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Gravity-induced bistable 2DOF piezoelectric vibration energy harvester for broadband low-frequency operation

Liu Chaoran, Zhang Wei, Yu Kaiping, Liao Baopeng, Zhao Rui, Liu Tao

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 3

art. no. e208, 2023

Bistability has been proven beneficial for vibration energy harvesting. However, previous bistable harvesters are usually cumbersome in structure and are not necessarily capable of low-frequency operation. To resolve this issue, this paper proposes a compact two-degree-of-freedom (2DOF) bistable piezoelectric energy harvester with simple structure by using an inverted piezoelectric cantilever beam elastically coupled with a swinging mass-bar. The swinging mass-bar possesses bistable property due to the combined effect of the gravity and the elastic joint. It is revealed that, under the inter-well periodic motion pattern which has large swinging amplitude, the swinging mass-bar can exert large force and moment on the piezoelectric cantilever beam, thereby generating large electrical output in this process. Moreover, the inter-well periodic swinging motion can occur in a very broad low-frequency region, enabling broadband low-frequency energy harvesting. An experimental prototype is tested under harmonic excitation and sine frequency sweeping excitation; high electrical output is gained in the frequency range of 2 Hz to 12.6 Hz with a peak power of 3.558mW and a normalized power density of 19.52mW/(g2·cm3), which validates the broadband low-frequency energy harvesting capability.

Design and experimental study of a quasi-zero-stiffness vibration isolator incorporating transverse groove springs

Liu Chaoran, Yu Kaiping

Archives of Civil and Mechanical Engineering

2020

Vol. 20, no. 3

41--61

The concept of quasi-zero-stiffness (QZS) vibration isolator was proposed in recent decades to improve the low-frequency isolation performance without increasing the static displacement. This work is devoted to the concrete realization of a QZS isolator by utilizing transverse groove springs. Firstly, the QZS isolator is theoretically analyzed and some dynamical indices are analytically calculated. Then, the transverse groove springs are designed and the isolator prototype is assembled; the QZS feature of the prototype is basically fulfilled. Finally, the experiments are conducted by means of an electrodynamic shaker which generates sinusoidal base excitation for the isolator prototype; the experimental results clearly show the good isolation performance of the QZS isolator and meanwhile reflect some practical factors that should be noticed in actual applications.