A Simplified Approach to the Prediction of Mixed and Boundary Friction

Abstract

Improving machine energy efficiency has led to the use of lower viscosity lubricants, and a greater chance of mixed/boundary contact occurring. A new equation, derived from experimental data, is proposed that enables simple calculation of the proportion of mixed/boundary friction in a contact, as a function of the λ ratio. It is also shown that some commonly used rough surface contact models (such as the Greenwood Tripp model) significantly underestimate mixed/boundary friction in the range 1 < λ < 3. The new model has the form of an S-curve, which suggests a new approach to rough surface contact modelling is to treat it as a growth/decay process, and the consequences of this approach are discussed