Utility of Information (UoI) for probabilistic fatigue monitoring

Fatigue crack is a problem of concerns for offshore structures. This paper studies the utility of information (UoI) based on the monitoring of fatigue crack. A center-crack specimen with an equivalent constant amplitude stress range is considered as an example to simulate the real fatigue load cases. The failure is introduced by an overload that is applied at a random point in time. Two cases are considered: the case where the fatigue crack is unknown (no possibility to act), and the case where the crack is monitored. With monitoring information, structural performance is assessed at high accuracy level in real-time. This would detect overload and cracks to avoid unnecessary repairing activities and failures. The metric of UoI as a generalization of the Value of Information (VoI) is proposed. The two cases are then compared to quantify the utility of the monitoring information based on the improved decisions. The framework of Sustainable and Resilient Based Engineering (SRBE) recently proposed by one of the authors is adopted. Numerical simulation shows the monitoring information is beneficial to detect critical overloading situations.