Experimental Investigation of Dry Reciprocating Wear Behaviour Using an Annular Common Edge Contact Configuration

Abstract

Experimental studies on wear often employ incomplete contact configurations which cause variations in uncontrolled variables as wear progresses, ultimately leading to coupled results. This study observes fundamental wear mechanisms under dry gross sliding conditions. Reciprocating wear experiments are conducted at constant normal load using annular samples having flat-on-flat common edge contact configuration that are made of Al 6082 T6. This configuration ensures constant nominal contact area and pressure, nominally uniform contact pressure distribution, an edge-free contact region along the sliding direction and uniform air exposure of the contact area. A comprehensive investigation of fundamental wear behaviour is conducted through measurements of wear mass, tangential and vertical displacement, hysteresis loop area, coefficient of friction and tangential contact stiffness. In contrast to some previous studies on annular contacts, the results show increasing wear mass with normal load. The findings also indicate that a reliable displacement measurement technique, here digital image correlation, is essential for accurate tracking of relative surface displacements. This enables correction for machine compliance and hence accurate tangential contact stiffness measurements, and accurate observation of dilatant motion. In contrast, the test machine’s nominal measurements are shown to be sufficient for work input calculations. The evolution of both the vertical displacement and the hysteresis loop area implies the presence of two distinct processes during the initial transient stage: surface roughening and debris bed formation. Competition between these processes is shown to govern transient wear.

Graphical Abstract