Synchronous low-frequency vibration mitigation and energy harvesting with tunable load bearing capacity and operation band

Vibrations are usually harmful in engineering and thus need to be mitigated, whereas they are also potential sources of useful energy and can be harnessed. Current difficulty in vibration mitigation and energy harvesting is to achieve both objectives synchronously, especially in low-frequency environments. In this paper, a device composed of quasi-zero-stiffness (QZS) pneumatic support and magnetic-piezoelectric cantilever beams is proposed for synchronous low-frequency vibration mitigation and energy harvesting. The pneumatic support enables the adaptability to different load masses while maintaining QZS. The magnetic spacing in the magnetic-piezoelectric cantilever beam can be adjusted to produce various stiffness properties, including nonlinear positive stiffness, QZS, and bistability. The nonlinear dynamic behaviors are studied and the performances are analyzed based on the electromechanical coupled equations. Results indicate that energy harvesting and vibration mitigation can be achieved at low frequencies, and most importantly the energy harvesting region is located within the vibration mitigation region, implying synchronization of the two objectives. Different situations induced by the bifurcation of magnetic spacing are studied and discussed. It is shown that the magnetic spacing that produces QZS for the cantilever beam is the best choice, and the energy harvesting region can be easily tuned by adjusting the magnetic spacing.