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

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.

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Opracowanie rekordu ze środków MNiSW, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2024)