“…One approach assumes that fatigue lives at different stress levels are independent random variables (Liao et al, 1995; Kam et al, 1998; Le and Peterson, 1999;Shen et al, 2000;Kaminski, 2002). The other approach assumes that fatigue lives at different stress levels are fully dependent random variables (Shimakawa and Tanaka, 1980;Kopnov, 1993Kopnov, , 1997Pascual and Meeker, 1999; Rowatt and Spanos, 1998;Ni and Zhang, 2000;Zheng and Wei, 2005). Liu and Mahadevan (2007) proposed a stochastic S-N curve representation technique to include the actual correlation of fatigue lives across different stress levels.…”