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.
KeywordsPiezoelectric vibration energy harvesting PZT stack 33-Mode Double acting compression mechanism
List of Symbols
Mass of a weight
Stiffness of a spring
Displacement of a damped single degree-of-freedom system
Displacement of base excitation
Maximum displacement of base excitation
Angular natural frequency
Maximum compressive load applied to a PZT stack
Elastic compliance at constant electric field
Piezoelectric coupling coefficient
Displacement of a PZT stack
Thickness of a piezoelectric layer
Actuation force to a PZT stack
The number of piezoelectric layers
Length of a PZT stack
Output electric power
External electrical resistance
This research was partially supported by the Main Project of Korea Institute of Machinery and Materials (Project Code: NK213E). This research was also supported by the National Research Council of Science & Technology (NST) grant by the Korea Government (MSIT) (No. CAP-17-04-KRISS).
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