Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Jul 29, 2001
The measurement of the V(z) curve, also called acoustical material signature has been used to det... more The measurement of the V(z) curve, also called acoustical material signature has been used to determine cij elastic constants. The method is based on the comparison of measured and calculated R(theta,f) reflection coefficient. The measured R(theta,f) is determined by inversion of the V(z) curve. The cij elastic constants are obtained by using an optimization method (simplex method), which minimizes the
Résumé: Le but de notre travail est de déterminer l'influence de la structure et de la conce... more Résumé: Le but de notre travail est de déterminer l'influence de la structure et de la concentration de glucides simples (oses) et composés (diholosides) sur l'atténuation ultrasonore de solutions contenant ce type de molécules. Les expériences montrent qu'il n'existe aucune différence d'atténuation entre une solution aqueuse de glucose (al-dose) et une solution de fructose (cétohexose) dans les mêmes concentrations molaires. Par conh'e les solutions aqueuses de saccharose (glucose-fructose) et de maltose (glucose-glucose) présentent des valeurs d'atténuation dif-férentes surtout aux basses fréquences (40-150 MHz). D'autre part, l'influence de la concentration des glucides sur l'absorption ultrasonore haute fréquence (50-500 MHz) a été mise en évidence au cours de nos travaux. Abstract: Our aim is to investigate the influence of the structure and concentration of simple and compound su-gars on the ultrasonic absorption of solutions c...
In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms... more In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms by combining three techniques, namely ul trasonic waves, acoustic emission and infrared thermography was achieved. Longitudinal waves in Cscan representation were used to characterize initial state of the tested materials, where high r esolution maps of velocity, attenuation and density were obtained and analyzed. The Acoustic Emission ( AE), InfraRed (IR) thermography and Lamb waves techniques were used for detection and identi fication of the occurred damage mechanisms under mechanical loading. The principal result of t his work is the development of an experimental technique for NDT combined tests to assess the dama ge according several different signatures. 1. Introduction and objectives Different types of PCM have recently been introduce d and studied in different scales from macro to nano composites [1]. Cross-ply Glass Fiber Reinforced Polymer (GFRP) l aminates are strongly used ...
ABSTRACT The velocity of leaky surface acoustic waves (SAWs) is obtained for different directions... more ABSTRACT The velocity of leaky surface acoustic waves (SAWs) is obtained for different directions of propagation (phi) from the V(z) curves by using the Kuschibiki method. The comparison of measured and calculated velocities consists in the minimization of the summation of the square difference Sigma|VPhic-Vphim|2 by using a Simplex method. The effect of the initial values of cij on the final result is discussed in the case of cubic-crystallite solids. The influence of the transducer parameters on the SAW velocity is also discussed. .
major issue. For example, thickness control of coated materials and microcracks detection are ver... more major issue. For example, thickness control of coated materials and microcracks detection are very important. In this work, the sample consists of a micrometric gold thin film deposited by evaporation on a silicon substrate. Surface acoustic waves generated and detected by laser are used for non destructive testing. This method has the advantage to be a contactless technique with a large bandwidth. In a first part, the film thickness influence on the first Rayleigh mode has been theoretically studied. Then, the effect of a film thickness variation has been highlighted. In order to predict the propagation of the first Rayleigh mode, a finite element method is also presented. Finally, the interaction of this mode with microcracks is theoretically and experimentally investigated.
Laser-ultrasound-based non-destructive testing (NDT) applications usually use circular or linear ... more Laser-ultrasound-based non-destructive testing (NDT) applications usually use circular or linear thermoelastic sources. This paper studies two more complex sources and presents their specific advantages. The first thermoelastic source is a regular line array, whereas the second one is a chirped line array. The surface acoustic waves generated on an aluminum sample by these two thermoelastic sources are detected by an interferometric optical probe, the measurements showing a good agreement with theoretical expectations. Finally, the potentialities of these two sources in NDT applications are described.
