Prediction of fatigue failure location on a component using a critical distance method

The prediction of fatigue failure from notches and other stress concentrators is complicated by factors relating to the local notch geometry and stress field. One problem which has received little attention is the fact that for a component containing several stress concentrating features, failure may occur from a feature which is not the one causing the highest stress. This paper reports the analysis of an automotive suspension component which demonstrates this phenomenon. Commercial software for fatigue life prediction was unable to predict systematically the correct failure location, taking stress-concentration effects into account. A critical distance approach gave a successful prediction, and a good estimate of the fatigue life. It is recommended that this approach be adopted in future predictive software.