The transmission loss of curved laminates and sandwich composite panels

Abstract

The paper describes a model to calculate the transmission loss of both curved laminate and sandwich composite panels within statistical energy analysis (SEA) context. The vibro-acoustic problem is developed following a wave approach based on a discrete lamina description. Each lamina is considered to consist of membrane, bending, transverse shearing and rotational inertia behaviors. Moreover, the orthotropic ply angle of each lamina is considered. Using such a discrete lamina description, the dispersion behaviors of the panel are correctly represented. Using the dispersion curves, the radiation efficiency, the modal density, as well as, the nonresonant and the resonant transmission are computed. Moreover, expression for the evaluation of the ring frequency and the critical frequencies of such panels is given. The described model is shown to handle accurately, both laminate and sandwich composite shells. Additionally, a transmission loss test is presented to confirm the validity of the presented model.

A spatial windowing technique to account for finite dimensions in 2.5D dynamic soil–structure interaction problems

“…The explanation for this observation is twofold. First, a finite block is only able to impede the transmission of that part of the wavefield that actually impinges on the block, and no reduction of vibration levels is obtained fork y >k R sin θ x , where sin θ x is defined in equation (15). This is similar to the behaviour of a finite trench discussed in subsection 4.1.…”

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“…energy dissipated per cycle maximum strain energy (19) Following the analysis in [25], the loss factor η j as a function of the frequency was calculated:…”

“…In [18] and [19] the authors used a multi-layer analytical model based on Mindlin theory to calculate the dispersion characteristics of layered structures. In this work, though, the symmetric mode of motion was not naturally expressed.…”