A methodology for including the effect of dissipative treatments in the mid-frequency domain using SmEdA method - Comparison with experiments
Résumé
Statistical modal Energy distribution Analysis (SmEdA) can be used to model a fluid-structure-problem based on modal information of the uncoupled-subsystems. Recently the method has been extended to include the effect of a dissipative treatment (i.e. damping or absorbing material). In this paper, SmEdA is tested on a steel plate with/without damping treatment coupled to an acoustic cavity: the numerical result of the energy ratio is compared to the experimental one The data are analyzed for a mid-to-high frequency domain (up to 10 kHz in 1/3 octave band). Both subsystems loss factors are experimentally obtained by a high-resolution modal analysis method based on the ESPRIT algorithm applied to impulse responses of the plate and the cavity. Predicting the energy level requires an accurate estimation of subsystem damping levels. The uncertainty on measured loss factors leads to an uncertainty in the energy ratio depending on min/max damping levels of individual modes in a given frequency band. Once min/max damping levels of subsystems are determined, SmEdA is used to compute the upper and lower limit of the subsystem energy ratio. Comparison with the experiment shows that the measurement data fits in between the SmEdA bounds. In this paper, two types of dissipative treatments are studied: i) a viscoelastic patch on the plate (modeled as an equivalent single layer plate) and ii) a porous material into the cavity (modeled as an equivalent fluid).
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