Elastohydrodynamic Lubrication Analysis for Quarter-Space Problems

Project: Research

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Description

This proposed work addresses a knowledge vacuum in the application of elasto-hydrodynamic lubrication (EHL) for contacts in quarter-space conditions.Many engineering components operate close to edges of free surfaces such as those in rolling element bearings, gears, and wheel-rail contacts, wherein free end surfaces exist without any stress, and this type of contact geometry is described as quarter space. Hitherto, all theoretical and numerical studies on EHL have been conducted using the elastic half-space model, but there is a clear need to understand the EHL behaviour at the unsupported edges of contacts where severe deviation of the predicted deformation, stress and film thickness distribution may take place.EHL numerical analyses usually require iterative procedures to achieve converged results that satisfy both elastic and hydrodynamic equations simultaneously. Relevant equations that can be solved reliably and effectively by numerical methods are needed. In the half-space model, the classical Boussinesq elastic deflection formula may be used. However, different elastic equations apply for deformation of the quarter space, which are available but are not readily incorporated into an EHL model. Hence, the EHL analysis for a quarter-space problem has not been obtained in spite of its practical significance.EHL theory for steady state conditions has become quite mature following significant contributions both theoretical and experimental in the 1960s to 1980s. Thereafter, the focus of EHL studies then shifted to more realistic problems such as transient behaviour, starvation, thermal, finite length, boundary slip, surface roughness, and surface textures.This proposed work is the first attempt to tackle quarter-space EHL problems.Why can we do it? It is because we have successfully obtained a rapid solution for complex quarter-space contact problems. Our new method uses matrices to realize the solution process and provides an explicit general solution. We have further succeeded in generating the flexibility matrices that are independent of loading and can be used for different loading cases. Therefore, the new method facilitates iterative numerical analyses for elastohydrodynamic lubricated contacts in the elastic quarter space. The results of the new method have been verified by comparison with existing published quarter-space results.The aims of this work are to (1) further develop the new matrix solution to cope with the more general case of free wedge surfaces, and (2) apply this matrix model to EHL analyses for quarterspace problems.The originality and innovativeness of this study are the proposed rapid solution to elastic quarter-space and wedge problems, and the provision of a more precise EHL modelling of lubricated finite line contacts.The success of this proposed research will provide a rapid solution to quarter-space EHL problems. The effect of free end surfaces on the calculated results in comparison with those based on conventional half-space EHL analyses can be evaluated, and whether the existing EHL formulae can be justified or have to be modified for application in practical conditions can then be clarified.

Detail(s)

Project number9042063
Grant typeGRF
StatusFinished
Effective start/end date1/01/1511/12/18

    Research areas

  • elastohydrodynamic lubrication,quarter-space ,finite line contact,contact mechanics,