A NEW METHOD FOR MODEL ORDER SELECTION AND MODAL PARAMETER ESTIMATION IN TIME DOMAIN

This paper mainly deals with the identification of structural modal parameters, from output accelerometers only, using a vector autoregressive moving average (VARMA(p, q)) model method. The problem of determining the order p of the AR part, or equivalently the number of modes in a frequency band, is also examined using a combination of the multivariate minimum description length (MDL) criterion and an overdetermined instrumental variable sequence. The AR coefficients are then obtained from this instrumental variable sequence. The companion matrix is formed and the modal parameters of the vibrating system deduced. Numerical and experimental results are treated to show the effectiveness of this new procedure.