Finite element, critical-plane, fatigue life prediction of simple and complex contact configurations

A finite element based critical plane approach is developed incorporating the Smith-Watson-Topper (SWT) multiaxial fatigue criterion. The approach is applied to a cylinder-on-flat fretting contact to predict failure locations, crack orientations and component lifetimes. The cylinder-on-flat conditions are based on a published study on contact size effects in fretting fatigue life prediction, in which volume-averaging of theoretically predicted contact stress and strain fields was required to emulate experimental trends. This contact size effect is captured by the finite element approach of the present work. The lifing methodology is subsequently applied to the more complex problem of a spline coupling susceptible to both fretting and plain fatigue cracking. The spline life and crack initiation predictions are compared with measured test results.