Peer-Reviewed Journal Details
Mandatory Fields
Nathan Jackson, Frank Stam, Oskar Olszewski, Hugh Doyle, Aidan Quinn, Alan Mathewson
Sensors and Actuators A-Physical
Widening the bandwidth of vibration energy harvesters using aliquid-based non-uniform load distribution
Optional Fields
Bandwidth, Energy harvester, Piezoelectric, Cantilever, Non-uniform massa
tVibration energy harvesters typically have a narrow bandwidth, which allows them to generate highamounts of power, but only at a specific frequency. This paper presents a novel method of increasing thebandwidth of a cantilever beam by creating a non-uniform load. The concept uses a liquid filled mass,which causes the structures overall centre of gravity to shift as the beam bends. The overall centre ofgravity shifts due to the mass change caused by the dynamic behaviour of the fluid. This paper validatesthe concept both numerically and experimentally by using a custom manufactured fluid filled mass ona piezoelectric cantilever. A water filled mass demonstrated a 2.8x increase in bandwidth for low accel-eration (<1 g) and low frequency cantilever (27 Hz) devices. The effects due to liquid density and liquidviscosity are also experimentally measured. The numerical estimations match well with the experimentalresults for low accelerations (<0.5 g). Above 0.5 g acceleration the liquid water used in the cavity becamechaotic, which caused liquid droplets to separate from the bulk liquid, thus reducing the overall mass forgiven point in time. This non-linear liquid dynamic behaviour further increases the bandwidth by creatinga larger variation in the resonant frequency. In addition, as the fluid viscosity increases, the accelerationfrom the vibration source required to cause movement in the fluid also increases. The measured opencircuit peak to peak voltage demonstrated an increase in bandwidth without significant loss in voltage.
Grant Details
Science Foundation Ireland