Abstract

Periodic structures are extensively used for vibration mitigation purposes due to the presence of frequency bandgaps, frequency ranges in which waves travelling in the structures attenuate. One of the physical mechanisms for the emergence of frequency bandgaps is Bragg scattering, multiple wave scattering leading to destructive wave interference. Conventional methods for determining frequency bandgaps are based on the classical Floquet theory and imply structures to be strictly periodic. The present talk aims to present theoretical approaches that can be used to study wave propagation and scattering in structures with disturbed periodicity, as well as in quasi-periodic and graded structures. Benefits of quasi-periodic and graded structures over conventional periodic ones in terms of vibration attenuation performance will be also briefly discussed.