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Dissertations / Theses on the topic 'Non Destructive Testing, Ultrasonic testing, Materials'
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Collison, Ian J. "Measurement of material nonlinearity using laser ultrasound." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493344.
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Sanderson, Terry. "Thermoelastic modeling of laser generated ultrasound for nondestructive materials testing." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/18978.
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Freemantle, Richard James. "Ultrasonic compression wave evaluation of adhered metal sheets and thin sheet materials." Thesis, Keele University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282635.
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Lawson, Joseph L. "On the determination of the elastic properties of geopolymeric materials using non-destructive ultrasonic techniques /." Online version of thesis, 2008. http://hdl.handle.net/1850/7356.
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Ikonen, Linus, and Daniel Nilsson. "Quality assessment of mineral wool insulation plates : Using ultrasonic non-destructive testing." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18223.
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In the manufacturing process of mineral wool insulation plates, defects arise, such as unmelted base minerals and uncured binder which gets embedded within the plates. To be able to sort out these defective plates from a manufacturing line, a reliable quality assessment is needed. The aim is to find an ultrasonic non-destructive testing method that can identify the embedded defects. This was achieved through experiments on defective insulation plates using three different ultrasonic non-destructive testing methods that were of interest. These methods were higher harmonics, pulse-echo and through transmission. Of these three, the through transmission method showed the most promising results in finding the defects that were sought after. The through transmission method utilizes two aligned transducers, one acting as a transmitter and one as a receiver. When the defective area passes through the sound beam between the transducers the intensity of the beam drops, indicating that a defect is present. The weakened intensity is due to the signal attenuation, mainly caused by the higher density of the defects compared to the base material in the surrounding insulation plate. The method is well suited for being implemented in a production line since it’s a fast method and, therefore, suited for moving objects. More measurements are needed to establish a reliable reference value to consistently distinguish the defects from the surrounding plate. The method was only evaluated in a small scale experimental environment so further experiments on a larger scale are needed to mimic and evaluate the reliability in the real case scenario of the production lines.<br>I tillverkningsprocessen av isolerskivor i stenull uppstår inneboende defekter i isolerskivorna, dessa defekter består av osmälta basmineraler och ohärdat bindemedel. För att kunna sortera bort dessa skadade skivor från tillverkningslinjen behövs en pålitlig metod för kvalitetsbedömning. Avsikten med det här arbetet är att hitta en oförstörande provningsmetod baserad på ultraljud som kan identifiera de inneboende defekterna. Detta genomfördes genom experiment på defekta isolerskivor med tre olika oförstörande provningsmetoder baserade på ultraljud. Dessa metoderna var, higher harmonics, pitch-echo och through transmission. Through transmission visade lovande resultat i att identifiera de båda typerna av skador. Metoden är baserad på att en sändare sänder ut ultraljud till en mottagare placerad i linje med sändaren. När ett defekt område passerar ultraljudsvågen mellan sändaren och mottagaren försvagas intensiteten av signalen. Försvagningen av signalen beror mestadels på att densiteten är högre hos defekterna än hos basmaterialet i isolerskivan. Denna försvagning indikerar att en defekt befinner sig i mätområdet. Metoden är väl implementerbar i en tillverkningslinje, då det är en snabb metod vilket den behöver vara då objektet är i rörelse. Mer mätningar behövs för att fastställa ett pålitligt referensvärde för att konsekvent kunna sortera ut de defekta isolerskivorna. Metoden är endast utvärderad i en småskalig laborationsmiljö och det behövs fler tester i en större skala undersöka pålitligheten i det verkliga scenariot med tillverkningslinjen.
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Punurai, Wonsiri. "Cement-based materials' characterization using ultrasonic attenuation." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04042006-171125/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.<br>Dr. Jennifer Michaels, Committee Member ; Dr. Jacek Jarzynski, Committee Member ; Dr. Jianmin Qu, Committee Member ; Dr. Laurence J. Jacobs, Committee Chair ; Dr. Kimberly E. Kurtis, Committee Co-Chair.
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Zlatev, Zahari. "Ultrasonic guided wave propagation in pipes coated with viscoelastic materials." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/12753.
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This work studies guided wave propagation in pipes coated with thick highly viscoelastic coating materials. The main motivation for this study is the problems associated with Long Range Ultrasonic Testing (LRUT) of coated pipelines. The results reported in the literature show that the proper determination of the optimum LRUT parameters depends strongly on the bulk acoustic properties of the coating materials. The bulk acoustic properties of coating materials reported in the literature show that they could vary significantly depending on the coating material age, temperature and bonding level. The methods for acoustic characterisation of coating materials reported by other researchers, have been studied and it was found that they do not take into account the temperature changes and bonding level variation. In this work, the bulk acoustic properties of two highly viscoelastic bitumen based coating materials are investigated. The conventional methods for acoustic characterisation are studied and a new method for independent measurement of bulk shear properties of bitumen is developed. The bulk acoustic properties of bitumen based coating materials are also studied by two new characterisation methods. The first method derives the bulk coating material properties from experimental data on guided wave reflection coefficients. The second method derives the coating material bulk properties from experimentally measured guided wave attenuation data. It is demonstrated that these new methods deliver much more accurate values for the bulk acoustic properties when compared to the data measured by conventional methods. The second method is used to study the temperature effect on the bulk acoustic properties and it is demonstrated that temperature has a significant effect. The validity of the acoustic properties for the two bitumen materials is investigated through comparison between numerical predictions and experimental data measured for guided wave reflection coefficients and attenuation of the torsional T(0,1) and longitudinal L(0,2) guided wave modes. Good agreement is achieved in the frequency range between 20 kHz and 100 kHz, which is typical for LRUT of pipes.
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Stolzenburg, Jens Christian. "Non-contact method to measure the material properties of layered media." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19312.
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Gex, Dominique. "Ultrasonic NDE testing of a gradient enhanced piezoelectric actuator (GEPAC) undergoing low frequency bending excitation." Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-04062004-171807/unrestricted/gex%5Fdominique%5Fc%5F200405%5Fmast.pdf.
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Thesis (M.S.)--Mechanical Engineering, Georgia Institute of Technology, 2004.<br>Berthelot, Committee Chair; Lynch, Committee Member; Jacobs, Committee Member. Includes bibliographical references (leaves 111-113).
