Different approaches for the vibro-acoustic modelling of cross-laminated timber panels

Vibro-acoustic modelling of cross-laminated timber (CLT) panels is challenging. CLT elements, being constituted by a certain number of layers of adjacent timber beams bonded together, represent a non-homogenous material whose elastic properties are not easy to determine. In this paper a comparison of two different approaches to model CLT panels is presented, considering structures with a different number of plies and a different ratio of the thickness of the layers. Each panel is rigorously modelled, by using a Finite Element (FE) software, as a multi-layer structure, in which each ply is an orthotropic elastic solid, or as an equivalent orthotropic thin plate, characterised by the flexural wavenumber along the two principal directions, by means of the transfer matrix method. The flexural wavenumber propagating along the two principal directions of the CLT panel are obtained from the FE model of the layered structure. The aim of this study is to investigate the reliability of approximating CLT structures to thin orthotropic panels described by a frequency-dependent bending stiffness. The comparison shows that the simplified model only provides a reliable and accurate transmission loss only below the thickness resonance frequency, while overestimates the results at higher frequencies.