Widening the bandwidth of vibration energy harvesters using a liquid-based non-uniform load distribution

•Novel bandwidth widening concept validated using liquid mass.•Increased bandwidth achieved using a water filled mass.•Demonstrated bandwidth effects by changing the liquid density.•Demonstrated bandwidth effects by changing the liquid viscosities. Vibration energy harvesters typically have a narrow bandwidth, which allows them to generate high amounts of power, but only at a specific frequency. This paper presents a novel method of increasing the bandwidth 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 of gravity shifts due to the mass change caused by the dynamic behaviour of the fluid. This paper validates the concept both numerically and experimentally by using a custom manufactured fluid filled mass on a piezoelectric cantilever. A water filled mass demonstrated a 2.8x increase in bandwidth for low acceleration (