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Pomarede, Pascal. "Détection de l'endommagement dans un composite tissé PA66,6/Fibres de verre à l'aide de techniques ultrasonores en vue d'une prédiction de la durabilité de pièces automobiles." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0024/document.
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Ces travaux de thèse portent sur l'étude expérimentale approfondie d'un composite à base polyamide 66/6 renforcé par des fibres de verres tissés suivant un motif sergé 2/2. L’objectif est de proposer des solutions de Contrôle Non Destructif (CND) basées sur les ultrasons afin de détecter différents niveaux d’endommagement induis. Pour cela, une étude approfondis des mécanismes d’endommagement apparaissant lors de sollicitations en traction suivant l’axe des fibres et hors axes est réalisé. Le cas d’impact induis par poids tombant est également étudiés. En effet, ces différents cas de sollicitions entraînent l’apparition de différent mécanismes d’endommagement. Ces derniers, ainsi que leur ordre d’apparition, sont caractérisés par Microscopie Electronique à Balayage (MEB) et tomographie à rayons X principalement. L’évaluation de la réduction du module élastique pré et post chargement ainsi que la fraction volumique de vide montrent une évolution de l’endommagement plus importante lors de chargement en traction hors axes des fibres que lors de chargement suivant l’axe. Lors des essais d’impact par poids tombant différents niveaux d’énergie sont considérés en restant proche du domaine des BVID en vue d’éprouver la sensibilité des méthodes de CND. Deux méthodes de CND par ultrasons étudiées durant ce projet peuvent être mises en avant. Premièrement, par mesure de la vitesse de propagation des ondes dans plusieurs directions du composites, le tenseur de rigidité est estimé dans tous ces cas de sollicitation mécanique pour différents niveaux d’endommagement. Des indicateurs d’endommagement basés sur ces mesures montrent une évolution de l’état d’endommagement similaire à celle discutée précédemment. Deuxièmement, une étude de la détection de l’endommagement par ondes guidées est menée. Aucun changement des modes transmit n’est visible lors de l’augmentation de l’état d’endommagement. L’évolution de l’énergie du signal transmis est alors proposée et validée comme indicateur d’endommagement efficace pour des chargements en traction mais pas pour l’impact. La mesure du décalage temporel à en revanche permis une localisation et une quantification de l’endommagement induit par impact<br>The present study is focused on the experimental study of a polyamide 66/6 based composite reinforced by a 2/2 twill weave glass fabric. The aim is to propose Non Destructive Evaluation (NDE) methods based on ultrasound that can efficiently distinguish different damage state. In order to do so, an investigation of the damage mechanisms induced by different type of mechanical solicitations. Tension along and off the axis of the fibers was considered as well as the case of drop weight impact. Those solicitations were shown to induce different damage mechanisms. The latter were characterized by means of Scanning Electronic Microscopy (SEM) and X-Ray tomography mostly. The decreasing of the elastic modulus and the void volume fraction evolution were shown to be more significant for the samples loaded in tension off-axis. During the drop weight impact tests, the energies were considered in order to remain close to the Barely Visible Impact Damage (BVID) regime in order to experience the capability of the ultrasound based NDE methods. Two NDE methods investigated during this study deserve to be highlighted. Firstly, the stiffness tensor was estimated by means of phase velocities measurements in different propagation direction. Damage indicators based on results from this method were proposed. They were found to give results similar with the one from the evaluation of damage discussed earlier on. Secondly, a study of the damage detection using guided waves was performed. No mode conversion effect was observed from this investigation. Consequently, the signal energy was proposed as damage indicator and was found to be suitable to detect damage induced by tension but not by impact. The measure of time shift allowed obtaining a localization and evaluation of the damage induced by impact
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Piñal, Moctezuma Juan Fernando. "Characterization of damage evolution on metallic components using ultrasonic non-destructive methods." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667641.
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When fatigue is considered, it is expected that structures and machinery eventually fail. Still, when this damage is unexpected, besides of the negative economic impact that it produces, life of people could be potentially at risk. Thus, nowadays it is imperative that the infrastructure managers, ought to program regular inspection and maintenance for their assets; in addition, designers and materials manufacturers, can access to appropriate diagnostic tools in order to build superior and more reliable materials. In this regard, and for a number of applications, non-destructive evaluation techniques have proven to be an efficient and helpful alternative to traditional destructive assays of materials. Particularly, for the design area of materials, in recent times researchers have exploited the Acoustic Emission (AE) phenomenon as an additional assessing tool with which characterize the mechanical properties of specimens. Nevertheless, several challenges arise when treat said phenomenon, since its intensity, duration and arrival behavior is essentially stochastic for traditional signal processing means, leading to inaccuracies for the outcome assessment.
In this dissertation, efforts are focused on assisting in the characterization of the mechanical properties of advanced high strength steels during under uniaxial tensile tests. Particularly of interest, is being able to detect the nucleation and growth of a crack throughout said test. Therefore, the resulting AE waves generated by the specimen during the test are assessed with the aim of characterize their evolution.
