JP4437884B2 - Tire performance prediction method, fluid simulation method, tire design method, recording medium, and tire performance prediction program - Google Patents

Description

【０１３７】
表１から理解されるように、実車テストによる雪上加速性能と本実施の形態による雪上性能予測による実施例の予測結果で、パターン間の性能の優劣が一致していることが理解される。このことから本性能予測は設計案の性能予測に有効であり、設計・製造・性能評価のタイヤ開発サイクルの一部を数値解析で置き換えることが可能である。これを活用することによって、タイヤ開発の効率化を行なえることが理解される。
【０１３８】
【発明の効果】
以上説明したように本発明によれば、雪などの弾塑性体や塑性体を少なくとも含む流体を考慮してタイヤの性能を予測したり解析したりすることを可能にし、タイヤ開発の効率を向上できると共に、良好な性能のタイヤを得ることができる、という効果がある。
【図面の簡単な説明】
【図１】本実施の形態にかかり、タイヤの性能評価にあたって、雪上トラクションを予測するプログラムの処理の流れを示すフローチャートである。
【図２】本発明の実施の形態にかかる、タイヤ性能予測方法を実施するためのパーソナルコンピュータの概略図である。
【図３】本実施の形態の計測に用いたタイヤのトレッドパターンを示す線図である。
【図４】雪面上でタイヤ単体の最大トラクションを計測したときの計測結果の一例を示す線図である。
【図５】雪の垂直応力σとせん断強度τの関係を関数式で近似することを説明するための説明図である。
【図６】（Ａ）はタイヤモデルのトレッドパターンを示し、（Ｂ）はタイヤモデル上のせん断応力分布を示した線図である。
【図７】（Ａ）は雪がラグ溝に入り込む状態を示し、（Ｂ）は垂直応力σ−せん断強度τの関係を示す線図である。
【図８】本実施の形態にかかり、空気入りタイヤの性能予測評価プログラムの処理の流れを示すフローチャートである。
【図９】タイヤモデル作成処理の流れを示すフローチャートである。
【図１０】タイヤモデルを示し、（Ａ）はタイヤ径方向断面モデル（Ｂ）はタイヤの３次元モデルを示し、（Ｃ）はパターンをモデル化したイメージを示す斜視図である。
【図１１】モデル化するときの要素を説明するためのイメージ図であり、（Ａ）はゴム部の扱いを説明するためのイメージ図、（Ｂ）補強材の扱いを説明するためのイメージ図である。
【図１２】流体モデルに関係するイメージを示し、（Ａ）はタイヤモデルが載置されるモデル化した流体モデル、路面モデルの斜視図であり、（Ｂ）は実際のタイヤがゆきの上を回動されたときの雪面を示し、（Ｃ）は解析で得られる流体モデルの表面を示すイメージ図である。
【図１３】転動時の境界条件設定処理の流れを示すフローチャートである。
【図１４】非転動時の境界条件設定処理の流れを示すフローチャートである。
【図１５】転動時の境界条件の設定を説明するための説明図である。
【図１６】非転動時の境界条件の設定を説明するための説明図である。
【図１７】境界条件付加処理の流れを示すフローチャートである。
【図１８】タイヤモデルと流体モデルとの干渉領域を示す線図である。
【図１９】流体要素を分割することを説明するための説明図であり、（Ａ）は分割前、（Ｂ）は分割後の流体側を示している。
【図２０】スムースタイヤモデル、パターンモデル(一部）、及びパターンに貼りつける部分のベルトモデルを示す斜視図である。
【図２１】スムースタイヤモデルに貼り付けたパターンモデルの一部がタイヤモデルの転動により推移することを示すイメージ図である。
【図２２】実施例のトレッドパターンを示すイメージ図であり、（Ａ）は第１実施例、（Ｂ）は第２実施例、（Ｃ）は第３実施例を示す。
【符号の説明】
１０ キーボード
１２ コンピュータ本体
１４ ＣＲＴ
２０ 流体モデル
３０ タイヤモデル
ＦＤ フレキシブルディスク（記録媒体）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire performance prediction method, a fluid simulation method, a tire design method, a recording medium, and a tire performance prediction program. The present invention relates to the performance of a tire having a tread pattern used in an automobile or the like, in particular, a fluid such as performance on snow. The present invention relates to a tire performance prediction method for predicting tire performance, a fluid simulation method for simulating a fluid flow around a tire, a tire design method, a recording medium, and a tire performance prediction program.
[0002]
[Prior art]
Conventionally, in the development of pneumatic tires, tire performance is obtained by actually designing and manufacturing tires, mounting them on automobiles, and performing performance tests. I have taken the steps of starting over. Recently, due to the development of numerical analysis methods such as the finite element method and the computer environment, for example, tire performance for paved road surfaces is predicted by performing load analysis and rolling analysis on tire rigid road surfaces with a computer. It has become possible, and several performance predictions can be made from here.
[0003]
The present applicant has proposed a tire performance prediction method in the case where the tire is used via a fluid, such as the drainage performance of the tire (see JP 2001-9838 A). This technology makes it possible to predict performance by numerical analysis of complex phenomena that require coupled analysis of water and tires, represented by drainage analysis of tread patterns. As a result, it is possible to replace part of the tire development cycle in design, manufacturing, and performance evaluation with numerical analysis for dry performance on paved road surfaces without fluid and wet performance between roads through water Thus, the development period has been shortened.
[0004]
[Problems to be solved by the invention]
However, for performance on snowy roads, it is still difficult to perform numerical modeling of snow and coupled analysis of snow and tires, so it is still difficult to predict performance for tire development. Currently. Specifically, it is known that snow has only a very low breaking strength in fresh snow with no load, but the breaking strength increases when it is stepped on. For example, snow that has been squeezed on the tire ground contact surface can generate a driving force (or braking force) necessary to travel (or stop) the vehicle. This indicates that snow has completely different properties depending on the load state, and it is very difficult to numerically model snow, which is essential for numerical analysis.
[0005]
The physical properties of snow have been studied by scientists and scientists (see “Basic Snow and Ice Study Course I: Structure and Physical Properties of Snow and Ice”, Kiichi Maeno / Toshio Kuroda, Kokon Shoin, etc.)・ The relationship between density and physical properties is becoming clear. However, there is still a big gap between these studies and actual engineering applications from the viewpoint of numerical modeling of snow to predict on-snow performance used for tire tread pattern design.
[0006]
Research on vehicle behavior on snow is also underway from the viewpoint of engineering applications (CRREL REPORT 90-9, "USA Cold Regions Research and Engineering Laboratory", CRREL Report 90-9, "Wheels and Tracks in SIlow Validation Study of the CRREL Shallow Snow Mobilly Model ", etc.). This technology conducts vehicle traction tests on snowy road surfaces, finds the relationship between snow normal stress and snow shear strength, and finds that these relational expressions can be expressed almost linearly regardless of vehicle, tire, and snow surface differences. Is shown. This is useful knowledge from the perspective of the relationship between snow and vehicles widely, but there is no specific method of use or efficient operation method that can be incorporated into the tire development cycle in terms of utilization in tire tread pattern design. It has not reached the practical stage.
[0007]
Furthermore, practical numerical analysis has not yet been achieved for both snow physical property research and snow engineering applied research. In particular, there is no example of a complicated numerically coupled analysis technique of a structure and snow represented by an analysis in which a tire having a tread pattern rolls on a snowy road.
[0008]
For these reasons, the current performance on the snow is not efficiently designed and evaluated using numerical analysis technology.
[0009]
In consideration of the above facts, the present invention makes it easy to predict the performance of a tire that is actually used via a fluid such as snow. It is an object to obtain a tire performance prediction method, a fluid simulation method, a tire design method, a recording medium, and a tire performance prediction program capable of obtaining a tire.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention predicts the performance of a tire that is actually used via a fluid such as snow, and can analyze the behavior of a fluid such as snow particularly when the tire is in contact with and rotating. The development has been streamlined to facilitate the provision of tires with good performance.
[0011]
  Specifically, the tire performance prediction method of the present invention includes the following steps (a) to (f).
(A) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid including at least a plastic body, and a part or all of the tire model is at least Contact with someIn addition, the elasto-plastic body or plastic body is modeled by approximating the relationship between the normal stress applied to the elasto-plastic body or plastic body and the shear strength of the elasto-plastic body or plastic body with a functional expression.Determining a fluid model;
(B) executing deformation calculation of the tire model;
(C) performing flow calculation of the fluid model;
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (b) and the fluid model after the flow calculation in the step (c), the boundary condition regarding the recognized boundary surface is set as the tire model and The calculation of the step (b) and the step (c) is performed on the tire model and the fluid model after being applied to the fluid model and the boundary condition is applied.Predetermined timerepeatLet me calculateThe fluid modelThePseudo-fluid stateYouStep.
(E) A step of obtaining a physical quantity generated in at least one of the tire model and the fluid model in step (c) or step (d).
(F) Predicting tire performance from the physical quantity.
[0012]
That is, in the tire performance prediction method of the present invention, first, in order to predict the performance of a tire design plan (change of tire shape, structure, material, pattern, etc.) to be evaluated, the tire design plan is used as a model for numerical analysis. Drop it. That is, a tire model (numerical analysis model) capable of numerical analysis is created. Furthermore, modeling of a fluid (including a road surface) related to a target performance including at least an elastoplastic body or a plastic body, creating a fluid model (numerical analysis model), a tire and a fluid (including a road surface) Possible), and numerically predict the target performance. Whether the tire design plan is acceptable or not is determined from the prediction result. If the result is good, the design plan is adopted, or a tire of this design plan is manufactured and performance evaluation is performed. If the result is satisfactory, the design plan is adopted. If the prediction performance (or actual measurement performance) by the design plan is insufficient, a part or all of the design plan is corrected, and the numerical analysis model is created again. With these procedures, the number of times of manufacturing and evaluating the performance of the tire is extremely small, so that the tire development can be made more efficient.
