Optimized vibro-acoustic design of suspended glass panels

Suspended glass panels are monolithic or laminated frameless windows sustained by a number of holders, typically located in the vicinity of the edges. These panels can be used, among other purposes, as noise barriers. The vibro-acoustic behaviour of glass windows is critical at low frequencies, where the problem is often tackled by increasing the thickness, thus the mass, of the panels. As a consequence, solutions which preserve low mass are greatly sought by industries. In this study, the vibro-acoustic behaviour of different suspended glass panels is addressed. An optimization procedure is implemented, aiming at finding the position of the holders which maximizes the acoustic transmission loss (TL) averaged at low- and very low- frequency ranges. First, an iterative procedure, based on comparison of experimental and numerical modal data, has been implemented to extract the material properties (Young’s modulus and Poisson’s ratio) of the panels. Second, these properties have been used in an optimization procedure based on finite difference approximation of the objective function, the averaged transmission loss. The vibro-acoustic analyses, required by the optimization procedure, have performed by means of hybrid finite element method/statistical energy analysis (FEM/ SEA). 16 different design cases have been considered in the optimizations, i.e. 2 different frequency ranges (20-300 Hz and 20-1000 Hz), 2 panel geometries (square 1m x 1m and rectangular 2.5m x 0.8m), 2 constitutive material properties (monolithic tempered glass and laminated tempered glass) and 2 mounting solutions (4 and 6 holders). The transmission losses of the optimized and the standard configurations, where the holders are placed close to the edges, are compared.