206 Int. J. Reliability and Safety, Vol. 4, Nos. 2/3, 2010 Copyright © 2010 Inderscience Enterprises Ltd. A Bayesian methodology for crack identification in structures using strain measurements S. Gaitanaros, G. Karaiskos, C. Papadimitriou* and N. Aravas Department of Mechanical Engineering, University of Thessaly, Pedion Areos, Volos 38334, Greece Email: stgaitan@uth.gr Email: gkaraiskos@uth.gr Email: costasp@uth.gr Email: aravas@uth.gr *Corresponding author Abstract: A Bayesian system identification methodology is presented for estimating the crack location, size and orientation in a structure using strain measurements. The Bayesian statistical approach combines information from measured data and analytical or computational models of structural behaviour to predict estimates of the crack characteristics along with the associated uncertainties, taking into account modelling and measurement errors. An optimal sensor location methodology is also proposed to maximise the information that is contained in the measured data for crack identification problems. For this, the most informative, about the condition of the structure, data are obtained by minimising the information entropy measure of the uncertainty in the crack parameter estimates. Both crack identification and optimal sensor location formulations lead to highly non-convex optimisation problems in which multiple local and global optima may exist. A hybrid optimisation method, based on evolutionary strategies and gradient-based techniques, is used to determine the global minima. The effectiveness of the proposed methodologies is illustrated using simulated data from a single crack in a thin plate subjected to static loading. Keywords: crack identification; Bayesian analysis; information entropy; sensor placement. Reference to this paper should be made as follows: Gaitanaros, S., Karaiskos, G., Papadimitriou, C. and Aravas, N. (2010) ‘A Bayesian methodology for crack identification in structures using strain measurements’, Int. J. Reliability and Safety, Vol. 4, Nos. 2/3, pp.206–237. Biographical notes: Stavros Gaitanaros is a PhD student in the Engineering Mechanics program at the University of Texas at Austin. He received his Diploma (2005) and MSc (2007) in Mechanical & Industrial Engineering from the University of Thessaly, Greece. His current research interests are in the micromechanical modelling and mechanics of cellular solids. Grigorios Karaiskos is a PhD student in Mechanical Engineering at the University of Thessaly, Greece. He received his Diploma (2005) in Mechanical Engineering from the University of Patras (Greece) and his MSc (2008) in Mechanical Engineering from the University of Thessaly. His current research interests are in the area of structural control and structural health monitoring.