Experimental study of a two-degree-of-freedom piezoelectric cantilever with a stopper for broadband vibration energy harvesting

This paper presents a two-degree-of-freedom (2-DOF) piezoelectric energy harvesting (PEH) system with a stopper for wideband operation. The proposed system consists of a folded piezoelectric cantilever with a stopper integrated. Two cases are considered where the stopper is placed at the free end of the outer beam and inner beam, respectively. It is shown experimentally that with the proper parametric combination we can move the anti-resonance point outside the two resonant peaks and widen the frequency responses of both the peaks. Large amplitude voltage output over 11 Hz can be obtained when we focused on the dynamics of the inner beam. In addition, it is demonstrated that arranging the stopper at the free end of the inner beam yields better perfor-mance than that with the stopper placed at the outer beam. Detailed parametric studies are performed to investigate the influences of the stopper distance, amplitude of base movement, and frequency sweep directions on the voltage output. A maximum power output of 713 mu W is obtained.