Vibro-acoustic response of a turboprop cabin with innovative sidewall viscoelastic treatment

In recent years, it's considerably grown the market demand for increasingly performing and comfortable aircrafts as a new mandatory design target. Among the determining factors for the internal comfort, are included the noise and vibrations, the source of which is detected mainly in the propulsion unit especially in the case of turboprop category: the most significant component of the noise perceived inside a cabin is undoubtedly the blade-passage load exerted by the propeller. Recently were therefore tested techniques, both active and passive, of vibration emission reduction and sound absorption, however the goal remains to find solutions by extremely low-weight and easy to apply on the real mock-up. As known, a damping treatment is typically used to reduce noise coming from fuselage structure vibration under acoustic loading excitation. In such research context, the vibro-acoustic performance of the viscoelastic material for replacing the conventional interior blanket of the fuselage sidewall have been investigated for the well-known higher dissipation capacity and energy storage. Starting from experimental tests by means of different measurement techniques carried out on an innovative foam sample, the dynamic parameters were estimated according to identify suitably the material performance database for further finite element analysis on a turboprop fuselage model. The outcomes achieved have emphasized a significant role of the viscoelastic foam than the standard blanket with respect to the internal sound pressure levels abatement as well as the thermal insulation. The developed foam prototype is also easily integrable with an outer layer ensuring a fully removable embedded solution for the maintenance inspections.