rim model 50, and the rim model 50 from the inner surface of the tire model 40. Since the heat flow conducted to the base portion 52 and released to the outside air can also be considered, the tire temperature distribution can be obtained with high accuracy. The thermal analysis calculation of the tread portion 41 is performed using an average heat flow in a state in contact with the road surface and a state in which the road surface is not in contact.

Next, the number of repetitions is set to k = 1 (step S16), and the temperature distribution F (k−1) (here, temperature distribution) obtained in step S15 is applied to each element of each rubber member of the tire model 10. F (0)) and a new stress analysis model M (k) that gives the elastic modulus / dynamic elastic modulus corresponding to the strain amount ε of each element calculated in step S13 is created (step S17). . The shape of the stress analysis model M (k) is the same as that shown in FIG. At this stage, since this is the first iteration, the stress analysis model is M (1), and the elastic modulus / dynamic elastic modulus measured in step S10 is used as the elastic modulus / dynamic elastic modulus.
FIGS. 5A and 5B are graphs showing an outline of tan δ and elastic modulus / dynamic elastic modulus (Modulus) used in this example. The values of tan δ and the elastic modulus / dynamic elastic modulus both increase in temperature. The temperature tends to decrease after increasing once, but during steady running (temperature of the tire tread; 40 ° C. to 80 ° C.) at 20 km / h to 80 km / h at an outside air temperature of 25 ° C., The elastic modulus / dynamic elastic modulus and tan δ are higher than the elastic modulus / dynamic elastic modulus and tan δ at 40 ° C. which is the initial set temperature.
Next, using the stress analysis model M (k), a load or rolling analysis is performed to calculate a stress σ and a strain amount ε acting on each part of the tire (step S18), and then one rotation of the tire of each element Is calculated by multiplying tan δ at a temperature corresponding to the temperature distribution F (k-1) of each element to calculate the strain energy loss of each element, and thereby calculating the heat distribution P (k of the tire). ) Is obtained (step S19). Then, the process proceeds to step S20, and after creating the thermal analysis model G (k) having the calculated heat generation distribution P (k), the thermal analysis calculation is performed using the thermal analysis model G (k). The temperature distribution inside and inside the tire is obtained again (step S21). Since the temperature distribution obtained in step S21 is a temperature distribution at the number of repetitions k, this is referred to as a temperature distribution F (k).
Next, proceeding to step S22, the temperature distribution F (k) obtained at step S21 is compared with the temperature distribution F (k-1) used at step S17 to determine the convergence of the temperature distribution. . Specifically, if the difference between the temperature distribution F (k) and the temperature distribution F (k−1) is within 5%, for example, it is determined that the convergence has occurred.
If the convergence determination is not made in step S22, the number of repetitions k is increased by 1 (step S23), the process returns to step S17, and the distortion amount ε of each element calculated in step S18 and the step S21 are obtained. A new stress analysis model M (k + 1) in which the elastic modulus / dynamic elastic modulus corresponding to the new temperature distribution F (k) is given to each element of the tire model 10 is created, and a new heat generation distribution P (k + 1) is obtained. After replacing the tan δ value of each element used at the time with tan δ at the temperature corresponding to the temperature distribution F (k), the operation from step S18 to step S21 is performed to obtain a new temperature distribution F (k + 1). In step S22, the temperature distribution F (k + 1) is compared with the temperature distribution F (k) to determine the convergence of the temperature distribution.
The final tire temperature distribution F (n) obtained by repeating such an operation until the convergence determination corresponds to the temperature distribution F (n−1) substantially equal to the temperature distribution F (n). The elastic modulus / dynamic elastic modulus corresponding to the stress and strain obtained using the stress analysis model M (n) giving the elastic modulus / dynamic elastic modulus, and tan δ in the temperature distribution F (n−1) Is the temperature distribution obtained by thermal analysis calculation using the thermal analysis model G (n) having the heat generation distribution P (n) obtained using Prediction accuracy can be greatly improved as compared with the predicted temperature distribution F (0).

