Coordinateurs du projet
Context
From a safety perspective, the probability of a ship colliding while maneuvering to avoid another ship or drifting due to propulsion failure can be considered significant.
Furthermore, numerical simulations of ship collisions with fixed jacket-type wind turbine foundations (Le Sourne, 2015) or monopile (Bela, 2017) and floating (Echeverry, 2019) wind turbine supports have clearly shown that, in certain perfectly realistic scenarios, an impact at relatively low speed can cause the wind turbine to collapse onto the ship’s deck. The consequences can be significant: loss of human life, perforation of the ship’s tanks leading to pollution or even an explosion in the case of a methane tanker, damage to the impacted wind turbines, rupture of the mooring lines leading to the platform drifting and colliding with other wind turbines in the farm.
Scientific breakthroughs and innovation
The ColFOWT research project aims to develop and validate a reliable and fast simulation tool for analyzing collisions between ships and floating wind turbines. This tool will combine analytical formulations derived from plastic limit analysis (super elements) with a solver dedicated to the overall movements of the floats, including the action of the mooring lines on the platform’s movements during and after the collision.
Expected technical and economic impact
The tool developed as part of the ColFOWT project will enable design offices to estimate, at the preliminary design stage, the consequences of a collision in terms of damage to the ship, the wind turbine, and the mooring lines. The speed of such a tool will also enable classification societies and maritime traffic regulatory bodies to process all the scenarios prescribed in a wind farm risk analysis. This will make it possible to identify the consequences of risky situations not only for wind farms but also for ships sailing in their vicinity.
Results
Initially, finite element simulation of the collision between a service vessel and a SPAR-type floating wind turbine made it possible to identify the various damage mechanisms and their sequence over time, and to confirm the importance of hydrodynamic forces. An in-depth study of the energy balance, including the latter, also highlighted certain limitations of the Ls-Dyna/MCOL code.
In a second step, analytical models based on limit analysis were developed to estimate the plastic resistance force for successive damage modes. These models were validated by comparison with numerical results for high impact energies. However, it was shown that when the impact energy remains moderate, it becomes necessary to (also) take into account the elastic behavior of the wind turbine.
At the same time, the response to the impact of a reinforced concrete panel was simulated, and several behavior laws proposed in Ls-Dyna were compared with experimental results from the literature. Existing analytical models for determining the panel’s resistance force were also studied. A model of the impact of a deformable bulb against a concrete slab was developed and validated by comparison with experimental and numerical results.
Finally, preparations were made for the upcoming impact testing campaign on a reinforced concrete structure (scheduled for the end of the year).