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Description
Noise mitigation is a challenging societal issue. To overcome the limitations of conventional sound-absorbing materials and classical Tuned Mass Oscillators for broadband low-frequency control, this work proposes the use of nonlinear absorbers, known as Nonlinear Energy Sinks (NES), with stiffness governed by a nonlinear law. The acousto-mechanical studied NES is made of a thin viscoelastic rubber membrane.When these systems are coupled to a primary system and excited at a sufficient level to activate their nonlinear behavior, an irreversible energy transfer occurs: energy is transferred from the primary system to the NES, where it is dissipated. These absorbers are limited by their high excitation threshold required for activation.This study focuses on using the NES to attenuate the first acoustic mode of a circular duct. A theoretical model is developed to optimize the energy transfer phenomenon and to lower the membrane’s activation threshold. The theoretical prediction model is compared to experimental data obtained through a vibro-acoustic testing bench for different membranes. Additionally, an analytical and experimental parametric study is carried out.