KR102202596B1 - How to determine the lateral groove pattern lateral pattern of a tire with improved water film performance using CFD analysis - Google Patents

Abstract

The present invention relates to a method for determining a shape of a tire pattern transverse groove with improved water film performance using CFD analysis, comprising: a process of modeling a tire cross section using an axisymmetric element; A process of modeling periodicity using an axisymmetric element; Modeling the overall shape of the tire using an axisymmetric element; A process of deriving a tire displacement/speed value using a finite element (FEM) analysis program through a structural model of a tire in which the overall shape is modeled while rotating at high speed; The process of determining the shape of the tire pattern transverse groove with improved water film performance by analyzing the fluid flow using a fluid analysis (CFD) analysis program for the value according to the displacement/speed of the tire and applying the pressure generated in the fluid to the tire structure model. It characterized in that it comprises, and using a CFD fluid analysis program, there is an effect of improving the tire pattern groove by using a flow field generated between the tire and the fluid to improve the water film performance.

Description

How to determine the lateral groove pattern lateral pattern of a tire with improved water film performance using CFD analysis}

The present invention uses a CFD (Computational fluid dynamics) fluid analysis program to improve the tire pattern groove using the flow field generated between the tire and the fluid, thereby improving the water film performance by using the CFD analysis. It relates to a method for determining the shape of a tire pattern lateral groove.

The main parameters that cause the water film phenomenon identified by previous researchers are tire-related variables such as tire pattern shape, internal pressure, and structure of tires, ground-related variables that take into account the condition of the road surface and drainage rate, and the depth of water. It is known as a fluid-related variable according to density (Horne and Dreher, 1963; Horn et al, 1986; Huebner et al, 1986).

Research to find these parameters of the water screening phenomenon has been dealt with in earnest since 1960 at NASA's Langley Research Center using the aircraft landing track to investigate various phenomena of the water screening phenomenon through experiments. Afterwards, tempered glass was installed on a part of the road surface and the shape of the tire tread and the behavior of the fluid were studied by high-speed photographing of the tire running on a water film of a certain thickness (Suzuki and Fujikawa, 2001). Further, driving speed, tire Research on the sliding resistance affected by factors closely related to the water film phenomenon, such as type, tire tread shape, wheel load, surface characteristics of the road surface, texture and water film thickness on the road surface, is actively conducted. (Rose and Gallaway, 1977; Anderson et al, 1998)

However, the experimental method requires a lot of time and cost because the experimental equipment must be manufactured and a separate test site is required. Therefore, studies of interpretive methods are continuing (Saal, 1936; Martin, 1996; Eshel, 1967; Grog-ger and Weiss, 1996; ZminDak and Grajcia r, 1997; Nakajima et al, 2000; Okano and koishi). , 2001; Koishi et al, 2001; Oh et al, 2008; Ong and Fwa, 2010)

Among these studies, Grogger and Weiss first introduced an analysis method using Computational Fluid Dynamics (CFD) (Grogger and Weiss, 1996), and also the finite element method by Zmindak. The analysis method of water film using (FEM; Finite Element Method) was first introduced (ZminDak, 1997). Since then, Nakajima, Okano, and Koishi are MSC, a commercial finite element method (FEM) code. Although the water film phenomena were analyzed for a water film thickness of 10 mm or more using MSC Dytran (Nakajima et al, 2000), an analysis was required for a water film thickness of 10 mm or less, which has a large influence of water viscosity. Therefore, Okano and Koishi performed a water film simulation considering the viscosity of water using another commercial code, LS-DYNA (Okano and koishi, 2001).

However, since Lagrangian elements for a large number of tires and Eulerian elements for water are used and simulations are performed several times for changes in water film thickness, a long analysis time is required. Therefore, a new simulation method to study the water film phenomenon and slip resistance using a mathematical model and a finite element model (FE model) was proposed as a method to reduce the analysis time (Oh and Jeong, 2008; Kim and Jeong, 2010; Ong and Fwa, 2010)

In particular, Oh and Jeong have developed a Finite Difference Method (FDM) code and a finite element tire model developed on the basis of Brown's mathematical formulations (Browne, 1975). FE tire model) for the first time to propose a water film simulation method.

