Acoustic Attenuation in Ferromagnetic Shape Memory Alloy Polymer Composites

Acoustic attenuation in ferromagnetic shape memory alloy and its composites has been measured using the newly designed and built experiment. This experiment has the ability to determine, simultaneously, the magnetic field, transmitted stress, threshold field and resonance frequency. Acoustic attenuation in polyurethane (PU) polymer composites with Ni-Mn-Ga particulate fillers have been reported which exhibits greater vibration absorption than polymer/ magnetostrictive composites due to the rearrangement of twin variants in Ni-Mn-Ga particles. It is observed that above the low frequency, the acoustic attenuation is gradually decreased from specimen and specimen. It is proposed that the Ni-Mn-Ga/PU polymer composite can be used as a suitable candidate for mechanical energy absorption applications. In this paper, some of the recent developments in both Ni-Mn-Ga single crystal and Ni-Mn-Ga/PU polymer composites, with special reference to the acoustically assisted magnetic-field-induced stress and mechanical energy absorption, are discussed.