A crashworthy device against ship-OWT collision and its protection effects on the tower of offshore wind farms

At present, more and more offshore wind farms have been built and numerous projects are on the drawing tables. Therefore, the study on the safety of collision between ships and offshore wind turbines (OWT) is of great practical significance. The present study takes the advantage of the famous LS-DYNA explicit code to simulate the dynamic process of the collision between a typical 3MW offshore wind turbine model with monopile foundation and a simplified 2000t-class ship model. In the simulation, the added mass effect of the ship, contact nonlinearity of collision, material nonlinearity of steel and aluminum foam and adaptive mesh technique for large structure deformation have been taken into consideration. Proposed is a crashworthy device for OWT of new conceptual steel sphere shell-circular ring aluminum foam pad, and the good performance of the device under the conditions of ship-OWT front impact and side impact has been verified from the views of theoretical analysis and numerical results. The new crashworthy device can effectively smooth the contact force and reduce the top structure dynamic response, using its own structure plastic deformation to absorb most of the ship collision energy. As a result, the main structure of the OWT and the inside key electric control equipments can be saved by scarifying the structural plastic deformation of new sphere crashworthy device. What is more, the sphere configuration design of the crashworthy device can effectively guide the ship to run away from the main OWT structure and reduce the damage of the ship and OWT to some degree during side impact.