Acoustic metamaterial analyses using Hershel-Quinke resonator array

• Grant number: 23/12112-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2023
• End date: October 31, 2024
• Field of knowledge: Engineering - Mechanical Engineering - Mechanics of Solids
• Principal Investigator: Jose Maria Campos dos Santos
• Grantee: Kael Holanda Cadete
• Host Institution: Faculdade de Engenharia Mecânica (FEM). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 18/15894-0 - Periodic structure design and optimization for enhanced vibroacoustic performance: ENVIBRO, AP.TEM

Abstract

Different types of acoustic filters, such as a ¼ wave tube, expansion chamber; Helmholtz resonator (HR) and Hershel-Quinke resonator (HQ) have been used widely in acoustic engineering as passive devices to reduce noise in narrow frequency bands. In recent decades, new approaches have been proposed to improve the performance of these filters. Many of these are based on adjusting the resonant frequency of the filter to broaden the bandwidth at resonance and increase sound transmission loss. An interesting and promising approach to obtain a wide attenuation range in a duct is to periodically distribute lateral ducts or resonators along the duct. This generates some frequency bands known as stop bands or bandgaps, where the waves are strongly attenuated. Bandgaps are generated due to the local resonance effect of these acoustic devices. However, when distributed periodically, they produce bandgaps generated by destructive interference from the Bragg scattering effect. This work intends to investigate this phenomenon in a periodic H-Q resonator-duct system. In order to understand the physical phenomena involved, simulating models (theoretical and numerical) of the system will be studied and formulated using the transfer matrix method, as well as, they will be transformed into computational codes. Variations of the resonator geometry and configurations of their spatial distribution in the duct-resonator set will be investigated in order to increase the bandgap width and the sound transmission loss generated by the metamaterial.