For this, on the introduction, a brief review about non-destructive methods emphasizing the AE phenomenon is introduced. Next is presented, an exhaustive analysis with regard to the challenge and deficiencies of detecting and segmenting each AE event over a continuous data-stream with the traditional threshold detection method, and additionally, with current state of the art methods. Following, a novel AE event detection method is proposed, with the aim of overcome the aforementioned limitations. Evidence showed that the proposed method (which is based on the short-time features of the waveform of the AE signal), excels the detection capabilities of current state of the art methods, when onset and endtime precision, as well as when quality of detection and computational speed are also considered. Finally, a methodology aimed to analyze the frequency spectrum evolution of the AE phenomenon during the tensile test, is proposed. Results indicate that it is feasible to correlate nucleation and growth of a crack with the frequency content evolution of AE events.<br>Cuando se considera la fatiga de los materiales, se espera que eventualmente las estructuras y las maquinarias fallen. Sin embargo, cuando este daño es inesperado, además del impacto económico que este produce, la vida de las personas podría estar potencialmente en riesgo. Por lo que hoy en día, es imperativo que los administradores de las infraestructuras deban programar evaluaciones y mantenimientos de manera regular para sus activos. De igual manera, los diseñadores y fabricantes de materiales deberían de poseer herramientas de diagnóstico apropiadas con el propósito de obtener mejores y más confiables materiales. En este sentido, y para un amplio número de aplicaciones, las técnicas de evaluación no destructivas han demostrado ser una útil y eficiente alternativa a los ensayos destructivos tradicionales de materiales. De manera particular, en el área de diseño de materiales, recientemente los investigadores han aprovechado el fenómeno de Emisión Acústica (EA) como una herramienta complementaria de evaluación, con la cual poder caracterizar las propiedades mecánicas de los especímenes. No obstante, una multitud de desafíos emergen al tratar dicho fenómeno, ya que el comportamiento de su intensidad, duración y aparición es esencialmente estocástico desde el punto de vista del procesado de señales tradicional, conllevando a resultados imprecisos de las evaluaciones. Esta disertación se enfoca en colaborar en la caracterización de las propiedades mecánicas de Aceros Avanzados de Alta Resistencia (AAAR), para ensayos de tracción de tensión uniaxiales, con énfasis particular en la detección de fatiga, esto es la nucleación y generación de grietas en dichos componentes metálicos. Para ello, las ondas mecánicas de EA que estos especímenes generan durante los ensayos, son estudiadas con el objetivo de caracterizar su evolución. En la introducción de este documento, se presenta una breve revisión acerca de los métodos existentes no destructivos con énfasis particular al fenómeno de EA. A continuación, se muestra un análisis exhaustivo respecto a los desafíos para la detección de eventos de EA y las y deficiencias del método tradicional de detección; de manera adicional se evalúa el desempeño de los métodos actuales de detección de EA pertenecientes al estado del arte. Después, con el objetivo de superar las limitaciones presentadas por el método tradicional, se propone un nuevo método de detección de actividad de EA; la evidencia demuestra que el método propuesto (basado en el análisis en tiempo corto de la forma de onda), supera las capacidades de detección de los métodos pertenecientes al estado del arte, cuando se evalúa la precisión de la detección de la llegada y conclusión de las ondas de EA; además de, cuando también se consideran la calidad de detección de eventos y la velocidad de cálculo. Finalmente, se propone una metodología con el propósito de evaluar la evolución de la energía del espectro frecuencial del fenómeno de EA durante un ensayo de tracción; los resultados demuestran que es posible correlacionar el contenido de dicha evolución frecuencial con respecto a la nucleación y crecimiento de grietas en AAAR's.
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Hood, John Paul. "Development of piezoelectric material aluminium nitride as a thin film transducer for the application of high temperature ultrasonic non destructive testing." Thesis, University of the West of Scotland, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.748624.
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Gómez, García Soledad. "Descriptores Geométricos y de Forma: Aplicación a la caracterización ultrasónica de materiales." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8722.
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Entre otras aplicaciones, el Grupo de Tratamiento de Señal (GTS) de la Universidad Politécnica de Valencia ha trabajado tradicionalmente en el campo de los ensayos no destructivos por ultrasonidos. el GTS ha desarrollado sofisticados algoritmos de procesado de señal para la detección y caracterización en materiales dispersivos.
El procedimiento de inspección ultrasónica de materiales implica la obtención de un registro o señal mediante un equipo emisor-receptor de ultrasonidos. Este registro será posteriormente procesado para obterner información del material. La extracción de características puede realizarse calculando parámetros temporales y/o frecuenciales de los registros en cuestión. Estos parámetros contienen información que está relacionada con propiedades físicas de los materiales y que podrán ser empleados en definitiva para clasificar y caracterizar el material.
El objetivo de la tesis es el de ampliar el conjunto de parémetros que se han venido usando de manera tradicional en el grupo. Los nuevos parámetros proponen un cambio de perspectiva mediante el uso de técnicas basadas en el tratamiento digital de imagen. Se presenta una colección de descriptores geométricos y de forma que serán aplicados a las imágenes obtenidas a partir de los diagramas tiempo-frecuencia. Los citados parámetros se aplicarán junto con los parámetros que componen el modelo tradicional, o versiones modificadas de éstos, a la caracterización ultrasónica de materiales dispersivos blandos.
En la tesis se presenta un modelo matemático afín a los tipos de materiales que han sido evaluados en este trabajo. Se define así un esquema que modela en el dominio de la frecuencia el registro de señal procedente de la inspección ultrasónica del material. Se proponen y estudian además diferentes métodos con el objetivo de llevar a cabo el análisis espectral de la señal ultrasónica y se discuten diferentes alternativas para la obtención y mejora de los diagramas tiempo-frecuencia.<br>Gómez García, S. (2010). Descriptores Geométricos y de Forma: Aplicación a la caracterización ultrasónica de materiales [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8722<br>Palancia
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Sirén, Sebastian. "Case depth measurements on inductionhardened crankshafts by using ultrasonic backscattering method." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325021.
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Induction hardening is a complex process that requires regular verification of the case depth and the microstructure. Today this verification is done by destructive testing where a cross section is analysed. The case depth is measured by several Vickers hardness impressions and the microstructure is analysed by a light optic microscope. This master thesis was performed in collaboration with Volvo GTO in Skövde, with the target to find out if an ultrasonic backscattering method is usable for analysing the case depths on induction hardened crankshafts. This was done by verifying the results provided by ultrasonic testing with the results provided by destructive testing. The measurements were done on several crankshafts with different case depths and steel composition. The result, for crankshafts with normal case depths, shows a good correlation between the destructive testing (DT) and the ultrasonic testing (UT). The mean value for the discrepancy was 0.39 mm with a standard deviation of 0.20 mm. The reproducibility of the method has a standard deviation of 0.074 mm.
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Derouiche, Ziane. "Caractérisation des milieux hétérogènes par traitement du signal ultrasonore haute fréquence rétrodiffusé." Valenciennes, 1994. https://ged.uphf.fr/nuxeo/site/esupversions/0953f68f-a6e3-4aeb-8bf3-8a70b23ca2d6.