[0013]
Therefore, in order to develop a tire based on performance prediction, an efficient and accurate numerical analysis model for predicting tire performance is indispensable. Therefore, in the present invention, in order to predict tire performance, in step (a), at least a tire model having a pattern shape that can be deformed by at least one of ground contact and rolling, and an elastoplastic body or a plastic body is provided. A fluid model that is partially or wholly filled with a fluid that contains and that contacts at least a portion of the tire model. A road surface model can be further determined. In step (b), deformation calculation of the tire model is executed, and in step (c), flow calculation of the fluid model is executed. In step (d), a boundary surface between the tire model after the deformation calculation in step (b) and the fluid model after the flow calculation in step (c) is recognized, and the boundary condition related to the recognized boundary surface is determined as the tire model. Then, the calculation of step (b) and step (c) is repeated for the tire model and the fluid model that have been applied to the fluid model and the boundary condition has been applied, until the fluid model is in a pseudo-flow state. In step (e), a physical quantity generated in at least one of the tire model and the fluid model in step (c) or step (d) is obtained, and in step (f), tire performance is predicted based on the physical quantity.
[0014]
When a fluid such as snow is applied, the internal structure (structure formed by cavities and ice crystals) changes and deforms. However, even if the load is unloaded, the deformation does not recover and return to the initial shape. For this reason, in order to express a fluid such as snow as a numerical model, the fluid such as snow is a plastic body. In addition, characteristics as an elastic body are given as necessary, and modeling is performed so as to generate an appropriate reaction force when a load is applied. Thus, by modeling a fluid such as snow as an elastoplastic body or a plastic body (rigid plastic body), the tire performance can be predicted with high accuracy.
[0015]
  Also bookinventionsoThe fluid model models an elastic-plastic body or plastic body by approximating the relationship between the normal stress applied to the elastic-plastic body or plastic body and the shear strength of the elastic-plastic body or plastic body by a functional expression.The
[0016]
An elastoplastic body or plastic body, which is a fluid such as snow, has a property of being squeezed by normal stress and increasing the shear strength. For this reason, by approximating these relationships with functional equations and modeling elastoplastic bodies or plastic bodies that are fluids such as snow, elastoplastic bodies that are fluids such as snow that are stepped on the ground surface by a tread pattern Different vertical stresses can be calculated at each location for a body or a plastic body, and a shear strength corresponding thereto can be applied to an elastoplastic body or plastic body that is a fluid such as snow. As a result, even if it is an elasto-plastic body or plastic body that is a fluid such as snow that has been squeezed by a complicated tread pattern, it is perpendicular to the elasto-plastic body or plastic body that is a fluid such as snow at each location on the ground plane. By obtaining the stress and considering the shear strength corresponding to the stress, the longitudinal force or lateral force generated by the entire ground plane can be calculated. In this way, a functional equation approximates the relationship between the vertical stress applied to an elastic-plastic body or plastic body that is a fluid such as snow in a fluid model such as a snow road surface and the shear strength of an elastic-plastic body or plastic body that is a fluid such as snow. By doing so, the tire performance can be predicted with high accuracy.
[0017]
  SaidThe fluid model is to model an elastoplastic body or plastic body by approximating the relationship between the normal stress applied to the elastoplastic body or the shear strength of the elastoplastic body or plastic body with a functional expression of a second or higher order polynomial.CanThe
[0018]
In order to predict the difference in performance of elastoplastics or plastics such as performance on snow due to differences in tire tread pattern design, a numerical model of elastoplastics or plastics that is a fluid such as snow with high precision is required. . In particular, since the values of vertical stress applied to elasto-plastic bodies or plastic bodies, which are fluids such as snow, vary from place to place even within the ground plane, such as groove search and block shape of the tread pattern, express differences in performance due to differences in tread patterns. Therefore, it is necessary to express the relationship between the elastoplastic body that is a fluid such as snow or the vertical stress applied to the plastic body and the shear strength of the elastoplastic body or the plastic body that is a fluid such as snow with high accuracy. Therefore, the fluid model uses a quadratic or higher order polynomial to express the relationship between the vertical stress applied to the elastic body or plastic body that is a fluid such as snow and the shear strength of the elastic body or plastic body that is a fluid such as snow. Express. In addition, it is still more preferable if it is 3rd order or more. Further, it may be expressed by a function (Fourier series or the like) having an accuracy substantially equal to or higher than that of a second-order or higher order polynomial.
[0019]
  SaidThe fluid model is to set a plurality of measurement conditions on the surface of a water-absorbing material including an elastic-plastic body or a material corresponding to the plastic body under substantially the same conditions in a tire test apparatus for measuring the performance of a single tire, and By using at least one of a plurality of tires of the same or different types and measuring the maximum traction of the tire in advance, calculating the contact area of the tire at the time of measurement, based on the maximum traction and the contact area, Calculate the shear strength of the elastoplastic body or plastic body on the surface of the water-absorbing material and the normal stress applied to the elastoplastic body or plastic body, and calculate the relationship between the calculated normal stress and shear strength of the elastoplastic body or plastic body as a function. Model an elastoplastic body or plastic body by approximating with an equationCanThe
[0020]
Performance evaluation tests are carried out without depending on the season and location (for example, the location where snow falls in winter) as one of the motives for improving tire development efficiency by predicting the performance of elasto-plastic bodies or plastic bodies that are fluids such as snow. For example, there is a demand for design and evaluation at any time throughout the year. The same applies to elastoplastic bodies that are fluids such as snow or numerical modeling of plastic bodies, such as the material properties of elastoplastic bodies or plastic bodies that are fluids such as snow (for example, the normal stress-shear strength of snow). It is not preferable that the time and place where the relational expression is measured is limited. Further, since it is costly to actually perform a test on a vehicle equipped with a test tire, it is preferable that the performance of an elasto-plastic body or plastic body, which is a fluid such as snow, can be evaluated with a testing machine of a single tire.
[0021]
Therefore, in a tire testing apparatus for measuring the performance of a single tire, a plurality of measurement conditions can be set on a water-absorbing material surface (for example, on a snow surface) containing an elastic-plastic body or a material corresponding to the plastic body under substantially the same conditions. The maximum traction of the tire is measured in advance by at least one of setting and using with a plurality of tires of the same or different types. For example, a technique described in Japanese Patent Application Laid-Open No. 2001-74613, which has already been proposed by the present applicant, can be adopted as a method for measuring the performance on the snow of a single tire by an indoor test. The water-absorbing material surface is a surface including an elastic-plastic material corresponding to a fluid such as snow or a material corresponding to the plastic material, and refers to, for example, a region in which a granular water-absorbing material is spread.
[0022]
In other words, in order to measure the relationship between normal stress and shear strength, which is a material property of an elastoplastic body that is a fluid such as snow, or the like, the normal stress of the elastoplastic body or plastic body is measured using multiple measurement conditions such as internal pressure. The shear strength of the elastoplastic body or plastic body may be measured by changing the vertical stress of the elastoplastic body or plastic body according to the difference in tread pattern or contact pressure distribution using a plurality of tire types. During these measurements, the elasto-plastic body or plastic body, which is a fluid such as snow, is controlled to a uniform and constant state, and the maximum traction of the tire is achieved on the surface of the water-absorbing material (on the snow surface) that can be regarded as substantially the same conditions. measure.
[0023]
Calculate the contact area of the tire at the time of measurement, and calculate the shear strength of the elastic-plastic body or plastic body on the surface of the water-absorbing material and the normal stress applied to the elastic-plastic body or plastic body based on the maximum traction and the contact area. Then, the elastic-plastic body or the plastic body is modeled by approximating the calculated relationship between the normal stress of the elastic-plastic body or the plastic body and the shear strength by a functional expression.
[0024]
Since the maximum traction is the shear force generated by snow on the ground contact surface, if the maximum traction is divided by the corresponding ground contact area for each tire type / measurement condition, shearing of an elastoplastic body or plastic body that is a fluid such as snow The intensity can be calculated. In addition, the normal stress applied to the elastic-plastic body or plastic body, which is a fluid such as snow, can be calculated from the tire load and the ground-contact area. Note that the method for calculating the normal stress and shear strength of an elastoplastic body or plastic body that is a fluid such as snow is not limited to the method given in the example, and the location of the ground plane in consideration of the ground pressure distribution of the tire. Other calculation methods such as calculating the normal stress every time may be used. The elastoplastic body or plastic that is a fluid such as snow controlled indoors by approximating the relationship between the normal stress and shear strength of the elastoplastic body that is the fluid such as snow or the like by a functional equation. Body material properties can be obtained. Also, if this is applied, tire development will be carried out so that the snow quality of various seasons and regions can be reproduced indoors and the material characteristics of each snow can be obtained, so that performance can be demonstrated against various snow quality. It can also be used.
[0025]
  SaidStep (a) further defines a road surface model in contact with the fluid model.CanThe
[0026]
The fluid model at least in contact with the tire model can include a road surface model.
[0027]
  SaidStep (b) is repeated for a predetermined time.CanThe
[0028]
  SaidThe predetermined time is 10 msec or less.
[0029]
  SaidStep (c) is to calculate repeatedly for a certain timeCanThe
[0030]
  The fixed time is 10 msec or less.
[0031]
  In the present invention,Step (d) is repeatedly calculated for a predetermined time..
