Professor Joseph MOYSAN graduated from the Mechanical Engineering school ECAM Lyon in 1989 and obtained his PhD from INSA Lyon in 1992 (FRANCE). He is now a full professor at Aix-Marseille University in the Mechanical Engineering Department of the Institute of Technology in Aix en Provence.He began research and teaching in NDT in 1993. He won the Gold Medal for the European NDT Innovation Awards in 1994 for his work concerning the automatic thresholding of ultrasound images. He developed NDT analysis for metallic welds (defects detection, grain noise analysis) and contributed to the development of the MINA model that describes weld microstructure at the ultrasonic scale. He is also interested in the development of NDT solutions for nuclear reactors since year 2001 and directed several PHD thesis in this domain. He also recently managed an extensive French program to develop innovative NDT solutions to evaluate nondestructive bond strength (ISABEAU). He is a member of the permanent scientific council for the French NDT association (COFREND) since 2015.
In a 4th generation Sodium Fast nuclear Reactor (SFR), liquid sodium -the coolant -is topped by a... more In a 4th generation Sodium Fast nuclear Reactor (SFR), liquid sodium -the coolant -is topped by an argon cover gas. Due to this presence of argon, various phenomena can lead to gaseous microbubbles presence within sodium. This study deals with the determination of the void fraction of the bubble cloud. The first experiments are conducted with an air-water experimental set-up. A Helmholtz resonator is used as container of the microbubble cloud. First, a linear acoustic method based on the Wood model is presented. It allows a quantitative link between low frequency speed of sound and void fraction. The obtained results with and without bubbles are in accordance with expected void fractions. Then we applied Nonlinear Resonant Ultrasound Spectroscopy (NRUS). Note that the Helmholtz resonance is far below the bubble's resonant frequency. We present a model and associated numerical simulation of NRUS experiments. The objectives were to observe nonlinear behaviour and to link it with bubble's characteristics: void fraction and size. The nonlinear behaviour of the cloud is clearly observed but it is difficult to analyze due to the presence of a cavitation phenomenon. This presence makes the second objective nearly impossible to reach...at present time.
Automatic thresholding methods have always difficulties to stand out in the NDT field as only one... more Automatic thresholding methods have always difficulties to stand out in the NDT field as only one malfunction could be harmful. We propose in this article not only an algorithm to automate thresholding but also an algorithm which gives information on the quality of its result. The solution used here is based on co-occurrence matrix analysis. This two-dimensional histogram allows multiple image analysis like thresholding and texture classification which are two major solutions for image segmentation [1–4]. Automatic thresholding was developed on BSCAN ultrasonic images [5–6] and completed to process other images [7]. We present here the most complete tool with quality indicators which are now available for eddy current images.
The present paper deals with the geometric characterization of a circumferential weld bead by rad... more The present paper deals with the geometric characterization of a circumferential weld bead by radioscopy. Weld control can only be performed by tangential irradiation. The series of images obtained by projection, for one rotation of the welded component, is then strongly degraded, as each image contains the projected section of the weld and the superposition of several other sections. The inverse problem is solved using a new image segmentation method, based on an "edge and area" combined approach. The edge approach defines the limits of the weld molten zone by minimum gradient points. The area approach uses a thresholding method based on histogram analysis to position the bottom of the bead exactly. This segmentation leads to fast and automatic control of the weld quality. A validation stage on industrial components shows the method reliability.
of the transducer. The same kind of methodology can be applied to the C-scan image. At the end of... more of the transducer. The same kind of methodology can be applied to the C-scan image. At the end of the processing we obtain a volume envelope containing different relevant information related to the defect. The proposed method allows different goals: first this type of segmentation corresponds to an automatic detection stage; second use of the algorithm produces, in the case of adjacent echoes, a very clear separation and a good sizing stage or a sorting between different wave modes or geometrical echoes. Finally the algorithm can be used in the case of bad signal-to-noise ratios: the pixels are correlated as functions of the phase coherence of the signal in two and three dimensions. The echo due to the noise being less correlated than the signal coming from the defect, the coherence or the length of the segments is then typical ofthe presence of a defect.
