Validation of a Computational Model for Predicting Fatigue Life

A new computer model to predict fatigue life based on the evolution of damage in a structure is presented. The experimental data used to validate the model is provided by the SAE FDE Committee. The implemented damage model assumes that damage evolution can be computed as a function of the dissipation of hysteresis loop for a sequence of Ramberg-Osgood equations for a sequence of fatigue load cycles. This model does not use the Paris-Erdogan equation for crack growth. Two model parameters are the coefficients of the Ramberg-Osgood equation. The third model parameter is the total dissipation for the damage variable to reach a value of 1.0. Computer simulations of fatigue tests with block loading are demonstrated. A high-resolution plane strain FEM analysis that resolves the strain field near a stress concentration is shown to be necessary to achieve accurate predictions of fatigue crack nucleation and fatigue crack growth.