[0032]
  SaidThe predetermined time is 10 msec or less.
[0033]
At least one of the deformation calculation and the flow calculation of the tire model can be repeated. In the deformation calculation of the tire model, an elapsed time of a predetermined time for repeated calculation can be 10 msec or less, preferably 1 msec or less, more preferably 1 μ · sec or less. Further, in the flow calculation, an elapsed time of a certain time for performing the repeated calculation can be 10 msec or less, preferably 1 msec or less, more preferably 1 μ · sec or less. If this elapsed time is too long, the fluid in the fluid model will not be in a pseudo-flow state that matches the behavior of the tire, and the accuracy as a numerical model will deteriorate. For this reason, it is necessary to adopt an appropriate value for the elapsed time. Further, iterative calculation can be performed even in the calculation until the fluid model becomes a pseudo-flow state. In this calculation, the elapsed time of the predetermined time for performing the repeated calculation can be 10 msec or less, preferably 1 msec or less, more preferably 1 μ · sec or less.
[0034]
  SaidWhen rolling the tire model, in step (a), the calculation is performed at the time of internal pressure filling and load calculation, and the tire model to which rotational displacement or speed or linear displacement is applied is determined.CanThe
[0035]
  SaidWhen rolling the tire model, in step (a), the fluid freely flows out on the upper surface of the fluid model, and the fluid does not flow in and out on other surfaces other than the upper surface of the fluid model. Assign inflow / outflow conditions to the fluid modelCanThe
[0036]
  When not rolling the tire model, in step (a), the calculation at the time of filling with internal pressure is performed, and the tire model subjected to the load calculation is determined after the calculation.CanThe This is effective in evaluating the rock brake performance on snow. Moreover, since snow has a property close to water depending on the moisture content, it may be lifted during running, which is also effective in evaluating this.
[0037]
  SaidWhen the tire model is not rolled, in step (a), the fluid flows in at the front speed of the fluid model, and the fluid freely flows out from the rear surface and the upper surface of the fluid model. Give the fluid model an inflow / outflow condition indicating that the fluid does not flow in and out on the side and bottom surfaces.CanThe
[0038]
The deformation calculation of the tire model in the step (b) can be performed when the deformation is given by at least one of the ground contact and the rolling. In this case, at least one of grounding and rolling may be determined as an input. When rolling the tire model, in step (a), calculation is performed at the time of internal pressure filling and load calculation, and a tire model to which rotational displacement or speed or linear displacement is applied is determined. Further, when the boundary condition regarding the recognized boundary surface is given to the tire model and the fluid model, the fluid model can be determined so that the fluid exists on the road surface model side from the boundary surface.
[0039]
  The tire model must have a partial patternCanThe
[0040]
The tire model may have a pattern partially. Further, the road surface model can reproduce the actual road surface state by selecting the friction coefficient μ to an appropriate value by DRY, WET, on ice, on snow, non-paved, etc. according to the road surface state.
[0041]
  SaidIn step (d), an interference portion between the tire model and the fluid model is generated, the interference portion is recognized, and the fluid model is divided into fluid elements with the tire model surface as a boundary surface.CanThe
[0042]
When applying the boundary condition, it is important that the fluid model recognizes the surface of the tire model as the boundary surface of the fluid. However, the microelements constituting the fluid model are always made sufficiently small with respect to the tire (especially pattern) model. Thus, it is difficult to increase the components of the fluid model, resulting in an increase in calculation time. Therefore, the minute elements that make up the fluid model are taken to a certain extent to prevent an increase in calculation time, and the tire model and the fluid model have an interference part (overlap), and the interference part is recognized and the tire model surface is recognized. It is preferable that the boundary surface between the tire model and the fluid model is recognized with high accuracy by dividing the fluid model with reference to the boundary surface.
[0043]
  SaidThe fluid model includes at least snow, uses the contact area of the tire model as the physical quantity, and predicts the tire snow performance as the tire performance.CanThe
[0044]
  SaidThe fluid model includes snow, and the normal stress and shear force of the fluid model on the snow road surface of the fluid model are used as the physical quantity, and the tire performance on the snow is predicted as the tire performance.CanThe
[0045]
The fluid model includes at least snow, and the contact area of the tire model is used as the physical quantity, and the tire snow performance can be predicted as the tire performance. The fluid model includes snow, and the normal stress and shear force of the fluid model on the snow road surface of the fluid model are used as the physical quantity, so that the tire performance on the snow can be predicted as the tire performance.
[0046]
  otherThe fluid simulation method of the present invention includes the following steps (a) to (d).
(A) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid containing at least a plastic body, and a part or all of the tire model is at least Contact with someIn addition, the elasto-plastic body or plastic body is modeled by approximating the relationship between the normal stress applied to the elasto-plastic body or plastic body and the shear strength of the elasto-plastic body or plastic body with a functional expression.Determining a fluid model;
(B) executing deformation calculation of the tire model;
(C) executing a flow calculation of the fluid model;
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (b) and the fluid model after the flow calculation in the step (c), and the boundary condition relating to the recognized boundary surface is defined as the tire model and Steps (b) and (c) are calculated for the tire model and the fluid model after the boundary condition is applied to the fluid model.Predetermined timerepeatLet me calculateThe fluid modelThePseudo-fluid stateYouStep.
[0047]
When simulating the behavior of the fluid around the tire, a tire model having a pattern shape that can be deformed by at least one of ground contact and rolling in step (a) and a fluid containing at least an elastoplastic body or a plastic body. Defining a fluid model that is partially or wholly filled and in contact with at least a portion of the tire model, performing deformation calculation of the tire model in step (b), and calculating fluid flow of the fluid model in step (c) In step (d), the boundary surface between the tire model after the deformation calculation in step (b) and the fluid model after the flow calculation in step (c) is recognized, and the recognized boundary surface Boundary conditions are applied to the tire model and fluid model, and the tire model and fluid model after the boundary conditions are applied If the calculation of step (b) and step (c) is repeated until the fluid model is calculated until it becomes a pseudo-flow state, the fluid flow around the tire is evaluated, the smoothness of the flow, It is possible to predict the occurrence of turbulence and use it for tire performance prediction.
[0048]
  otherThe tire designing method of the invention includes the following steps (1) to (7).
(1) A plurality of tire models having a pattern shape capable of being deformed by at least one of ground contact and rolling, and the tire model partially or entirely filled with an elastic-plastic body or a fluid containing at least a plastic body. In contact with at least part ofIn addition, the elasto-plastic body or plastic body is modeled by approximating the relationship between the normal stress applied to the elasto-plastic body or plastic body and the shear strength of the elasto-plastic body or plastic body with a functional expression.Determining a fluid model;
(2) A step of executing deformation calculation of the tire model.
(3) A step of performing flow calculation of the fluid model.
(4) Recognizing a boundary surface between the tire model after the deformation calculation in the step (2) and the fluid model after the flow calculation in the step (3), the boundary condition regarding the recognized boundary surface is set as the tire model and The calculation of the step (2) and the step (3) is performed on the tire model and the fluid model after being applied to the fluid model and the boundary condition is applied.Predetermined timerepeatLet me calculateThe fluid modelThePseudo-fluid stateYouStep.
(5) A step of obtaining a physical quantity generated in at least one of the tire model and the fluid model in the step (3) or the step (4).
(6) A step of predicting tire performance from the physical quantity.
(7) A step of designing a tire based on a tire model having a tire performance selected from the plurality of tire performances.
[0049]
When designing a tire, a plurality of tire models having a pattern shape that can be deformed by at least one of ground contact and rolling in step (1), and an elastic-plastic body or a fluid containing at least a plastic body or Defining a fluid model that is fully filled and in contact with at least a portion of the tire model, performing deformation calculation of the tire model in step (2), and performing flow calculation of the fluid model in step (3). In step (4), the boundary surface between the tire model after the deformation calculation in step (2) and the fluid model after the flow calculation in step (3) is recognized, and the boundary condition regarding the recognized boundary surface is determined. Step (2) and step (2) are performed on the tire model and the fluid model after being given to the tire model and the fluid model and after the boundary condition is given. ) Is repeated until the fluid model becomes a pseudo-flow state, and the physical quantity generated in at least one of the tire model and the fluid model in step (3) or step (4) in step (5) is calculated. In step (6), the tire performance is predicted based on the physical quantity, and in step (7), the tire is designed based on the tire model of the tire performance selected from the plurality of tire performances. It is possible to evaluate the flow of the tire, predict the smoothness of the flow and the occurrence of turbulence, and use it for the design while predicting the tire performance.
[0050]
  otherAccording to the present invention, there is provided a recording medium on which a tire performance prediction program for predicting tire performance by a computer is recorded, and includes the following steps.
(A) a tire model having a pattern shape that can be deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid containing at least a plastic body, and a part or all of the tire model is at least Contact with someIn addition, the elasto-plastic body or plastic body is modeled by approximating the relationship between the normal stress applied to the elasto-plastic body or plastic body and the shear strength of the elasto-plastic body or plastic body with a functional expression.Determining a fluid model;
(B) A step of performing deformation calculation of the tire model.
(C) performing flow calculation of the fluid model.
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (B) and the fluid model after the flow calculation in the step (C), and the boundary condition regarding the recognized boundary surface is set as the tire model and The calculation of the step (B) and the step (C) is performed for the tire model and the fluid model after being applied to the fluid model and the boundary condition is applied.Predetermined timerepeatLet me calculateThe fluid modelThePseudo-fluid stateYouStep.
