This paper presents activities developed by the authors within the EC funded research program named FACE (Friendly Aircraft Cabin Environment) aimed at characterising some aeronautical composite structural components from the vibro-acoustic behaviour point of view. In this document will be also presented the overall analysis of a carbon resin primary fuselage structure from low to medium-high frequency range. Vibro-acoustic behaviour is simulated by means of numerical predictive methods. The modelling techniques are shown with reference to the simulation of dynamic behaviour of panels coupled with a fluid volume, in order to predict Transmission Loss properties. Particularly, the models and results have been referred to a typical aeronautical structure for fuselage: 4 bay fuselage side panel, made of skin, stringers and frames. The first test article consists in a composite panel that has been modeled numerically and tested in order to characterize its vibro-acoustic behaviour. It is a curved panel, global dimensions of 2.2 m x 1.5 m, where the skin is a pre-preg composite laminate, frames are Z-section pre-preg composite laminate and stringers are T-section braided tube with a pre-preg offset bulb. Numerical simulations have been carried on, in order to reproduce the vibrations and noise transmission: in low frequency range by means of Finite Element Method (FEM), and in medium-high frequency range by means of Statistical Energetic Analysis (SEA). For what concerning the FEM dynamic analysis the mesh size values of the elements are consistent with the maximum frequency chosen. According to the procedures described in the work, a FEM model has been built, having 9266 nodes and 14069 elements; the skin has been modeled with shell elements; the frames have been modeled with beam elements and stringers have been split, modeling the stringer foot with shell elements, web and bulb with beam elements. The MSC/NASTRAN has been used throughout the F.E. calculations of this article. The numerical modal analysis has been performed in [0-2000] Hz frequency range, considering panel as free-free suspended. For what concerning the SEA, the modelling approach employed has been a mixed “ribbed plate“ – “subsystem” approach. Source and receiving rooms have been modelled as acoustic cavities subsystems with one of the enclosing faces of each room corresponding with the panel area and geometry. Correlation between numerical and experimental modal analysis results has been used in order to validate numerical FEM models, while energetic parameters (mean square velocity) and modal density have been used for SEA models validation. Subsequently, model sensitivity has been analysed by varying some geometrical parameters critical from an acoustic point of view. Results confirm the theory at the basis of noise transmission and give some important information about the composite materials behavior used in primary structures in place of well known metallic materials. Final result of the work is the model of a fuselage section assembled by mixing many Graphite Fibres Reinforced Panels layups.

Aircraft composite structures modeling and vibro-acoustic optimization analysis / Monaco, Ernesto; Amoroso, Francesco; Massimiliano di, Giulio; Antonio, Paonessa. - (2007), pp. ND -Paper nr 3572-ND -Paper nr 3572. (Intervento presentato al convegno 13th AIAA/CEAS Aeroacoustics Conference tenutosi a Roma, Italy nel May, 21-23).

Aircraft composite structures modeling and vibro-acoustic optimization analysis

MONACO, ERNESTO;AMOROSO, FRANCESCO;
2007

Abstract

This paper presents activities developed by the authors within the EC funded research program named FACE (Friendly Aircraft Cabin Environment) aimed at characterising some aeronautical composite structural components from the vibro-acoustic behaviour point of view. In this document will be also presented the overall analysis of a carbon resin primary fuselage structure from low to medium-high frequency range. Vibro-acoustic behaviour is simulated by means of numerical predictive methods. The modelling techniques are shown with reference to the simulation of dynamic behaviour of panels coupled with a fluid volume, in order to predict Transmission Loss properties. Particularly, the models and results have been referred to a typical aeronautical structure for fuselage: 4 bay fuselage side panel, made of skin, stringers and frames. The first test article consists in a composite panel that has been modeled numerically and tested in order to characterize its vibro-acoustic behaviour. It is a curved panel, global dimensions of 2.2 m x 1.5 m, where the skin is a pre-preg composite laminate, frames are Z-section pre-preg composite laminate and stringers are T-section braided tube with a pre-preg offset bulb. Numerical simulations have been carried on, in order to reproduce the vibrations and noise transmission: in low frequency range by means of Finite Element Method (FEM), and in medium-high frequency range by means of Statistical Energetic Analysis (SEA). For what concerning the FEM dynamic analysis the mesh size values of the elements are consistent with the maximum frequency chosen. According to the procedures described in the work, a FEM model has been built, having 9266 nodes and 14069 elements; the skin has been modeled with shell elements; the frames have been modeled with beam elements and stringers have been split, modeling the stringer foot with shell elements, web and bulb with beam elements. The MSC/NASTRAN has been used throughout the F.E. calculations of this article. The numerical modal analysis has been performed in [0-2000] Hz frequency range, considering panel as free-free suspended. For what concerning the SEA, the modelling approach employed has been a mixed “ribbed plate“ – “subsystem” approach. Source and receiving rooms have been modelled as acoustic cavities subsystems with one of the enclosing faces of each room corresponding with the panel area and geometry. Correlation between numerical and experimental modal analysis results has been used in order to validate numerical FEM models, while energetic parameters (mean square velocity) and modal density have been used for SEA models validation. Subsequently, model sensitivity has been analysed by varying some geometrical parameters critical from an acoustic point of view. Results confirm the theory at the basis of noise transmission and give some important information about the composite materials behavior used in primary structures in place of well known metallic materials. Final result of the work is the model of a fuselage section assembled by mixing many Graphite Fibres Reinforced Panels layups.
2007
9781563478963
Aircraft composite structures modeling and vibro-acoustic optimization analysis / Monaco, Ernesto; Amoroso, Francesco; Massimiliano di, Giulio; Antonio, Paonessa. - (2007), pp. ND -Paper nr 3572-ND -Paper nr 3572. (Intervento presentato al convegno 13th AIAA/CEAS Aeroacoustics Conference tenutosi a Roma, Italy nel May, 21-23).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/427056
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