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Author: search.filters.author.Khatir, SamirSubject: search.filters.subject.Damage detection

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    Damage detection and localization in composite beam structures based on vibration analysis
    (2015) Khatir, Samir; Belaidi, Idir; Serra, Roger; Magd, Abdel Wahab; Khatir, Tawfiq
    This paper presents an approach of inverse dam-age detection and localization based on model reduction. The problem is formulated as an inverse problem where an optimization algorithm is used to minimize the cost func-tion expressed as the normalized difference between a fre-quency vector of the tested structure and its numerical model. A finite element model of bi-dimensional monolith-ic composite beam reinforced by a graphite-epoxy is used to define a numerical model of the tested structure in which different scenarios of damage are considered by stiffness reduction. Then, calculations are made on a re-duced model built by the technique of proper orthogonal decomposition coupled by radial basis functions. The accu-racy of the method is verified through different damage configurations. The results show that the developed algo-rithm is a feasible methodology of predicting damage in short computing time and with high accuracy. The effect of noise on the accuracy of the results is investigated in some cases for the structure under consideration
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    Genetic algorithm based objective functions comparative study for damage detection and localization in beam structures
    (Institute of Physics Publishing, 2015) Khatir, Samir; Belaidi, Idir; Serra, R.; Benaissa, Brahim; Ait Saada, Aicha
    The detection techniques based on non-destructive testing (NDT) defects are preferable because of their low cost and operational aspects related to the use of the analyzed structure. In this study, we used the genetic algorithm (GA) for detecting and locating damage. The finite element was used for diagnostic beams. Different structures considered may incur damage to be modelled by a loss of rigidity supposed to represent a defect in the structure element. Identification of damage is formulated as an optimization problem using three objective functions (change of natural frequencies, Modal Assurance Criterion MAC and MAC natural frequency). The results show that the best objective function is based on the natural frequency and MAC while the method of the genetic algorithm present its efficiencies in indicating and quantifying multiple damage with great accuracy. Three defects have been created to enhance damage depending on the elements 2, 5 and 8 with a percentage allocation of 50% in the beam structure which has been discretized into 10 elements. Finally the defect with noise was introduced to test the stability of the method against uncertainty