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Le développement du cnd s'est accéléré ces dernières années en raison de l'intérêt que portent les industriels à ces nouvelles méthodes de contrôle, pour des raisons techniques et économiques. L’arrivée de nouveaux matériaux de structure de plus en plus complexe et aux performances élevées par rapport aux matériaux classiques exige des contrôles de qualité très stricts durant le processus de fabrication et jusqu'au suivi en utilisation. Notre travail contribue à la caractérisation des matériaux hétérogènes par ultrasons, avec des applications sur des matériaux composites a matrices métallique et organique. Notre démarche consiste à combiner l'apport des ultrasons haute fréquence à celui du traitement du signal pour fournir des informations quantitatives sur des matériaux étudiés. L’utilisation d'ondes ultrasonores de fréquence élevée permet d'obtenir un meilleur pouvoir de résolution ainsi qu'une sensibilité plus importante des ondes aux microstructures. Nous présentons des méthodes de traitement du signal permettant d'extraire la signature des réflexions sur les hétérogénéités; et l'évaluation du paramètre d'espacement moyen entre diffuseurs de la structure hétérogène, à partir des informations contenues dans le signal rétrodiffusé
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Wildofsky, Jacob. "Multi-Scale Computational Modeling of Ni-Base Superalloy Brazed Joints for Gas Turbine Applications." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574809064215922.
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McLaren, S. "High-resolution ultrasonic non-destructive testing." Thesis, City University London, 1987. http://openaccess.city.ac.uk/8335/.
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The use of ultra-short pulse wideband ultrasonic transducers in Non-Destructive-Testing (NDT) has been investigated both theoretically and experimentally. It is demonstrated that the resolution of pulse-echo NDT is affected by diffraction effects which also complicate the interpretation of echo signals. These diffraction effects are interpreted in terms of the plane- and edge-wave model of *transducer fields. Improverents can be obtained by the use of non-uniformly excited transducers of two basic types: the first, the plane-wave-only (PWO) source; is more strongly excited at its centre than towards the rim, where the excitation is gradually reduced to zero in order to remove the edge wave. The second type, an edge-wave-only (EWO) source, is more strongly excited at its rim than in the centre, thereby effectively removing the plane wave. Computer modelling of pressure waveforms in the field of PWO and EWO sources has been carried out using an extension to the impulse response method. Experimental point-pressure waveform measurements in the field of a prototype EWO transducer, made using a miniature ultrasonic probei are in reasonable agreement with the calculated results. Detailed calculations are made of the transmit-receive mode (pulse-echo) responses arising from solid targets of various size in a flu- id medium interrogated by uniformly and non-uniformly excited sources. The theoretically predicted results are in good agreement with experimentally measured results obtained using a conventional transducer and an equivalent prototype EWO transducer. The effects of target size, field position and material on both the amplitude and shape of the echo responses are investigated. The structure of the responses is explained in terms of the plane and edge waves radiated by the source. Implications for the use of techniques to both size (Distance, Gain, Size curves) and characterise (ultrasonic spectroscopy) defects are examined. The applications of new, nonuniformly excited transducers in high-resolution NDT and ultrasonic imaging are evaluated.
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Lebental, Bérengère. "Instrumentation immergée des matériaux cimentaires par des micro-transducteurs ultrasoniques à nanotubes de carbone : perspectives pour le contrôle non destructif in-situ de durabilité." Phd thesis, Université Paris-Est, 2010. http://pastel.archives-ouvertes.fr/pastel-00574780.
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Le contrôle non destructif in-situ de durabilité des matériaux cimentaires est essentiel à la prédiction et la prévention des défauts de fonctionnement des constructions. Alors que les dégradations, et donc la perte de durabilité, des matériaux cimentaires sont déclenchées et contrôlées par les caractéristiques et les évolutions de leur microporosité, il n'existe pas à notre connaissance de méthode non destructive d'instrumentation in-situ de la microporosité elle-même. Nous proposons un concept innovant d'évaluation de la durabilité des matériaux cimentaires fondé sur l'instrumentation in-situ de leur microstructure. La méthode repose sur l'investigation ultrasonore haute fréquence de micropores individuels au moyen de micro-transducteurs ultrasoniques capacitifs (μ-cMUT) immergés en grand nombre dans le matériau. Le dispositif proposé pour répondre aux multiples contraintes applicatives et technologiques est un μ-cMUT dont la plaque vibrante est constituée d'une couche mince de nanotubes de carbone monoparoi densément alignés. Nous avons traité la question de la pertinence de ce principe d'instrumentation en modélisant par un problème élasto-acoustique microfluidique l'interaction entre la plaque vibrante d'un μ-cMUT et le fluide, air ou eau, contenu dans un pore de taille micrométrique. La spécificité du modèle réside dans la prise en compte du comportement dissipatif du fluide. La résolution de ce problème couplé a nécessité le développement d'une méthode numérique ad-hoc. Nous avons constaté numériquement que la dissipation cause une diminution des fréquences de résonance. La couche limite a une épaisseur importante par rapport à la taille du domaine. Les amplitudes de vibration des plaques sont particulièrement sensibles au contenu des pores et à la géométrie des pores remplis d'eau. Nous en avons déduit que les μ-cMUT proposés pourraient être pertinents dans les matériaux cimentaires pour le suivi de l'hydratation, pour la détection des dégradations et le suivi de leur évolution. Pour étudier la faisabilité d'un μ-cMUT à nanotubes opérationnel à haute fréquence dans l'air et l'eau, nous avons tout d'abord réalisé par diélectrophorèse des dépôts denses et minces de nanotubes bien alignés. Un des dépôts est monocouche, ce qui constitue une performance remarquable pour un dépôt par diélectrophorèse. Nous avons ensuite suspendu les nanotubes, obtenant ainsi des membranes rigides et longues. L'épaisseur de ces membranes suspendues est particulièrement faible et leur facteur de forme particulièrement élevé par rapport à l'état de l'art des cMUT. Nous avons enfin montré par vibrométrie laser que les membranes vibrent à basse fréquence avec des amplitudes atteignant 5 nm pic-à-pic. Il s'agit à notre connaissance de la première mise en évidence de vibrations de nanotubes de carbone monoparoi par vibrométrie laser. Ces résultats démontrent une brique de base essentielle de l'étude complète de faisabilité du dispositif imaginé. Ils indiquent aussi la faisabilité à court terme de microdétecteurs d'air pour le suivi de la microporosité gazeuse des matériaux cimentaires. En regroupant ainsi une étude numérique de pertinence et une étude technologique de faisabilité, la thèse constitue une contribution significative à la mise au point d'une nouvelle méthode de suivi de durabilité de matériaux cimentaires fondé sur l'immersion au coeur du matériau d'un grand nombre de microcapteurs intégrant des nanotechnologies
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Billson, Duncan Robert. "Advanced non-contacting ultrasonic techniques for non-destructive testing." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/107577/.
