RATE OF CONVERGENCE ESTIMATES FOR THE SPECTRAL APPROXIMATION OF A GENERALIZED EIGENVALUE PROBLEM by Carlos CONCA Departamento de Ingenieria Matematica Fac. de Cs. Fis. y Mat., Universidad de Chile, Casilla 170/3, Correo 3, Santiago, Chile. Mario DURAN Fac. de Matematicas, Universidad Catolica de Chile, Casilla 306, Santiago 22, Chile and CMAP Ecole Polytechnique, 91128 Palaiseau, France. Jacques RAPPAZ Departement de Mathematiques, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland. The aim of this work is to derive rate of convergence estimates for the spectral approximation of a mathematical model, which describes the vibrations of a solid-fluid type structure. First, we summarize the main theoretical results and the discretization of this variational eigenvalue problem. Then, we state some well known abstract theorems on spectral approximation and apply them to our specific problem, which allow us to obtain the desired spectral convergence. Under classical regularity assumptions, we are able to establish estimates for the rate of convergence of the approximated eigenvalues and the gap between generalized eigenspaces. The whole paper is available as a compressed Postscript file by internet procedure FTP anonymous on host barbes.polytechnique.fr ( 129.104.4.100) in the directory pub/RI/1995 under the name conca.duran.rappaz_319.fev.ps.gz or by Xmosaic or any other www client via the CMAP www server "http://blanche.polytechnique.fr/"