OS1531 High-Precision Prediction of Fatigue Life for Nonlinear Loading under Random Vibration

This article verifies a method of predicting the fatigue life of materials under random vibration containing nonlinear loading. We approximated stress frequency distribution in nonlinear range by exponential function. Next, fatigue lives were predicted with stress frequency distribution calculated by Dirlik's method and mathematically-formulated frequency in nonlinear range. As the result of the comparison, the error in the predicted fatigue lives calculated by Dirlik's method to those calculated by proven Rainflow method was within 50 percents. In addition, the predicted fatigue lives calculated by Dirlik's method were 1.79 times as much as those resulted from random fatigue tests with sheet welding test pieces in average (Rainflow method was 1.93 times). We indicated this improved method could predicted the fatigue live with same precision with Rainflow's method.