Influence of nanosilica on the acoustic properties of epoxy and evaluation of the composite as a coating for aircraft panels

Abstract

The present research work involves a systematic investigation to evaluate the influence of epoxy/nanosilica coating on vibro-acoustic characteristics of aircraft panels. Impedance tube-based Sound Transmission Loss (STL) and Sound Absorption Coefficient (SAC) measurements are performed for different weight percentages of nano silica (NS) in epoxy (1%, 2.5%, 4%, 5.5%, 7% NS) at low-mid and high-frequency segments. The optimal wt% of nanosilica in Araldite LY556, which exhibits better soundproofing in terms of SAC and STL at low-mid and high-frequency regions, is determined. 4% NS exhibited the highest STL value of 60 dB at 805 Hz in the low-mid-frequency band and 55 dB at 4900 Hz in the high-frequency band. In case of sound absorption, the highest SAC of 0.62 at 1370 Hz in low-mid-frequency band and 0.34 at 3112 Hz in the high-frequency band was achieved for the 4% NS sample. Hence, 4% NS is the optimum weight percentage to be used as a coating on the AA 2024-T3 aircraft panel. Owing to the high STL performance of the said sample, it is considered that epoxy - nanosilica exhibits better sound insulation than sound absorption performance. It is observed that the coated AA 2024-T3 sample exhibits better STL of 32.5 dB at 820 Hz in the low-mid-frequency range and 50 dB at 5000 Hz in the high-frequency range. The goal of the research to decrease noise effects experienced in fuselage cabin panels at the engine region of aircraft is validated, and it can be achieved by using Araldite LY556 – 4% NS polymer nanocomposite coating on aircraft panels.