A Stochastic Analysis of Plastic Area on Rough Surface Contact in Relation with Transition from Mild to Severe Wear

Abstract

Burwell and Strang supposed that the transition from mild to severe wear mode would occur when the total area of plastic regions on a soft surface contacting with a hard surface reached to the apparent contact area. This paper describes a modification of the theory in the previous paper which made approximately a stochastic analysis of the total area of plastic regions on a flat surface contacting with a rough surface employing the roughness model by Greenwood-Williamson (GW) and Johnson' cavity model to obtain the plastic area surrounding an asperity contact. The analytical results show that the contact severity defined by the ratio of the total plastic area to the nominal contact area is affected only by the ratio of the standard deviation of roughness summit heights to the mean radius of the summits which relates to the plasticity index defined by GW and as a result this supports the experimental results on the transition load for wear mode by Hirst and Hollander. In addition, the effect of temperature characteristics of materials hardness on the contact severity is shown and it can be seen that the softening temperature is significant under operating condition of high pV (pressure-velocity) value.

Keywords

• tribology
• contact mechanics
• rough surface
• plastic area, seizure
• material softening
• temperature