An exact model is proposed for sound transmission through a sandwich cylindrical shell of infinite extent that includes a tunable electrorheological fluid core, and is obliquely insonified by a pla...

Active damping of sound transmission through an electrorheological fluid-actuated sandwich cylindrical shell:

Low-resilience polyurethane foams including several additive constituents were synthesized to improve their vibro-acoustic performances, as well as the thermal insulation viscoelastic polymer additive can attenuate vibrations and absorb sound energy the vibro-acoustic properties of two innovative viscoelastic treatments fabricated with polyurethane foams are discussed in this paper using a typical aeronautical panel test setup Since an aircraft insulation arrangement must provide both noise and thermal insulation for the specified operating conditions and expected thermal comfort of passengers, the thermal conductivity of the samples has been examined assuming a testing range between 20 °C (room temperature) and − 40 °C (cruise altitude) the results highlighted an optimal behavior of the novel viscoelastic foams in terms of both acoustic and thermal performance, offering a very interesting self-embedded solution with a good weight to performance ratio, compared to standard blanket composed by extra viscoelastic treatments

Sound proofing and thermal properties of an innovative viscoelastic treatment for the turboprop aircraft fuselage

Damping assessment of new multifunctional epoxy resin for aerospace structures

Nowadays, the design choices of the new generation aircraft are moving towards the research and development of innovative technologies, aimed at improving performance as well as to minimize the environmental impact. In the current “greening” context, the morphing structures represent a very attractive answer to such requirements: both aerodynamic and structural advantages are ensured in several flight conditions, safeguarding the fuel consumption at the same time. An aeronautical intelligent system is therefore the outcome of combining complex smart materials and structures, assuring the best functionality level in the flight envelope. The Adaptive Trailing Edge Device (ATED) is a sub-project inside SARISTU (Smart Intelligent Aircraft Structures), an L2 level project of the 7th EU Framework programme coordinated by Airbus, aimed at developing technologies for realizing a morphing wing extremity addressed to improve the general aircraft performance and to reduce the fuel burning up to 5%. This specific study, divided into design, manufacturing and testing phases, involved universities, research centers and leading industries of the European consortium. The paper deals with the aeroelastic impact assessment of a full-scale morphing wing trailing edge on a Large Aeroplanes category aircraft. The FE (Finite Element) model of the technology demonstrator, located in the aileron region and manufactured within the project, was referenced to for the extrapolation of the structural properties of the whole adaptive trailing edge device placed in its actual location in the outer wing. The input FE models were processed within MSC-Nastran® environment to estimate stiffness and inertial distributions suitable to construct the aeroelastic stick-beam mock-up of the reference structure. Afterwards, a flutter analysis in simulated operative condition, have been carried out by means of Sandy®, an in-house code, according to meet the safety requirements imposed by the applicable aviation regulations (paragraph 25.629, parts (a) and (b)-(1)).

Aeroelastic analysis of an adaptive trailing edge with a smart elastic skin

In the present work, vibroacoustic (VA) characteristics, namely sound transmission loss (STL), overall sound pressure levels (OASPLs) of aircraft panels made up of aluminum, composites and fiber me...

Vibroacoustic performance assessment of aircraft panels in low, mid and high frequency regimes

Over the years, the interior noise levels have been improved, and nowadays a high acoustical comfort is of major importance for the commercial success of propeller aircraft. The use and development of high vibro-acoustic performance devices and their integration on the primary structure are, therefore, among the most critical topics in the greening of the next generation air transportation. The purpose of this research was properly focused on the analysis of a dynamic control system appointed to increase the noise attenuation transmitted in the propeller aircraft fuselage. Passive and active dynamic devices have been studied and characterized in this work. Simulations and tests performed on the first stage demonstrator structure highlighted how the passive tuned vibration absorber increases the comfort controlling the structural behaviour of the fuselage at the first blade pass frequency. Further improvements of fuselage comfort can be reached using active devices. A conceptual design of a hybrid active device able to act on the first three blade pass frequencies has been outlined. The characterization of the whole active noise control system has been described and its effect on noise reduction in fuselage of propeller aircraft has been evaluated.

M. Di Giulio

Papers

Progress in Studying Passive and Active Devices for Fuselage Noise Reduction for Next Generation Turboprop