Early fatigue failure due to dents in EHL contacts
Résumé
An experimental and numerical study of early fatigue failure due to dents in EHL contacts is presented. Tests are conducted on a two-disk machine with different operating conditions. Disks are made of AISI 52100 bearing steel. The surface of one disk is smooth. The other one is initially indented by M50 steel powder using the procedure presented in previous papers (1), (2). The oil is a synthetic one qualified under the MIL-L-23699 specification The lubricant is cleaned during tests by using a beta(3 mu m) = 200 cleaning filter: An optical microscope and a profilometer are used to describe the dent evolution, as the tests are stopped at regular intervals. The test bench is described and the experimental procedure is presented. The role of sliding direction is underlined. Experimental results are finally compared with numerical calculations. It is shown that the spall starts ahead of the dent in the direction in,which the surface travels through the contact when the dent is on the follower surface, it starts behind the dent when the dent is located on the driver surface.