A fatigue reliability analysis method including super long life regime

An affordable and feasible method with moderate accuracy is developed to realize fatigue reliability assessment and life prediction including super long life regime (SLLR) through series of experimental researches on a railway axle steel and real axles. A competition damage mechanism for fatigue crack initiation and growth in SLLR is revealed to fascinate an understanding on wide fatigue damage behavior and to provide a weigh and balance on material primary quality control and on-line inspection capacity. Affordable material probabilistic strength–life (S–N) curves including SLLR are presented by an extrapolation approach on a concurrent probability rule between the S–N relations in mid-long life regime and the fatigue limits with a specified life definition. And then, structural probabilistic S–N curves are deduced by considering scale-induced effect on the material curves. Random cyclic stress–strain (CSS) relations are depicted for constructing structural random stressing history. Reliability assessment and fatigue life prediction are conducted by an interference model of the applied stress deduced from the random CSS relations and the strength capacity derived from the structural probabilistic S–N curves. Availability and feasibility of the present method are indicated by a successful application on a railway axle steel.