Nonlinear analysis of the crashworthy component of an eagle wave energy converter in rotating-collision

The Eagle wave energy converter (WEC) is novel device and has high power generation efficiency demonstrated by the small-scale model in the tank tests. During the sea trials of 10 kW full-scale prototype performed from 2012 to 2014, a design problem occurred that the crashworthy component (namely End Beam) was crashed up by the rotor. In order to investigate the damage mechanism of End Beam and improve the design of the Eagle WEC, an impact analysis was conducted utilizing ANSYS/LS-DYNA. In the simulation, structures were modeled as full-scale parameters and assumed to be elastic-plastic. Meanwhile, the bottoms of End Beam were presumed to be standstill. Moreover, the influences of water surrounding the WEC structures were considered using added mass method. Through the simulation, the stress and strain distributions, collision force and the energy absorption of the system were obtained. The results fit well with the actual damage situation. Furthermore, three improvement schemes were proposed including enhancing the structure of End Beam, increasing the upward angle of the rotor and adding energy accumulator. The simulation results demonstrated that the third method can effectively absorb the kinetic energy of the rotor and prevent the WEC from destruction in the rough sea states.