[0051]
When the tire performance is predicted by a computer, a tire model having a pattern shape that can be deformed by at least one of ground contact and rolling in step (A), and part of the fluid including at least an elastoplastic body or a plastic body Alternatively, a fluid model that is completely filled and that contacts at least a part of the tire model is determined, a deformation calculation of the tire model is performed in step (B), and a flow calculation of the fluid model is performed in step (C). And executing step (D), recognizing a boundary surface between the tire model after the deformation calculation in step (B) and the fluid model after the flow calculation in step (C), and the boundary relating to the recognized boundary surface The tire model and the fluid model after the condition is applied to the tire model and the fluid model and the boundary condition is applied are described above. Data is collected by repeating the calculation of the step (B) and the step (C) to cause the fluid model to be calculated until it becomes a pseudo-fluid state, storing the tire performance prediction program including each step in a storage medium, and executing the program. By doing so, it can be used for comparison with past performance evaluation and for future data accumulation.
[0052]
When the tire performance is predicted by a computer, the tire performance can be predicted easily and simply by causing the computer to execute the following program.
[0053]
  OtherThe present invention includes a tire performance prediction program including the following steps for predicting tire performance by a computer.
(I) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid including at least a plastic body, and a part or all of the tire model is at least Contact with someIn addition, the elasto-plastic body or plastic body is modeled by approximating the relationship between the normal stress applied to the elasto-plastic body or plastic body and the shear strength of the elasto-plastic body or plastic body with a functional expression.Determining a fluid model;
(II) A step of executing deformation calculation of the tire model.
(III) A step of executing flow calculation of the fluid model.
(IV) Recognizing a boundary surface between the tire model after the deformation calculation in the step (II) and the fluid model after the flow calculation in the step (III), and the boundary condition related to the recognized boundary surface is defined as the tire model and The calculation of the step (II) and the step (III) is performed on the tire model and the fluid model after the boundary condition is applied to the fluid model.Predetermined timerepeatLet me calculateThe fluid modelThePseudo-fluid stateYouStep.
[0054]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0055]
In the first embodiment, the present invention is applied to performance prediction of a pneumatic tire.
[0056]
FIG. 2 shows an outline of a personal computer for performing performance prediction of the pneumatic tire of the present invention. The personal computer includes a keyboard 10 for inputting data and the like, a computer main body 12 that predicts tire performance according to a pre-stored processing program, and a CRT 14 that displays calculation results of the computer main body 12 and the like.
[0057]
The computer main body 12 includes a flexible disk unit (FDU) into which a flexible disk (FD) as a recording medium can be inserted and removed. Note that processing routines and the like described later can be read from and written to the flexible disk FD using the FDU. Therefore, a processing routine to be described later may be recorded in the FD in advance and the processing program recorded in the FD may be executed via the FDU. Further, a mass storage device (not shown) such as a hard disk device is connected to the computer main body 12, and the processing program recorded on the FD is stored (installed) in the mass storage device (not shown) and executed. Also good. Recording media include optical discs such as CD and DVD, and magneto-optical discs such as MD and MO. When these are used, instead of or in addition to the FDU, a CD-ROM device, a CD-RAM device, a DVD- A ROM device, DVD-RAM device, MD device, MO device, or the like may be used.
[0058]
First, an outline of a process for predicting the on-snow performance of a tire for a fluid containing snow when performing tire performance prediction evaluation will be described.
[0059]
FIG. 1 shows a processing routine of a performance prediction evaluation program when snowy traction prediction is adopted as the on-snow performance of a tire. In this process, actual snow quality measurement is performed, and after inputting the snow quality, a predicted value of on-snow performance is obtained by numerical calculation. In the numerical calculation, snow and a tire are coupled, a shear stress distribution corresponding to a contact pressure acting on the tire is obtained, and then a traction is obtained to obtain a predicted value.
[0060]
Specifically, in step 300 of FIG. 1, snow quality is measured by a tire test, and the measurement results are compiled into a database. The design and evaluation based on the performance evaluation test of actual road surface conditions including snow, which is limited to the winter season, such as when a test tire is mounted on a vehicle, is highly dependent on the season. Although it is possible to carry out an actual test as described above, in this embodiment, the material characteristics (performance on snow) of snow are measured by an indoor testing machine for a single tire. As a method for measuring the performance on the snow of the tire alone by an indoor test, a technique already proposed by the present applicant can be adopted (see Japanese Patent Application Laid-Open No. 2001-74613). In this technology, as an on-snow test equipment for tires, artificial snow made of granular water-absorbing material added with water and swollen is arranged in layers, and the artificial snow layer is rotatably provided and the tire is supported for rolling. The test is performed by changing the pressure for pressing the tire onto the artificial snow layer, changing the driving force and braking force of the tire, and changing the slip angle of the tire.
[0061]
In the present embodiment, the relationship between the normal stress of snow and the shear strength is measured as the material characteristics of snow. This relationship can be achieved by changing the vertical stress of snow using multiple measurement conditions such as the internal pressure of the tire to be measured, or by changing the vertical stress of snow due to differences in tread pattern and ground pressure distribution using multiple tire types. What is necessary is to measure the shear strength of snow.
[0062]
In the present embodiment, a case where snow is assumed as a fluid in contact with the tire will be described, but the present invention is not limited to this. The fluid may include at least an elasto-plastic material or a plastic material, and examples thereof include a fluid containing particulate ice blocks, a fluid containing soil and mud, and frosted soil and mud.
[0063]
In FIG. 3, the tread pattern of the measurement tire used for the measurement of this Embodiment was shown. 3A is a tread pattern in which blocks are closely arranged, FIG. 3B is a tread pattern in which a plurality of blocks are closely arranged and a plurality of blocks are spaced apart, and FIG. 3C is a plurality of blocks in which a plurality of blocks are closely arranged. An example of a tread pattern having a large gap is shown.
[0064]
In the measurement, first, snow (or a material corresponding to snow) is controlled to a uniform and constant state to form a snow surface that can be regarded as substantially the same condition, and the maximum traction of the tire alone is measured on the snow surface. An example of the measurement result is shown in FIG. Next, the tire contact area under the measurement conditions is measured.
[0065]
That is, since the maximum traction is a shearing force generated by snow on the contact surface, the maximum traction T is divided by the contact area S of the corresponding tire (T / S) for each tire type and test condition. The shear strength τ (= T / S) can be calculated. Further, the normal stress σ (= M / S) applied to the snow on the contact surface can be calculated from the tire load M and the contact area S.
[0066]
Since one measurement result can be obtained for the tire measurement and calculation described above, the measurement result of snow quality for various tires can be obtained by measuring a plurality of the same tire and also by measuring different tires or the same type of tires. Obtainable. This measurement result is made into a database. Thereby, snow quality data can be freely used.
[0067]
Note that the method for calculating the normal stress and shear strength of snow is not limited to the method given as an example, and other methods such as calculating the normal stress for each location of the contact surface in consideration of the contact pressure distribution of the tire. A calculation method may be used.
[0068]
In the next step 302, the relationship between the normal stress σ of snow and the shear strength τ is approximated by a function. Here, the relationship between the normal stress σ and the shear strength τ of snow obtained in step 300 is approximated by a functional expression, thereby obtaining highly accurate snow material characteristics controlled indoors. Specifically, the snow normal stress σ data and the shear strength τ data stored in the database in step 300 are shown in FIG. Plot on a graph with the shear strength τ as the axis. Using this result, the relationship between the normal stress σ and the shear strength τ of snow is approximated as a function. This approximation can be approximated by a least square method or a method based on a polynomial formulation. In the present embodiment, approximation is performed using the following cubic polynomial.
τ = c1 + c2 · σ + c3 · σ²+ C4 · σ^Three
However, c1, c2, c3, and c4 are coefficients.
[0069]
This approximate expression may be stored as the relationship between the normal stress σ of the snow and the shear strength τ, that is, as the material characteristics of the snow.
[0070]
Note that the above approximation is not limited to a third-order polynomial, and is preferably a third-order or higher polynomial in order to improve accuracy. Further, it may be expressed by a function (such as a Fourier series) having an accuracy substantially equal to or higher than that of a second-order or higher order polynomial.
[0071]
In the next step 304, snow is modeled as an elasto-plastic body based on a functional expression of σ-τ, and a fluid model (snow model) and a tire model are coupled. Here, although details will be described later, first, after creating a tire model of a design plan of a tire to be evaluated (change of tire shape, structure, material, pattern, etc.), a fluid model including snow is created.
[0072]
The material model of the snow road surface expressed by the fluid model models snow as an elasto-plastic body or a plastic body. This is because when snow is loaded, the internal structure (structure formed by cavities and ice crystals) changes and deforms, but even when unloaded, the deformation does not recover and return to the initial shape. For this reason, in order to express this as a numerical model, snow is treated as a plastic body. Further, if necessary, a characteristic as an elastic body is also provided, and modeling is performed so that an appropriate reaction force is generated when a load is applied.
[0073]
When the creation of the fluid model is completed, a road surface model in which the road surface condition covered by the fluid is input is given, and the transient flow related to the tire performance prediction is simulated in consideration of the analysis boundary between the tire model and the fluid model. In order to create the tire model, the tire model is subjected to deformation calculation and fluid calculation (flow calculation) based on the rotational displacement and linear displacement of the tire model, and the load load.
[0074]
In the next step 306, the normal stress σ is calculated for each element of the fluid model (snow model), and the shear strength τ with respect to the vertical stress σ is calculated by the above function formula. The fluid model is divided into small elements and used for numerical analysis. The vertical stress σ is calculated for each element at this time, and the shear strength τ with respect to the vertical stress σ is calculated using the above functional formula.
