Dynamic Metamaterials for Structural Stopband Creation 2016-01-1791

The NVH performance of conventional panels and structures is mainly driven by their mass. Silence often requires heavy constructions, which conflicts with the emerging trend towards lightweight design. To face the challenging and often conflicting task of merging NVH and lightweight requirements, novel low mass and compact volume NVH solutions are required. Vibro-acoustic metamaterials with stopband behavior come to the fore as possible novel NVH solutions combining lightweight requirements with superior noise and vibration insulation, be it at least in some targeted and tunable frequency ranges, referred to as stopbands. Metamaterials are artificial materials or structures engineered from conventional materials to exhibit some targeted performance that clearly exceeds that of conventional materials. They consist typically of (often periodic) assemblies of unit cells of non-homogeneous material composition and/or topology. Their superior performance may arise from the intrinsic properties of the individual unit cells and from the mutual interaction between the cells. If the transfer path of vibrations is known, metamaterials targeting different frequency zones can be applied to achieve wider stop bands to block vibrations traveling along the given transfer path. This paper investigates the efficiency of different metamaterial solutions for blocking vibrations along a certain transmission path: sequential metamaterial lay-out versus a mixed lay-out. The efficiencies of the different strategies for vibration attenuation are numerically and experimentally evaluated and compared.