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This thesis describes research towards the development of ultrasonic methods to test samples that are difficult to test using conventional techniques, with particular emphasis being given to non-contacting methods. The samples investigated in detail were adhesively bonded structures and zircalloy (a zirconium-niobium alloy). The adhesively bonded structures were investigated ultrasonically using an ultrasonic resonance technique (referred to as ultrasonic spectroscopy) to analyse suitable ultrasonic waveforms. This thesis starts by explaining a new approach to ultrasonic spectroscopy, and then describes a number of transduction techniques (both contacting and non-contacting) that were devised to obtain waveforms suitable for spectroscopic analysis. These including conventional piezoelectric transducers, laser generation of ultrasound, EMAT reception of ultrasound, and a novel couplant-free transducer. Tests were undertaken on a variety of samples under a number of different conditions, with the experimental results comparing well with those predicted by theory. Zircalloy was investigated next in an effort to evaluate non-destructively the concentration of hydride in the alloy. This was performed using velocity-temperature measurements (at temperatures up to 500°C) for both shear and longitudinal waves, and by dilatometry (thermal expansion) measurements. Both sets of tests successfully determined the hydride concentrations of test samples. A separate chapter is devoted to the description of some of the novel transducers developed during the course of this research, including a couplant-free transducer, and several transducers for airborne ultrasound. These transducers were found to operate well, the couplant-free transducer being particularly successful (subsequently finding a number of industrial applications). The final experimental chapter describes the building of both a photoelastic, and a schlieren rig that were used to visualise ultrasound, with the intention of giving an insight into some of the ultrasonic phenomena that were associated with the rest of the work. The results obtained were invaluable in analysing the results from previous chapters.
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Lam, Hung-yiu. "Pulse compression filter design for ultrasonic non-destructive testing /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18933580.
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Tsang, Wai-ming Peter. "Computer aided ultrasonic flaw detection and characterization /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12344928.
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Schulze, Michael. "Non-destructive testing and evaluation of magnetostrictive materials." Thesis, University of Hull, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306801.
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Mong, Seng Ming. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175032a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2005.<br>At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
24
Lau, Connie K. Y. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174441a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2005.<br>At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 1, 2006) Includes bibliographical references.
25
Blum, Frank. "A focused, two dimensional, air-coupled ultrasonic array for non-contact generation." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180005/unrestricted/blum%5Ffrank%5F200312%5Fms.pdf.
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Campbell, M. A. "An evaluation of monolithic phased arrays for Non destructive testing." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381502.
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Bourne, Simon James. "Novel hydrophilic polymer couplant for application in ultrasonic non destructive testing." Thesis, Cranfield University, 2001. http://hdl.handle.net/1826/4454.
Full textAbstract:
Ultrasonic Non Destructive Testing (NDT) is used to inspect materials and
structures for defects. Water is commonly used in NDT as a couplant to
improve ultrasonic transfer between an interrogating probe and test piece.
Unfortunately, the presence of water can cause corrosion and/or degradation
of the test piece material. The aim of this investigation was to evaluate
hydrated cross-linked hydrophilic polymers as candidate solid contact
ultrasonic couplant for use in the field of ultrasonic NDT.
The fact that hydrophilic polymers can absorb and retain large quantities of
water suggested that they might demonstrate the desirable ultrasonic
properties of water without the risks associated with conventional water
coupling. To test this, the ultrasonic properties of a range of hydrophilic
polymers were assessed. Excellent results were achieved, attenuation as low
as 0.36 and 0.71dB mm-1 at 5 and 1OMHz respectively being measured.
Great potential for efficient coupling was established due to acoustic
impedance in the region of 1.81VIN S M-3.
A polymer dependant coupling pressure of less that 1kg CM-2 was required to
achieve optimum coupling to a smooth steel block. Mechanical longevity,
evaluated by life testing, showed that polymers of up to 70% equilibrium water
content were best suited for dynamic testing applications. Temperature was
shown to effect ultrasonic properties; a drop from 5 to
-120C caused an
increase in attenuation of 3dB mm-1 and velocity of 350m s-1. Pressure
demonstrated no influence on attenuation but affected an increase in velocity
of 44m s-1 per kg CM-2
.
Further investigation into the unique ultrasonic
properties of hydrophilic polymers showed that the water sorption process
caused an increase in attenuation prior to saturation being reached. This was
attributed to the absorption of sound during the polymer transformation from
the glassy to rubbery condition observed during hydration. Dehydration from
100 to 37% saturation in a 60% equilibrium water content polymer caused an
increase in attenuation of 1.8dB mm-1 at 5MHz.
The research concluded with the design and development of a prototype
wheel probe employing hydrophilic polymer as the tyre. Operation at 5MHz in
pulse echo mode demonstrated results competitive to conventional immersion
testing. An MMA-VP cross-linked hydrophilic polymer of approximately 60%
equilibrium water content was found most suitable to this application.
This thesis suggests that there is a clear role for hydrophilic polymers in
ultrasonic NDT. The success of the wheel probe design developed as a result
of this research has resulted in patent application in both the UK and USA.
28
Cooper, J. A. "Laser-generated ultrasound with applications to non-destructive evaluation." Thesis, University of Hull, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375636.
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Prado, Vander Teixeira [UNESP]. "Ultrasonic non-destructive testing of plate-like structures using piezoelectric array transducers." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/111127.
