CONTACT STRESS ANALYSIS DURING FRETTING OF A SURFACE MODIFIED FLAT-ON- FLAT WITH ROUND EDGE

摘要

In the present work, a two-dimensional finite element analysis is carried out to understand the influence of contact geometry and surface treatment on the fretting behavior of a flat with round edge-on-flat plate contact. The fretting pad and plate are modeled using isotropic elastic material properties of Ti-6Al-4V. The mating pair was subjected to a constant normal load followed by a tangential displacement. The effect of contact geometry was studied by independently varying length of the central flat region and radii of corners. Parameters important from the context of fretting viz. contact pressure and normal stress (in tangential direction) were extracted. The effect of surface treatment was studied by modeling two layers of different elastic modulus and yield strength on the mating surfaces. It is found that addition of intermediate layers of lower elastic modulus and yield strength than the parent material leads to a reduction in both contact pressure and peak tensile stress; the influence was more on the peak tensile stress than contact pressure. Further, the addition of softer and less stiff layers on the pad is noted to be less advantageous than adding it on both pad and substrate or substrate only case. The study suggests that contact geometry should be taken into account while carrying out surface modifications of contact pairs.