Wave Propagation Identification of Viscoelastic and Metallic Mechanical Metamaterials

Abstract

Mechanical Metamaterials (MMs) are artificially engineered composites which have unconventional mechanical properties that stem from their microstructural geometry rather than from their chemical composition. Several studies have shown the effectiveness of viscoelastic MMs in vibration attenuation due to their inherent vibration dissipation properties. This study investigates different metamaterial wave transmission properties, namely viscoelastic phononic crystals and plates with locally resonant zigzags, hence giving rise to the two MMs vibration attenuation phenomena called Bragg scattering and local resonance. First, an analytical dispersion relation of an arbitrary multilayered crystal using the transfer matrix method was investigated. The analytical results from this computation served as a topology design tool for bilayered phononic crystals later in the study. Second, a multi-objective optimization was introduced to find the viscoelastic phononic crystal with the lowest vibration transmission in a targeted frequency range. Another objective was optimization of the phononic crystal mass since inertia correlates with vibration attenuation. Experimental testing and finite element analysis were used to support the optimization procedure. An electrodynamic shaker was used to measure the vibration transmission of the three control specimens and the optimal specimen in the frequency range of 1 to 1200Hz.