Determination of Acoustic Characteristics of Melamine foam withExperimental Validation

Abstract

Space launch vehicles experience severe dynamic loadings throughout the flight. Acoustic loads are one such load that is very critical to the launch vehicle at the time of ignition and take off. The amplitudes of acoustic loadings are generally very high and required to be diminished to save electronic components. Typically, one of the most common and efficient insulating materials is Melamine Foam (MF). This paper analyses the acoustic and environmental noise reduction using MF panels of variable thicknesses (25, 50, and 75 mm). Commercial FEA software is used to estimate the acoustic parameters, which are experimentally, validated using an impedance tube based on the transfer matrix method. The impedance tube can measure the normal incident sound absorption coefficient and transmission loss for the frequency range of 64 Hz to 6.2 kHz. A conventional, two-microphone impedance tube is connected to a sample holder downstream of the first microphone pair and a section downstream of the sample holder that accommodates a second pair of microphones. Two separate arrangements of impedance tubes are used to measure the absorption coefficient and transmission loss. The FEA and experimental results are compared and found in good agreements. Furthermore, the optimized insulation foam thickness is obtained based on required acoustic parameters.