A quasi-zero stiffness energy harvesting isolator with triple negative stiffness

Vibration isolation for low frequency excitation and the power supply for low power monitoring sensors are important issues in bridge engineering. The main problem is how to effectively combine the vibration isolator with the energy harvester to form a multi-functional structure. In this paper, a system called quasi-zero stiffness energy harvesting isolator (QZS-EHI) with triple negative stiffness (TNS) is proposed. The TNS structure consists of linear springs, rigid links, sliders, and ring permanent magnets. Newton’s second law and Kirchhoff’s law construct dynamic equations of the QZS-EHI, and a comparison is made to contrast it with other QZS and linear isolators. The comparison field includes the QZS range, amplitude-frequency relationship, force transmissibility, and energy harvested power. The isolator can be applied to many engineering fields such as bridges, automobiles, and railway transportation. This paper selects bridge engineering as the main field for the dynamic analysis of this system. Considering the multi-span beam bridge, this paper compares different situations including the bridge with QZS-EHI support, with linear stiffness isolator support, and with single beam support. All results show that the QZS-EHI is not only better than the traditional isolator with linear stiffness under both harmonic and stochastic excitation, but also better than some QZS isolators with double or single negative stiffness in bridge vibration isolation and energy harvesting. Theoretical analysis is verified to correspond to the simulation analysis, which means the proposed QZS-EHI has practical application value.