Optimization of Wave Filtering Characteristics Based on Locally Resonant Metamaterials

Abstract

Lightweighting, with respect to structural design, is required to reduce environmental impact. However, typical lightweighting requirements conflict with noise and vibration (NV) performance. To satisfy both lightweighting and NV requirements, vibro-acoustic metamaterials are being investigated as innovative alternatives. These metamaterials have wave-filtering characteristics, referred to as bandgaps, caused by structural periodicities. To apply vibro-acoustic metamaterials to engineering applications, it is important to adequately address their finite periodic structures. This paper presents an analytical model of wave transmission to determine the bandgaps of finite periodic structures. To understand the formation mechanism of these band gaps, a one-dimensional waveguide model is employed, and block diagrams of elastic wave propagation inside periodic structures are constructed. Finally, a metamaterial with structural periodicities caused by distributed local resonators is optimized to minimize the transmission ratio of elastic waves.