Review of Progress in Quantitative Nondestructive Evaluation, 1999
Surface acoustic waves, whose energy remains confined to a small layer typically one acoustic wav... more Surface acoustic waves, whose energy remains confined to a small layer typically one acoustic wavelength thick, are used in various non destructive testing applications [1–3]. The detection of defects lying at a small depth inside the bulk of materials or evolving perpendicularly to their surface, which are not easily attainable by other methods, may then be performed. In non destructive testing domain, it is of great interest to use focused acoustic waves in order to increase sound intensity and to improve spatial resolution [3–6]. The detection of defects with their longer dimension perpendicular to the sample surface, like some cracks, need a focusing of surface acoustic waves. This operation allows to increase the sensitivity of the method. The traditional SAW generation systems may not be used for focusing Rayleigh waves on nonpiezoelectric substrates. For this purpose one must use geodesical lenses or thin layer coatings inserted along the SAW propagation path [7]. Recently some authors have worked on the focusing problem. They used a dispersed wide beam width giving a poor lateral resolution [8] or a PFDF transducer at low frequency [9,10]. A new ultrasonic system working at 30 MHz is reported here for the generation of focused surface acoustic waves on nonpiezoelectric materials. Using a simple geometrical model, the resolution and conversion efficiency of the system are estimated. Experimental results on ceramic samples with artificial defects are reported and the performances of the technique are analyzed.
Composite materials are more and more used in some engineering domains like aeronautics and autom... more Composite materials are more and more used in some engineering domains like aeronautics and automotive industry. The elaboration of these materials and their mechanical response under stress is very different from those of metals. The detection of critical defects calls then for more involved specialized control methods. The usefulness of acoustic spectroscopy in this area is presented here. Selective absorption frequencies, related to the internal structure of the materials, are evidenced.
In this paper, we present a non-destructive method for estimating residual stress profiles, based... more In this paper, we present a non-destructive method for estimating residual stress profiles, based on the Barkhausen noise effect. Validated on several batches of bearings, this method has been shown to be rapid, well suited to industrial imperatives connected to on-line measurement and easily adapted to the circular geometries of the bearing rings. Given the industrial imperative to characterize parts,
ABSTRACT In the first part of this paper, laser ultrasonics has been performed in an original way... more ABSTRACT In the first part of this paper, laser ultrasonics has been performed in an original way to evaluate the thickness of a gold thin film deposited on a silicon substrate. To this end, the influence of the film thickness and the elastic parameters of both materials on the first Rayleigh mode propagation has been theoretically studied. Then, using simultaneously the head wave and the Rayleigh wave propagating on the substrate, its elastic parameters were determined. These parameters allowed us to deduce the film thickness by matching the experimental group velocity dispersion curve with the theoretical one in a frequency range up to 25 MHz. In the second part, the effect of a void, consisting of a circular area without layer, on the first Rayleigh mode propagation has been investigated. The experimental results show clearly time of flight shifts proportionally to the size of the area and depending on the considered frequency component. A good agreement was obtained with finite-element modeling. This effect could be the basis for a frequency-selective surface acoustic lens.
ABSTRACT Non destructive testing has been performed on a thin indium layer deposited on a two inc... more ABSTRACT Non destructive testing has been performed on a thin indium layer deposited on a two inches silicon wafer. Guided waves were generated and studied using a laser ultrasonic setup, and a two-dimensional Fourier transform technique was employed to obtain the dispersion curves. The inverse problem, in other words the determination of the layer thickness and the elastic constants of the substrate, has been solved by means of a feedforward neural network. These parameters were then evaluated simultaneously, the dispersion curves being entirely fitted. The experimental results show a good agreement with the theoretical model. This inversion method was found to be prompt and easy to automate.
The determination of elastic constants in anisotropic solids by line-focus acoustic microscopy (L... more The determination of elastic constants in anisotropic solids by line-focus acoustic microscopy (LFAM) is discussed. The velocity of leaky surface acoustic waves (SAWs) has been obtained for different directions of propagation (f) from the V(z) curves. The elastic constants are determined from the comparison of measured and calculated velocities. The principle is based on the minimization of the summation of the square difference P uV c F 2 V m F u 2 ; by using a Simplex method. This paper deals with the case of cubic-crystallite solids de®ned by three independent elastic constants. The in¯uence of the initial values of c ij on the ®nal result is discussed in the case of MgO substrate and TiN deposited on MgO substrate. Experimental SAW velocity pro®le is measured on (100) silicon substrate as a function of f between [100] and [010] directions. The in¯uence of the transducer parameters and defocusing distance are also discussed.
