Dual-coupling beams energy harvester for random vibrations and human motions: Modeling and experimental validation

Most of the realistic low-frequency vibrations in an ambient environment are random. Although white Gaussian noise is considered as a more accurate representation of ambient vibration than harmonic excitation, it is still interesting to explore the performance of the energy harvester subjected to a practical application, such as human motions. In this paper, a theoretical and experimental investigation of a dual-coupling beams energy harvester (DEH) is carried out under random excitation and human motion. The proposed DEH comprises two piezoelectric cantilever beams connected with a linear coupling spring. Numerical and experimental results verify that the proposed harvester has a larger output power compared to the traditional bistable energy harvester (BEH) and the linear energy harvester (LEH). When the power spectral density is 0.02 g2/Hz, the RMS power of the DEH with a spring stiffness of 57 N/m (in the monostable region) is increased by 71.2 % than its counterpart. In addition, when the coupling spring stiffness is 26 N/m (the DEH is in the bistable region), experimental results show that the RMS power of the DEH is increased by 525 %, 135.8 %, and 125.6 % at a human motion speed of 2, 4, and 6 km/h, compared to the traditional BEH and LEH.