Vibration–damping capacity of lotus-type porous magnesium

Lotus-type porous magnesium with cylindrical pores aligned unidirectionally was fabricated by the unidirectional solidification of molten magnesium under pressurized hydrogen atmosphere. The apparent attenuation coefficient of the free vibration of lotus-type porous magnesium was measured by hammering–vibration–damping tests, which revealed that the apparent attenuation coefficient increases with increase in porosity, i.e., the damping capacity of lotus magnesium is higher than that of non-porous magnesium. The mechanism of high damping capacity was analyzed by using the Fourier transform technique, which revealed that various vibration modes of high frequency are excited by a hammering. The excited vibrations of high frequency enhance the damping capacity of lotus-type porous magnesium.