Nous nous sommes attachés dans ce travail, à déterminer expérimentalement l'atténuation des ultra... more Nous nous sommes attachés dans ce travail, à déterminer expérimentalement l'atténuation des ultrasons dans le sang en fonction de ses constituants essentiels (plasma et globules rouges) dans une gamme de fréquences s'étendant de 50 à 400 MHz à la température de 20°C. L'originalité et l'intérêt d'une telle entreprise consistent en une prospection plus fine des caractéristiques acoustiques du sang étant donné que dans cette gamme de fréquences, les longueurs d'ondes deviennent comparables à la taille des diffuseurs (les globules rouges). Toutefois, le choix de l'atténuation en tant que moyen de caractérisation hautes fréquences n'est pas le plus judicieux, car il semblerait qu'il n'existe pas de corrélation remarquable entre la taille des diffuseurs et la longueur d'onde d'une part et l'atténuation mesurée avec un transducteur sensible à la phase d'autre part. Il sera nécessaire d'étudier l'évolution d'autres grandeurs telle que la répartition spatiale du diffusé en fonction de la fréquence. Des mesures de l'atténuation en fonction de l'hématocrite révèlent la même dépendance en fréquence des diverses courbes. L'atténuation montre une évolution croissante jusqu'à un hématocrite de 22.5%, se stabilise entre 22.5% et 36% et évolue de nouveau jusqu'à 45%. Il a également été mis en évidence que le plasma participe dans une proportion de 36% à l'atténuation dans le sang.
This study deals with characterization of the damage and thermomechanical behavior of the Glass F... more This study deals with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP), submitted to static tensile loadings, using a passive infrared thermography technique. During mechanical testing, thermal measurements are performed by means of an IR camera. The thermal data post-processing involves the analysis of both the thermal maps and the thermomechanical behavior of the material. The thermal maps analysis allows qualitative evaluation of the created material damage at high stress levels. While the thermomechanical analysis gave us a quantitative evaluation of the material damage, for both low and high stress levels, through definition of a new thermoelastic damage variable.
Le Centre pour la Communication Scientifique Directe - HAL - Diderot, Jul 29, 2001
The measurement of the V(z) curve, also called acoustical material signature has been used to det... more The measurement of the V(z) curve, also called acoustical material signature has been used to determine cij elastic constants. The method is based on the comparison of measured and calculated R(theta,f) reflection coefficient. The measured R(theta,f) is determined by inversion of the V(z) curve. The cij elastic constants are obtained by using an optimization method (simplex method), which minimizes the
Résumé: Le but de notre travail est de déterminer l'influence de la structure et de la conce... more Résumé: Le but de notre travail est de déterminer l'influence de la structure et de la concentration de glucides simples (oses) et composés (diholosides) sur l'atténuation ultrasonore de solutions contenant ce type de molécules. Les expériences montrent qu'il n'existe aucune différence d'atténuation entre une solution aqueuse de glucose (al-dose) et une solution de fructose (cétohexose) dans les mêmes concentrations molaires. Par conh'e les solutions aqueuses de saccharose (glucose-fructose) et de maltose (glucose-glucose) présentent des valeurs d'atténuation dif-férentes surtout aux basses fréquences (40-150 MHz). D'autre part, l'influence de la concentration des glucides sur l'absorption ultrasonore haute fréquence (50-500 MHz) a été mise en évidence au cours de nos travaux. Abstract: Our aim is to investigate the influence of the structure and concentration of simple and compound su-gars on the ultrasonic absorption of solutions c...
In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms... more In this study, Non-Destructive Testing (NDT) of the Polymer Composite Materials damage mechanisms by combining three techniques, namely ul trasonic waves, acoustic emission and infrared thermography was achieved. Longitudinal waves in Cscan representation were used to characterize initial state of the tested materials, where high r esolution maps of velocity, attenuation and density were obtained and analyzed. The Acoustic Emission ( AE), InfraRed (IR) thermography and Lamb waves techniques were used for detection and identi fication of the occurred damage mechanisms under mechanical loading. The principal result of t his work is the development of an experimental technique for NDT combined tests to assess the dama ge according several different signatures. 1. Introduction and objectives Different types of PCM have recently been introduce d and studied in different scales from macro to nano composites [1]. Cross-ply Glass Fiber Reinforced Polymer (GFRP) l aminates are strongly used ...
