Intermittent brittle crushing often occurs in the movement of an ice sheet against an offshore structure. Matlock’s ice-structure interaction model is used to simulate the behavior of the ice crushing by modeling ice teeth indentation contacting a spring-mass-dashpot structure. The dynamic behavior of this analytical ice-structure interaction system is studied using Fourier analysis to efficiently predict the response amplitude of specific dynamic periodicity at a given indentation speed. The system’s equations of motion are established based on the assumption of continuous ice indentation. This assumption well captures the ice crushing failure by allowing immediate contact of the offshore structure with the next ice tooth at the time of fracturing of a previous tooth. The fourth mode shape of a numerical wind tower system is studied to convert the physical parameters to the parameters of the spring-mass-dashpot system.
The time histories of ice tooth deflections are expressed through the non-linear dynamic equations. The kinematic initial conditions and the response amplitude of the wind turbine structure can be predicted at targeted periodicity via the Fourier analysis. Given a representative offshore wind tower system, the mode shapes of the physical system are calculated as inputs for the ice-structure interaction model. As an extended validation, the amplitudes of the structural dynamic vibrations predicted by the analytical models at specific periodicity and using the mathematical closed-form simulation are compared with the numerical simulation results.
