Transmission loss of orthogonally stiffened laminated composite plates

Abstract

Sound transmission through laminated composite plates reinforced by two sets of orthogonal stiffeners is investigated theoretically. A layerwise shear deformable theory is used to model the vibration of the laminated composite face-panel; A governing equation of I section composite beam is introduced, which accounts for the extensional, flexural, torsional and their coupling effects. The Euler-Bernoulli beam theory and torsional wave equation are employed to describe the flexural and rotational motions of the rib stiffeners, respectively. The technique of Fourier transform is applied to solve the governing equations resulting in infinite sets of simultaneous algebraic coupled equations, which are numerically solved by truncating them into a finite range insofar as the solutions converge. The accuracy of the numerical solutions is checked by comparing the present model predictions with existing literature. The validated model is subsequently employed to quantify the effects of the spacing of the stiffeners and the stacking geometry of the laminated composite face-panel and stiffeners on sound transmission through the structure. It is demonstrated that both the stiffener spacing and the stacking geometry have significant influences on the sound transmission loss across the structure. The proposed theoretical model successfully characterizes the process of sound penetration through stiffened laminated composite plates, which should be much helpful for the practical design of such structures with acoustic requirements.