Ce rapport presente une etude sur le traitement des i mages ultrasonores de type BSCAN obtenues e... more Ce rapport presente une etude sur le traitement des i mages ultrasonores de type BSCAN obtenues en controle non destructif de soudure. L'objectif de cette etude est de definir ce que peuvent apporter les techniques de traitement d' image pour ameliorer l'exploitation des donnees de controle et plus particulierement pour isoler les echos ultrasonores qui permettent de caracteriser et de dimensionner le defauts. Le rapport introduit le domaine du controle par ultrasons de soudure pour l'industrie nucleaire et decrit les particularites de la propagation des ultrasons dans les aciers austenitiques. Il fait le point des techniques utilisees pour ameliorer la qualite et le traitement de l ' information contenue dans ces images. Une nouvelle analyse de l'image ultrasonore est ensuite developpee. Elle se base sur un outil tres complet du traitement d'image : la matrice de co-occurence. Cette matrice permet de representer de maniere globale les relations entre les amplitude de couples de pixels dans l'image. A partir de l'analyse de cette matrice, une nouvelle methode complete et automatique a ete mise au point pour definir un seuil qui separe les echos ultrasonores du bruit de l'image, elle permet alors d'envisager une interpretation automatique de l'image. Les resultats obtenus sur des defauts, de type fissures, en soudure ont permis de valider completement cette methode.
We develop a modeling of acoustic waves propagation in liquid sodium environment under conditions... more We develop a modeling of acoustic waves propagation in liquid sodium environment under conditions similar to those present in a Sodium-cooled Fast Reactor (SFR). Our goal is to propose a new Structural Health Monitoring (SHM) tool dedicated to the monitoring of the nominal operating temperature above the core of a reactor. Using ultrasonic time-of-flight, local temperature measurements would be possible. For this, we investigate the computational aspects related to the use of the simulation code named SPECFEM, initially dedicated to the propagation of seismic waves in arbitrary configurations 1D, 2D or 3D. In our study case, the spatial and temporal scales are very different from those used for seismic waves. The data used for this work are derived from tests simulating of the thermal-hydraulic characteristics of the core output of SFR.
In some polycrystalline materials, ultrasonic non destructive testing is affected by structural n... more In some polycrystalline materials, ultrasonic non destructive testing is affected by structural noise and attenuation. Those phenomena can cause significant loss in detection performances, thus their prediction is of great practical interest. During previous works at CEA-LIST, noise and attenuation models have been developed and implemented into the simulation software for non destructive testing CIVA. These two models are based
The presence of microscopic gas pockets trapped on a non-wetting solid/liquid interface induces a... more The presence of microscopic gas pockets trapped on a non-wetting solid/liquid interface induces a significant decrease of the transmitted ultrasonic energy. This phenomenon can reduce the performance of ultrasonic inspection in sodium-cooled fast reactors (SFR) for instance. To explain this event, a hypothesis was formulated in a previous study: under the effect of ultrasound, the gas pockets could coalesce, forming a gas film which would prevent the passage of the ultrasound. This coalescence hypothesis can be studied by visual observation of the phenomenon. This paper is presenting an original experiment which simulates this phenomenon in water. This experiment consists in observing the ultrasound-induced behaviour of gas pockets over various time scales. The results allow dismissing the coalescence hypothesis. Our conclusion indicates how future works are reoriented to improve the design of ultrasonic transducers dedicated to SFR inspection.
Macro-crack characterization in concrete by diffuse ultrasound under low frequency dynamic loadin... more Macro-crack characterization in concrete by diffuse ultrasound under low frequency dynamic loading Proceedings of Meetings on Acoustics 16, 045016 (2012);
ABSTRACT The inspection of austenitic welds used in the nuclear field with ultrasound involves pr... more ABSTRACT The inspection of austenitic welds used in the nuclear field with ultrasound involves problems of interpretation: intense grain noise makes the detection of the crack difficult. The formation B-scan images and their digital processing increase the effectiveness of testing. A segmentation method based on the cooccurrence matrix is presented. It separates defect zones and noise zones. The calculation of statistical parameters makes it possible to automate and to improve image thresholding. Defect sizing through the analysis of the modified image is the final goal. Some examples of segmentation improvement applied to artificial defects are presented
This paper presents a generalization to eddy current images of a thresholding method developed fo... more This paper presents a generalization to eddy current images of a thresholding method developed for ultrasonic imaging. It is also shown how to improve the thresholding strength through the definition of a cooperation rule between two threshold assessment measures. This rule is also used to reduce time of calculus. These measures are calculated from the image cooccurrence matrix. The aim
European Journal of Environmental and Civil Engineering, 2011
For non destructive stress evaluation in prestressed concrete, we describe in this paper a promis... more For non destructive stress evaluation in prestressed concrete, we describe in this paper a promising ultrasonic method. In "ordinary" isotropic homogeneous materials such as steel, ultrasonic determination of third order elastic constants provides means for stress evaluation since half a century. Acoustoelasticity is aimed at measuring ultrasonic velocity changes at progressively increasing applied stress. In case of concrete, example of a class of materials that exhibit strong multiple scattering as well as significant elastic nonlinear response, accurate velocity monitoring is challenging. In this paper, we purpose a novel method originally from geophysics. This treatment is aimed at detecting small changes in velocity or attenuation in the earth crust, by analyzing coda waves. So called "coda wave interferometry", this technique is transposed to concrete. We show that intense scattering can be applied to robustly determine velocity changes. CWI is implemented at progressively increasing applied stress, and thereby, we extract nonlinear elastic coefficients. We show that the nonlinear behavior of concrete is around two order magnitude greater than ordinary materials such as steel or aluminum. In addition, we show how this method could be transposed in case of in situ measurements in concrete structures and outline future possible applications.
