Data Block Length Effects on Damage Detection

Damage detection can be obtained by several methods based on experimental modal analysis carried out on the undamaged and damaged structures. Some of these methods require natural frequency shift data and mode shape measurements from the frequency response functions. Obviously the experimental errors heavily affect the results achievable in the damage detection and these errors can vary according to the experimental techniques used in the modal analysis. In this paper the effects of the finite data block length are presented. Some examples, numerical and experimental, give the idea of the influence of the truncation on the spatial matrices evaluation and in turn on the damage detection.