A method to measure elastic and dissipative properties of the constituents of a sandwich structure is proposed and validated. The method relies on the comparison between (a) the modal frequen- cies and dampings of a thick plate as predicted by an extended Rayleigh-Ritz procedure and (b) the their values as given by experimentation or numerical simulation. On real plates, a one-point measurement of free vibrations is sufficient, provided that a high-resolution modal analysis [1] is used [2]. For valida- tion purposes, the experimental modal analysis is replaced by a finite-element model analysis (numerical measurement). Minimising the differences between the modal characteristics yields an estimation of the values of the elastic and dissipative material properties. Agreement between estimated and original mechanical parameters is shown to be good for the parameters which are influential in plate vibration.

See http://hal.archives-ouvertes.fr/docs/00/59/28/82/ANNEX/r_0PBFPY04.pdf