WAVE DECOMPOSITION FOR COMPUTING VIBRATIO N ENERGY OF STRUCTURES

At medium frequency range (MFR), numerous vibroacoustic problems deal with systems of large number of modes where classical modal methods mu st cope with resolution of huge linear system. In the idea of reducing theses models a mode hybridization method proposed in [1] gives one e quivalent mode when modes of the complex structure are known. Another method [2],[4] based on reducing size of dynamic model in the MFR, giv es a prediction of the vibration response of a structure by using a li mited number of modes of the homogeneous master structure in order to interpolate the response of modes of whole structure with attached het erogeneities. The method presented here gives a prediction of plate vi bration using a wave decomposition instead of modal calculation. It al lows one to consider homogeneous structure of complex geometry without making mode calculations before. The corresponding wave function of t he Fourier transform of the displacement is approximated the best by a chieving the extremalization of the Hamiltonian of the plate. Quadrati c velocity of the structure is derived and the convergence study of th e method shows that global quantities involving frequency average can be obtained with reduced models of small size.