Ferrofluids for concurrent vibration absorption and energy harvesting

This paper proposes a novel Tuned Magnetic Fluid Damper (TMFD) with energy harvesting capabilities to concurrently mitigate structural vibrations and harvest vibratory energy. The energy harvesting TMFD consists of a rectangular container carrying a magnetized ferrofluid and mounted on a vibrating structure. The ferrofluids geometric and material properties (height, surface area, magnetization) are tuned such the first modal frequency of the fluid column matches the first modal frequency of the structure. The one-to-one resonant interactions between the structure and the fluid column results in a direct energy transfer mechanism which mitigates the vibration of the structure by channeling energy to the ferrofluid. Consequently, the fluid undergoes a sloshing motion with large-amplitude surface waves that change the orientational order of the magnetic dipoles in the fluid. This creates a time-varying magnetic flux, which induces an electromotive force in a coil wound around the container. The electromotive force transforms a small part of the fluids kinetic energy into electricity by generating a current in the coil. Experimental studies performed on an actual TMFD prototype clearly demonstrate its vibration suppression potential and energy generation capabilities.