Relating Surface Roughness to Subsurface Stress

Abstract

Understanding and anticipating the effects of surface roughness on subsurface stress in the design phase can help ensure that performance and life requirements are satisfied. The specific approach taken in this work to address the goal of improved surface design is to relate surface characteristics of real, machined surfaces to subsurface stress fields for dry contact. This was done by digitizing machined surfaces, simulating point contact numerically, calculating the corresponding subsurface stress field, and then relating stress results back to the surface. The relationship between surface characteristics and subsurface stress is evaluated using several different approaches including analyses of trends identified through stress field visualization and extraction of statistical data. One such approach revealed a sharp transition between cases in which surface characteristics dominated the stress field and those in which bulk, or global contact effects dominated the stress. This transition point was found to be a function of the contact operating conditions, material properties, and most interestingly, the roughness of the surface.