Browsing by Author "Nabil Benhadda"

Now showing 1 - 7 of 7
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    Composite Material Characterization using Eddy Current by 3D FEM Associated with Iterative Technique
    (ADVANCED ELECTROMAGNETICS, 2019-03-01) Nabil Benhadda
    In this paper, an iterative technique, employing the ⃗T -formulation associated with the finite element method, based on Maxwell equations and the Biot and Savart law, is used for analyzing the density of eddy currents in composite carbon fiber reinforced polymer (CFRP) materials. For this purpose, a code has been developed for solving an electromagnetic 3D non-destructive evaluation problem. This latter permits the characterization of this CFRP and determinate of fibers orientation using the impedance variation which is implanted in polar diagram. Firstly, the obtained results are compared with those of the analytical model. This comparison reveals a high concordance which proves the validity of the proposed method. Secondly, three different applications are shown for illustrating the characterization of unidirectional, bidirectional and multidirectional piece using a rectangular coil plotted in normalized impedance variation diagram.
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    Composite Material Characterization using Eddy Current by 3D FEM Associated with Iterative Technique
    (ADVANCED ELECTROMAGNETICS, 2019-03-01) Nabil Benhadda
    In this paper, an iterative technique, employing theT ⃗ -formulation associated with the finite element method, based on Maxwell equations and the Biot and Savart law, is used for analyzing the density of eddy currents in composite carbon fiber reinforced polymer (CFRP) materials. For this purpose, a code has been developed for solving an electromagnetic 3D non-destructive evaluation problem. This latter permits the characterization of this CFRP and determinate of fibers orientation using the impedance variation which is implanted in polar diagram. Firstly, the obtained results are compared with those of the analytical model. This comparison reveals a high concordance which proves the validity of the proposed method. Secondly, three different applications are shown for illustrating the characterization of unidirectional, bidirectional and multidirectional piece using a rectangular coil plotted in normalized impedance variation diagram.
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    Development of Multi-Coils Circular Eddy Current Sensor for Characterization of Fibers Orientation and Defect Detection in Multidirectional CFRP Material
    (Research in Nondestructive Evaluation, 2019-07-30) Nabil Benhadda
    This article presents a study of a Multi-coils circular eddy current non-destructive testing sensor for determining the fibers orientation as well as the detection of defect in multidirectional carbon fibers reinforced polymer (CFRP). The developed sensor contains 16 rectangular coils connected in series and supplied by a single-phase sinusoidal source. This sensor allows the annulations of the mechanical rotation of the conventional sensors and it permits to reduce the inspection procedure duration. The electromagnetic phenomena are calculated by using 3D finite element method (FEM) based on the electromagnetic AV-A formulation. Finally, the Multi-coils circular sensor responses are analyzed through polar diagrams of the impedance variation, where the defect is taken into consideration. A great concordance between the obtained results and those of literatures has been noticed. The provided results show that the proposed sensor allows an efficient characterization of multidirectional CFRP and detection of defects in different layers.
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    EXCITING COIL OPTIMIZATION CRITERIA FOR EDDY CURRENT DETECTION OF SMALL CRACKS UNDER FASTENER HEAD
    (Journal of Electrical Engineering www.jee.ro, 2014-02-14) Nabil Benhadda
    The aim of this paper consists of presenting optimization criteria of coil dimensions and the exciting field frequency in order to improving eddy current probe sensitivity for small and deep cracks under fasteners. To accomplish this task, we have studied the influence of coil inner radius, coil height and exciting frequency on probe sensitivity. Then, an algorithmic searching technique is applied to determine the optimal values of the previous parameters. Hence, the obtained results have revealed that the optimum inner radius corresponds exactly to the fastener head outer radius. Furthermore, it has been noticed that as well as the coil height is reduced while keeping the same number of turns, the probes sensitivity increases. Indeed, the use of stacking flat micro-coils is well adapted. In addition, the calculation of the optimum values of the frequency demonstrate that this parameter depend relatively on the defect position, its radial and vertical depth.
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    Influence of Conductive Pollution on Eddy Current Sensor Signals
    (Russian Journal of Nondestructive Testing, 2018-06-06) Nabil Benhadda
    This paper presents a study of a surface crack detection in which the volume is filled by conductive substances due to the polluting environment. Hence, this investigation demonstrates by numerical simulation that electric conductivity is a crucial property that has to be added to the other defect geometrical characteristics in order to complete the developed models. Consequently, introducing the tolerance in percent in the measured impedance is necessary in some conditions. So, the obtained results demonstrate that the signal amplitude passes from 0 to 78% of the maximal amplitude when the defect conductivity rises from 0 to 0.5 Ms/m. On the other hand, the relative difference of the resistance partincreases according to defect volume. For example, for a defect of 0.3 MS/m, the relative difference of the resistance varies from 52 to 62% of the maximal amplitude when the defect depth varies from 0.5 to 2.25 mm. These results can be exploited to show the effect of the conductive substances occupying the crack volume. In fact, the controller using EC-NDT technique must take into consideration the presence of conductive polluting elements in the crack volume. So, this condition becomes primordial and necessary according to the degree and nature of pollution.
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    Numerical investigation to study the influence of thickness and electrical conductivity of metal-sheets on the LOI-Point of a PEC sensor
    (Nondestructive Testing and Evaluation, 2023-07-10) Nabil Benhadda
    The aim of this article is to determine a similar point to the Lift-Off intersection point (LOI) obtained from a geometric configuration of a Pulsed Eddy Current (PEC) sensor. This configuration enables easy determination of the LOI point through a single measurement, thus avoiding measurement noise. The sensor consists of an external excitation coil and two internal probes that overlap and have similar characteristics for reception. The similar point LOI is determined by the intersection of the signals from the transient response of the sensor’s internal probes. Importantly, this point is independent of lift-off variation. Moreover, the amplitude and time measurement of this point vary with the variation of the physical and geometric properties of the sample. To assess the effectiveness of this similar point, a numerical code based on electromagnetic phenomena was developed. This code investigates the impact of thickness and electrical conductivity of metal sheets on the response of the PEC sensor, both with and without a ferrite core at this point. Additionally, a practical sensor prototype was constructed to validate the results obtained from the numerical model. The obtained results demonstrated a strong correlation between the numerical and experimental outcomes, thus confirming the effectiveness of the proposed technique
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    STUDY OF THE INFLUENCE OF CONDUCTIVE DEFECT CHARACTERISTICS ON EDDY CURRENT DIFFERENTIAL PROBE SIGNAL
    (Journal of Electrical Engineering www.jee.ro, 2014-02-18) Nabil Benhadda
    Nowadays, numerical modelling has become an interesting tool for determining impedance variations due to various conductive flaws in eddy current non-destructive evaluation systems. These kinds of defects, rarely treated in the published works, are taken into consideration in the modelling while introducing them as electrically conductive volumes with a finite electric resistivity. This step is very important since it permits to improve qualitatively several models developed so far by many authors whose consider the defect as loss of material only. However, in several applications, the defect can occur with a finite resistivity such as impurity, small burns and micro-solder. On the other hand, even though the defect appears with a loss of materials, some polluting materials can fill the affected region. Indeed, the volume of the initial defect will be completely or partially occupied by these conducting pollutant materials. For this reason, this contribution consists of studying the effect of physical and geometrical characteristics of this kind of defect on the differential sensor response. Furthermore, we shall explain the necessity of taking the defect electric conductivity as an important parameter in order to develop a reliable and accurate inverse method allowing a full characterization of conductive defects.