Estimation of acoustic parameters for metallic and composite configurations with experimental validation

Acoustic energy is the primary source of vibration input to a Space Launch Vehicle. The Sound Pressure Level produced by high velocity gases can have adverse effect on subsystem reliability if not subsided to an allowable limit. In this research, the theory underlying the transfer matrix approach is described first followed by a description of the experimental setup using Impedance tube. Various results, including the absorption coefficient and normal incidence Transmission Loss are presented for an acoustic insulation of variable Melamine Foam thickness from 25 mm to 70 mm; different Honeycomb / Carbon sandwich; and metallic structures. The results are first estimated numerically using COMSOL and later validated experimentally. The working frequency range is described with the placement of small and large diameter tubes from 31.5 Hz to 8000 Hz. The resonance features are obtained due to sample constraint around its edges. The acoustic characteristics of Melamine Foam with different thicknesses are presented to optimize acoustic insulation blanket within Payload Fairing to protect satellite and other avionics from harmful Sound Pressure Level. Since the primary vibroacoustic environment occurs at the very beginning of a mission, such failures are likely to have a greater mission impact than failures induced by other space environments over time. Consequently, an optimized acoustic insulation is mandatory for Payload Fairing to attenuate acoustic loads up to a desired level. This approach of sound attenuation is equally applicable for other applications which are vulnerable against acoustic loads.