Abstract
This paper focuses power generation and nonlinear dynamic behaviors on a new bistable piezoelectric-electromagnetic energy harvester. Three different kinds of piezoelectric cantilever beam structures, which include the monostable piezoelectric cantilever beam, the bistable piezoelectric cantilever beam with spring and magnet, and the bistable piezoelectric cantilever beam with spring, magnet, and coil, are designed. The power generation efficiency and dynamic behaviors for each structure are experimentally studied, respectively. Due to the spring introduced, the system easily goes through the potential barrier. Experimental results show that the power generation structure of the bistable piezoelectric-electromagnetic harvester can vibrate between two steady states in a wider range of the frequency. Therefore, the effective frequency bandwidth is broadened about 2 Hz when the spring is introduced under the condition of the suitable magnetic distance. Comparing with the power generation efficiency for three different kinds of structures, it is found that the bistable piezoelectric-electromagnetic harvester has the optimum characteristics, which include the optimal magnetic distance of 15 mm, the optimal load of 8 MΩ, and the parameters variation law of coils. For this structure, the influences of the external excitation and the magnetic distance on the output voltage and dynamic behaviors of the system are examined.
Highlights
Guest Editor: Viet- anh Pham is paper focuses power generation and nonlinear dynamic behaviors on a new bistable piezoelectric-electromagnetic energy harvester. ree different kinds of piezoelectric cantilever beam structures, which include the monostable piezoelectric cantilever beam, the bistable piezoelectric cantilever beam with spring and magnet, and the bistable piezoelectric cantilever beam with spring, magnet, and coil, are designed. e power generation efficiency and dynamic behaviors for each structure are experimentally studied, respectively
Experimental results show that the power generation structure of the bistable piezoelectric-electromagnetic harvester can vibrate between two steady states in a wider range of the frequency. erefore, the effective frequency bandwidth is broadened about 2 Hz when the spring is introduced under the condition of the suitable magnetic distance
Erturk and Inman [6] explored the relation between the power generation efficiency and nonlinear vibration of the bistable piezoelectric cantilever beam. ey found that the magnetic piezoelectric structure had a larger vibration amplitude and a greater output power than the piezoelectric structure without magnet
Summary
The piezoelectric cantilever beam, coils, magnets, and the spring are fixed on the fixture. e fixture is fixed on the vibration exciter. e signals are sent to the power amplifier by the signal generator to control vibration of the piezoelectric cantilever beam. e displacement of vibration of the piezoelectric cantilever beam is captured by using the high precision laser detector, and the time-displacement data are obtained. en, data are sent to computer by the LK-G controller. e output voltage of the system is measured by multimeter. The piezoelectric cantilever beam, coils, magnets, and the spring are fixed on the fixture. E signals are sent to the power amplifier by the signal generator to control vibration of the piezoelectric cantilever beam. E displacement of vibration of the piezoelectric cantilever beam is captured by using the high precision laser detector, and the time-displacement data are obtained. E piezoelectric material used in the experiment is the PVDF. Experimental Materials e materials used in the experiment are the piezoelectric beam, coils, resistances, springs, magnets, and wires, as shown in Figure 2. e piezoelectric material used in the experiment is the PVDF. e PVDF material is not damaged when the cantilever beam vibrates with a large vibration amplitude. e base layer of the piezoelectric beam is the brass. e PVDF layers and the brass are combined by the conductive adhesive. e length of the piezoelectric beam is 90 mm, the width is 10 mm, and the thickness is 0.51 mm, respectively. e thickness of the PVDF layer is 30 microns. e piezoelectric materials on the upper and lower layers are fully covered. e piezoelectric strain constant is 17 PC/N. e piezoelectric voltage constant is 0.2 Vm/N. e size of the square magnet at the end of the piezoelectric beam is 8 mm × 5 mm × 2 mm. e diameter of the cylindrical magnet at the end of the spring is 10 mm, and the thickness is 8 mm. e coil is the copper wire. e length of the soft spring is 20 mm, and the initial wire diameter of the spring is 0.5 mm. e initial spring stiffness is 1018 N/m, as calculated by the formula k (Gd4/8D3), where k indicates the spring stiffness; G denotes the shear module of the spring and
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