[0075]
In the next step 308, a shear stress distribution acting on the tire model is calculated. In step 306, since the relationship between the vertical stress σ and the shear strength τ for each minute element is obtained, in step 308, a shear stress distribution given by a fluid model composed of an assembly of each minute element, that is, acting on the tire model is obtained.
[0076]
FIG. 6 shows the vicinity of the tread pattern of the tire model. 6A shows the tread pattern of the tire model, and FIG. 6B shows the shear stress distribution on the tire model. In the figure, a hatched area SNa indicates a portion where shear stress is generated. The tire traction on the snow is obtained by integrating the shear stress over the entire contact surface. It can be understood from FIG. 6B that traction is generated in the lug groove portion. That is, snow enters the lug groove of the tire and this snow enters and generates traction. Liquefied snow and moisture are scattered around the snow. Accordingly, the shear stress distribution is obtained corresponding to the lug groove.
[0077]
As shown in FIG. 7A, the snow becomes snow (1) (hatched diagram in FIG. 7) entering the lug groove and snow (2) which is stepped on. As shown in FIG. 7B, these snows differ in the relationship of normal stress σ-shear strength τ. Therefore, an accurate vertical stress σ (= tire contact pressure on the snow surface) can be obtained for each position of the block surface, lug groove, etc. according to the tread pattern. Since the shear strength τ corresponding to the normal stress σ is obtained by the above approximate expression, the shear stress which is the relationship between them can be obtained.
[0078]
Since the traction is obtained by integrating the shear stress, in the next step 310, the traction is calculated by integrating the shear stress obtained in the above step 308. The obtained traction value is output as a predicted value for snow traction in the next step 312.
[0079]
In this way, it is possible to reproduce the snow quality of various times and regions indoors, obtain the material characteristics of each snow, and obtain traction from the data, so various tires that rotate on snow can be used in various ways. Performance against snow quality can be predicted.
[0080]
The predicted value is expressed numerically to the extent that the predetermined allowable values and allowable characteristics are matched to each output value and distribution of output values using the output value and output value distribution of the prediction result. The evaluation value can be determined by.
[0081]
Next, the performance prediction evaluation process of a pneumatic tire based on the above snowy traction prediction will be described in detail.
[0082]
FIG. 8 shows a processing routine of the performance prediction evaluation program of this embodiment. In step 100, a design plan (change of tire shape, structure, material, pattern, etc.) of the tire to be evaluated is determined. In step 100, the measurement results in the database and the relationship between the normal stress σ and the shear strength τ, that is, the approximate expression are read (steps 300 and 302 in FIG. 1).
[0083]
In the next step 102, a tire model is created in order to drop the tire design proposal into a numerical analysis model. The creation of the tire model differs slightly depending on the numerical analysis method used. In this embodiment, a finite element method (FEM) is used as a numerical analysis method. Therefore, the tire model created in step 102 is divided into a plurality of elements by element division corresponding to the finite element method (FEM), for example, mesh division, and the tire is created based on a numerical / analytical method. This is a digitized input data format for computer programs. This element division refers to dividing an object such as a tire, a fluid, and a road surface into several small (finite) small parts. After calculating every small part and calculating all the small parts, the whole response can be obtained by adding all the small parts. Note that a difference method or a finite volume method may be used as a numerical analysis method.
[0084]
In the creation of the tire model in step 102, a pattern is modeled after a tire cross-section model is created. Specifically, a tire model creation routine shown in FIG. 9 is executed. First, in step 200, a tire radial section model is created. That is, tire cross-section data is created. The tire cross-section data is obtained by measuring the tire outer shape with a laser shape measuring instrument or the like. Also, the exact structure of the tire is taken from the design drawings and actual tire cross-section data. The rubber and the reinforcing material in the tire cross section (belt, ply, etc., which is a bundle of reinforcing cords made of iron / organic fibers, etc., which are bundled in a sheet shape) are modeled according to the modeling method of the finite element method, respectively (FIG. 10). (See (A)).
[0085]
In the next step 202, tire cross-section data (tire radial cross-section model), which is two-dimensional data, is developed by one turn in the circumferential direction to create a three-dimensional (3D) model of the tire (FIG. 10B, ( C)). In this case, it is desirable to model the rubber portion with an 8-node solid element and the reinforcing material with an anisotropic shell element capable of expressing an angle. For example, as shown in FIG. 11 (A), the rubber part can be handled by an eight-node solid element, and the reinforcing material (belt, ply) is handled as a shell element as shown in FIG. 11 (B). The angle θ of the reinforcing material can be considered two-dimensionally.
[0086]
In the next step 204, the pattern is modeled. This pattern is modeled by either of the following procedures (1) and (2).
Procedure {circle around (1)}: A part or all of the pattern is separately modeled and attached to the tire model as a tread portion.
Procedure {circle over (2)}: Create a pattern in consideration of rib and lug components when developing the tire cross-section data in the circumferential direction.
[0087]
After the tire model is created as described above, the process proceeds to step 104 in FIG. 8 to create a fluid model. This fluid model is a fluid containing snow, and in the present embodiment, a fluid containing an elastic-plastic material or the like is assumed. In creating a fluid model, first, a part (or all) of a tire, a ground contact surface, and a fluid region including a region where the tire moves and deforms are divided and modeled. The fluid region is preferably divided by a rectangular parallelepiped, and the fluid element that is the rectangular parallelepiped to be divided is preferably divided by an 8-node Euler mesh. In addition, the tire model and the fluid model are defined by overlapping each other. The tire model has a complex surface shape in the pattern part, and it is not necessary to define a fluid mesh according to this surface shape, which can greatly reduce the time and effort of modeling the fluid model and efficiently predict performance Important to do.
[0088]
In this way, when the creation of the fluid model is completed, the environment construction that can be evaluated is completed by inputting the road surface state together with the creation of the road surface model. Here, the road surface is modeled and input to set the modeled road surface to an actual road surface state. The road surface is modeled by dividing the road surface shape into elements and selecting the road surface friction coefficient μ and inputting the road surface state. That is, since there is a road friction coefficient μ corresponding to dry (DRY), wet (WET), on ice, snow, non-paved, etc., depending on the road surface condition, by selecting an appropriate value for the friction coefficient μ, The road surface condition can be reproduced. Further, the road surface model only needs to be in contact with at least a part of the fluid model, and can be arranged inside the fluid model.
[0089]
In addition, since the fluid region to be a fluid model includes a region where the tire moves, in modeling in a state where the tire model does not roll (hereinafter referred to as tire non-rolling), the contact direction is at least 5 times the contact length in the width direction. Model a region that is at least three times the ground contact width and 30 mm or more in the depth direction. In modeling in a state in which the tire model is rolled (hereinafter referred to as tire rolling), a fluid region of, for example, 2 m or more (for one tire rotation or more) is modeled in the traveling direction. An image related to the fluid model thus modeled is shown in FIG. 12A is a perspective view of a modeled fluid model and road surface model on which the tire model is placed, and FIG. 12B shows a snow surface when the actual tire is rotated on the snow. FIG. 12C is an image diagram showing the surface of the fluid model obtained as a result of evaluation described later.
[0090]
In the next step 108, boundary conditions are set. That is, since a part of the tire model is interposed in a part of the fluid model, it is necessary to simulate the behavior of the tire and the fluid by giving analytical boundary conditions to the fluid model and the tire model. This procedure is different when the tire is rolling and when the tire is not rolling. The selection at the time of tire rolling and at the time of tire non-rolling may be input in advance, or may be selected at the beginning of execution of this processing, and further, both are executed and selected after obtaining each. You may do it.
[0091]
In the setting of the boundary condition at the time of tire rolling in step 108, the processing routine of FIG. 13 is executed. First, the process proceeds to step 400 where boundary conditions relating to inflow / outflow are given to the fluid model (fluid region) 20. As shown in FIG. 15, the boundary condition regarding the inflow / outflow is that the upper surface 20A of the fluid model (fluid region) 20 freely flows out, and the other front surface 20B, rear surface 20C, side surface 20D, and lower surface 20E are walls (inflow).・ No spillage) In the next step 402, internal pressure is applied to the tire model, and in the next step 404, at least one of rotational displacement and straight displacement (displacement may be force or speed) and a predetermined load load are applied to the tire model. In addition, when considering friction with the road surface, only one of rotational displacement (or force or speed) or straight displacement (or force or speed) may be used.
[0092]
Further, in the setting of the boundary condition at the time of tire non-rolling in step 108, the processing routine of FIG. 14 is executed. First, in step 410, boundary conditions regarding inflow / outflow are given to the fluid model. Here, since the analysis is performed in a steady state, the tire model is stationary in the traveling direction, and a fluid model in which the fluid flows toward the tire model at the traveling speed is considered. That is, in step 412, a flow velocity is given to the fluid in the fluid model (fluid region). As shown in FIG. 16, the boundary condition regarding inflow / outflow is that the front surface of the fluid model (fluid region) 20 flows in at an advancing speed, the rear surface is outflow, and the upper surface, side surface, and lower surface are the same as when rolling. In step 414, an internal pressure is applied to the tire model, and in the next step 416, a load is applied to the tire model.
[0093]
Next, based on the numerical model created or set up to step 108, deformation calculation of the tire model as analysis A and fluid calculation (flow calculation) as analysis B, which will be described in detail below, are performed. In order to obtain a transient state, the deformation calculation of the tire model and the fluid calculation of the fluid model are each performed within 1 msec, and the boundary conditions of both are updated every 1 msec.