Since this mathematical formulation becomes an illconditioned matrix when the thickness of the meninges is thin, an asymptotic method was proposed to obtain pressure distribution and lift force. In addition, a water film phenomenon was simulated using LS-DYNA's full FE simulation method, and the two simulation methods were compared.

However, in the case of an analysis method using FDM codes, since mathematical programming is required, a complex and series of iterative processes are required. In addition, in the simulation method using LS-DYNA, an abnormal case occurred in which negative lift force occurred, and the normal force against speed could not be clearly defined due to severe oscillation. .

As described above, an analytical study on the water film phenomenon was conducted using various methods.

However, most of the above-mentioned analytic studies are the results of the water film thickness of 5mm or more, so the region of the very thin water film thickness (less than 1mm) where the influence of viscosity dominates cannot be considered. In particular, in the case of an explicit analysis method using a commercial explicit code such as LS-DYNA, not only a large number of European elements for water are used, but also less than 1mm. Due to the very small element size for the water film thickness of, considerable analysis time is required. In addition, when using a complex pattern tire such as Kim and Jeong's research, since the water element must have a smaller size than the tread pattern, it takes more analysis time and is less than 1mm. It is very difficult to obtain an analysis result considering the very thin water film thickness of.

Therefore, in the past, in order to design a pattern, the artistic shape by a designer was changed to an engineering design by a pattern tuning engineer. In this process, the pattern tuning engine engineer changed the design using his own experience, or proceeded with tuning according to statistical theory.

In this process, especially the tire water film phenomenon is one of the important safety design factors for pattern tuning engines.

When a tire water film phenomenon occurs, the tire falls off the ground due to the pressure caused by the water film, which greatly adversely affects the driver's safety. In tire design related to this important safety, the shape of the pattern groove is an important design factor.

In order to improve such groove design, in the past, pattern tuning engines used their own experience to change the design, or performed tuning according to statistical theory.

To improve this, a CFD analysis program is used to propose a transverse groove design method for the water flow generated in the tire water film, and a method for appropriately distributing water pressure.

Republic of Korea Patent Publication No. 2015-0017927 (published on February 23, 2015)

In order to solve the above problems, the present invention uses a CFD analysis program to design a tire pattern to improve water film performance, to identify turbulent flow, and to arrange transverse grooves where turbulence occurs, thereby improving water film phenomenon. An object of the present invention is to provide a method for determining the shape of a tire pattern transverse groove with improved water film performance by using the CFD analysis.

In addition, existing pattern tuning engines can use their own experience to change tire pattern groove design or perform tuning according to statistical theoretical equations using CFD fluid analysis program to arrange optimal transverse grooves. It is an object of the present invention to provide a method for determining the shape of a tire pattern transverse groove with improved water film performance by using CFD analysis that can be lowered.

The present invention is a means for achieving the above object,

Modeling a tire cross section using an axisymmetric element; A process of modeling periodicity using an axisymmetric element; Modeling the overall shape of the tire using an axisymmetric element; A process of deriving a tire displacement/speed value using a finite element (FEM) analysis program through a structural model of a tire in which the overall shape is modeled while rotating at high speed; The process of determining the shape of the tire pattern transverse groove with improved water film performance by analyzing the fluid flow using a fluid analysis (CFD) analysis program for the value according to the displacement/speed of the tire and applying the pressure generated in the fluid to the tire structure model. It provides a method for determining the shape of a tire pattern transverse groove with improved water film performance using CFD analysis, comprising:

The shape determination of the transverse groove of the present invention is characterized in that a point is applied to a place where turbulence occurs by fluid in a tire using a CAD program, and the angle of the transverse groove is determined using a function at the position passing through the applied point. do.

The present invention has the effect of improving the water film performance by improving the tire pattern groove by using the flow field generated between the tire and the fluid using a CFD fluid analysis program.

