On Heat Generation in Rolling Contacts Under Boundary and Mixed Lubrication

Abstract

This paper reports on experiments and theoretical analyses of heat generation and scuffing failure in rolling contacts. The experiments were conducted with dry contacts, and the theoretical analyses were carried out using a deterministic thermal contact model. The research reveals that heat generated by asperity plastic deformation in the direction normal to the contact can be significant in high-load, high-speed contacts under boundary and mixed lubrication conditions. Under near rolling conditions, heat generated by the plastic deformation largely dominates that by the friction and is the main source leading to contact scuffing. This heat generation is shown to be significant compared to frictional heating even at relatively large slide-to-roll ratios. Parametric studies show that the ratio of asperity-plastic-deformation heating to frictional heating is sensitive to slide-to-roll ratio, hardness and surface finish but insensitive to contact load, rolling velocity and fluid/asperity load sharing.

A mathematical model for rolling/sliding line contacts in boundary and near boundary lubrication

“…This flattening is indeed seen in the numerical solutions of dry concentrated contacts as shown in Chang et al. 5 The flattening of the roughness structure is also shown in the numerical solutions of EHL contacts with a Newtonian lubricant, which enables large oil pressure spikes to be generated directly above the roughness peaks. 6 Thus, it is reasonable to assume a single-contact model especially for high-performance systems of significant loading and well finished surfaces.…”