Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods
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Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods Chongxin Yuan & Otto Bergsma & Adriaan Beukers
Received: 28 January 2011 / Accepted: 30 March 2011 / Published online: 15 April 2011 # The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract Increase of sound transmission loss(TL) of the fuselage is vital to build a comfortable cabin environment. In this paper, to find a convenient and accurate means for predicting the fuselage TL, the fuselage is modeled as a composite cylinder, and its TL is predicted with the analytical, the statistic energy analysis (SEA) and the hybrid FE&SEA method. The TL results predicted by the three methods are compared to each other and they show good agreement, but in terms of model building the SEA method is the most convenient one. Therefore, the parameters including the layup, the materials, the geometry, and the structure type are studied with the SEA method. It is observed that asymmetric laminates provide better sound insulation in general. It is further found that glass fiber laminates result in the best sound insulation as compared with graphite and aramid fiber laminates. In addition, the cylinder length has little influence on the sound insulation, while an increase of the radius considerably reduces the TL at low frequencies. Finally, by a comparison among an unstiffened laminate, a sandwich panel and a stiffened panel, the sandwich panel presents the largest TL at high frequencies and the stiffened panel demonstrates the poorest sound insulation at all frequencies. Keywords Sound transmission loss . SEA . Fuselage . Cylinder
1 Introduction Acoustic transmission is one of the principal design drivers for composite fuselages [1]. Therefore the prediction of sound transmission loss (TL) of a fuselage structure is of major importance. There are two major noise sources when the airplane is in flight; one is the turbulent boundary layer noise and the other is the engine noise. The engine noise can also be divided into airborne noise and structure-born noise. In this study only the airborne noise is considered as the noise source. C. Yuan (*) : O. Bergsma : A. Beukers Department of Production Technology, Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands e-mail: [email protected]
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Appl Compos Mater (2012) 19:865–883
For the airborne noise from the engine, a large number of investigations have been devoted to the prediction of fuselage TL. In these studies the fuselage structure was usually idealized as the cylinder. The published models mainly considered three classical types of constructions: monolithic, stiffened and sandwich. Koval [2] studied the TL of infinite isotropic cylinders considering the external airflow and internal shell pressurization. The impedance of the shell and its content were used to determine the TL. He also developed a theory to investigate the TL of orthotropic and laminated composite shells [3, 4]. A program to predict the noise trans
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