[0094]
That is, when the setting of the boundary condition is completed in step 108, the process proceeds to step 110, where the tire model deformation calculation is performed, and in the next step 112, it is determined whether the elapsed time is within 1 msec. If the determination in step 112 is affirmative, the process returns to step 110 and the tire model deformation calculation is performed again. If the determination in step 112 is negative, the process proceeds to step 114 and fluid calculation is performed. In the next step 116, it is determined whether or not the elapsed time is within 1 msec. If the result is affirmative, the process returns to step 114, the fluid calculation is performed again, and if the result in step 116 is negative, the process proceeds to step 118.
[0095]
(Analysis) Deformation calculation of tire model
Based on the tire model and the given boundary conditions, deformation calculation of the tire model is performed based on the finite element method. In order to obtain a transient state, the tire model deformation calculation is repeated while the elapsed time (single elapsed time) is 1 msec or less, and after 1 msec, the next calculation (fluid) is started.
[0096]
(Analysis B) Fluid calculation
Based on the fluid model and given boundary conditions, fluid calculation is performed based on the finite element method. In order to obtain a transient state, fluid calculation is repeated while the elapsed time (single elapsed time) is 1 msec or less, and when 1 msec elapses, the next calculation (deformation of the tire model) is started. Although details will be described later, a fluid is assumed as an elastoplastic material, and a traction can be obtained from the relationship between the above-described normal stress σ and shear strength τ to obtain a shear stress distribution acting on the tire model.
[0097]
Note that either (Analysis A) or (Analysis B) may be calculated first or in parallel. That is, steps 110 and 112 and steps 114 and 116 may be exchanged.
[0098]
In the above calculation (Analysis A and Analysis B), the case where repeated calculation is performed during a preferable elapsed time in which the elapsed time (single elapsed time) is 1 msec or less has been described. In the present invention, the elapsed time is set to 1 msec. The elapsed time of 10 msec or less can be employed, preferably 1 msec or less, and more preferably 1 μsec or less. Further, this elapsed time may be set to a different time between the analysis A and the analysis B.
[0099]
In the next step 118, the tire model deformation calculation and the fluid calculation are performed separately for 1 msec each, and then, in order to couple them, the boundary surface of the fluid model is recognized according to the deformation of the tire model, and the boundary condition In step 119, surface pressure is applied to the tire model (details will be described later).
[0100]
That is, after the boundary condition update in step 118, the pressure calculated by the fluid calculation in step 119 is added to the tire model as the tire model boundary condition (surface force), and the deformation of the tire model due to the fluid force is applied to the next tire model. Calculation is performed by deformation calculation (analysis A). On the fluid side, the surface shape of the deformed tire model is taken into the boundary condition as a new wall, and on the tire model side, the fluid pressure is taken into the boundary condition as a surface force acting on the tire model. By repeating this every 1 msec, a transient flow related to tire performance prediction can be created in a pseudo manner. Here, 1 msec is a time that can sufficiently express the process in which the pattern in the contact surface is deformed by rolling the tire.
[0101]
In the above, the repetition time (single elapsed time) taken into the boundary condition is set to 1 msec. However, the present invention is not limited to 1 msec, and a time of 10 msec or less can be adopted, preferably 1 msec or less. Yes, and more preferably, a time of 1 μ · sec or less can be employed.
[0102]
In the next step 120, it is determined whether or not the calculation is completed. If the result in step 120 is affirmative, the process proceeds to step 122. If the result in step 120 is negative, the process returns to step 110, and the tire model deformation calculation and fluid calculation are performed again. A single calculation is performed every 1 msec. In addition, as a specific determination method, there are the following examples.
[0103]
(1) If the tire model is a non-rolling model or a rolling model with an all-round pattern, the target physical quantity (fluid reaction force, pressure, flow rate, etc.) can be regarded as a steady state (previously calculated physical quantity and The calculation is repeated until the condition can be regarded as the same, and if the calculation is completed, an affirmative determination is made. Or, it is repeated until the deformation of the tire model can be regarded as a steady state. Furthermore, it is also possible to end the process when a predetermined time is reached. The predetermined time in this case is preferably 100 msec or more, more preferably 300 msec or more.
[0104]
(2) If the tire model is a rolling model and only a part of the pattern is modeled, the calculation is repeated until the deformation of the pattern part to be analyzed is completed. . The deformation of the pattern portion refers to the deformation until the pattern portion is separated from the road surface model after contact with the road model due to rolling, or until the pattern portion is contacted with the fluid model after rolling and contact with the road surface model. . The deformation of the pattern portion may be performed from the time when the tire contacts one of the models after rolling for one or more rotations. Furthermore, it is also possible to end the process when a predetermined time is reached. The predetermined time in this case is preferably 100 msec or more, more preferably 300 msec or more.
[0105]
Here, details of step 118 will be described. The processing routine of FIG. 17 is executed as processing for recognizing the boundary surface of the fluid in accordance with the tire model deformation and adding the boundary condition in step 118. First, in step 500, in order to determine which part of the fluid model (fluid region) 20 is hidden behind the tire model 30, an interference part 40 between the fluid model 20 and the tire model 30 is calculated. This is performed for all elements (fluid elements) obtained by dividing the fluid model 20, that is, the fluid region into small parts (see FIG. 18).
[0106]
In the next step 502, it is determined whether or not the fluid element is completely hidden in the tire model. If the fluid element is completely hidden in the tire model, an affirmative determination is made in step 502 and the process proceeds to step 504. Since it is inside the tire model and fluid does not flow in or out, boundary conditions are added as walls.
[0107]
On the other hand, when the result in step 502 is negative, the process proceeds to step 506, where it is determined whether or not a part of the fluid element is hidden in the tire model. If a part of the fluid element is hidden in the tire model, an affirmative determination is made in step 506, and in the next step 508, a cut surface that is a surface that bisects the fluid element on the surface 32 of the tire model 30 is calculated (see FIG. 19), the next step 510 further divides the fluid element 22 at this cut surface. In the next step 512, the region 22A that is not hidden by the tire model among the divided fluid elements is newly defined as a fluid model (fluid region), and this portion is used for fluid calculation. Further, since the surface corresponding to the cut surface of the new fluid element is in contact with the tire model, a boundary condition as a wall is added.
[0108]
In addition, since it is not preferable to further divide the divided fluid elements because it increases the calculation time, there is a restriction on the division of the fluid elements (in this case, a restriction that the elements once divided are not divided). Is preferred.
[0109]
In the next step 514, it is determined whether or not the above processing has been performed for all the fluid elements. If unprocessed fluid elements remain, the result in step 514 is negative and the process returns to step 500. On the other hand, when the above process is completed for all fluid elements, this routine is terminated. Thereby, the surface shape of the tire model can be taken into the fluid calculation as a boundary condition.
[0110]
As described above, the method of defining the tire model and the fluid model by overlapping them can greatly reduce the labor for creating the calculation model. Furthermore, by dividing the fluid elements that are partially hidden in the tire model, the initial fluid mesh can be made larger, and it can be prevented that the calculation time increases due to an increase in the fluid elements, and performance prediction can be performed efficiently. .
[0111]
In step 119, the pressure calculated by the fluid calculation is added to the tire model as a boundary condition (surface force) of the tire model. On the fluid side, the surface shape of the deformed tire model is taken into the boundary condition as a new wall, and on the tire model side, the fluid pressure is taken into the boundary condition as a surface force acting on the tire model.
[0112]
That is, as described above, the vertical stress σ is calculated for each element of the fluid model (snow model), the shear strength τ with respect to the vertical stress σ is calculated by the above functional formula, and the shear stress acting on the tire model is calculated. The distribution is calculated (steps 306 and 308 in FIG. 1).
[0113]
In this way, after changing the boundary condition and adding the boundary condition (surface force) for the analysis A, the analysis B, and the coupling between the two, the process returns to the analysis A and the calculation is performed with the changed boundary condition. This is repeated until the calculation is completed. When the calculation is completed, the result is affirmative in step 120, the process proceeds to step 122, the calculation result is output as the prediction result, and the prediction result is evaluated.
[0114]
In the above description, the case where the analysis A, the analysis B, and the boundary condition change are repeated and the calculation is completed and the calculation result is output and the prediction result is evaluated has been described. May be output, and the output may be evaluated or sequentially evaluated. In other words, output and evaluation may be performed during the calculation.
[0115]
When the shear stress is obtained as a prediction result, the traction is obtained by integrating the shear stress. Therefore, the shear stress obtained as a result may be integrated to obtain the traction, and the prediction result may be obtained. This processing corresponds to the processing in steps 310 and 312 in FIG.
[0116]
Further, as the output of the prediction result, values or distributions such as shear force, shear stress, fluid force, flow velocity, flow rate, pressure, and energy can be adopted. Specific examples of the output of the prediction result include output of fluid reaction force, output and visualization of fluid flow, and output and visualization of stress distribution. The fluid reaction force is a force by which fluid (for example, snow) moves the tire forward and stops but pushes it upward. The flow of the fluid can be calculated from the velocity vector of the fluid, and can be visualized by representing both the flow and the periphery of the tire model and the periphery of the pattern with a diagram or the like. To visualize the stress distribution of the fluid, the tire model periphery and pattern periphery may be created as a diagram, and the stress value may be displayed on the figure corresponding to the color or pattern.
[0117]
In addition, the evaluation includes an evaluation of whether the traction is an acceptable value, a subjective evaluation (whether it is flowing smoothly, judgment of turbulence depending on the direction of flow, etc.), and pressure / energy is rising locally. It is possible to adopt whether there is no flow rate, a necessary flow rate is obtained, a fluid force is not increased, a flow is not stagnated, or the like. Moreover, in the case of a pattern, it can also be adopted whether it is flowing in the groove. Also, in the case of a tire model, when the tire rotates, the tire sandwiches fluid such as water near the ground contact surface and the ground contact surface, and there is a large amount of forward spray pushed forward, or whether it is flowing sideways on the road surface, Can be adopted.
