Defect acceptability under full-scale fretting fatigue tests for railway axles

This paper presents a new approach based on the application of a multiaxial high cycle fatigue criterion together with the use of El-Haddad correction for investigation of fretting fatigue in railway axles. Stress path along the axle–wheel contact, determined by the FE analysis, was implemented into different multiaxial fatigue criteria in order to predict critical sites of nucleation. The equivalent fatigue limit expressed by the applied criterion is compared with the crack size dependent fatigue limit described by El-Haddad correction in order to define a defect size acceptability criterion. Verification of the proposed approach was done by post-test failure investigation of the full-scale axle tests conducted as a part of Euraxles project. Scanning electron microscope (SEM) examination of the failed press-fit sections revealed a critical defect size in the order of 200 μμm in depth for non-propagating cracks. The obtained results were found to be consistent with the estimations made by the proposed approach.