Computational fatigue analysis of contacting mechanical elements

Abstract

The paper investigates the influence of different parameters on stress distribution in the contact area of mechanical elements. The study is aimed to determine particular positions in the contacting bodies, where small crack should be initiated due to large stresses resulting from different contact conditions. A two-dimensional equivalent contact model together with Hertzian contact theory is used for all computational analyses utilising the finite element method. The distribution of the maximum equivalent von Mises stress under the contacting area is first determined for pure Hertzian contact conditions, where the maximum stresses appear at a certain depth under the contacting surface. Then a parametric study to determine the influence of loading, contact surface curvature, contact friction, residual stresses and elasto-hydro-dynamic lubrication on the stress distribution is performed. They tend to increase the stresses and move their maximum to or very close to the contacting surface, which can lead to sub-surface or surface crack initiation. In this study the surface crack initiation and propagation on the gear teeth flank is presented. The virtual crack extension (VCE) method, implemented in the finite element method, is used for simulating the fatigue crack propagation from the initial crack up to the formation of the surface pit. Comparison between the results of the numerical simulation and the results of experimental testing shows good correlation.