Damage detection based on model updating methods

The paper examines the problem of detecting the location and extent of structural damage from measured vibration test data. The method is based upon a mathematical model representing the undamaged vibrating structure and a local description of the damage, e.g. a finite element for a cracked beam. The problem of modeling errors and their influence to damage localisation accuracy is discussed and an approach to obtain reliable results in this case is presented. The concept of inverse sensitivity equations is used which can be based on any type of data, e.g. modal data, FRFs, time series, or a combination of these. The resulting inverse problem usually is ill-posed, and therefore special attention is required for an accurate solution. The application to damage detection problems requires the reduction of a large set of damage parameter candidates to a small subset of one or two parameters that actually describes the local change of the system. An orthogonalisation strategy is given to reduce the parameter set. The method is demonstrated through application to laboratory structures in the frequency domain using frequency response functions and in the time domain. (C) 1998 Academic Press Limited.