Digital Twin Method for Global Motion and Stress Monitoring of a Steel Lazy Wave Riser

This study proposes digital twin methods for global behavior and stress monitoring of risers based on the collected motion sensor signals. An FPSO (Floating Production Storage and Offloading) vessel with SLWR (steel lazy-wave riser) is selected as a demonstration case. The reference model is initially built using the time-domain fully-coupled dynamics simulation model for validation of digital twin models, which considers the fully coupled interaction among the FPSO, mooring lines, and risers. Numerical sensor data (motions at two points) are acquired from the reference model and inputted to two separate digital twin models (single riser models). In the digital twin models, there is no environmental load as input, while only time histories of sensor data are inputted at sensor locations as boundary conditions. Time histories and statistical values of the riser’s estimated and actual motions, bending moments, and tensions are compared, which demonstrates the feasibility of the developed digital-twin-based monitoring.