CRACK IDENTIFICATION IN A CANTILEVER BEAM FROM MODAL RESPONSE

A damage detection and assessment algorithm is developed based on syst em identification using a finite element model and the measured modal response of a structure. The measurements are assumed to be sparse and polluted with noise. A change in an element constitutive property fro m a baseline value is taken as indicative of damage. An adaptive param eter grouping updating scheme is proposed to localize the damage zones in the structure and a Monte Carlo method is used with a data perturb ation scheme to provide a statistical basis for assessing damage. Dama ge indices computed from the Monte Carlo sample of data perturbations are used to assess damage. The threshold values, which distinguish dam age from measurement noise, are established through Monte Carlo simula tion on the baseline structure. The proposed algorithm is applied to t he problem of locating a crack in a cantilever beam. A Bernoulli-Euler beam model and a plane stress model are employed to illustrate the us e of the method and compare the efficacy of the two models for crack d etection. (C) 1996 Academic Press Limited