Estimate of SEA parameters by laser vibrometer measurements

In this paper an experimental analysis on the energy transmission of vibrating structures is developed. Most of the traditional numerical techniques such as FEM and BEM fail when one tries to solve high-frequency dynamic problems. The statistical Energy Analysis (SEA) is, at present, the most acknowledged theory for the solution of high frequency vibroacoustic problems. SEA provides information on the stored mechanical energy and on the dissipated mechanical power between modal subsystems. Aim of the present work is the identification of the SEA parameters, coupling loss factors (CLFs) and internal loss factors (ILF) for a system composed of three coupled plates, by an inverse application of SEA, and to compare the SEA solution obtained with these identified parameters with the measured energy. The energy values are obtained by measuring the velocity at a grid of points by a laser surface velocimeter. Two different configurations are used. In the first test a "T" structure is considered, with one plate forming an angle of 90° with the other two; in the second test the same plate forms an angle of 30° with one plate and 150° with the other. Some considerations on the efficiency of the SEA analysis are finally provided.