Experimental Investigation of Squeezed MRF Film Stopper and Its Effect on Vibrating Bimorph for Frequency Tuning of an Energy Generator

This paper proposed a frequency tuning concept using magnetorheological fluids (MRF) in squeeze mode as a stopper. The MRF is a smart fluid that changes from a liquid state into a semi-solid state within milliseconds when a magnetic field is applied. The change from liquid state to semisolid state demonstrated in this study is achieved by varying the distance between two magnets and hence the magnetic field. The experimental results show that the frequency of the vibrational system was increased by 16% when the MRF was activated at 0.1T. The damping was also increased by 48.8% when a magnetic field of 0.3T was added to MRF. The change in damping also affected the stiffness of the piezoelectric cantilever beam and hence the power generated from the piezoelectric bimorph cantilever. The generated power from the cantilever without MRF damping was calculated to be 1.1 μW at a resistance of 330 kΩ but increased to 9 μW when the damping of 0.1T was applied.