Fatigue Failure Under Complex Stress Histories

Abstract

An expression for predicting fatigue failure of a structure subjected to sinusoidal stress cycles of different amplitudes and different mean values is derived. The derivation is based on a steady-state model of fatigue crack growth. For two cases, predicting in-service fatigue failure and predicting crack growth in a laboratory test, the derived expression is substantially equivalent to the classical linear damage rule. The crack-growth derivation extends the classical linear damage concept to the problem of predicting the remaining fatigue life of a partially damaged structure.