Authors: Jung-Hoon Kim, Young-Gu Kim, Young-Do Jo
Structural components unavoidably are affected by defects such as surface scratches, surface roughness and weld defects of random sizes, which usually occur during the manufacturing and handling process. These defects are shown to have an important effect on the fatigue life of the structural components by promoting crack initiation sites. In general, the fatigue and fracture performance of cracks contains a significant number of uncertainties. Fatigue phenomena have a deep stochastic behavior that must be taken into account. Equivalent initial flaws size(EIFS) has been developed as useful design tools to make life predictions for structural reliability problems. For probabilistic fatigue assessment by using EIFS in this study, the LEFM-based fatigue reliability approach is used based on a limit state function related to crack size and a damage accumulation function. From analysis results, the probabilistic reliability method can provide lifetime fatigue performance in terms of reliability and number of cycles, based on LEFM. This is useful for estimating both the cumulative number of cycles and remaining fatigue life.
Keywords: equivalent initial flaws size; probabilistic fatigue assessment; steel structures; linear elastic fracture mechanics