1 is a flow chart showing step by step a method of determining the shape of a tire pattern transverse groove with improved water film performance using CFD analysis according to the present invention.
FIG. 2 is a diagram showing the configuration of a tire pattern transverse groove shape determination system that performs structural analysis and fluid element analysis of a tire in order to determine the displacement/speed of the tire and the shape of the transverse groove through the modeling of the tire shown in FIG. 1 ,
3 is a view showing an initial grounding shape of a tire and a grounding pressure state at 90km/h.
4 is a view showing a state in which the shape of a fluid pressure field is grasped through the system shown in FIG. 2,
5 is a view showing a state in which the shape of the fluid velocity field is grasped through the system shown in FIG. 2,
6 is a view showing a state in which a shape of a turbulent flow field is identified through the system shown in FIG. 2,
7 is a view showing a state in which the transverse groove shape angle is reflected through the CAD program of the turbulent flow field shown in FIG. 6,
FIG. 8 is a diagram illustrating a state in which the image shown in FIG. 6 is divided into a grid using a CAD program.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in the following description and the accompanying drawings, detailed descriptions of known functions or known configurations that may obscure the subject matter of the present invention will be omitted. In addition, it should be noted that the same components are indicated by the same reference numerals as possible throughout the drawings.

The terms or words used in the present specification and claims described below should not be construed as being limited to a conventional or dictionary meaning, and the inventor is appropriate as a concept of terms for describing his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention on the basis of the principle that it can be defined.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical spirit of the present invention, and thus various equivalents that can replace them at the time of application It should be understood that there may be water and variations.

A method of determining the shape of a tire pattern transverse groove with improved water film performance using the CFD analysis according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a flow chart showing step by step a method of determining the shape of a tire pattern transverse groove with improved water film performance using CFD analysis according to the present invention, and FIG. 2 is a displacement/speed of a tire through modeling of the tire shown in FIG. A diagram showing the configuration of a tire pattern transverse groove shape determination system that performs structural analysis and fluid element analysis of a tire to determine the shape of the transverse groove, and FIG. 3 shows the initial fold shape of the tire and the state of the contact pressure at 90 km/h. FIG. 4 is a diagram showing a state in which the shape of a fluid pressure field is recognized through the system shown in FIG. 2, and FIG. 5 is a state in which the shape of a fluid velocity field is recognized through the system shown in FIG. And FIG. 6 is a view showing a state of grasping the shape of a turbulent flow field through the system shown in FIG. 2, and FIG. 7 is a horizontal groove shape angle through a CAD program using the turbulent flow field shown in FIG. It is a diagram showing a reflecting state, and FIG. 8 is a diagram showing a state in which the image shown in FIG. 6 is divided into a grid shape using a CAD program.

When described in detail with reference to FIGS. 1 to 8, the method for determining the shape of the tire pattern transverse groove with improved water film performance using the CFD analysis according to the present invention includes a process of modeling a tire cross section using an axisymmetric element (S10) and ; A process of modeling periodicity using an axisymmetric element (S20); Modeling the entire shape of the tire using an axisymmetric element (S30); A process of deriving a value of the displacement/speed of the tire using a finite element (FEM) analysis program through a structural model of a tire in which the overall shape of the modeled tire rotates at high speed and advances (S40); The process of determining the shape of the tire pattern transverse groove with improved water film performance by analyzing the fluid flow using a fluid analysis (CFD) analysis program for the value according to the displacement/speed of the tire and applying the pressure generated in the fluid to the tire structure model. (S50) is included.

In order to interpret the water film phenomenon using a computer program, the following phenomena must be reflected.

As shown in FIG. 2, a finite element (FEM) analysis program that analyzes a tire that actually rotates and moves forward at a high speed and a fluid analysis (CFD) analysis program that is linked to and communicated with the finite element analysis program should be applied.

The finite element (FEM) analysis modulates the tire using a conventional method, at this time using hyperelastic to give physical properties and give the tire a linear motion and rotational motion at a speed (50 to 100 KPH).

In addition, it is calculated using the linear speed and rotational speed of the tire applied during the finite element (FEM) analysis, and when buoyancy due to the water speed is generated, the difference between the linear travel speed and the rotational speed (radius X angular speed) occurs. Deterioration of performance due to water film occurs.

And in the fluid analysis (CFD) analysis, the value according to the tire shape is transmitted to the fluid (CFD) analyzer, and only the fluid flows at the same speed as the tire speed (50-100KPH). The fluid (CFD) analyzer results visualize the pressure field, velocity field, and turbulent flow field using its own program.

