Assessment of Equivalent Properties for Flat Multilayered Panels

Within homogenization techniques, an equivalent properties strategy can be utilized to equivalently represent complex structures into simple ones. This work aims to highlight the limitations of three strategies using a single layer flat panel to represent the vibro-acoustics of flat multilayered structures. The presented limitations provide insight into the potential applicability of this strategy in complex heterogeneous structures. Equivalent material properties and equivalent stiffness coefficients are obtained from the dispersion curves of the reference structures and thereafter utilized to build an equivalent simple structure. To demonstrate the accuracy and limitations of the homogenization strategies, three carefully selected flat multilayered structures are presented. The particular effects of asymmetry, orthotropy, soft core and high damping (structural loss factor, η > 0.5) in multilayered structures are addressed. A wave and forced analysis is performed utilizing the General Laminate Model (GLM) and four different vibro-acoustic indicators (total energy, input and radiated power, as well as diffuse field transmission loss) are computed and compared with reference solutions. The comparisons show that, in general, a single layer plate can equivalently represent flat multilayered structures within the studied frequency range ([50 Hz, 5 kHz]). Inaccuracies of the proposed strategies are also discussed, highlighting the challenge of correctly homogenizing structures with soft core and, in particular, high damping.