Abstract: Firstly , the residual life distribution is experimentally studied under two-level cyclic loading. It is shownthat , in the situation of no fatigue failure , the residual life standard deviation under the high-level load becomes larger after low-level cyclic load acting , or vice versa. According to the two-level cyclic stress experiment result , equations are developed to simulate the residual fatigue life distribution parameters. Then , an approach is developed tocalculate fatigue reliability by means of damage state analysis. With such an approach ,the fatigue reliability underrandom loading can be calculated as long as the original P-S-N curve is available.

Key words: fatigue, reliability, residual life, interference model, random load