In addition, finite element analysis analyzes the structural model, and the shape of the rotating tire must be transmitted as it is by transmitting the tire displacement/speed to the fluid analyzer as the result of the analysis.

Using this analysis result, the fluid analyzer analyzes the fluid flow and transfers the pressure generated in the fluid to the tire structure model to proceed with the linkage analysis.

At about 90 km/h, it can be seen that the tire loses the ground plane due to the pressure flowing out of the fluid analyzer as shown in FIG. 3.

In this process, the fluid velocity field and the pressure field shape among the fluid analysis results can be identified as shown in FIGS. 4 and 5.

However, since the tire drainage performance occurs most actively in the turbulent flow field, the turbulent flow field is shown in FIG. 6.

6, it can be seen that the turbulent flow has a streamlined shape. Applying this streamlined shape to the improved tire pattern can improve the drainage performance of the tire.

As shown in Fig. 6, a point is applied to a place where turbulence occurs in the turbulent field analysis image using a CAD program as shown in Fig. 7, and the transverse groove shape angle is reflected using a function where the point passes. It's showing you how to do it.

The image shown in FIG. 6 is imported into CAD and divided into a grid of about 0.1 to 1 cm in size, and the points are arranged in a portion where the turbulent flow field is actively generated, so that the points are turbulent flows with improved drainage. It is based on the shape of the tire transverse groove by placing a point on it.

The grid generated using the CAD program is converted to line information to convert to CAD data, and the converted value to line information is converted using a function such as a polynomial, and through an n-order regression equation using this line information. It is used for CAD information. And when the shape of the image is simple, a linear function is used, and when the shape is complex, it is expressed as a higher order function.

Import a file such as a JPG/PNG file from the CAD, adjust it to 1:1 scale, divide the grid into a checkerboard pattern in CAD as described above, and arrange points on the grid to list the coordinates.

For the function passing through these points, a sixth order function can be applied from a quadratic function, and a spline can be applied on the CAD.

If these lines are applied at the pattern design stage, the water film phenomenon can be improved.

Table 1 below shows the comparison of the performance before and after the improvement by the same method as described above. As shown in the actual car results, the improved tire using the turbulent flow field using the fluid analysis program shows superior performance than the tire before the improvement.

division Before improvement After improvement Water film performance 100.0% 112.3%

Referring to Table 1, it can be seen that the CFD fluid analysis program is used as described above to improve the tire pattern groove by using the flow field generated between the tire and the fluid to improve the water film performance.

While this specification includes details of a number of specific implementations, these should not be construed as limiting to the scope of any invention or claim, but rather as a description of features that may be peculiar to a particular embodiment of a particular invention. It must be understood. Certain features described herein in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination. Furthermore, although features operate in a particular combination and may be initially described as so claimed, one or more features from a claimed combination may in some cases be excluded from the combination, and the claimed combination may be a subcombination. Or sub-combination variations.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are only presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is apparent to those of ordinary skill in the art that other modified examples based on the technical idea of the present invention may be implemented.

Claims (2)

delete A process of modeling a tire cross section using an axisymmetric element (S10);
A process of modeling periodicity using an axisymmetric element (S20);
Modeling the entire shape of the tire using an axisymmetric element (S30);
A process of deriving a value of the displacement/speed of the tire using a finite element (FEM) analysis program through a structural model of a tire in which the overall shape of the modeled tire rotates at high speed and advances (S40);
The process of determining the shape of the tire pattern transverse groove with improved water film performance by analyzing the fluid flow using a fluid analysis (CFD) analysis program for the value according to the displacement/speed of the tire and applying the pressure generated in the fluid to the tire structure model. (S50); Including,
Determination of the shape of the transverse groove,
A tire pattern that analyzes the tire structure and fluid elements to determine the displacement, velocity and shape of the lateral groove through the modeling of the tire. This image shows the state of understanding the shape of the turbulent flow field through the lateral groove shape determination process. Bring in and divide the grid into a size of about 0.1 to 1 cm, and arrange points at a portion where the turbulent flow field is actively generated to grasp the turbulent flow in which drainage is improved by the points,
A method of determining the shape of a horizontal groove of a tire pattern with improved water film performance using CFD analysis, characterized in that the angle of the horizontal groove is determined using a function at the position passing through the applied point.

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