Multi-Modal Behaviour of Nonlinear Piezoelectric Energy Harvesters

Abstract

Piezoelectric energy harvesters convert vibrational energy into electrical energy, thereby reducing the dependence of wireless devices on batteries. However, most existing harvesters have a limited bandwidth, generating usable power only within a narrow range of excitation frequencies. Buckled beam harvesters address this issue by intentionally introducing nonlinear behaviour, but systematic design strategies for such devices are still missing due to the absence of versatile models and limited understanding of their dynamics.
In this thesis, these challenges are addressed by developing a model that combines finite element analysis with lumped-parameter equations and validating it experimentally. The resulting framework captures higher-order vibration modes and nonlinear dynamic phenomena such as secondary resonances and softening behaviour. It is demonstrated that these effects can be exploited to optimize the design and broaden the bandwidth of buckled beam piezoelectric energy harvesters. Based on the improved physical understanding, several practical design improvements are proposed.