Method of predicting crack initiation based fatigue life

摘要

A method of predicting crack initiation based fatigue life includes the steps of plotting the elastic finite element stress states of a stress history for a given component at a predetermined critical location in the stress space and determining the least square fit ellipsoid of the stress states by a straight line through the center of gravity. An aspect ratio lambda 2/ lambda 1 is defined where lambda 1 and lambda 2 are the two largest eigen values of the eigen system of matrix M which defines the least square fit ellipsoid and where lambda 1>/= lambda 2. A multiaxial fatigue analysis is performed where the aspect ratio exceeds a predetermined value.