Fatigue Reliability Of A Stiffened Panel Subjected To Crack Growth

Fatigue fracture is one of the most significant factors which have effect in the safety of naval architecture and ocean engineering structures.Stiffened panels as the important integral part of hull may probably be broken caused by crack growth under alternate loads if there are initial cracks in them.Considering the safety of stiffened panels,in this paper the fatigue reliability of a stiffened panel subjected to correlated crack growth of cracks is analyzed based on fracture mechanics and theory of reliability.To analyze fatigue reliability of a stiffened panel,it is assumed that the crack growth in a stiffened plate is a combination of crack propagation in the plate and the stiffener.The stress intensity factor for the different correlation factors of the crack sizes in the plate and the stiffener are calculated by finite element method.Singular elements are used to establish the 3D stiffened panel model.Then the geometry correction functions of the stiffened panel are obtained.The wave loads applied on the stiffened panel are predicted based on the 3D potential flow theory.Then the probability distribution of the local loads is achieved.The Paris–Erdogan law is used to predict the crack propagation.Monte Carlo simulation is employed to define the statistical descriptors of the crack growth in the stiffened panel under different correlation functions.The least square method is applied to make the regression of the results of crack growth from Monte Carlo simulation.The probabilistic model of the stiffened panel subjected to correlated crack growth of cracks is achieved.The fatigue assessment diagram is used for estimating the critical crack length.The Fatigue reliability index and the failure probability are analyzed finally based on the probabilistic model of the stiffened panel subjected to correlated crack growth of cracks under different correlation factors.