Double Acting Compression Mechanism (DACM) for Piezoelectric Vibration Energy Harvesting in 33-Mode Operation

Piezoelectric vibration energy harvesting (PVEH) has been emerged as an alternative solution for sustainable powering to electronics. It has been well known that a PZT stack operating in 33-mode has higher mechanical to electrical energy conversion efficiency and higher mechanical reliability, compared to a cantilevered PZT bimorph operating in 31-mode. However, there are two challenges to improve the output performance of a PZT stack at a low frequency environment. First, the lower tensile strength of a PZT stack compared to the compressive strength makes it difficult to fully utilize maximum strain at harsh vibration conditions. Second, the relatively high stiffness of a PZT stack prevents being resonant with a base structure vibrating at a low frequency. To solve these challenges, this study thus proposes a double acting compression mechanism (DACM)-based PVEH stack operating in 33-mode. The DACM-based PVEH stack can convert mechanical vibration into elevated two-way compressive loading. The analytic model is used to investigate the electroelastic behaviors of the DACM-based PVEH device at given vibration conditions. The comparative study is performed to verify the effectiveness of the DACM-based PVEH stack over other mechanisms. It can be concluded that the DACM-based PVEH stack enables to generate higher power with the same volume of PZT using elevated two-way compressive loading.