Trim and Floor Influence on Vibrational Response of an Aircraft Fuselage Model

Abstract

The ine uence of the interior trim and the e oor partition on the vibratory response of the physical model of an aircraft fuselage model was investigated experimentally. The one-third scale model faithfully replicated the salient structural features of a rear-engine aircraft fuselage. Detailed modal analysis of the green fuselage, i.e., the bare fuselage skin without any e oor, trim, or lining, was e rst performed. The effects of adding a honeycomb e oor partition, a sound-absorbing blanket, and a thin plastic interior lining on the modal parameters of the structure were then determined. It was found that the addition of the sound-absorbing blanket signie cantly increased the structure’ s modal damping coefe cients for its e rst e ve modes of resonance. Notable changes in the structural responseat higher frequencieswere also observed. These results strongly suggest, in agreement with recent studies reported in the literature, that sound-absorbing blankets do add signie cant damping to the vibration response of the structure (in addition to absorbing sound energy from the cabin interior ). These damping properties may be used advantageously for the optimal design of skin-damping aircraft noise-control treatments for minimal added weight, and minimal cost.