Analyzing friction and scratch tests without in situ observation

This paper presents an algorithm which allows one to estimate the elastic recovery in a scratch test without in situ observation of the true contact area between the tip and the surface. The algorithm is based on determination of the threshold normal forces at the end of elasticity and beginning of plasticity by measurement of the width of the residual groove left on the surface. The elastic recovery may then be estimated and hence the local friction and contact pressure. The estimated local friction lies between the experimental apparent friction and the true local friction derived from a flow line model and independent of the model. This analytical method is especially suitable for analysis of the scratching of polymer surfaces.