Acoustic metamaterials (AMMs) are nowadays a promising means for overcoming heavy and expensive sound isolation designs. Unusual low-frequency sound transmission loss (STL) properties are shown to come with lattices of substructures, arranged onto stiffer and lightweight primary structures (thus resulting in an AMM), which make the AMMs to be ideal for vibroacoustic isolation applications that impose mass addition constraints. Each array unit can be devised for either causing impedance variations in the material (Bragg scattering) or as linear resonators (mechanical or electromechanical absorbers). Yet the use and effects of nonlinear absorbers for realizing AAMs are research challenges that have not been investigated. This research project contributes to the development of AMMs by deepening on the study of nonlinear energy sink (NES) lattices, realized in the form of piezoelectric patches shunted by nonlinear electrical circuits. When coupled to a linear oscillator (e.g. a primary mechanical structure), NES systems are shown to act as dynamic absorbers that feature enhanced operation bandwidths. This property, together with their demonstrated capability in kinetic energy harvesting, make the NES concept to be attractive in the design of AMMs. With the aid of numerical studies that address the behavior and implications on the periodicity or quasi-periodicity of the AMM, number of NES-based cells in the lattice, as well as on the influence of uncertainties that arise from the actual materials and manufacturing methods, one- and/or two-dimensional host structures are targeted for the implementation of the obtained lattices. The capability of AMMs in kinetic energy harvesting is also set as a goal in this research project, based on the premise of improving the activation energy property of the NES-based cells as a function of the lattice topology. In this manner, this research project aims at proposing a numerical framework for designing AMMs featuring improved broadband STL properties and the capability for supplying usable electric energy, with corresponding validations through real-world experiments.
News published in Agência FAPESP Newsletter about the scholarship: