Defects of the Classic Formulation of a Nonsteady EHL Problem for a Journal Bearing. New Problem Formulation

Abstract

A nonsteady problem for an elastohydrodynamically lubricated (EHL) journal bearing is considered. It is shown that under certain circumstances contact pressure and shaft normal velocity are discontinuous functions of time. The initial normal velocity of the shaft has a certain value which is predetermined by the shaft initial position and applied load. Therefore, the EHL solution cannot accommodate any different initial normal velocity of the shaft. These defects pertain to any nonsteady EHL problem in the “classic” formulation. The main goal of this paper is to propose a modified formulation of the EHL problem free from the above defects. For purely squeezed lubrication film an analytical and numerical analysis of a dynamic bearing response to abrupt changes in external load is performed based on the classic and “modified” problem formulations leading to discontinuous and smooth solutions, respectively.