Implementation of digital twin-enabled virtually monitored data in inspection planning

Marine structures are subjected to cyclic wave loads in ocean environments, leading to progressive forms of structural degradation such as fatigue cracks. To ensure fitness-for-service of these critical assets, there has been increasing interest in the application of digital twin-enabled virtual monitoring techniques. Whilst numerous studies have focused on computational algorithms dedicated to virtual monitoring, little effort has been devoted to establishing a practical digital-to-physical connection and decision-making based on virtually monitored data. This paper bridges this research gap by proposing an approach for implementing digital twin-enabled virtually monitored data in inspection planning for marine structures. The inspection of fatigue-prone structural components plays a crucial role in structural integrity management. Reliability-informed inspection, which employs a probabilistic approach that prioritises inspections based on probability of failure, offers a cost-effective approach by avoiding unnecessary inspections and reducing life-cycle costs. However, conducting a comprehensive structural reliability analysis requires thorough knowledge of the actual operational profile and current state of a structure (e.g. consumed fatigue life) in order to accurately predict its future performance (e.g. remaining fatigue life). Although design specifications and assumptions can serve as guidelines, a high degree of uncertainty may arise due to the discrepancy between the actual operational profile and the design assumptions. The approach developed in this paper consists of four main elements: virtual monitoring, data-driven forecasting, fatigue reliability, and inspection planning. This provides a practical means for establishing a connection between condition monitoring and assessment in the digital world and decision-making in the physical world. An illustrative numerical example is then presented to demonstrate the application of the proposed framework. Finally, avenues for future research and developments in this field are discussed.