In civil and mechanical engineering, the monitoring of structures is still a frequently investigated research topic. The basis of the present monitoring concept is the analysis of non-destructive measurements taken at regular time intervals to provide information about the current state of damage in a structure. The approach includes two steps: First, a data-driven stochastic subspace identification is applied to obtain a mathematical description of the system. Using a special state-space transformation, we transfer this result into physically meaningful system properties. Thereby the modal information can be separated into a part which describes the undamped system response and a second contribution which represents the influence of the damping. In the second step, we discretise the experimental setup by means of finite elements and apply an iterative finite element model updating algorithm to localise and to determine the damage. One important innovative aspect of the contribution lies in the updating of an entire damage evolution in order to estimate the lifetime of the structure. The experimental laboratory setup is based on a cantilever beam which is damaged locally and progressively with the help of a special device.

In this contribution we derive and experimentally validate the Stochastic Subspace Identification. Additionally we compare the results with an updated finite element model. *

This contribution gives an overview about the present state of our research in the project B4 in the Collaborative Research Center 398 at the Ruhr University Bochum. The subject of the research topic is the diagnosis and localisation of discrete damage by vibration measurement with the aim of lifetime estimation. First of all, we discuss the verification of eigensystem realization algorithms for system identification. In the second part, a method for finite element model updating is investigated in view of its application for damage localization. A contribution of both methods is validated by means of a numerical example.

In this contribution we present a validation of an identification procedure and a modeling method with regard to detection, localisation and quantification of damage in a structure. Vibration measurements of an excited experimental structure are used as input for a stochastic subspace system identification algorithm. The identified experimental modal data (eigenvalues and mode shapes) serve to update the underlying finite element model. The experimental setup consists of a cantilever beam and an additional equipment to damage the structure locally and progressively. In contrast to earlier contributions the evolution of damage is quantified in order to estimate the lifetime of the structure.

In this contribution we derive the iterative finite element model updating algorithm. The ability of the method to detect the damage is verified by means of a simulation with a reference finite element model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)