Sound transmission through laminated composite cylindrical shells using analytical model

Abstract

Composite structures are often used in aircraft because of advantages offered by a high strength to weight ratio. Sound transmission through an infinite laminated composite cylindrical shell is studied in the context of the transmission of airborne sound into aircraft interior. The shell is immersed in an external fluid medium and contains an internal fluid, and airflow in an external fluid medium moves with a constant velocity. The different parameters were used to see how laminate specification affected noise transmission. An exact solution is obtained by solving the vibration equation of laminated composite shell and acoustic wave equations simultaneously. Transmission losses (TLs) obtained from numerical solution are compared with those of other authors. The effects of different source condition, structural properties and flight conditions on TL are studied for a range of values, especially, incident angle of the plane wave, Mach number and flight altitude of aircraft, stack sequences, angle of warp and damping.

Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods

“…By collecting the equations of motion (6)(7)(8) and boundary condition (16)(17), a system of five equations consist of P 0 , U n , V n , W n , A n and B n is obtained. Finally the solutions for <U n , V n , W n , A n , B n > vector are expressed by P 0 which can be eliminated later.…”

“…On the internal and external shell surfaces, the particle velocities of the acoustic media in the radial direction have to be equal to the normal velocity of the shell [7]. Applying Newton's second law, the equations which describe the effect of acoustic pressure on the motion of the shell can be derived as:…”

“….). 2 is the Hankel function of the second kind with integer n; it represents the outgoing wave from the cylinder [7]. ξ n is the Neumann factor given by:…”

“…Results show that the shear waves transmit sound through the shell, resulting in a decrease of TL in high frequencies. K. Daneshjou et al [7,8] combined the work of Koval and Yvette to generate two more explicit analytical models with thin shell and first order theory respectively. Besides the analytical models, some commercial software has also been used to predict the TL of more complex structures.…”

Study on effects of wood fiber content on physical, mechanical, and acoustical properties of wood-fiber-filled gypsum composites

“…Analytical and experimental studies are conducted by Lee and Kim sound transmission through the infinitely long circular cylindrical shell 12 . Daneshjou et al 13,14 obtained an exact solution to calculation of the transmission loss of orthotropic and laminated composite cylindrical shells by considering all three displacements of the shell. Harris 15 studied acoustic emission through flat panels.…”