DESIGN OF MECHANICAL METAMATERIALS BASED ON BIPHASIC PERIODIC MICROSTRUCTURES

The passive control of elasto-acoustic wave propagation is a very active field of research, currently fuelled by the theoretical advancements in multiscale design, accompanied by the technological development of additive manufacturing techniques. In this work, we present a mechanical metamaterial, characterized by a biphasic (fluid and solid) periodic cell, that exhibits acoustic as well as elastic bandgaps in the dispersion spectrum, which – in principle – could provide insulation from both sound and vibration in prescribed frequency ranges. Bandgaps arise when voids and channels open in the repetitive cell. We aim at studying the geometric parameters that influence the metamaterial performance. Through a tuning of the mechanical properties of the metamaterial, waves of given nature and frequency can be remarkably attenuated simultaneously in the two different domains, the fluid domain where acoustic waves propagate and the solid domain where elastic waves propagate. A finite element model is used to determine the dispersion curves and investigate the frequency band structure, which is found to be governable through the selection of the geometric parameters of the repetitive cell.