The goal of this investigation is to determine how the sedimentation of the magnetorheological (MR) fluid within an MR sandwich beam affects the beam’s dynamics. To discover this phenomenon, the authors measured the natural frequency and damping of a beam under several conditions, such as outer-layer stiffness, magnet location, and magnetic field strength, for beams whose MR fluid had sedimented and beams that were shaken to redistribute the fluid within the beam. The collected data was compared to previously measured modal data of the same beams when they were first built. The results show that the beams’ natural frequency lowered when the MR fluid sedimented and was shaken, but the damping rose for sedimented and shaken beams.
The purpose of this research is to measure the free-decay dynamics of a magnetorheological (MR) sandwich beam when influenced by a semi-active magnetic field and comparing the resulting damping performance to those of baseline fields. The research effort involved an experiment where the beam freely decayed while in a magnetic field that influences the MR sandwich beam, altering its damping performance. In addition to baseline cases of no magnetic field or a constant field, the electromagnet also had a field that would shut off after a set time and a field that would switch between a high and low field strength at a certain frequency. These results were also recreated numerically, which required an experimental modal analysis to gather certain material property data. The experimental findings showed little variation in the damping performance regardless of the magnetic field used, while the numerical analysis indicate that the magnetic fields would quicken damping, but only slightly. The results suggest that improvements to the sandwich beam structure may yield the greatest improvement in MR-fluid-based damping performance.
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