Prediction of Sound Transmission in Aircraft over the Mid and High Frequency Range

Designing aircraft involves high degree of structural complexity for getting high stiffness and low mass distribution. Consequently, critical frequencies of the various aircraft parts are low with high radiation efficiency and high-related sensitivity to sound pressure loads over mid and high frequency ranges. Moreover, noise sources are both random-(in-flight turbulent flow induced pressure) and harmonics (engine related sound pressure level). Vibrations also propagate throughout the fuselage radiating energy at a distance inside the cabin. Statistical Energy Analysis (SEA) is therefore of crucial interest for handling both structural complexity and aircraft size, a frequency-limiting factor for discretize-deterministic vibroacoustic solvers (FEM or BEM). SEA methodology nevertheless needs adaptation to aircraft specificity. Traditional analytical modeling may appear too coarse for robust enough description of aircraft design involving shell ribbing and composite multilayered skins. The SEA implicit assumption of weak coupling between subsystems is also limitative when assembling segments of fuselage of similar properties. Series of included technical illustrations show the way for predictive SEA model construction on one hand mixing measurement, FEM and analytic modeling and on the other hand improving accuracy of analytical SEA descriptors.