As described above, in the best mode, a stress analysis model composed of the tire model 10, the rim model 20, and the road surface model 30 is created, and the density, elastic modulus, and thermal conductivity coefficient are added to the elements of the models 10 to 30, respectively. The material physical properties such as the above are given as initial characteristics, the stress analysis is performed assuming that the temperature distribution is uniform, the stress σ and the strain amount ε acting on each part of the tire are calculated, and the heat generation distribution P (0 ), And thermal analysis calculation is performed based on the heat generation distribution to obtain the temperature distribution F (0) under the initial setting conditions on the surface and inside of the tire. The elastic modulus corresponding to the temperature and the amount of strain obtained in the previous time (when the number of repetitions is (k-1)) of the elastic modulus of each rubber member obtained in advance by experiment in each element of 10 rubber members New stress analysis A model M (k) is created, a stress analysis is performed using the new stress analysis model M (k), and the stress σ and the strain amount ε are calculated again. Then, the heat generation distribution P (k) obtained using the stress σ and the strain amount ε and the value of the tan δ of each rubber member obtained in advance in the experiment in the previously obtained temperature distribution F (k−1). A thermal analysis calculation is performed using a thermal analysis model G (k) having a tire model 40 having a tire temperature distribution F (k) of a new tire. Then, F (k-1) and F (k) are compared to determine the convergence of the temperature distribution. If the convergence is not determined, the elasticity corresponding to the temperature distribution F (k) is determined. A new stress analysis model M (k + 1) and thermal analysis model G (k) are created using the modulus / dynamic elastic modulus and tan δ, and the temperature distribution F (k + 1) is obtained again to determine the convergence of the temperature distribution. By repeating the operation to predict the temperature of the tire surface and the inside, the prediction accuracy can be greatly improved.
Further, when performing the thermal analysis calculation, a three-dimensional model or a two-dimensional analysis model (thermal analysis) in which the tire model 40 and the rim model 50 are added with an internal air model 60 obtained by dividing the air inside the tire into a finite number of elements. Model G (k)) is created, and thermal analysis calculation is performed on the thermal analysis model G (k) to obtain the temperature distribution on the surface and inside of the tire, which is close to the actual heat dissipation process of the tire. Thermal analysis calculation of the state can be performed, and the temperature distribution of the tire can be predicted with higher accuracy.

In the above embodiment, a model in which the same elements are arranged in the tire rotation direction is adopted as the tire model. However, the tire model is modeled in consideration of a tread pattern, or a small overlap of members as in a real tire. If the change in thickness and the change in rigidity are modeled to create a non-uniform model in the rotational direction, the accuracy of the analysis can be further improved.
In addition, since the heat generation of the tire is mainly in the tread portion, the stress analysis performed in step S13 may be performed only with the tire model 10.
In the thermal analysis calculation of the above example, the rim model 50 in which only the rim portion is modeled is used. However, since the materials constituting the rim portion and the disk portion of the wheel have good thermal conductivity, in the thermal analysis calculation, If the entire wheel is modeled, the tire temperature prediction accuracy can be further improved.
Further, in the above example, it is possible to improve the prediction accuracy with respect to tan δ and the elastic modulus / dynamic elastic modulus even if only the temperature dependency is provided. By providing each element with a temperature corresponding to the predicted temperature distribution and a tan δ and an elastic modulus / dynamic elastic modulus corresponding to the calculated strain amount ε, the prediction accuracy can be improved with certainty.
In addition, although the accuracy of thermal analysis calculation is improved if a three-dimensional model is used, there are problems that not only the boundary conditions become complicated, but the calculation time becomes enormous. Since the tire is a rotating body, calculation can be efficiently performed by using a cut sample type or an axially symmetric two-dimensional analysis model (thermal analysis model G (k)) as in this example. .

