Corrosion fatigue and multiple site damage reliability analysis

This paper proposes a comprehensive seven-stage life prediction model for the reliability analysis of aging aircraft structures under multiple site damage (MSD) due to corrosion fatigue. The damage process is divided into an interaction stage and a noninteraction stage in order to consider the interactions of the MSD cracks. The structural initial state at the interaction stage is determined by bridging the pitting corrosion and MSD. Once interaction sets in, progressive failure analysis is implemented through an iterative finite element analysis procedure. The onset of crack coalescence is assumed to correspond to the onset of structural failure. The probability of crack coalescence under MSD is evaluated by using system reliability concepts. An adaptive multimodal importance sampling technique is developed for efficiency and accuracy in probabilistic life estimation under MSD due to corrosion fatigue.