RESIDUAL-STRESSES DUE TO DEBRIS EFFECTS IN EHL CONTACTS

Debris in lubricated contacts significantly reduces the contact fatigu e life. The life reduction is due to the surface damage caused by debr is denting and the subsequent overrolling of the dent in the EHL conta ct. High pressure spikes are generated due to the dent which will modi fy the contact stress profiles, leading to stress concentration at or near the surface. In this paper, the residual stresses caused by debri s effects are investigated. The residual stresses originate from the d ebris denting process and from the overrolling process of the dent in EHL contacts. The finite element method was used to investigate the re sidual stresses due to each process and their combined effects on the internal stress distribution of an EHL contact. It was found that the residual stress from debris denting will increase the internal stresse s in an EHL contact. However, the residual stresses from overrolling o f dent will reduce the internal stresses. The residual stresses are la rgely dependent on the plastic modulus of the contacting materials and need to be considered when investigating the internal stresses in hea vily loaded lubricated contacts.