Experimental structure intensity analysis of an Airbus A400M fuselage structure using high-resolution vibration measurements

Abstract

An ongoing challenge in the analysis of aircraft cabin vibrations in the mid-frequency range is the analysis of transfer paths through the complex fuselage structure. Knowing these paths would allow for simpler and more cost efficient counter measures to harmonic noise sources like engines or the auxiliary power unit. The A400M-MSN5 fuselage structure located at the University of the Federal Armed Forces in Hamburg (HSU) is a production line A400M fuselage repurposed as a test facility for experimental studies allowing for full scale tests of novel experimental methods for acoustics and structure-born noise. In this paper, the results of the deployment of a fully automated and autonomous Laser-Doppler-Vibrometer scanner used to measure the structure vibration above the cabin floor at a high spatial resolution are presented. A total of more than 17000 individual measurement positions spaced approximately 9 cm apart was measured, using both a loudspeaker system and a shaker as an excitation source. Utilizing the measured high resolution deflection shapes energy transfer paths were calculated using a hybrid Numerical-Experimental approach to structural intensity analysis.