An evaluation of parameters for predicting fretting fatigue crack initiation

There are numerous fatigue parameters that can be used to determine the ons et of crack initiation in a component subjected to constant amplitude plain fatigue, This study evaluated how well some of these parameters predict fr etting fatigue crack initiation in titanium alloy, Ti-6Al-4V. The following crack initiation parameters were evaluated; the strain-life parameter, the maximum strain corrected for strain ratio effects, the maximum principal s train corrected for principal strain ratio effects, the Smith-Watson-Topper (SWT) parameter, the critical plane SWT parameter and the Fatemi and Socie (F-S) parameter. The Ruiz parameters, which are specific to fretting fatig ue condition, were also evaluated. The evaluation was based on the paramete r's ability to predict the number of cycles to initiation and location for crack initiation. The results indicated that the maximum strain amplitude a t the contact interface was an important parameter for fretting fatigue cra ck initiation. Furthermore, the results indicated that when the applied loa ding was corrected for the effects of contact and mean stress or strain rat io, titanium alloy, Ti-6Al-4V exposed to the fretting fatigue condition beh aved in a manner similar to the plain fatigue condition. (C) 2000 Elsevier Science Ltd. All rights reserved.