[0118]
The evaluation of the prediction result is expressed numerically by using the output value of the prediction result and the distribution of the output value, and how well the predetermined allowable value and the allowable characteristic are adapted to each output value and the distribution of the output value. By doing so, an evaluation value can be determined.
[0119]
Next, in step 124, it is determined from the evaluation of the prediction result whether or not the prediction performance is good. The determination in step 124 may be made by keyboard input, and when the allowable range is set in advance in the evaluation value and the evaluation value of the prediction result is within the allowable range, the prediction performance is good. You may make it judge that there exists.
[0120]
As a result of the evaluation of the predicted performance, if the target performance is insufficient, the result is negative in step 124, the design plan is changed (corrected) in the next step 134, the process returns to step 102, and the processing so far is repeated. On the other hand, if the performance is sufficient, an affirmative decision is made in step 124. In the next step 126, a tire having the design plan set in step 100 is manufactured, and performance evaluation is performed on the manufactured tire in the next step 128. . When the result of the performance evaluation in step 128 is satisfactory performance (good performance), the result in step 130 is affirmed, and in the next step 132, the design proposal modified in step 100 or step 134 is improved. Adopt as a thing and end this routine. The adoption of the design plan in step 132 outputs (displays or prints) that the design plan has good performance, and stores the data of the design plan.
[0121]
In the above embodiment, the case where the tire performance prediction and evaluation for one design plan is repeated while correcting the design plan and the design plan to be adopted is obtained is described, but the present invention is limited to this. Instead, a design plan to be adopted from a plurality of design plans may be obtained. For example, tire performance prediction and evaluation may be performed for a plurality of design plans, and the best design plan may be selected from each evaluation result. Further, the best design plan can be obtained by executing the above embodiment for the selected best design plan.
[0122]
Next, a second embodiment will be described. Since this embodiment has the same configuration as that of the above embodiment, the same portions are denoted by the same reference numerals and detailed description thereof is omitted. In the present embodiment, water is used as the fluid.
[0123]
If analysis is performed with a pattern on the entire circumference of the tire model, the amount of calculation becomes enormous and the results cannot be obtained easily. Therefore, in this embodiment, in order to easily obtain a tire performance prediction result while considering the coupling between the tire and the fluid, the tire performance prediction is performed by providing a pattern only in a part of the tire model. is there.
[0124]
The present inventor paid attention to the pattern of the stepped portion with respect to the behavior of the tire in predicting the performance of the tire. The stepping portion refers to the vicinity of the tire approaching or contacting the road surface when the tire rolls.
[0125]
In the present embodiment, the tire model 30 is basically a smooth tire model with a flat entire circumference, and analysis is performed with the smooth tire model having some patterns necessary to facilitate the analysis of the stepped-in portion. In the following description, this analysis is referred to as GL (Global-Local) analysis.
[0126]
Next, GL analysis in the present embodiment will be described. The outline of this GL analysis can be implemented by the following procedure 1 to procedure 4.
<GL analysis procedure>
Step 1: Prepare a smooth tire model, a pattern model (part) and a belt model to be attached to the pattern (see Fig. 20)
Step 2: Smooth tire model rolling and analysis
(Global analysys: G analysis)
Procedure 3: Calculate the rolling trajectory of the belt model (same as part of the pattern model) to be attached to the pattern part (part) from the result of the smooth tire model. Specifically, the displacement during rolling of all the nodes of the belt model (shell) is output (this may be converted into a speed and output. It should be noted that the constraints on the FEM software and the displacement are obtained as they are. The pattern model (part) can be attached to the belt model, and a forced speed (displacement is acceptable) is applied to the node of the belt model.
Procedure 4: Since it is possible to roll only the pattern part (a part) by Step 3, prepare a fluid mesh corresponding to the pattern part, and perform a coupled analysis only on the pattern part.
(Local analysys: L analysis, see Fig. 21)
Evaluation is performed by fluid reaction force / distribution / flow analysis.
[0127]
In detail, it is substantially the same as that of the said embodiment, and a tire model and a fluid model are created first (steps 100-104 of FIG. 2). In this case, the tire model is a smooth tire model. In addition, a pattern model (part) and a belt model of a portion to be attached to the pattern are created. Next, boundary conditions at the time of tire rolling or tire non-rolling are set, and deformation calculation and fluid calculation of the tire model are performed (steps 108 to 120 in FIG. 2). This is rolling and analysis of a smooth tire model (global analysys: G analysis).
[0128]
Then, the rolling trajectory of the belt model (same as part of the pattern model) to be attached to the pattern part (part) is calculated from the result of the smooth tire model. As a result, only the pattern portion (a part) is rolled (FIG. 21), so a fluid mesh corresponding to the pattern portion is prepared and only the pattern portion is analyzed. This is an analysis of only the pattern part which is a part of the pattern model (local analysys: L analysis). Here, as shown in FIG. 21, the pattern portion transitions from the position state L <b> 1 to the position state L <b> 13 by rolling of the pattern portion (a part).
[0129]
As described above, in the present embodiment, since the GL (Global-Local) analysis is performed based on the smooth tire model and using a part of the pattern, the following three advantages can be obtained.
1: Shorten calculation time.
2: Various models can be easily created. In particular, it is not necessary to prepare a pattern all around the tire model.
3: The stepping portion pattern can be easily analyzed.
[0130]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to performance prediction of a radial tire.
[0131]
As a tire standard, the load is a standard load, and the standard load is a maximum load (maximum load capacity) of a single wheel in an application size described in the following standard. The internal pressure at this time is the air pressure corresponding to the maximum load (maximum load capacity) of the single wheel in the applicable size described in the following standard. The rim is a standard rim (or “Approved Rim” or “Recommended Rim”) in an applicable size described in the following standard. The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Book”, in Europe “The European Tire and Rim Technical Organization Standards Manual”, and in Japan, the Japan Automobile Tire Association “JATMA Year Book”. ing.
[0132]
After modeling for performance prediction based on this tire, performance prediction of the tire model was performed, and the prediction results and actual measurement results were shown together.
[0133]
The tire modeled and prototyped as this example has a tire size of 195 / 65R15, and the tread pattern has a structure without sipes. Modeling involves measuring the outer shape of the tire with a laser profilometer, creating a tire cross-section model from the cross-sectional data from the design drawing and the actual tire, and developing it in the circumferential direction to create a tire 3D model (numerical model) did. For the pattern, a 3D model was created based on the design drawing, and was pasted as a tread portion on the tire 3D model.
[0134]
In the performance evaluation test, the above tire was assembled to a rim of 6J-15 at an internal pressure of 200 kPa and mounted on a passenger car, and a snow road start test was performed. The start was evaluated based on the time (acceleration time) until the accelerator fully traveled from a stationary state and traveled 50 meters. The result is expressed as an index of acceleration time, and a large index is good.
[0135]
FIG. 22 (A) shows the tread pattern of the tire of the first embodiment, FIG. 22 (B) shows the tread pattern of the tire of the second embodiment, and FIG. 22 (C) shows the third tread pattern. The tread pattern of the tire of the example is shown. Table 1 below shows the performance prediction results on snow for the tires of the first to third examples.
[0136]
[Table 1]

[0137]
As understood from Table 1, it is understood that the superiority or inferiority of the performance between the patterns is consistent between the acceleration performance on snow by the actual vehicle test and the prediction result of the example by the performance prediction on snow according to the present embodiment. Therefore, this performance prediction is effective for the performance prediction of the design plan, and it is possible to replace a part of the tire development cycle of design / manufacturing / performance evaluation with numerical analysis. It is understood that the efficiency of tire development can be improved by utilizing this.
[0138]
【The invention's effect】
As described above, according to the present invention, it is possible to predict and analyze the performance of a tire in consideration of an elastic-plastic material such as snow and a fluid containing at least a plastic material, thereby improving the efficiency of tire development. In addition, there is an effect that a tire with good performance can be obtained.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a processing flow of a program for predicting traction on snow in tire performance evaluation according to the present embodiment.
FIG. 2 is a schematic diagram of a personal computer for carrying out a tire performance prediction method according to an embodiment of the present invention.
FIG. 3 is a diagram showing a tread pattern of a tire used for measurement in the present embodiment.
FIG. 4 is a diagram showing an example of a measurement result when measuring the maximum traction of a single tire on the snow surface.
FIG. 5 is an explanatory diagram for explaining that the relationship between the normal stress σ of snow and the shear strength τ is approximated by a functional equation;
6A is a diagram showing a tread pattern of a tire model, and FIG. 6B is a diagram showing a shear stress distribution on the tire model.
7A is a diagram showing a state where snow enters a lug groove, and FIG. 7B is a diagram showing a relationship of normal stress σ-shear strength τ.
FIG. 8 is a flowchart showing a processing flow of a performance prediction evaluation program for a pneumatic tire according to the present embodiment.
FIG. 9 is a flowchart showing a flow of a tire model creation process.
FIG. 10 shows a tire model, (A) is a tire radial cross-sectional model (B) is a three-dimensional model of a tire, and (C) is a perspective view showing an image obtained by modeling a pattern.
11A and 11B are image diagrams for explaining elements when modeling, FIG. 11A is an image diagram for explaining the handling of a rubber part, and FIG. 11B is an image diagram for explaining the handling of a reinforcing material.
12A and 12B show images related to a fluid model, in which FIG. 12A is a perspective view of a modeled fluid model and a road surface model on which a tire model is placed, and FIG. The snow surface when moved is shown, (C) is an image diagram showing the surface of the fluid model obtained by analysis.
