Optimization and application of a crashworthy device for the monopile offshore wind turbine against ship impact

• A new crashworthy device contains a rubber blanket and outer steel shell.
• The crashworthy device can reduce the damage of monopile offshore wind turbine.
• The rubber hardness and the rubber and steel shell thicknesses are optimized.
• The effects of optimal crashworthy device are a decrease of the collision-force and nacelle acceleration.
• The optimal crashworthy device meets the requirement of the weight limitation.

The risk of offshore wind turbines collision with ships is on the rise during the service period with the increase of offshore wind farms and ship routings. In order to minimize the damage of offshore wind turbines caused by ship impact, a crashworthy device, which contains a rubber blanket and outer steel shell, is proposed. The rubber hardness and the rubber and steel shell thicknesses of the crashworthy device are optimized by comparing the collision-force and nacelle acceleration using LS-DYNA explicit code. The main reason for lessening the maximum collision-force and nacelle acceleration is that the rubber blanket could absorb a portion of ship energy by using its own structure deformation. Therefore, an optimal crashworthy device for the monopile offshore wind turbine, meeting the weight constraint, is suggested and implemented in various impact scenarios. The obvious effects of crashworthy devices are a decrease of the maximum collision-force and nacelle acceleration, especially for ships with smaller initial kinetic energy. The damage area of plastic strain for foundations is reduced to zero when crashworthy devices are used in the analysis scenarios. This paper may be useful in anti-impact design of offshore wind turbines.