• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1995.06a
• /
• pp.31-36
• /
• 1995

본 논문에서는 유한차분법과 뉴우튼-랍슨 방법을 사용하여 타원접촉 EHL 문제를 수치해석하고 그 결과를 H-D의 해석결과 및 그들의 유막두께식과 비교하였다. 최소유막의 크리 뿐만 아니라 중앙부의 유막두께도 H-D이ㅡ 결과와 차이를 보이며, 특히, 하중변화에 대한 중앙부 유막두께는 상당히 크게 차이를 나타내고 있다. 따라서 본 논문에서 구한 정확한 수치해석결과를 사용하면 H-D나 Chittenden 등의 유막두께식에 비하여 EHL 상태에서의 유막두께를 보다 정확하게 예측할 수 있는 새로운 유막두께식을 제시할 수 있을 것으로 생각되며 이를 위해서 추가적인 연구가 요구된다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.2
• /
• pp.262-270
• /
• 1988

A numerical solution of the elastohydrodynamic lubrication problem for an axially profiled cylindrical roller is presented. The problem is analyzed using finite difference method and Newton-Raphson method. The effect of side leakage and compressibility of lubricants are considered and axially nonuniform grid is constructed over the computation zone. Isobars, contours and section graphs show pressure variation and film shape. Contours plot is very similar to the previously reported experimental observations based upon optical interferometry. The maximum pressure and the minimum film thickness occur near the start of the profiling. The method used makes it possible to design an optimum axial profile of the roller to increase the life of rolling bearings.

• Tribology and Lubricants
• /
• v.28 no.4
• /
• pp.153-159
• /
• 2012

Tapered roller bearings are widely used in high axial-load and radial-load applications. In this study, a numerical analysis is performed to study a finite line contacts EHL problem between a tapered roller and raceway in tapered roller bearings. Converged solutions are obtained for moderate load and material parameters using a finite difference method with non-uniform grids and the Newton-Raphson method. The contours and sectional plots of pressure distribution and film shape are compared. The pressure distribution and film shapes near both ends of the roller are very different from those in the central part and are transversely asymmetric. The maximum pressure and absolute minimum film thickness always occur at the small end of the roller.

• Tribology and Lubricants
• /
• v.26 no.5
• /
• pp.263-271
• /
• 2010

The rollers of cylindrical roller bearing are axially profiled to relieve high edge stress concentration caused by mainly their finite length and by misalignment. In this paper, a numerical analysis is carried to study the EHL of misaligned (tilted) rollers with axially profiled ends. Using a finite difference method with non-uniform grids and the Newton-Raphson method, the highly nonlinear EHL problems are systematically solved. Physically consistent solutions are obtained for moderate load, material parameters and very small misalignment. For different misalignment angles, contours and sectional plots of pressure and film shape near both edge regions are compared. The asymmetric pressure distributions and film shapes show that the EHL results of finite line contacts are highly dependent upon very small amounts of roller misalignment. Especially, the effect of misalignment on the EHL pressure distribution is much higher than the film shapes.

• Tribology and Lubricants
• /
• v.29 no.6
• /
• pp.353-359
• /
• 2013

The rollers and/or races in cylindrical and tapered roller bearings should be profiled to relieve high edge stress concentrations caused by their finite lengths and misalignment. In this study, a numerical analysis was performed to investigate the elastohydrodynamic lubrication (EHL) of a Lundberg profile-type cylindrical roller. A finite difference method with fully nonuniform grids and the Newton-Raphson method were used to present detailed EHL pressure distributions and film shapes, as well as the variations in the minimum and central film thicknesses with the profile modification coefficient. In the Lundberg profile, the maximum pressure and minimum film thickness always occurred near the edges. Proper modification of the Lundberg profile considerably increased the minimum film thickness.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.6
• /
• pp.1975-1981
• /
• 1991

A new numerical solution of the elastohydrodynamic lubrication(EHL) problem of an axially profiled cylindrical roller is presented. A finite difference method and the Newton-Raphson method are used to solve the nonlinear system equations. A non-uniform grid system is adopted to reduce the number of grid points and to obtain accurate solution. For two different types of profiles which have similar elastostatic pressure distribution, the EHL results show large differences. Especially the difference in film shape is larger than in pressure distribution. Therefore, the magnitude of the minimum film thickness should be a major criteria to design the axial profile of the roller. Variations of the minimum film thickness with dimensionless parameters show considerably different behavior from those of infinite solution and show a good agreement with the experimental data in literatures. Present numerical scheme can be used generally in the analysis of three-dimensional EHL problem.