Multiple solutions and corresponding power output of a nonlinear bistable piezoelectric energy harvester

We examine multiple responses of a vibrational energy harvester composed of a vertical beam and a tip mass. The beam is excited horizontally by a harmonic inertial force while mechanical vibrational energy is converted to electrical power through a piezoelectric patch. The mechanical resonator can be described by single or double well potentials depending on the gravity force from the tip mass. By changing the tip mass we examine the appearance of various solutions and their basins of attraction. Identification of particular solutions of the energy harvester is important as each solution may provide a different level of power output

A ferrofluid-based energy harvester: An experimental investigation involving internally-resonant sloshing modes

The conformable nature of liquid-state transduction materials offers unprecedented opportunities for designing complex-shaped vibratory energy harvesters that are, otherwise, hard to realize using solid-state transduction elements. To achieve this goal, we propose an electromagnetic energy harvester which exploits the sloshing of a magnetized ferrofluid column in a base-excited container to transform vibratory energy into electricity. The sloshing of the magnetized ferrofluid column generates a change in magnetic flux which, in turn, induces a current in an adjacent closed-loop conductor. In this study, we specifically choose the dimensions of the container and the height of the fluid column such that the modal frequencies of the sloshing ferrofluid are nearly commensurate. It is shown that this choice of parameters activates a two-to-one internal energy pump between the commensurate modes resulting in two response peaks and large-amplitude voltages over a wide range of frequencies, thereby improving the steady-state bandwidth of the harvester. Influence of several of the key design parameters on the harvester's performance is also discussed