Effects on the various rubber fenders of a tripod offshore wind turbine substructure collision strength due to boat

An analysis is conducted to minimize the damage to tripod type offshore wind turbines substructure caused by collisions with boat. The impact of a wind turbine and a boat takes a complicated form. ANSYS LS-Dyna, a commercial FEM tool, is employed for the impact analysis. The FE model generated using equivalent beams for the blades which are verified the method through the results of static and dynamic analysis between full 3D blade model and equivalent beam model. The investigation is conducted in order to determine the influences of various boat speeds, which result in different loading conditions, and various rubber materials for the fender on strain energy, total deformation, plastic strain, internal energy, and permanent deformation. Natural rubber, composite rubber, and neoprene are modeled using Mooney-Rivlin constants, which are determined by material tests, and a time-marching analysis is conducted to account for their nonlinearity. Based on the analysis results, the minimum thickness of a rubber fender is suggested to decrease the effects of impact for the structures. This study provides relationship trends between the structure thickness and the rubber fender thickness, which may be useful in developing the structural design of a tripod type offshore structure. (C) 2013 Elsevier Ltd. All rights reserved.