Structural reliability analysis of secondary hull detail

Abstract

A reliability model for analyzing the possible occurrence of crack propagation of a secondary structural detail is developed. Vibration response due to engine excitation is formulated by a stochastic model based on analysis of a general cargo hold structure. Engine speed and cargo tank filling level are taken as stochastic variables. A limit state is formulated based on a threshold stress intensity factor for crack growth and expresses the possible occurrence of fatigue crack propagation. Failure probabilities are estimated by Monte Carlo simulations and reliability approximation methods (FORM/SORM). The adequacy of the applied stochastic model for vibration is evaluated and the robustness of the estimated failure probabilities is assessed. One main remark is that the reliability-based design of secondary details may lead to an improvement in the fatigue capacity of the detail.