Reliability based inspection planning using fracture mechanics based formulations for ship structures

Abstract

Surveys of ship structures are periodically carried out to ascertain the structural integrity of the hull. With increasing ship size, number of such details would be quite large calling for extensive efforts to survey the hull. Reliability based inspection is a rational way for ensuring the effectiveness of the surveys. Using fracture mechanics based formulations; preparation of reliability based inspection plans has been demonstrated for Very Large Crude Carrier (VLCC) structural details. The uncertainties in various parameters related to the loads, materials as well as the parameters of fatigue crack growth have been taken into account. Scheme for updating of reliability of a given ship structural detail considering various survey outcomes has been presented which employs a Bayesian approach. Effect of utilization of various inspection techniques has been demonstrated. The paper demonstrates that reliability based inspections are a feasible technique for integrity management of ship structural details.