In a 4th generation Sodium Fast nuclear Reactor (SFR), liquid sodium -the coolant -is topped by a... more In a 4th generation Sodium Fast nuclear Reactor (SFR), liquid sodium -the coolant -is topped by an argon cover gas. Due to this presence of argon, various phenomena can lead to gaseous microbubbles presence within sodium. This study deals with the determination of the void fraction of the bubble cloud. The first experiments are conducted with an air-water experimental set-up. A Helmholtz resonator is used as container of the microbubble cloud. First, a linear acoustic method based on the Wood model is presented. It allows a quantitative link between low frequency speed of sound and void fraction. The obtained results with and without bubbles are in accordance with expected void fractions. Then we applied Nonlinear Resonant Ultrasound Spectroscopy (NRUS). Note that the Helmholtz resonance is far below the bubble's resonant frequency. We present a model and associated numerical simulation of NRUS experiments. The objectives were to observe nonlinear behaviour and to link it with bubble's characteristics: void fraction and size. The nonlinear behaviour of the cloud is clearly observed but it is difficult to analyze due to the presence of a cavitation phenomenon. This presence makes the second objective nearly impossible to reach...at present time.
Automatic thresholding methods have always difficulties to stand out in the NDT field as only one... more Automatic thresholding methods have always difficulties to stand out in the NDT field as only one malfunction could be harmful. We propose in this article not only an algorithm to automate thresholding but also an algorithm which gives information on the quality of its result. The solution used here is based on co-occurrence matrix analysis. This two-dimensional histogram allows multiple image analysis like thresholding and texture classification which are two major solutions for image segmentation [1–4]. Automatic thresholding was developed on BSCAN ultrasonic images [5–6] and completed to process other images [7]. We present here the most complete tool with quality indicators which are now available for eddy current images.
The present paper deals with the geometric characterization of a circumferential weld bead by rad... more The present paper deals with the geometric characterization of a circumferential weld bead by radioscopy. Weld control can only be performed by tangential irradiation. The series of images obtained by projection, for one rotation of the welded component, is then strongly degraded, as each image contains the projected section of the weld and the superposition of several other sections. The inverse problem is solved using a new image segmentation method, based on an "edge and area" combined approach. The edge approach defines the limits of the weld molten zone by minimum gradient points. The area approach uses a thresholding method based on histogram analysis to position the bottom of the bead exactly. This segmentation leads to fast and automatic control of the weld quality. A validation stage on industrial components shows the method reliability.
of the transducer. The same kind of methodology can be applied to the C-scan image. At the end of... more of the transducer. The same kind of methodology can be applied to the C-scan image. At the end of the processing we obtain a volume envelope containing different relevant information related to the defect. The proposed method allows different goals: first this type of segmentation corresponds to an automatic detection stage; second use of the algorithm produces, in the case of adjacent echoes, a very clear separation and a good sizing stage or a sorting between different wave modes or geometrical echoes. Finally the algorithm can be used in the case of bad signal-to-noise ratios: the pixels are correlated as functions of the phase coherence of the signal in two and three dimensions. The echo due to the noise being less correlated than the signal coming from the defect, the coherence or the length of the segments is then typical ofthe presence of a defect.
Ce rapport presente une etude sur le traitement des i mages ultrasonores de type BSCAN obtenues e... more Ce rapport presente une etude sur le traitement des i mages ultrasonores de type BSCAN obtenues en controle non destructif de soudure. L'objectif de cette etude est de definir ce que peuvent apporter les techniques de traitement d' image pour ameliorer l'exploitation des donnees de controle et plus particulierement pour isoler les echos ultrasonores qui permettent de caracteriser et de dimensionner le defauts. Le rapport introduit le domaine du controle par ultrasons de soudure pour l'industrie nucleaire et decrit les particularites de la propagation des ultrasons dans les aciers austenitiques. Il fait le point des techniques utilisees pour ameliorer la qualite et le traitement de l ' information contenue dans ces images. Une nouvelle analyse de l'image ultrasonore est ensuite developpee. Elle se base sur un outil tres complet du traitement d'image : la matrice de co-occurence. Cette matrice permet de representer de maniere globale les relations entre les amplitude de couples de pixels dans l'image. A partir de l'analyse de cette matrice, une nouvelle methode complete et automatique a ete mise au point pour definir un seuil qui separe les echos ultrasonores du bruit de l'image, elle permet alors d'envisager une interpretation automatique de l'image. Les resultats obtenus sur des defauts, de type fissures, en soudure ont permis de valider completement cette methode.
