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Dive into the research topics where Jean-Claude Baboux is active.

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Featured researches published by Jean-Claude Baboux.


Ndt & E International | 1997

Pulsed eddy current signal analysis: application to the experimental detection and characterization of deep flaws in highly conductive materials

Bruno Lebrun; Yves Jayet; Jean-Claude Baboux

Eddy current tests in sinusoidal mode are of great interest to detect flaws in metallic structures. A limitation of this classical method concerns the detection of deep defects in very conductive materials. Such a drawback can be reduced by operating in the transient mode, using a pulsed eddy current technique. In fact, the pulsed character of the electric excitation allows a high peak value of the density of eddy currents in the material; also the broadband signal contains optimized frequencies to probe the sample over a more extended depth. The analysis of the resulting signals is then different from those issue of the sinusoidal mode. The purpose of this paper is to apply pulsed eddy current techniques to specimens containing cracks of different size and depth. First, an original signal analysis was developed to extract the characteristics of well known defects. Then, this approach has been validated by probing different samples with real flaws.


Journal of Physics D | 1996

The influence of bonding defects on the electric impedance of a piezoelectric embedded element

N Saint-Pierre; Yves Jayet; I Perrissin-Fabert; Jean-Claude Baboux

When a piezoelectric element is inserted into a medium, it is now well-established that the viscoelastic properties of this medium can easily be deduced from the measurement of the electrical impedance of this element and by using an appropriate optimization algorithm. This paper essentially deals with the influence of bonding defects at the interface between the piezoelectric sensor and the tested medium. First, a model is proposed to calculate the modifications of the electrical impedance due to defects of this type. The validity of this approach is demonstrated by comparing the theoretical predictions with the results obtained experimentally for different samples with well-defined bonding defects. Then, with this model, it is easy to determine the electrical impedance of an embedded piezoelectric element, whatever the value of the relative area on which the bonding defect occurs. In order to simulate what will happen in practice when we ignore that these defects are present, such simulated electrical impedances are processed with the usual optimization algorithm, assuming perfect bonding. Obviously, the viscoelastic properties of the tested medium are subject to error, as the size of the non-bonded area increases. It is shown that a very efficient tool based on the Kramers - Kronig relationships can be used to check the correctness of the extracted parameters.


Journal of Applied Physics | 1999

Theoretical and experimental responses for a large-aperture broadband spherical transducer probing a liquid–solid boundary

J. Zhang; Philippe Guy; Jean-Claude Baboux; Yves Jayet

A theoretical analysis of a spherical focusing transducer for broadband acoustic microscopy is proposed. The originality of the present contribution is the particular attention we have paid to describe, as rigorously as possible, the diffraction phenomena. Our analysis starts in the harmonic domain with the well-known angular spectrum method, and then gets into the time domain. A new formulation of the angular spectrum in the focal plane has been obtained and compared to other expressions previously reported. This article is deliberately limited to isotropic semi-infinite plane reflectors in order to carry out the inverse Fourier transform in an analytical way. The analytical approach is helpful for the physical interpretation of particular interesting phenomena observed in the transient analysis. A new kind of contribution to the echographic response has been identified and named “geometrical edge waves.” The weight and the arrival time of each discontinuity of the impulse response is analytically evalua...


Journal of Physics D | 1976

Generation of a stepped ultrasonic plane wave: application to piezoelectric transducer calibration

F Lakestani; Jean-Claude Baboux; P Fleischmann; M. Perdrix

A method allowing the generation of an ultrasonic plane wave by means of a thick piezoelectric transducer excited by a short current impulse is described. The resulting pressure step is then used to determine experimentally, in shape and amplitude, the time and frequency responses of different probes subjected to a step, as well as, pressure impulse (obtained by derivation). Finally, the validity of the results is confirmed after comparison with those provided by a receiving transducer, already calibrated using the reciprocity method.


Journal of Physics D | 2004

Optimal determination of the elastic constants of woven 2D SiC/SiC composite materials

A. Mouchtachi; R. El Guerjouma; Jean-Claude Baboux; D. Rouby; D. Bouami

For homogeneous materials, the ultrasonic immersion method, associated with a numerical optimization process mostly based on Newtons algorithm, allows the determination of elastic constants for various synthetic and natural composite materials. Nevertheless, a principal limitation of the existing optimization procedure occurs when the considered material is at the limit of the homogeneous hypothesis. Such is the case of the woven bidirectional SiC matrix and SiC fibre composite material. In this study, we have developed two numerical methods for the determination of the elastic constants of the 2D SiC/SiC composite material (2D SiC/SiC). The first one is based on Newtons algorithm: the elastic constants are obtained by minimizing the square deviation between experimental and calculated velocities. The second method is based on the Levenberg–Marquardt algorithm. We show that these algorithms give the same results in the case of homogeneous anisotropic composite materials. For the 2D SiC/SiC composite material, the two methods, using the same measured velocities, give different sets of elastic constants. We then note that the Levenberg–Marquardt algorithm enables a better convergence towards a global set of elastic constants in good agreement with the elastic properties, which can be measured using classical quasi-static methods.


REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Volume 19 | 2000

Anisotropic damage evaluation in polymer fiber composites under hygrothermal aging by means of ultrasonic techniques

D. Ducret; R. El Guerjouma; Yves Jayet; Jean-Claude Baboux

Ultrasonics is a suitable technique for nondestructive evaluation of structural materials degradation. Although the most common objective of ultrasonic testing is the detection and location of overt flaws, ultrasonics can be used to identify microstructural factors that alter strength and performance. However, while single large defects can be individually detected and characterized, widely dispersed discontinuities are impossible to resolve and only their global effects on bulk properties can be observed and measured. The aim of this paper is, using an immersion technique, to characterize damage progression of a glass fiber epoxy matrix composite during hygrothermal aging by means of attenuation frequency-dependence measured in normal incidence and longitudinal and transversal ultrasonic velocities measured as function of the propagation direction. The anisotropic elastic constants of the material are recovered from the ultrasonic velocities using an optimization process. Effects of hygrothermal aging on...


Fifth European Conference on Smart Structures and Materials | 2000

Health monitoring of smart composite structures using ultrasonic guided waves

Thomas Monnier; Philippe Guy; Yves Jayet; Jean-Claude Baboux; Michelle Salvia

The health of a structure depends on both the homogeneously distributed degradation of its mechanical properties during its life cycle and the presence of localised defects such as cracks or delaminations. The proposed non-destructive health monitoring method allows to recover both kinds of information using ultrasonic waves. To avoid traditional techniques limitations, such as coupling reproducibility for instance, we propose here to integrate a piezoelectric element into the plate-like composite structure. The element dimensions are determined in order to uncouple the frequency ranges of the thickness and radial vibration modes. The thickness mode is used to monitor the homogeneous ageing of the structure through electrical impedance measurement. As for the radial vibrations, they are used to generate and detect Lamb waves, which have the advantage of propagating over long distances and offering specific sensitivity of various modes to different kinds of defects. The present work focuses on this last application and studies the ability of the proposed technique to detect and identify defects such as low speed impact-induced delaminations and cracks incomposite plate-like structures.


IEEE Transactions on Sonics and Ultrasonics | 1985

Theoretical and Experimental Investigation of a Piezoelectric Transducer with a Nonparallel-Faced Wearplate

Yves Jayet; Jean-Claude Baboux; Fereydoun Lakestani; Michel Perdrix

Abstmet-Using a theoretical model, we establish an analytical result giving the average pressure emitted by an ultrasonic piezoelectric transmitter, the wearplate of which has a lack of parallelism between its two faces. Verification of the model’s validity is carried out hy recording the simulated and experimental responses of piezoelectric transmitters with different degrees of parallelism defect for the wearplate. This study is carried out for a quarter-wave wearplate at the resonance frequency of the piezoelectric element.


internaltional ultrasonics symposium | 1992

Nondestructive evaluation of graphite by ultrasonic velocity measurement using cross-correlation and Hilbert transform methods

R. El Guerjouma; A. Mouchtachi; Yves Jayet; Jean-Claude Baboux

The suitability of ultrasonics for materials evaluation of graphite components is investigated. The ultrasonic velocity is measured using cross-correlation techniques and a method based on the Hilbert transform of the pulse response function. The measurements are made on different grades of graphite with different particle sizes and porosities. Comparison of the two methods shows similar results for the graphites having small particle size and low attenuation. For large particle size and highly attenuating graphites, the measured quantities are different. The velocities and some identified elastic constants are correlated with the physical properties of the material (grain size and porosity) on specific examples in order to show the ability and the limits of ultrasonics to evaluate large grain size graphite.<<ETX>>


IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control | 1998

Influence of a parallelism defect of the external medium on the electrical impedance of a piezoelectric inserted element

Nicolas Saint-Pierre; Yves Jayet; Jacques Tatibouet; Jean-Claude Baboux

When a piezoelectric element is inserted in a medium, the viscoelastic properties of this medium can be deduced from the measurement of the electrical impedance of this insert, by means of optimization techniques, if all the concerned interfaces exhibit a strict parallelism. However, in practical cases, this assumption is not always respected. We have developed a model to evaluate the consequences of such a parallelism defect. Comparisons between experimental results and simulations have been carried out to check this theoretical approach. For different parallelism defects, the validity of the acoustical parameters deduced from an optimization method have been tested using criteria based on the Kramers-Kronig relations. The maximum parallelism misfit that can be tolerated for a correct application of this technique has also been evaluated.

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Dive into the Jean-Claude Baboux's collaboration.

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Yves Jayet

Institut national des sciences Appliquées de Lyon

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A. Mouchtachi

Arts et Métiers ParisTech

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R. El Guerjouma

Institut national des sciences Appliquées de Lyon

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Jacques Tatibouet

Institut national des sciences Appliquées de Lyon

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M. Dubuget

Électricité de France

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Mourad Bentahar

Institut national des sciences Appliquées de Lyon

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Philippe Guy

Institut national des sciences Appliquées de Lyon

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Thomas Monnier

Institut national des sciences Appliquées de Lyon

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Nicolas Saint-Pierre

Centre national de la recherche scientifique

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R. El Guerjouma

Institut national des sciences Appliquées de Lyon

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