Research partener : GeM
To achieve a global transition to renewable energies, offshore wind energy is a promising alternative, but its large-scale deployment poses several challenges. Recently, several collision cases between ships and offshore wind turbines have been reported and, as offshore wind farming expands, the likelihood of collisions between ships and floating offshore wind turbines (FOWT) is expected to increase. The consequences of such collisions can be significant: perforation of the ship’s tanks resulting in pollution or even in explosion in the case of a methane tanker or a hydrogen-propelled ship, damage to impacted wind turbines up to collapse of the tower, rupture of the anchoring lines leading to the drift of the platform and a collision with other wind turbines in the park.
Although the finite element approach allows for a high-fidelity representation of the complex physical phenomena that take place in a ship-FOWT collision event, including large deformations, plasticity, fracture, and fluid-structure interaction, its implementation remains challenging in terms of computation time and expertise needed for model preparation.
Simplified methods based on analytical formulations are thus very useful to assess the damage of both the ship and the wind turbine, especially at preliminary design stage associated to risk assessment, where structural optimization and damage stability analysis require the simulation of hundreds of collision scenarios, involving different striking ships and impact conditions.
The present research aims to develop a fast and reliable tool, based on the super element (SE) approach, capable of predicting the outcomes of a collision between a ship and various types of floating offshore wind turbines. It is based on thesis work previously undertaken at ICAM1 and University of Liège. Up to now, no development that accounts for the striking ship’s deformation has been made, leading to overconservative predictions of the FOWT’s damage. Moreover, the effect of some hydrodynamic forces such as the ones generated by the ship bow wave before and during the impact is still unclear.
In the proposed PhD thesis, the deformation of both bodies will be investigated and integrated into a single solver, which will significantly improve the assessment of the crashworthiness of both the vessel and the wind turbine. The resulting industry-oriented tool will allow the estimation of the damage sustained by the ship and the wind turbine, taking into account different geometries and impact speeds. In addition, the existing “fluid” solver MCOL, that considers the hydrodynamic forces during the collision, will be extended to account for the action of the ship bow wave. Validations of the developed tools will be conducted using LS-Dyna non-linear finite element software.
The plan to achieve the above objectives is organized as follows:
- Step 1: Analysis of literature related to existing analytical, numerical and experimental works that involve ship collisions against offshore wind turbines.
- Step 2: Set-up of LS-Dyna models based on the Coupled Eulerian Lagrangian approach to analyze the influence of both the deformability of the striking ship and the hydrodynamic forces induced by the bow wave.
- Step 3: Development of a new SE solver to quickly assess the ship’s deformation in case of head-on and side-way impacts and coupling with existing FOWT SE solvers.
- Step 4: Extension of the existing “fluid” solver MCOL by integrating the action of hydro-dynamic forces induced by the bow wave.
- Step 5: Validation of the coupled MCOL-SE solver by comparison with LS-Dyna results.
- Step 6: Publication of the results in peer-reviewed international journals and redaction of a PhD dissertation.
Download the offer and the bibliography in French.
Download the offer and the bibliography in English.
Renewable energies, Offshore wind, Ship collisions, Numerical modeling, Naval engineering, Hydrodynamics, Simulation, Scientific research
