Sensitivity analysis of fatigue-induced sequential failure using system reliability approaches

Fatigue-induced sequential failure is one of the major failure modes of various structures. To avoid the collapse of a structure, an adequate level of structural redundancy should be provided, and such structural safety can be ensured through proper structural design and maintenance. The sensitivity of structural reliability with respect to the random parameters related to a structure is useful information for effective reliability-based structural design and maintenance. However, it is challenging to perform sensitivity analysis of fatigue-induced sequential failure because it requires system-level reliability analyses and sensitivity calculations. In this study, two recently-developed approaches of system reliability analysis are introduced to estimate the sensitivity of structural reliability. First, the Branch-and-Bound method employing system reliability Bounds (B3 method) is employed to estimate the structural risk of fatigue-induced sequential failure at the system level, to identify the most critical failure sequences, and to conduct sensitivity analysis at the component level. Second, the Matrix-based System Reliability (MSR) method is applied to achieve the sensitivity of structural risk at the system level, based on the component-level sensitivities obtained from the prior B3 analysis. The integration of these two system reliability approaches allows us to perform sensitivity analysis of fatigue-induced sequential failure effectively, and the proposed method is tested through its application to a multi-layer Daniels system.