なお、上記表１の数字は、試験車両を、上記シミュレーションと同様の条件で走行させて熱平衡状態となった時のベルト端の実測温度を１００としたときの予測温度である。
実施例１は熱解析をタイヤモデルのみで行ったもので、実施例２は、図６（ａ）に示すような、タイヤとリムと内部空気をモデル化した熱解析モデルを用いて熱解析を行ったものである。一方、従来例は、ゴム部材の弾性率／動弾性率とを一定にし、かつ、タイヤモデルのみ熱解析を行ったものである。
表１から明らかなように、弾性率／動弾性率とｔａｎδとして、予測した温度のものを用いた実施例１の方が、弾性率／動弾性率とｔａｎδを一定とした従来例よりも、ベルト端の予測温度が高く、しかも、実測温度との差が指数で従来例の約半分であることから、本発明の方法により、タイヤ温度の予測精度が向上していることが確認された。
また、実施例２は、指数が１０３とほぼ実測温度に近い値となったことから、リム及び内部空気を介した放熱を考慮した熱解析を行うことにより、タイヤ温度の予測精度を大幅に向上させることができることが確認された。 FIGS. 5A and 5B show a model in which a tire having a tire size of PSR195 / 65R14 is incorporated in a wheel, and the elastic modulus / dynamic elastic modulus and tan δ given to each element constituting the rubber member are shown in FIGS. As a result of simulation that predicts the tire temperature distribution by rolling on the road surface at a room temperature of 45 ° C., a speed of 60 km / h, and a load of 105%. Is shown in Table 1 below.

The numbers in Table 1 are predicted temperatures when the measured temperature of the belt end when the test vehicle is run under the same conditions as in the simulation and is in a thermal equilibrium state is taken as 100.
In Example 1, thermal analysis was performed only on a tire model, and in Example 2, thermal analysis was performed using a thermal analysis model that models a tire, a rim, and internal air as shown in FIG. It is what I did. On the other hand, in the conventional example, the elastic modulus / dynamic elastic modulus of the rubber member is made constant, and only the tire model is subjected to thermal analysis.
As is apparent from Table 1, the elastic modulus / dynamic elastic modulus and tan δ in Example 1 using the predicted temperature were higher than the conventional example in which the elastic modulus / dynamic elastic modulus and tan δ were constant. Since the predicted temperature at the belt end is high and the difference from the measured temperature is an index that is about half that of the conventional example, it was confirmed that the prediction accuracy of the tire temperature was improved by the method of the present invention.
In Example 2, since the index was 103, which was close to the actually measured temperature, the accuracy of prediction of the tire temperature was greatly improved by conducting a thermal analysis that considered heat dissipation through the rim and internal air. It was confirmed that it can be made.

実施例３は熱解析をタイヤモデルのみで行ったもので、実施例４は、図６（ｂ）に示すような、タイヤとリムと内部空気をモデル化した熱解析モデルを用いて熱解析を行ったものである。また、従来例は、ゴム部材の弾性率／動弾性率とを一定にし、かつ、タイヤモデルのみ熱解析を行ったものである。
表２から明らかなように、Ｔタイプのタイヤにおいても、弾性率／動弾性率とｔａｎδとして予測した温度のものを用いた実施例３の方が、弾性率／動弾性率とｔａｎδを一定とした従来例よりも、それぞれの測定箇所での予測温度が高く、しかも、実測温度との差が指数で従来例の約半分であることから、本発明の方法により、タイヤのタイプによらず、タイヤ温度の予測精度が向上することが確認された。
また、実施例４は、実測温度との指数の差がいずれも上記実施例３の半分以下であり、熱解析をタイヤとリムと内部空気をモデル化したもので行えば、タイヤのタイプによらず、タイヤ温度の予測精度を大幅に向上させることができることが確認された。 Also, as shown in FIG. 6B, a model in which a tire (two types of structures) having a tire size of TBR295 / 75R22.5 is incorporated in a wheel is prepared, and the same method as in the first and second embodiments is performed. The results of predicting the tire temperature distribution are shown in Table 2 below.
In the T-type tire, as the predicted location and the measurement location, the 3 belt end, the ply end, the nylon chafer end (when the ply end is higher than the wire chafer end) or the wire chafer end ( In the case of a tire having a structure in which the end of the wire chafer is higher than the end of the ply;

