A study on elasto-plastic impact friction

A purpose-built pendulum machine was used to study the oblique impact and t he behaviour of the surface layers of a normalized low alloy steel subjecte d to the impact of hard oc-alumina balls. The effect of relative tangential velocity on impulses, restitution coefficient and impact energy loss, was analysed. The morphology of the impact indentations was characterized and r elated to the impulses obtained. There was lip formation in the target mate rial with ejection of a small fragile oxidized chip, at a certain critical sliding speed. The impact duration and the impulse ratio have maximum value s. These values seem to be related to the critical angle of attack, common in abrasive and erosive ductile processes. The experimental results were co mpared with some impact models and theories. (C) 1999 Elsevier Science S.A. All rights reserved.