ESTIMATION OF MODAL PARAMETERS THROUGH A NONLINEAR OPTIMISATION TECHNIQUE

The estimation of modal parameters through Goal Programming, an optimisation technique, is presented. The estimation, performed in the frequency domain, seeks to minimise the total squared error between experimental and estimated values of the frequency response functions. Its purpose is to obtain greater accuracy than classical methods in complex cases (highly damped systems, systems of high modal density and noisy experimental data). Numerical simulations that reproduce complex practical applications were carried out with a set of frequency response functions. An experimental test with a small-scale model of an offshore fixed platform was also analysed. The results obtained through the developed algorithm were compared with those obtained through a classical modal parameter estimation method––the orthogonal polynomials method.