In Example 3, thermal analysis was performed only on a tire model, and in Example 4, thermal analysis was performed using a thermal analysis model that models a tire, a rim, and internal air as shown in FIG. 6B. It is what I did. In the conventional example, the elastic modulus / dynamic elastic modulus of the rubber member is kept constant, and only the tire model is subjected to thermal analysis.
As is apparent from Table 2, even in the T-type tire, the elastic modulus / dynamic elastic modulus and tan δ are constant in Example 3 using the temperature predicted as the elastic modulus / dynamic elastic modulus and tan δ. Since the predicted temperature at each measurement location is higher than the conventional example, and the difference from the measured temperature is an index that is about half of the conventional example, the method of the present invention does not depend on the tire type, It was confirmed that the prediction accuracy of the tire temperature was improved.
Further, in Example 4, the difference in index from the actually measured temperature is less than half of that in Example 3, and if the thermal analysis is performed by modeling the tire, the rim, and the internal air, it depends on the tire type. Therefore, it was confirmed that the prediction accuracy of the tire temperature can be greatly improved.

  As described above, according to the present invention, the temperature distribution inside and inside the tire can be accurately simulated, so that the durability of the tire can be accurately evaluated, and the design and development efficiency of the tire can be improved. Can be made.

It is a flowchart which shows the temperature prediction method of the tire which concerns on the best form of this invention. It is a figure which shows the stress analysis model used for the load or rolling analysis of this invention. It is a figure which shows the thermal analysis model used for the thermal analysis of this invention. It is a figure for demonstrating the thermal radiation state of the tire in a thermal analysis model. It is a figure which shows the outline | summary of the temperature change of tan-delta and elastic modulus / dynamic elastic modulus. It is a figure which shows an example of the thermal analysis model used for the Example of this invention. It is a figure which shows the tire model used for the temperature distribution prediction of the conventional tire. It is a flowchart which shows the temperature distribution prediction method of the conventional tire.

Explanation of symbols

M (k) Stress analysis model, 10 tire model, 11 tread part,
12 side parts, 13 bead wires, 14 belts, 15 carcass plies,
20 rim model, 30 road surface model,
G (k) thermal analysis model, 40 tire model, 41 tread part,
42 side part, 46 bead part, 50 rim model, 51 flange part,
52 base, 60 internal air model.

Claims (8)

