Cost-Based Optimum Scheduling of Inspection and Monitoring for Fatigue-Sensitive Structures under Uncertainty

Inspection and monitoring of deteriorating structures are generally performed to assess structural integrity and predict the remaining service life. For deteriorating structures, a reliable prediction of damage occurrence and the time-dependent damage evaluation depend on the accuracy of deterioration models under uncertainty. A probabilistic approach to establish optimum cost-based inspection and monitoring schedules of fatigue-sensitive structures is proposed in this paper. The inspection schedule is the solution of an optimization problem to minimize the expected total cost, including the costs of inspections or monitorings, and the expected failure cost. The failure criterion uses damage detection time and time for damage to reach the critical state. The uncertainties associated with damage occurrence/propagation and damage detection time are both considered. The solution of the optimization provides the inspection times and quality of inspections. The formulation of the optimization for inspection scheduling is extended to monitoring scheduling. Effects of the failure cost on inspection and monitoring scheduling are also studied. The proposed approach is applied to a fatigue-sensitive structure.