FIG. 13 is a flowchart showing the flow of boundary condition setting processing during rolling.
FIG. 14 is a flowchart showing a flow of boundary condition setting processing during non-rolling.
FIG. 15 is an explanatory diagram for describing setting of boundary conditions during rolling.
FIG. 16 is an explanatory diagram for describing setting of boundary conditions during non-rolling.
FIG. 17 is a flowchart showing a flow of boundary condition addition processing.
FIG. 18 is a diagram showing an interference area between a tire model and a fluid model.
19A and 19B are explanatory diagrams for explaining division of a fluid element, where FIG. 19A shows a fluid side before division and FIG. 19B shows a fluid side after division.
FIG. 20 is a perspective view showing a smooth tire model, a pattern model (part), and a belt model of a portion to be attached to the pattern.
FIG. 21 is an image diagram showing that a part of the pattern model pasted on the smooth tire model changes due to rolling of the tire model.
22A and 22B are image diagrams showing a tread pattern of an example, where FIG. 22A shows the first example, FIG. 22B shows the second example, and FIG. 22C shows the third example.
[Explanation of symbols]
10 Keyboard
12 Computer body
14 CRT
20 Fluid model
30 tire model
FD flexible disk (recording medium)

Claims (21)

A tire performance prediction method including the following steps.
(A) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid including at least a plastic body, and a part or all of the tire model is at least A fluid model that models an elastic-plastic body or plastic body by approximating the relationship between the normal stress applied to the elastic-plastic body or the plastic body and the relationship between the shear strength of the elastic-plastic body or the plastic body with a functional formula , Steps to determine.
(B) executing deformation calculation of the tire model;
(C) performing flow calculation of the fluid model;
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (b) and the fluid model after the flow calculation in the step (c), the boundary condition regarding the recognized boundary surface is set as the tire model and The tire model and the fluid model that have been applied to the fluid model and the boundary condition have been repeatedly calculated for the predetermined time for the tire model and the fluid model, so that the fluid model is in a pseudo-flow state. to that step with.
(E) A step of obtaining a physical quantity generated in at least one of the tire model and the fluid model in step (c) or step (d).
(F) Predicting tire performance from the physical quantity.   In the fluid model, an elastic-plastic body or plastic body is modeled by approximating the relationship between the vertical stress applied to the elastic-plastic body or the plastic body and the shear strength of the elastic-plastic body or the plastic body by a functional expression using a second or higher order polynomial. The tire performance prediction method according to claim 1. The fluid model is to set a plurality of measurement conditions on the surface of a water-absorbing material including a material corresponding to an elastic-plastic body or a plastic body under substantially the same conditions in a tire test apparatus for measuring the performance of a single tire, And at least one of using a plurality of tires of the same or different types to measure the maximum traction of the tire in advance,
Calculate the contact area of the tire at the time of the measurement,
Based on the maximum traction and the ground contact area, calculate the shear strength of the elastic-plastic body or plastic body on the surface of the water-absorbent material, and the normal stress applied to the elastic-plastic body or plastic body,
2. The tire performance prediction method according to claim 1, wherein the elastoplastic body or the plastic body is modeled by approximating the calculated elastoplastic body or the relationship between the normal stress of the plastic body and the shear strength by a functional expression. 3. The tire performance prediction method according to any one of claims 1 to 3 , wherein the step (a) further defines a road surface model in contact with the fluid model. Wherein step (b), tire performance prediction method according to any one of claims 1 to 4, characterized in that to calculate repeatedly for a predetermined time. The tire performance prediction method according to claim 5 , wherein the predetermined time is 10 msec or less. The tire performance prediction method according to any one of claims 1 to 6 , wherein the step (c) is repeatedly calculated for a predetermined time. The tire performance prediction method according to claim 7 , wherein the predetermined time is 10 msec or less. The tire performance prediction method according to claim 1 , wherein the predetermined time is 10 msec or less. In the case of rolling the tire model, in step (a), calculation is performed at the time of filling with internal pressure and at the time of load calculation, and a tire model to which rotational displacement, speed, or linear displacement is given is defined. The tire performance prediction method according to any one of claims 1 to 9 . When rolling the tire model, in step (a), fluid freely flows out on the upper surface of the fluid model, and fluid does not flow in and out on other surfaces other than the upper surface of the fluid model. The tire performance prediction method according to any one of claims 1 to 10 , wherein an inflow / outflow condition to be expressed is assigned to the fluid model. If not to roll the tire model, in the step (a), it is performed with the calculation of internal pressure filling claims 1, characterized in that determining a tire model subjected to loads calculated after the calculation The tire performance prediction method according to any one of 9 . When the tire model is not rolled, in step (a), the fluid flows in at the front speed of the fluid model, and the fluid freely flows out from the rear surface and the upper surface of the fluid model. tire performance on the side and bottom surfaces according to any one or claims 12 to claims 1 to 9, characterized in that confer inflow and outflow conditions indicating that the fluid does not flow in and out to the fluid model Prediction method. The tire performance prediction method according to any one of claims 1 to 13 , wherein the tire model partially has a pattern. In the step (d), an interference part between the tire model and the fluid model is generated, the interference part is recognized, and the fluid model is divided into fluid elements with the tire model surface as a boundary surface. The tire performance prediction method according to any one of claims 1 to 14 . The tire model according to any one of claims 1 to 15 , wherein the fluid model includes at least snow, uses a contact area of a tire model as the physical quantity, and predicts tire performance on the snow as the tire performance. The tire performance prediction method described. Wherein the fluid model includes the snow, the normal stress and shear forces of the fluid model in snowy road surface of the fluid model is used as the physical quantity, claims 1 to, characterized in that to predict tire performance on snow as the tire performance Item 17. The tire performance prediction method according to any one of Items 16 . A fluid simulation method including the following steps.
(A) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid containing at least a plastic body, and a part or all of the tire model is at least A fluid model that models an elastoplastic body or plastic body by approximating the relationship between the normal stress applied to the elastoplastic body or plastic body and the shear strength of the elastoplastic body or plastic body with a functional equation while contacting a part , Steps to determine.
(B) executing deformation calculation of the tire model;
(C) executing a flow calculation of the fluid model;
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (b) and the fluid model after the flow calculation in the step (c), and the boundary condition relating to the recognized boundary surface is defined as the tire model and imparting vital to fluid model, it is calculated by repeating a predetermined time calculated in the step for the tire model and the fluid model after applying the boundary conditions (b) and the step (c), the pseudo-flow state the fluid model to that step with. A tire design method including the following steps.
(1) A plurality of tire models having a pattern shape capable of being deformed by at least one of ground contact and rolling, and the tire model partially or entirely filled with an elastic-plastic body or a fluid containing at least a plastic body. Model that models an elastic-plastic body or plastic body by approximating the relationship between the normal stress applied to the elastic-plastic body or plastic body and the shear strength of the elastic-plastic body or plastic body with a functional equation And a step of determining.
(2) A step of executing deformation calculation of the tire model.
(3) A step of performing flow calculation of the fluid model.
(4) Recognizing a boundary surface between the tire model after the deformation calculation in the step (2) and the fluid model after the flow calculation in the step (3), the boundary condition regarding the recognized boundary surface is set as the tire model and The tire model and the fluid model that are given to the fluid model and the boundary condition are given, and the calculation of the step (2) and the step (3) is repeated for a predetermined time, so that the fluid model is in a pseudo-flow state. to that step with.
(5) A step of obtaining a physical quantity generated in at least one of the tire model and the fluid model in the step (3) or the step (4).
(6) A step of predicting tire performance from the physical quantity.
(7) A step of designing a tire based on a tire model having a tire performance selected from the plurality of tire performances. A recording medium recording a tire performance prediction program for predicting tire performance by a computer, the recording medium recording a tire performance prediction program characterized by including the following steps.
(A) a tire model having a pattern shape that can be deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid containing at least a plastic body, and a part or all of the tire model is at least A fluid model that models an elastic-plastic body or plastic body by approximating the relationship between the normal stress applied to the elastic-plastic body or the plastic body and the relationship between the shear strength of the elastic-plastic body or the plastic body with a functional formula , Steps to determine.
(B) A step of performing deformation calculation of the tire model.
(C) performing flow calculation of the fluid model.
(D) Recognizing a boundary surface between the tire model after the deformation calculation in the step (B) and the fluid model after the flow calculation in the step (C), and the boundary condition regarding the recognized boundary surface is set as the tire model and The tire model and the fluid model that are given to the fluid model and the boundary condition are given, and the calculation of the step (B) and the step (C) is repeated for a predetermined time so that the fluid model is in a pseudo-flow state. to that step with. A tire performance prediction program comprising the following steps for predicting tire performance by a computer.
(I) a tire model having a pattern shape capable of being deformed by at least one of ground contact and rolling, and an elastoplastic body or a fluid including at least a plastic body, and a part or all of the tire model is at least A fluid model that models an elastic-plastic body or plastic body by approximating the relationship between the normal stress applied to the elastic-plastic body or the plastic body and the relationship between the shear strength of the elastic-plastic body or the plastic body with a functional formula , Steps to determine.
(II) A step of executing deformation calculation of the tire model.
(III) A step of executing flow calculation of the fluid model.
(IV) Recognizing a boundary surface between the tire model after the deformation calculation in the step (II) and the fluid model after the flow calculation in the step (III), and the boundary condition related to the recognized boundary surface is defined as the tire model and imparting vital to fluid model, is calculated by repeating a predetermined time calculated in the step for the tire model and the fluid model after applying the boundary conditions (II) and the step (III), the pseudo-flow state the fluid model to that step with.

Images