Rotational Motion of Pendula Systems for Wave Energy Extraction

Rotational Motion of Pendula Systems for Wave Energy Extraction
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The main aim of this work is to investigate different planar base excitation schemes, with respect to energy extraction from a mechanical pendulum. Focus is placed on how each forcing configuration affects the stable rotational motion or stability boundaries associated with stable rotations.

The main aim of this work is to investigate different planar base excitation schemes, with respect to energy extraction from a mechanical pendulum. Focus is placed on how each forcing configuration affects the stable rotational motion or stability boundaries associated with stable rotations.

Excitation schemes, which cause the system to favour rotational motion compared to the vertically excited pendulum case, have been identified. Throughout this study two base excitation configurations combining both horizontal and vertical components of forcing have been considered. The dynamics of the aforementioned pendulum systems have been studied in three ways: firstly, rigorous numerical studies have been carried out, focussing on the bifurcations associated with periodic motions of the pendula in the forcing parameter, frequency-amplitude plane. Bifurcations associated with rotational motion of the forced pendula have been concentrated on, however an overview of the bifurcations associated with periodic oscillations (up to period-4) is also provided. In addition and secondly, analytical techniques have been applied to provide closed form solutions for the bifurcations and trajectories associated with period-one rotational motion and good corroboration with the numerical results has been shown. Thirdly, an experimental rig has been designed & built and exhibits the dynamics of the parametrically excited pendulum, whose excitation is along a tilted axis. The results of finding the sta- bility boundary of period-one rotational motion in the frequency-amplitude plane, are shown experimentally. Finally, the linear approximations of the rotational stability boundary are compared with the experimentally measured results and corroboration is good (less than 10% error).

Speaker
Bryan Horton
Venue
FN, G011