Full textAbstract:
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000799830.pdf: 4517190 bytes, checksum: 4566f2d205fed1f4cb035a7c44ec4214 (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Esta tese apresenta o estudo e implementação de técnicas de inspeção de estruturas delgadas tipo placa utilizando arrays de transdutores piezelétricos e ondas acústicas guiadas, associados a métodos de formação e composição de imagens. A detecção de danos em estruturas através de ondas guiadas e arrays de transdutores é um campo de pesquisa de grande importância, principalmente em áreas como a aeroespacial e de geração de energia, que utilizam estruturas delgadas e que exigem inspeção eficaz e completa, visando confiabilidade e segurança. O emprego de ondas acústicas guiadas permite inspecionar grandes áreas utilizando sensores sem a necessidade de realizar varreduras pela peça, de maneira não-destrutiva. Além disso, apresenta sensibilidade a diversos tipos de defeitos, como furos, corrosão, variação de espessura e defeitos superficiais. São estudados aspectos de propagação de ondas, diferentes modos de propagação e dispersão, assim como as principais características dos arrays e a formação de imagens. Os estudos teóricos são acompanhados por simulações usando os softwares MATLAB e PZFlex para obtenção dos modos de propagação das ondas, interação com defeitos e diagramas de radiação dos transdutores, cujos resultados são validados por meio da análise experimental em placas de materiais isotrópicos (alumínio). Montou-se um array linear de transdutores piezelétricos com 16 elementos na borda de uma placa de alumínio com defeitos artificiais. Os sinais provenientes de todas as possíveis combinações dos pares transmissor-receptor foram adquiridos para a utilização de técnicas de abertura sintética. A primeira contribuição deste trabalho é um método para detecção dos defeitos baseado na fase instantânea dos sinais. Substituindo-se a informação de amplitude dos sinais pela fase instantânea (IP) no método de formação de imagem, ...<br>This thesis presents the study and implementation of non-destructive testing techniques of platelike structures using piezoelectric array transducers and guided acoustic waves, associated with beamforming techniques and image compounding methods. Damage detection in structures using guided waves and arrays is a promising research area, especially in the aerospace and energy fields, where the use of plate-like structures demands thorough inspection due to the high safety levels of operation. Guided acoustic waves techniques can be used to inspect relatively large areas without the necessity of moving the transducers, in a non-destructive way. There are different propagation modes that can be coupled to the plate, and each mode is sensitive to specific types of defects, like notches, delamination and surface defects. Wave propagation, different propagation modes and dispersion characteristics, as well as arrays characteristics and imaging algorithms, are studied. MATLAB and PZFlex simulations are used to get further insight in the theoretical aspects, to obtain dispersion curves, interaction with defects and array response. Experimental results validate the simulations with isotropic materials (aluminum). A 16-elements piezoelectric linear array is mounted at the border of an aluminum plate with artificial defects. The signals related to all combinations of transmit-receive pairs are obtained with burst excitation, for use with synthetic aperture (SA) techniques. The first contribution of this work is a method for defect detection based on the instantaneous phase of the aperture data. The instantaneous phase (IP) image is obtained by replacing the amplitude information by the instantaneous phase in the conventional SA beamforming. From the analysis of the IP image, a threshold level is proposed in terms of the number of signals used for imaging. This threshold is applied to the IP image, resulting ...<br>FAPESP: 10/02240-0<br>FAPESP: 10/16400-0<br>FAPESP: 13/00330-0
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Chan, Tony T. T. "Ultrasonic method of non-destructive test in metals effects of grain size on ultrasound wave at various frequencies /." access abstract and table of contents access full-text, 2006. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21456276a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2006.<br>"Master of Science in Materials Engineering & Nanotechnology dissertation." Title from title screen (viewed on Nov. 21, 2006) Includes bibliographical references.
31
Liu, Wai-yin. "Ultrasonic reflection tomography over circular aperture /." [Hong Kong] : University of Hong Kong, 1992. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13440019.
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Seifried, Robert. "Propagation of guided waves in adhesive bonded components." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19494.
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White, John D. H. "A random signal ultrasonic test system for highly attenuating media." Thesis, Keele University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315234.
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Choamnak, Sitdhichai. "Nondestructive and destructive testing of covered timber bridge members." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177444570.
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Smith, P. "A recording and presentation system for manual ultrasonic inspections using a speech recognition interface." Thesis, University of the West of Scotland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265930.
Full textAbstract:
Reliability and repeatability are fundamental concepts in ultrasonic nondestructive testing. An inspection technique must be able to accurately detect, characterize, position and size any defect indication. In manual ultrasonic inspection, however, the operator can be a frequent source of error. Mistakes often arise due to the volume of information the operator must memorize and process. Existing solutions require mechanical probe manipulators that restrict the operator's movements and often require changes to trusted methods and procedures. The aim of this research programme was to investigate the potential of a computer system that assists the operator in the analysis of echodynamic patterns. The system allows the operator to record A-scan sequences, store them to disk, and recall them for review. The system's flexible user interface gives the operator freedom to retain existing inspection practices, in addition to the benefits of computer recording. A novel feature of the system was a speech recognition system to provide hands-free control, which minimizes disruption to the flow of the inspection. Trials were conducted to assess the recognizer's reliability under various conditions. The trials showed that focusing upon echodynamic pattern analysis is a valid and useful approach. Only a limited trial was conducted, however, so the research program was not able to conclusively show that the system will reduce operator errors or improve inspection reliability. In user testing sessions, operators agreed that such a system would be helpful during a manual inspection and there were few objections to the imposition of new hardware. Users quickly became used to the speech recognizer, and the speed of interaction and 'flow' of inspection were greatly enhanced. The author suggests that a computerized assistant is worthy of further development, and has the potential to be a valuable tool in manual ultrasonic inspection.
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Thornicroft, Keith. "Ultrasonic guided wave testing of pipelines using a broadband excitation." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/14001.
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Guided Wave Testing (GWT) is a relatively new development in non-destructive testing. Conventional Ultrasonic Testing (UT) methods are operated at high frequencies (MHz) and are capable of detecting very small (down to micrometre-scale) flaws within a range of millimetres from a transducer. GWT, however, is carried out at lower frequencies (kHz) and is capable of highlighting the position of volumetric structural detail and discontinuities, such as gross corrosion at a minimum of 9% of the cross-sectional area, tens of metres from a test location. Conventional ultrasonic testing relies on the transmission of bulk waves whereas GWT employs so-called ultrasonic guided waves (UGW). To simplify UGW inspections, several tests are conducted sequentially at a range of different excitation frequencies. The frequency bandwidth of each of these tests needs to be controlled to avoid complexities caused by the frequency dependent nature of the propagation of guided waves. This gives rise to the current GWT inspection procedure, where a number of different narrowband tests are conducted at several distinct frequencies. It is also found that different test circumstances (such as pipe coating or defect type) are inspected more easily with certain excitation frequencies than with others - and the optimum frequency can not always be predicted ahead of time. Thus, where time allows it is often beneficial to carry out a frequency sweep, whereby a large range of excitation frequencies are incrementally generated - for example, from 20 to 80kHz in 1kHz steps. This research proposes a novel approach to the existing pipeline inspection procedure by utilising the information contained within a broadband response. The overarching proposition given by this research is that the current collection procedure be entirely rewritten. This thesis will present ideas related to every area of the inspection procedure beginning with the tuning of excitation signals and concluding with recommendations on how tooling and excitation configuration can be modified to further optimise the technique for broadband excitation.
