Since structural damage accompanies lots of economical cost and social problems, inspection has become to be important in the safety of structure and economical aspect. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The objective of this paper is to get optimal inspection plan containing inspection interval and method. Crack is one of the most frequent structural damages and can lead to collapse of structure. In this paper, the crack propagation process is idealized as Markov chain model. The deteriorating process in corrosive environments and the effect of inspection are also considered in the model. The probabilistic characteristics of cracks are changed, because ship is operating in corrosive environments and the scantling of structural members is reduced due to corrosion. Non-stationary Markov chain model is used to represent the process of corrosion in structural members. Genetic algorithm is used to accomplish the optimization of inspection plan. In this paper, the characteristics of individual inspection plan are investigated by numerical examples for the change of corrosion rate, the cost due to scheduled system down and target failure probability. From the numerical example, it can be seen that the improvement of fatigue strength for the members with shorter fatigue life is the most effective way in order to reduce total maintenance cost.
Since structural damage accompanies lots of economical cost and social problems, inspection has become to be important in the safety of structure and economical aspect. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The objective of this paper is to get optimal inspection plan containing inspection interval and method. Inspection is one of the most effective tools for keeping structural safety.