We develop a modeling of acoustic waves propagation in liquid sodium environment under conditions... more We develop a modeling of acoustic waves propagation in liquid sodium environment under conditions similar to those present in a Sodium-cooled Fast Reactor (SFR). Our goal is to propose a new Structural Health Monitoring (SHM) tool dedicated to the monitoring of the nominal operating temperature above the core of a reactor. Using ultrasonic time-of-flight, local temperature measurements would be possible. For this, we investigate the computational aspects related to the use of the simulation code named SPECFEM, initially dedicated to the propagation of seismic waves in arbitrary configurations 1D, 2D or 3D. In our study case, the spatial and temporal scales are very different from those used for seismic waves. The data used for this work are derived from tests simulating of the thermal-hydraulic characteristics of the core output of SFR.
In some polycrystalline materials, ultrasonic non destructive testing is affected by structural n... more In some polycrystalline materials, ultrasonic non destructive testing is affected by structural noise and attenuation. Those phenomena can cause significant loss in detection performances, thus their prediction is of great practical interest. During previous works at CEA-LIST, noise and attenuation models have been developed and implemented into the simulation software for non destructive testing CIVA. These two models are based
The presence of microscopic gas pockets trapped on a non-wetting solid/liquid interface induces a... more The presence of microscopic gas pockets trapped on a non-wetting solid/liquid interface induces a significant decrease of the transmitted ultrasonic energy. This phenomenon can reduce the performance of ultrasonic inspection in sodium-cooled fast reactors (SFR) for instance. To explain this event, a hypothesis was formulated in a previous study: under the effect of ultrasound, the gas pockets could coalesce, forming a gas film which would prevent the passage of the ultrasound. This coalescence hypothesis can be studied by visual observation of the phenomenon. This paper is presenting an original experiment which simulates this phenomenon in water. This experiment consists in observing the ultrasound-induced behaviour of gas pockets over various time scales. The results allow dismissing the coalescence hypothesis. Our conclusion indicates how future works are reoriented to improve the design of ultrasonic transducers dedicated to SFR inspection.
Macro-crack characterization in concrete by diffuse ultrasound under low frequency dynamic loadin... more Macro-crack characterization in concrete by diffuse ultrasound under low frequency dynamic loading Proceedings of Meetings on Acoustics 16, 045016 (2012);
ABSTRACT The inspection of austenitic welds used in the nuclear field with ultrasound involves pr... more ABSTRACT The inspection of austenitic welds used in the nuclear field with ultrasound involves problems of interpretation: intense grain noise makes the detection of the crack difficult. The formation B-scan images and their digital processing increase the effectiveness of testing. A segmentation method based on the cooccurrence matrix is presented. It separates defect zones and noise zones. The calculation of statistical parameters makes it possible to automate and to improve image thresholding. Defect sizing through the analysis of the modified image is the final goal. Some examples of segmentation improvement applied to artificial defects are presented
This paper presents a generalization to eddy current images of a thresholding method developed fo... more This paper presents a generalization to eddy current images of a thresholding method developed for ultrasonic imaging. It is also shown how to improve the thresholding strength through the definition of a cooperation rule between two threshold assessment measures. This rule is also used to reduce time of calculus. These measures are calculated from the image cooccurrence matrix. The aim
European Journal of Environmental and Civil Engineering, 2011
For non destructive stress evaluation in prestressed concrete, we describe in this paper a promis... more For non destructive stress evaluation in prestressed concrete, we describe in this paper a promising ultrasonic method. In "ordinary" isotropic homogeneous materials such as steel, ultrasonic determination of third order elastic constants provides means for stress evaluation since half a century. Acoustoelasticity is aimed at measuring ultrasonic velocity changes at progressively increasing applied stress. In case of concrete, example of a class of materials that exhibit strong multiple scattering as well as significant elastic nonlinear response, accurate velocity monitoring is challenging. In this paper, we purpose a novel method originally from geophysics. This treatment is aimed at detecting small changes in velocity or attenuation in the earth crust, by analyzing coda waves. So called "coda wave interferometry", this technique is transposed to concrete. We show that intense scattering can be applied to robustly determine velocity changes. CWI is implemented at progressively increasing applied stress, and thereby, we extract nonlinear elastic coefficients. We show that the nonlinear behavior of concrete is around two order magnitude greater than ordinary materials such as steel or aluminum. In addition, we show how this method could be transposed in case of in situ measurements in concrete structures and outline future possible applications.
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Papers by Joseph Moysan