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Weise, Victoria Louise. "Ultrasonic techniques for adhesive bond examination of production automotive structures." Thesis, Keele University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263198.
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Ennami, Mohamed Mahmud. "Applications of gamma ray tomography to non-destructive testing of industrial materials." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47425.
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Weston, Miles. "Advanced ultrasonic digital imaging and signal processing for applications in the field of non-destructive testing." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/advanced-ultrasonic-digital-imaging-and-signal-processing-for-applications-in-the-field-of-nondestructive-testing(12406082-d270-43a0-8520-aed175695115).html.
Full textAbstract:
Non-destructive testing (NDT) is the process of non-invasive material examination. Within this field, ultrasonic inspection is one method of examination used to detect flaws in structural and functional industrial components, to assess their structural integrity and fitness for service. Conventional NDT ultrasonic array techniques transmit on multiple elements in parallel, according to a focal law, which facilitates beam steering, focussing and scanning within the test component. Received signals are then 'stacked' to generate images of the test component. With the advent of affordable high speed computing, novel data acquisition techniques based on sequential transmission are now able to be developed, which allow images to be generated using advanced signal processing and image reconstruction algorithms. One such data acquisition technique known as Full Matrix Capture (FMC), has received considerable research attention in recent years, largely because it allows fully focused images of test components to be generated. This project provides an improved understanding of the FMC technique and associated signal processing algorithms. It achieves this through the development of novel inspection techniques and signal processing algorithms. Collectively algorithms developed within this work were termed Sequential Phased Array (SPA). Initially comparisons were made between conventional ultrasonic techniques and the SPA algorithms in terms of image quality and speed of inspection. A novel approach was then suggested to facilitate inspection through dual-layered media, separated by a refractive interface using the SPA algorithms. The use of sparse arrays to enhance the speed of inspection using the SPA algorithms was also investigated, and the trade-off between speed of inspection against image degradation was addressed. Finally a novel approach to calibration of a FMC based system was developed, in order to provide uniform image sensitivity during inspection.
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Peycheva, Kira. "Nondestructive testing of metals and composite materials using ultrasound thermography : Comparison with pulse-echo ultrasonics." Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29592/29592.pdf.
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Hall, Ian Damon. "Generation of high resolution tomographic images for NDT applications." Thesis, University of Strathclyde, 2001. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24263.
Full textAbstract:
Techniques for the generation of quantitative ultrasonic images in non-destructive testing have generally involved a substantial cost in terms of data storage and computational time, and have thus found limited application. Preference has therefore been given to the more straightforward imaging methods, such as main beam projection, which detect the presence of defects and provide a limited flaw sizing capability. The relatively small number of flaws requiring detailed examination, coupled with substantial increases in available data storage and computational power, have made it possible to use a number of straightforward tomographic reconstruction methods to produce high resolution images of flaws contained within the material under examination. A set of these images are then fused together using a novel fuzzy logic image fusion technique into a single image from which more accurate measurements of flaw size, shape and orientation can be made. However, if the quality of the raw A-scan data is not sufficiently high then the data will be filtered using Maximum Likelihood Deconvolution (MLD). The aim of this blind deconvolution method is to improve the time resolution and Signal to Noise Ratio of the A-scan data with only knowledge obtained from the data, this is in contrast to the majority of techniques currently used for this purpose. The three tomographic methods which have been implemented in this work are Reflection tomography, Time-of-flight Diffraction tomography and Transmission tomography. In addition a Single Bounce Image Enhancement method has been developed to improve the images. Selection of images used in the fusion process depends on the nature of the flaw, as each of these methods identifies different characteristics of the flaw shape. The components of the imaging system have been validated experimentally by the generation of high resolution images from a variety of flaws contained within cylindrical aluminium test specimens.
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Kaynak, Mehmet. "Non-destructive Testing Of Columns Under Axial Compression Using Tranverse Vibration Technique, And Ultrasonic Approaches." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1260465/index.pdf.
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The level of axial compressive load on an existing column is one of the most
important parameters to be known. This thesis aims to investigate current
state of the art of NDT techniques, their application, and investigate
alternative ways of using current technology to estimate the axial
compressive load on columns. For this purpose, transverse vibration
technique, ultrasonic pulse velocity method, and waveform and frequency
content evaluation of ultrasound are investigated and implemented.
Analytical and experimental studies on column transverse vibration frequency
and axial load relationship are conducted and presented. The measured
experimental lateral vibration frequency of the first bending mode decreased
under increased axial compressive load as expected from analytical studies.
Relationships between axial load and vibration frequency are derived and
defined for different boundary conditions. Relationship charts are prepared
for complicated solution sets. Numerical calculations, laboratory and field
tests revealed that natural frequencies of slender columns are more sensitive
to axial load changes.
The available ultrasonic methods are investigated and described. Stress
wave propagation in anisotropic solids is studied. Previous works have
shown that the propogation velocity of stress waves depends on the density,
Poisson&rsquo<br>s ratio, modulus of elasticity of the medium, and the state of stress.
The orientation of the loading direction to the wave propogation direction, the
couplant (ultrasonic transmission gel) uniformity, variability in the pressure
applied to hold the transducers, alignment of the transmitting and recieving
transducers, accuracy and modelling of Poisson&rsquo<br>s ratio make the ultrasonic
testing more complicated.
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Chapman, Michael James. "Experimental determination of in-situ serviceability of Sitka spruce timber by ultrasonic non-destructive testing." Thesis, University of Ulster, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370087.
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McCarthy, Rachel Frances Matrona. "The application of ultrasonic wave propagation models to the non-destructive testing of surface coatings." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620429.
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Rodat, Damien. "Simulation opérationnelle en contrôle non destructif." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS535.
