Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
An Experimental Investigation of the Influence of Excitation, Damping, and Sound Insulation on Sound Radiation and Transmission
Submission Author:
Luisa Piccolo Serafim , SC , Brazil
Co-Authors:
Luisa Piccolo Serafim, Thiago Cavalheiro, Fabio Kulakauskas, Luiz Lenzi Neto, Lucas Val Quintans Kulakauskas, Arcanjo Lenzi
Presenter: Luisa Piccolo Serafim
doi://10.26678/ABCM.COBEM2021.COB2021-2323
Abstract
Increasing the level of acoustic comfort inside the cabin has been a significant issue for the market-leading aircraft and their manufacturers. The noise level in the cabin is mainly induced by the structural vibration of panels that make up the sidewall, ceiling, and floor, having engines and turbulent airflow around the aircraft as the primary external sources of excitation. Although the vibroacoustic study of panels is a well-known topic and widely explored in the literature, it maintains relevance due to its diverse applications in different conditions. This paper proposes the study of the relationship between radiation efficiency, damping, the use of porous materials, and the type of excitation on the vibroacoustic behavior of different aeronautical panel systems. The study is conducted from a series of measurements of transmission loss, radiation efficiency, and damping loss factor performed in reverberation and semi-anechoic rooms. The influence of those parameters on the panel's response is discussed: how resonant and non-resonant modes contribute to sound radiation and how the inserted damping acts over the response spectrum. The evaluation is done using a variety of system configurations, containing four types of stiffened panels, four types of sound insulation material, including glass fibers and polymer foams, a honeycomb trim panel, and viscoelastic patches, subjected to two types of excitation: punctual force and diffuse sound field. Through the analysis of the obtained data, it is noted, for example, that the efficiency of noise and vibration treatment depends on the type of excitation, that the porous material inserts damping in the panel in the spectrum range below the coincidence frequency, and that the increase in the radiation efficiency might counter-intuitively mean in reducing cabin noise. The conclusions of this study help in the design decision-making process of aeronautical panels and acoustic treatment according to the specificities of each application.
Keywords
Vibroacoustics, Sound Transmission Loss, Radiation efficiency, Damping loss factor
