Inertial amplified metamaterial for vibration isolation

Phononic crystals, artificial materials constituted by a periodical repetition of elements, can inhibit the propagation of elastic or acoustic waves in certain frequency ranges, referred to as bandgaps. These frequency gaps originate from destructive interference when the characteristic length of the periodicity within the phononic crystal is equal to half the wavelength of the incoming waves. Therefore, unless an extremely large lattice constant is considered, achieving large stop bandwidths at low frequencies is practically impossible. However, recent observations show that inertial amplification mechanisms can elude this limitation. In this work, an inertial amplification mechanism is used to design a periodic structure endowed with a low frequency bandgap. Simplified analytical and finite element models of the unit cell are developed to obtain the dispersion properties of the infinite structure. Finally, we perform a frequency response analysis on the finite structure to investigate the transmission of mechanical vibrations and assess the attained attenuation level.