Abstract: It is coming of age to apply the fundamental knowledge of plastic deformation dealing various failures of engineering structures. One of topical problems is issue of strain-based fatigue reliability analysis to consider the intrinsic scattering of fatigue damage. Up to now, limited studies have been made in this issue since 1990s. They all almost derived their approaches by assuming that the fatigue strength and ductile coefficients are independent random variables and the fatigue strength and ductile exponents are constants in the Coffin-Manson cyclic strain-life (CSL) relation. Actually, these material constants should be dependent random variables coming from fits of test CSL data by the relation. Therefore, the existent approaches are only feasible for the approximation when the test data are not available. In addition, a worthy note problem is the random cyclic stress – strain (CSS) responses of engineering material revealed by Zhao et al’s experiment. A fundamental forward project is to establish a strain-based method, which can take into account the random responses and treat the material constants in the CSL and CSS relations as dependent random variables. On basis of this method, an important further forward project is to extrapolate the method into the cases of non-symmetrical and multi-axial CSS conditions to be suitable for engineering practice.

Key words: Fatigue, Mean strain/stress effect, Random cyclic stress-strain responses, Reliability, Strain analysis