Papers by Author: Costas P. Providakis

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Authors: Costas P. Providakis
Abstract: This paper presents the use of statistically rigorous algorithms combined with electromechanical (E/M) impedance approach for health monitoring of engineering structures. In particular, a statistical pattern recognition procedure is developed, based on frequency domain data of electromechanical impedance, to establish a decision boundary for damage identification. In order to diagnose damage with statistical confidence, health monitoring is cast in the context of outlier detection framework. Inappropriate modeling of tail distribution of outliers imposes potentially misleading behavior associated with damage. The present paper attempts to address the problem of establishing decision boundaries based on extreme value statistics so that the extreme values of outliers associated with tail distribution can be properly modeled. The validity of the proposed method is demonstrated using finite element method (FEM) simulated data while a comparison is performed for the extreme value analysis results contrasted with the standard approach where it is assumed that the damage-sensitive features are normally distributed.
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Authors: Costas P. Providakis
Abstract: In the present paper, the repair of a cracked structure under dynamic load using the electromechanical admittance (EMA) approach is investigated. Conceptually, appropriate electrical field are applied on the outer surfaces of piezoelectric (PZT) patches to effect closure of the crack. This has the effect of altering the electromechnaical (E/M) admittance signature, extracted at the electrical terminals of a specific PZT patch, considered as an admittance calculating sensor (ACS) patch, towards that of the healthy structure, which is the criterion concept used for the repair in this paper. To demonstrate the present repair methodology, a cantilever 3D beam numerical example is considered in combination with a FEM-based minimization of the difference between the healthy and cracked structure’s (E/M) admittance signature, for specific frequency ranges.
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Authors: Costas P. Providakis
Abstract: The present work considers the possibility of simultaneous health monitoring and active repair of the edge debonding in dynamically loaded smart concrete structures strengthened with fiber reinforced plastic (FRP) composite materials. This is achieved by using local piezoelectric (PZT) actuators/sensors, the electro-mechanical admittance concept and extreme value statistics.
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