A unified numerical approach for multiaxial fatigue limit evaluation

A unified numerical approach to evaluate the endurance limit for general mu ltiaxial fatigue loading, under proportional or nonproportional loading, is presented. A minimum circumscribed ellipsoid approach is proposed for comp uting the amplitude and mean value of the equivalent shear stress, and an e fficient numerical algorithm is developed for solving the min-max problem b y using a constrained optimization method. The approach is general and effi cient, especially suitable for computer-aided design and optimization. With this approach, nonproportional loading effects can be taken into account, overcoming limitations of many other multiaxial fatigue criteria. Experimen tal results collected from the literature are compared with results predict ed by the numerical approach proposed in this paper. The comparison shows t hat the predictions agree well with experiments for both proportional and n onproportional loading situations.