A stress analysis model composed of a three-dimensional tire model or a three-dimensional tire model and a road surface model is created, and an elastic modulus is given to each rubber member element of the tire model, and a load or rolling analysis is performed to analyze each part of the tire. After calculating the stress and strain amount, the tire is subjected to thermal analysis calculation based on the heat generation distribution of the tire obtained using the calculated stress and strain amount of each part of the tire and the loss tangent of the rubber member. A tire temperature distribution prediction method for predicting the temperature distribution inside and outside the tire,
After predicting the temperature distribution of the tire giving the loss tangent of a predetermined temperature to the elements of the rubber members of the tire model, the elasticity of the elastic modulus of the elements of the rubber members of the tire model with the predicted temperature calculating the stress and strain of the tire each unit again performs load or rolling analysis using the new stress analysis model by replacing the rate, in the calculated stress and strain amount and the upper Symbol predicted temperature Rutotomoni seek heat generation distribution of the tire with the loss tangent of the rubber member, the tire model within the air model divided the air inside the tire to a finite number of elements, and, or a portion of the wheel including at least the rim portion all the finite number of elements divided either or both the thermal analysis model is created by adding the Rimumoderu, the tire temperature distribution predicted by performing thermal analysis calculated based on the heat generation distribution There compares the predicted temperature distribution in the new thermal analysis calculations, the predicted temperature distribution in the previous thermal analysis calculations, to determine the convergence of the temperature distribution, when the temperature distribution does not converge Provides the elastic modulus and loss tangent at the temperature predicted by the new thermal analysis calculation to each rubber member of the tire model, and predicts the temperature distribution of the tire to determine the convergence of the temperature distribution operation was repeated until the temperature distribution converges, the temperature distribution prediction method of the tire, characterized in that so as to predict the temperature distribution of the tire.   The thermal conductivity according to the material of the wheel is given as a physical property value to each element of the rim model, and the thermal conductivity of air is given as a physical property value to each element of the internal air model. The tire temperature distribution prediction method described. The convergence determination is performed when the difference between the temperature distribution predicted by the new thermal analysis calculation and the temperature distribution predicted by the previous thermal analysis calculation is within 5%. Alternatively, the tire temperature distribution prediction method according to claim 2 . Temperature distribution method for predicting tire according to any one of claims 1 to 3, characterized in that so as to obtain by experiment the relationship between the elastic modulus and the loss tangent and the temperature given to the respective rubber members. In addition to the predicted temperature distribution, the elastic modulus when performing load or rolling analysis using the new stress analysis model and the loss tangent used when obtaining the heat generation distribution again are added to the previous load. The tire temperature distribution prediction method according to any one of claims 1 to 4 , wherein the tire temperature distribution is set based on a strain amount of each part of the tire obtained by rolling analysis. 6. The tire temperature distribution prediction method according to claim 5 , wherein the relationship between the elastic modulus and loss tangent applied to each rubber member and the amount of strain are obtained in advance by experiments . The tire temperature distribution prediction method according to any one of claims 1 to 6 , wherein the thermal analysis calculation is performed using a cut sample type or an axisymmetric two-dimensional analysis model. A calculation program for predicting and calculating the temperature distribution inside and outside the tire using an analytical model in which the tire is divided into a finite number of elements,
A first step of previously determining the temperature dependence and strain dependence of the elastic modulus and loss tangent of each rubber member constituting the tire;
A second step of creating a stress analysis model comprising a three-dimensional tire model or a three-dimensional tire model and a road surface model;
A third step of giving an elastic modulus and a loss tangent at a predetermined temperature to elements of each rubber member of the tire model;
A fourth step of calculating a stress and a strain amount of each part of the tire by performing a load or rolling analysis using an analysis model given an elastic modulus;
A fifth step of obtaining a strain energy density distribution from the calculated stress and strain amount of each part of the tire and multiplying the density distribution by a loss tangent to obtain a heat generation distribution of the tire;
A part or all of the above three-dimensional tire model, or an internal air model in which the air inside the tire is divided into a finite number of elements in the cut sample type or axisymmetric two-dimensional tire model, and at least part of the wheel including the rim portion the create a thermal analysis model obtained by adding one or both of Rimumoderu divided into a finite number of elements, with the above thermal analysis model, by performing the thermal analysis calculations based on the heat generation distribution, surface and internal of the tire A sixth step for obtaining a temperature distribution of
Based on the temperature distribution, a three-dimensional analysis model for load analysis or rolling analysis in which an elastic modulus in the temperature and strain amount of each rubber member of the tire model is given as a new stress analysis model. And a seventh step of replacing the loss tangent used in obtaining the heat generation distribution with the loss tangent at the temperature of the element;
An eighth step of obtaining a new temperature distribution by repeating the fourth step to the sixth step using the new stress analysis model and the replaced loss tangent;
A ninth step of comparing the temperature distribution obtained in the eighth step and the temperature distribution obtained in the sixth step to determine the convergence of the temperature distribution;
If the convergence determination is not made in the ninth step, the process returns to the seventh step to create a new stress analysis model based on the temperature distribution obtained in the eighth step and Predicting the temperature distribution of a tire, wherein the loss tangent of each element used in the determination is replaced with the loss tangent based on the above temperature distribution, and the temperature distribution is predicted again to confirm the convergence of the temperature distribution Calculation program .

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