Floating oscillating-bodies are a kind of wave energy converter developed for harvesting the great amount of energy related to water waves; see Falcão  for a review.
In this paper a particular energy converter model is considered. A nonlinear analysis of its dynamic behavior is conducted both in the time and the frequency domains.
The model involves a tightly moored single-body floating wave energy converter. It captures motion in the horizontal and vertical directions. The nonlinear stiffness and damping forces are functions of the horizontal and vertical displacements and velocities and make the system a nonlinear one. In addition to the time-domain analysis of the nonlinear behavior of the system, the method of equivalent linearization is used to determine iteratively the effective linear stiffness and damping matrices and the response of the buoy in the frequency domain. The analysis pertains to the surge and the heave directions response of the wave energy converter under harmonic mono-frequency excitation (regular waves). The reliability of the linearization based approach is demonstrated by comparison with time domain integration data.
This approach offers the appealing feature of conducting efficiently a variety of parameter studies which can expedite preliminary evaluations, inter alia, of competing design scenarios for the energy converter. Suggestions for extending this approach to the case of fully nonlinear and random irregular waves are also included.