ABSTRACT The velocity of leaky surface acoustic waves (SAWs) is obtained for different directions... more ABSTRACT The velocity of leaky surface acoustic waves (SAWs) is obtained for different directions of propagation (phi) from the V(z) curves by using the Kuschibiki method. The comparison of measured and calculated velocities consists in the minimization of the summation of the square difference Sigma|VPhic-Vphim|2 by using a Simplex method. The effect of the initial values of cij on the final result is discussed in the case of cubic-crystallite solids. The influence of the transducer parameters on the SAW velocity is also discussed. .
major issue. For example, thickness control of coated materials and microcracks detection are ver... more major issue. For example, thickness control of coated materials and microcracks detection are very important. In this work, the sample consists of a micrometric gold thin film deposited by evaporation on a silicon substrate. Surface acoustic waves generated and detected by laser are used for non destructive testing. This method has the advantage to be a contactless technique with a large bandwidth. In a first part, the film thickness influence on the first Rayleigh mode has been theoretically studied. Then, the effect of a film thickness variation has been highlighted. In order to predict the propagation of the first Rayleigh mode, a finite element method is also presented. Finally, the interaction of this mode with microcracks is theoretically and experimentally investigated.
Laser-ultrasound-based non-destructive testing (NDT) applications usually use circular or linear ... more Laser-ultrasound-based non-destructive testing (NDT) applications usually use circular or linear thermoelastic sources. This paper studies two more complex sources and presents their specific advantages. The first thermoelastic source is a regular line array, whereas the second one is a chirped line array. The surface acoustic waves generated on an aluminum sample by these two thermoelastic sources are detected by an interferometric optical probe, the measurements showing a good agreement with theoretical expectations. Finally, the potentialities of these two sources in NDT applications are described.
Review of Progress in Quantitative Nondestructive Evaluation, 1999
Surface acoustic waves, whose energy remains confined to a small layer typically one acoustic wav... more Surface acoustic waves, whose energy remains confined to a small layer typically one acoustic wavelength thick, are used in various non destructive testing applications [1–3]. The detection of defects lying at a small depth inside the bulk of materials or evolving perpendicularly to their surface, which are not easily attainable by other methods, may then be performed. In non destructive testing domain, it is of great interest to use focused acoustic waves in order to increase sound intensity and to improve spatial resolution [3–6]. The detection of defects with their longer dimension perpendicular to the sample surface, like some cracks, need a focusing of surface acoustic waves. This operation allows to increase the sensitivity of the method. The traditional SAW generation systems may not be used for focusing Rayleigh waves on nonpiezoelectric substrates. For this purpose one must use geodesical lenses or thin layer coatings inserted along the SAW propagation path [7]. Recently some authors have worked on the focusing problem. They used a dispersed wide beam width giving a poor lateral resolution [8] or a PFDF transducer at low frequency [9,10]. A new ultrasonic system working at 30 MHz is reported here for the generation of focused surface acoustic waves on nonpiezoelectric materials. Using a simple geometrical model, the resolution and conversion efficiency of the system are estimated. Experimental results on ceramic samples with artificial defects are reported and the performances of the technique are analyzed.
Composite materials are more and more used in some engineering domains like aeronautics and autom... more Composite materials are more and more used in some engineering domains like aeronautics and automotive industry. The elaboration of these materials and their mechanical response under stress is very different from those of metals. The detection of critical defects calls then for more involved specialized control methods. The usefulness of acoustic spectroscopy in this area is presented here. Selective absorption frequencies, related to the internal structure of the materials, are evidenced.
