Estudo de um absorvedor ativo de ruído utilizando material piezoelétrico

Abstract

The purpose of this work is the application of piezoelectric materials in the active control of sound transmission for reducing unwanted noise aiming to overcome the limitations of passive methods that are ineffective for the low frequencies and unsuitable for applications in clean rooms. This work is aimed at developing an active absorbing noise using piezoelectric material. Initially, for evaluation the efficiency of piezoelectric materials glued in a thin plate structure as acoustic actuators at low frequency was conducted an experimental of implementing techniques active noise control based on the principle of destructive interference of waves, in substitution to traditional loudspeakers. Were experimentally tested the controllers feedforward, feedback and hybrid with adaptive LMS (Least Mean Square) algorithm and filtering techniques X-LMS. After verified the efficiency of the piezoelectric materials in the active noise control in a second stage of this work was made a numerical evaluation, via Finite Element Method (FEM), and experimental assessment of active noise absorber to promote the active control transmission in a duct with plane waves propagating through the use of Active Structural–Acoustic Control (ASAC) techniques using a manual and a PI (Proportional and Integral) controller, to mitigate the reflected sound pressure at low frequencies and, thus, maximize the sound absorption coefficient of the structure. The experimental tests of active control of sound transmission performed in this study, with the purpose of low-frequency sound attenuation in a impedance tube using as control actuator a thin plate instrumented with piezoelectric material, were implemented in Matlab-Simulink® software with the aid a data acquisition system dSPACE® .