Behavior of Traction Force at Elliptic Contact between Wheel and Rail. Some Experimental Results using a Special Rolling Contact Testing Machine under Water Lubrication.

Abstract

So far we have treated wheel/rail contact problems as a two-dimensional line contact and studied the behavior of traction force under various surface conditions. Here, in order to investigate the influence of lateral slip or traction on the longitudinal traction, we carried out some experiments of elliptic contact under water lubrication. The longitudinal traction force and slip were measured by applying a force perpendicular to the rolling direction with a special rolling contact testing machine. The relationship between traction coefficient and slip ratio obtained through experiments was compared with the results of our numerical analysis which used the boundary element method. It was recognized that under water lubrication, the experimental results approached the numerical ones as the rolling speed decreased, which gave the same tendency as our former line contact experiments and two-dimensional analytical results. When the force perpendicular to rolling direction increased, the maximum traction coefficient decreased. It could be explained through numerical analysis that the decrease of longitudinal traction due to lateral force was attributable to the increase of slipregion on the contact surface.