Monaco E., Franco F., Lecce L.

This paper presents the activities carried on by the authors within the first years of the research project named M.E.S.E.M.A. (Magnetoelastic Energy Systems for Even More Electric Aircraft) funded by the European Commission and coordinated by the “Dipartimento di Progettazione Aeronautica” of the University of Naples “Federico II”. One of the main targets for the MESEMA Consortium consists in reducing the level of disturbance noise in turbofan aircraft; for such scope a noise & vibration control system using magnetostrictive actuators will be designed, developed and tested, with the goal of controlling broadband noise & vibrations in a frequency range between 150 – 500 Hz. The environmental noise & vibration excitations will be representative of a small/medium turbofan aircraft case. During the first part of the project a numerical (Finite Element) model of the test article (a fuselage mock-up of an ATR42) has been developed coupling the structural part with the interior acoustic volume and has been correlated with experimental tests results. The model permitted to derive the requirements of the actuation system in terms of number of “inertial” actuators needed and, as a consequence, the required performances in terms of force amplitudes to be supplied to the host structure. Dedicated genetic algorithms have been employed in order to optimise the positioning of the actuators to reach the maximum theoretical interior noise level reduction predicted by the well known pseudo-inverse approach where responses were obtained from the correlated F.E. model. Such approach represented an interesting tool for the definition of actuators required performances and also of their initial locations. This last aspect may result in fact particularly critical due to the complex acoustic modes shapes (many circumferential and longitudinal acoustic waves) of the internal air volume at the highest selected control frequencies.