Exploring the real potential of the parametric pendulum for wave energy harvesting

The aim of this thesis is the exploration of the parametric pendulum as main mechanism to be used in a wave energy converter. A pendulum, if parametrically excited (changing somehow the parameters that control its dynamics) with the right excitation frequency and amplitude, can change its type of movement from an oscillatory behaviour to a rotational behaviour; this would enhance the PTO efficiency, since the electrical generator would work better with a rotational motion rather than an ever changing oscillatory one. Given that there are only theoretical studies about the rotational behaviour of a parametric pendulum, this thesis tries to build a bridge between the theoretical world and the practical WEC world, since it is conducted in collaboration with MOREnergy Lab of Politecnico di Torino, to understand the feasibility of the concept. The thesis is organized in chapters, following this order: introduction - where the aim of the thesis is explained; state of art - in which the world of the already existing and functioning WEC technologies is presented, with the last part of this chapter focused on the concepts and prototypes developed by the MOREnergy Lab; modelling - where the physical, then mathematical and then numerical models developed on purpose are presented; first analisys - in which the validation of the created model is carried on as well as a damping analisys to understand how, this factor, influences the behaviour of the parametric pendulum (since, in theory, the higher the damping the higher the electric energy produced); real prototype - where the model is loaded with sizes and weights of a modular existing prototype of a pendulum from another type of WEC under development in the same Lab; comparison - in which, starting from the same initial conditions, the created model and the adapted model of the same other WEC under development outputs are compared to highlight the difference between the excitation given to the pivot point and the ecitation given to a hull (that transmits it to the pivot point); design for experimental trial - the Lab has a Stewart platform on which the prototypes are tested, but this platform has some limitations that make it uncompatible with the excitation values requested by the prototype pendulum to reach the rotation: a new prototype is designed to be capable of rotating on the existing excitation platform; conclusion - this last chapter is self-described by its name.