ABSTRACT
This paper presents a rapid collision simulation tool for Floating Offshore Wind Turbines (FOWTs), with specific focus on spar-buoy floating platforms. The tool is based on a semi-coupled approach, applying the rigid-body dynamics program MCOL to simulate external dynamics. Internal mechanics is modeled based on an elastoplastic simplified method for the impact response of standalone tubular OWT supports. First, the overall algorithm is explained: an overview of both internal mechanics and external dynamics solvers is provided along with a detailed description of the coupling method. Second, the presented collision tool is validated by comparing against simulations performed with LS-DYNA/MCOL. The case study consists of a 6000-tons offshore supply vessel impacting an NREL 5MW baseline turbine mounted on an OC3 Hywind reference spar platform at velocities of 2 m/s and 5 m/s. Results demonstrate that the tool is capable of accurately capturing the response of both the turbine and the vessel, accounting for the effects of water added mass, wave radiation and viscous damping, as well as hydrostatic restoring forces. It presents a user-friendly and inexpensive alternative to NLFEA, with good accuracy for early-design stage.