In this paper, we present a non-destructive method for estimating residual stress profiles, based... more In this paper, we present a non-destructive method for estimating residual stress profiles, based on the Barkhausen noise effect. Validated on several batches of bearings, this method has been shown to be rapid, well suited to industrial imperatives connected to on-line measurement and easily adapted to the circular geometries of the bearing rings. Given the industrial imperative to characterize parts,
ABSTRACT In the first part of this paper, laser ultrasonics has been performed in an original way... more ABSTRACT In the first part of this paper, laser ultrasonics has been performed in an original way to evaluate the thickness of a gold thin film deposited on a silicon substrate. To this end, the influence of the film thickness and the elastic parameters of both materials on the first Rayleigh mode propagation has been theoretically studied. Then, using simultaneously the head wave and the Rayleigh wave propagating on the substrate, its elastic parameters were determined. These parameters allowed us to deduce the film thickness by matching the experimental group velocity dispersion curve with the theoretical one in a frequency range up to 25 MHz. In the second part, the effect of a void, consisting of a circular area without layer, on the first Rayleigh mode propagation has been investigated. The experimental results show clearly time of flight shifts proportionally to the size of the area and depending on the considered frequency component. A good agreement was obtained with finite-element modeling. This effect could be the basis for a frequency-selective surface acoustic lens.
ABSTRACT Non destructive testing has been performed on a thin indium layer deposited on a two inc... more ABSTRACT Non destructive testing has been performed on a thin indium layer deposited on a two inches silicon wafer. Guided waves were generated and studied using a laser ultrasonic setup, and a two-dimensional Fourier transform technique was employed to obtain the dispersion curves. The inverse problem, in other words the determination of the layer thickness and the elastic constants of the substrate, has been solved by means of a feedforward neural network. These parameters were then evaluated simultaneously, the dispersion curves being entirely fitted. The experimental results show a good agreement with the theoretical model. This inversion method was found to be prompt and easy to automate.
The determination of elastic constants in anisotropic solids by line-focus acoustic microscopy (L... more The determination of elastic constants in anisotropic solids by line-focus acoustic microscopy (LFAM) is discussed. The velocity of leaky surface acoustic waves (SAWs) has been obtained for different directions of propagation (f) from the V(z) curves. The elastic constants are determined from the comparison of measured and calculated velocities. The principle is based on the minimization of the summation of the square difference P uV c F 2 V m F u 2 ; by using a Simplex method. This paper deals with the case of cubic-crystallite solids de®ned by three independent elastic constants. The in¯uence of the initial values of c ij on the ®nal result is discussed in the case of MgO substrate and TiN deposited on MgO substrate. Experimental SAW velocity pro®le is measured on (100) silicon substrate as a function of f between [100] and [010] directions. The in¯uence of the transducer parameters and defocusing distance are also discussed.
Nous nous sommes attachés dans ce travail, à déterminer expérimentalement l'atténuation des ultra... more Nous nous sommes attachés dans ce travail, à déterminer expérimentalement l'atténuation des ultrasons dans le sang en fonction de ses constituants essentiels (plasma et globules rouges) dans une gamme de fréquences s'étendant de 50 à 400 MHz à la température de 20°C. L'originalité et l'intérêt d'une telle entreprise consistent en une prospection plus fine des caractéristiques acoustiques du sang étant donné que dans cette gamme de fréquences, les longueurs d'ondes deviennent comparables à la taille des diffuseurs (les globules rouges). Toutefois, le choix de l'atténuation en tant que moyen de caractérisation hautes fréquences n'est pas le plus judicieux, car il semblerait qu'il n'existe pas de corrélation remarquable entre la taille des diffuseurs et la longueur d'onde d'une part et l'atténuation mesurée avec un transducteur sensible à la phase d'autre part. Il sera nécessaire d'étudier l'évolution d'autres grandeurs telle que la répartition spatiale du diffusé en fonction de la fréquence. Des mesures de l'atténuation en fonction de l'hématocrite révèlent la même dépendance en fréquence des diverses courbes. L'atténuation montre une évolution croissante jusqu'à un hématocrite de 22.5%, se stabilise entre 22.5% et 36% et évolue de nouveau jusqu'à 45%. Il a également été mis en évidence que le plasma participe dans une proportion de 36% à l'atténuation dans le sang.
This study deals with characterization of the damage and thermomechanical behavior of the Glass F... more This study deals with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP), submitted to static tensile loadings, using a passive infrared thermography technique. During mechanical testing, thermal measurements are performed by means of an IR camera. The thermal data post-processing involves the analysis of both the thermal maps and the thermomechanical behavior of the material. The thermal maps analysis allows qualitative evaluation of the created material damage at high stress levels. While the thermomechanical analysis gave us a quantitative evaluation of the material damage, for both low and high stress levels, through definition of a new thermoelastic damage variable.
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