Analytical modeling and experimental verification of a S-shaped vibration energy harvester

During the last decade, significant research effort has been spent on simple Cantilever Piezoelectric Vibration Energy Harvesters (PVEHs). These types of harvesters have their maximum efficiency in a very narrow bandwidth around their natural frequency and are therefore unfit for being used in presence of random or wide spectrum excitation. In this study, a periodic substructure for multi-frequency energy harvesting with single piezoelectric patch is proposed. This system is able to harvest energy from several modes (the lower ones) and, through proper design, these modes may be obtained in a narrow frequency band. The substructure is designed through an analytical model that allows to place modes exactly where required and tests are carried out to validate the proposed analytical model. The results confirm the validity of the proposed model that could be exploited to determine solutions for further improving both the bandwidth and overall efficiency of the harvester by helping of nonlinearity phenomena.