Wave propagation across double-walled laminated composite cylindrical shells along with air-gap using three-dimensional theory

This paper presents a complete model to calculate the sound transmission loss across laminated composite cylindrical shells based on three-dimensional equations of anisotropic elasticity. This model is included a double-walled laminated composite cylindrical shell with infinite length along with an air-gap impinged upon incidence oblique plane wave and immersed in a fluid. Therefore, the equations of motion are derived for each monoclinic anisotropic layer of both walls of double-walled laminated composite cylindrical shell; then, these equations are rewritten using the state space method. Hence, the state space governing formulation of each layer of both walls has been solved using the approximate laminate model along with the local transfer matrix approach. Finally, using the global transfer matrix method and considering the appropriate boundary conditions the transmission loss (TL) of the double-walled laminated composite cylindrical shell is calculated. Comparison of the presented results with those of other researchers for both single-walled and double-walled cylindrical shells indicates the accuracy and validity of the present study. Moreover, the effects of each parameter on TL are investigated. The results show the TLs of three-dimensional theory is of higher accuracy rather than other theories, because it doesn't consider any assumptions in simplifying the governing equations.