Investigation of power transmission across laminated composite doubly curved shell in the presence of external flow considering shear deformation shallow shell theory

2017 ◽  
Vol 24 (19) ◽  
pp. 4492-4504 ◽  
Author(s):  
R Talebitooti ◽  
MR Zarastvand ◽  
HD Gohari

This study applies shear deformation shallow shell theory to inspect the acoustic behavior of laminated composite infinitely long doubly curved shallow shells subject to a radiating oblique plane sound wave. Herewith, a procedure is developed to investigate sound transmission loss through this shell, clarified as a ratio of incident power to transmitted power in the existence of mean flow. In a further step, displacements are developed as a linear combination of the thickness coordinate to designate an analytical solution based on shear deformation shallow shell theory. Consequently, an exact solution for sound transmission loss is brought forward by combining acoustic wave equations as a result of wave propagation through this shell with doubly curved shell equations of motion. Afterwards, the accuracy of the present formulation (shear deformation shallow shell theory) is determined by comparing the achieved results with those available in the literature and some assumptions associated with the geometric specifications of the plate are investigated. Finally, because of the remarkable achievement of the current formulation results in reduction of noise transmission into such structures, some effective parameters on sound transmission loss are used in numerical results, to solve this problem.

2020 ◽  
Vol 57 (6A) ◽  
pp. 150
Author(s):  
Thanh Ngoc Pham

A theoretical study of sound transmission loss across a clamped double-laminated composite plate filled with poroelastic material is formulated. Biot’s theory is employed to describe wave propagation in elastic porous media. The two face composite plates are modeled as classical thin plates. By using the modal superposition theory, a double series solution for the sound transmission loss of the structure is obtained with the help of the Galerkin method. The analytical model is validated against previous experimental results of a single sound wave under normal incidence. The numerical results suggest that the density of poroelastic material, the type of composite materials and the composite plies arrangement have significant effects on the sound transmission loss of considered structure.


2022 ◽  
pp. 107754632110567
Author(s):  
Hasan Seilsepour ◽  
Mohamadreza Zarastvand ◽  
Roohollah Talebitooti

A viscoelastic model is proposed in this approach to determine the sound transmission loss coefficient of a sandwich shell system with double curvature. The structure is composed of a double-walled composite shell subjected to a viscoelastic core. Investigating the efficient impresses of rotary inertia and shear deformation, vibration equations of both outer and inner shells are extracted within the framework of shear deformation shallow shell theory. Besides, the Zener mathematical model is used for viscoelastic material, which is based on a spring connected in series with a parallel mixture of spring and dashpot. This model presents the dynamic response in the whole frequency domain at which shear modulus and bulk complex modulus are frequency dependent. Since the performed studies on the sound transmission loss of this kind of structures are insignificant, the outcomes of plate models with a viscoelastic core are used to provide a reliable sound transmission loss comparison. The results show that the applied strategy can improve the acoustic characteristics of the system at high frequencies compared to that of a single-layer one with the same mass. This issue is more highlighted while the thickness of the viscoelastic layer enhances, which confirms the positive performance of the viscoelastic materials in this range of frequency, particularly in the resonant frequency. In addition to the curvature effect on acoustic features, the vibration response of the system is configured based on various frequencies and materials.


2020 ◽  
Vol 57 (6A) ◽  
pp. 150
Author(s):  
Thanh Ngoc Pham

A theoretical study of sound transmission loss across a clamped double-laminated composite plate filled with poroelastic material is formulated. Biot’s theory is employed to describe wave propagation in elastic porous media. The two face composite plates are modeled as classical thin plates. By using the modal superposition theory, a double series solution for the sound transmission loss of the structure is obtained with the help of the Galerkin method. The analytical model is validated against previous experimental results of a single sound wave under normal incidence. The numerical results suggest that the density of poroelastic material, the type of composite materials and the composite plies arrangement have significant effects on the sound transmission loss of considered structure.


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