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La simulation opérationnelle a déjà été développée pour diverses activités dont l'exercice en conditions réelles peut s'avérer coûteux voire dangereux : le pilotage d'avion, les interventions chirurgicales, etc. L'idée consiste à remplacer la réalité par une simulation suffisamment réaliste pour donner l'impression aux utilisateurs qu'ils réalisent réellement l'activité.Le Contrôle Non-Destructif (CND) regroupe l'ensemble des méthodes mises en œuvre pour tester l'intégrité des pièces mécaniques sans les altérer. Dans ce domaine, la simulation opérationnelle n'a été introduite que très récemment par un brevet déposé par Airbus. Cette approche permet de simuler numériquement la présence de défauts sans avoir à les ajouter réellement dans les pièces. Les pièces aéronautiques étant coûteuses, la simulation opérationnelle permet de réduire les coûts liés à la formation des opérateurs, à l'évaluation des performances des méthodes ou aux tests en conditions réelles de nouvelles procédures.La présente thèse vise à développer les outils scientifiques et technologiques nécessaires à donner vie au concept de simulation opérationnelle en CND. Pour remplacer la réalité par la simulation, les défis à relever sont de trois ordres : le réalisme de la simulation, la rapidité des calculs et l'instrumentation. Nous avons choisi d'illustrer ces trois aspects dans le cadre de l'inspection par ultrasons de pièces en matériaux composites. Les modèles de simulation couramment employés --- basés sur la résolution des équations de la physique --- n'offrent pas des temps de calculs suffisamment courts pour satisfaire les pré-requis de la simulation opérationnelle. Par ailleurs, le réalisme des simulations souffre parfois de la difficulté à paramétrer correctement les modèles. Nous explorons donc une autre approche : les modèles sont construits à partir de données expérimentales. Cette stratégie est exploitée pour traiter différents types de phénomènes tels que l'endommagement par impact, le trou à fond plat ou encore les perturbations de la micro-structure des matériaux. Par ailleurs, une solution matérielle et logicielle sont proposées et un premier prototype de simulateur opérationnel est mis au point. Ce système permet d'exploiter les modèles développés et de montrer que les signaux synthétiques peuvent sembler aussi réalistes que la réalité. Cette thèse court ainsi du concept jusqu'au prototype<br>Several fields have already adopted the concept of operational simulation to limit risks and costs. For instance, part of the training phase of airline transport pilots or surgerons can now rely on simulations instead of real-life situations.Non-Destructive Testing (NDT) assesses the integrity of structural and mechanical components without damaging them. Operational simulation has drawn attention of the NDT community only recently through an Airbus patent. In this field, the operational simulation can be used to simulate the presence of a defect in a component without actually inserting the defect. For expensive parts such as aeronautical structures, this approach can reduce the costs of training operators, evaluating NDT method performances or testing new procedures in real-conditions.This thesis work aims to apply the concept of operational simulation to NDT. Three main scientific and technological challenges are to be tackled: the simulation realism, the computation speed and the instrumentation. We chose to focus this study on the ultrasound NDT technique applied to composite materials. Classical simulation approaches based on physical equations are not fast enough for a real-time synthesis of ultrasound signals. Moreover, the realism is often limited by the fidelity of the inspection set-up description. For instance, the material properties are not always well-known and bring to a drop of realism. Thus, we investigate an alternative way: the models are built directly from experimental data. This strategy is applied to model the effect of several phenomena such as impact damages, flat bottom holes or material micro-structure. Hardware and software solutions are also studied to propose a first prototype. We have shown that the replacement of real signals by on-the-fly simulated ones is achievable: the simulation is realistic enough to be considered as reality by operators. thus, this thesis work brings the concept to a first prototype dedicated to ultrasound NDT
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Karimian, Seyed Fouad. "Evaluation of Adhesive Joints with Ultrasonic Digital Image Correlation." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2054.
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Increasing use of composite materials in industry brings the need for newer and more practical methods to evaluate them. Widespread use of composite materials heavily depends on the manufacturer’s ability to unquestionably ensure its safety, given how much the user trusts them. Non-Destructive Evaluation (NDE) can be used to evaluate adhesive bondline health. This thesis employs Digital Image Correlation (DIC) method, one of the known methods in NDE, and combines it with an embedded speckle pattern in order to obtain valuable information from within the adhesive bondline. By recording the movement of the speckles and analyzing their behavior according to DIC algorithms, a strain map of the adhesive is drawn. An adhesive strain map helps find defects that might be out of sight using conventional NDE methods. This thesis discusses different possible materials to be used as the speckle pattern and chooses the one shows better results based on different criteria. Then employing the material, it records the speckle pattern using optical and ultrasonic methods to draw a strain map. By analyzing the obtained strain maps, defects within the bondline are revealed.
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Facchini, Mauro. "Optical techniques applied to the study of building materials and to the inspection of civil structures." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/27863.
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Where the evaluation of the mechanical properties and behaviour of building materials is concerned, there is still not a universally accepted solution for making such measurements. Optical diagnostic techniques are particularly attractive for a non-destructive evaluation of a surface's state and the detection of incipient damage. Non-contact, high precision measurements and full-field of observation are features that can bring enormous advantages in experimental tests.
48
Shih, Jeanne-Louise. "Flexible ultrasonic tranducers using ferroelectric sol-gel composite films for non-destructive testing and structual health monitoring." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114146.
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High temperature (HT) flexible ultrasonic transducers (FUTs) for nondestructive testing (NDT) and structural health monitoring (SHM) were developed using the sol gel spray method. Although the integrated ultrasonic transducer (IUT) is highly desirable as a NDT and SHM solution since it is a technique of directly coupling a fabricated UT to an inspected structure such an on-site fabrication solution may not be particularly attractive. FUTs acting as small and lightweight UTs may be fabricated off-site and then on-site installed. Lead-zirconate titanate composite (PZT-c) and bismuth titanate composite (BIT-c) films were sprayed onto 75 µm or 38 µm thick metallic membranes. At room temperature, these FUTs demonstrate consistently high piezoelectric performance comparable to commercially available UTs when used to perform thickness measurements over flat surfaces. Such FUTs offer the advantage that they may be conformed to curved surfaces. Additionally, these may be fabricated off-site and installed on-site. Therefore, bonding techniques such as glueing and brazing onto pipes were studied with the brazing demonstrating operability at 490ºC, thereby offering a HT, conformable, semi-permanent and on-site installed NDT and SHM solution. Techniques of room temperature selective area Corona poling and expanded area Corona poling were demonstrated, allowing for the patterning of the films and a method for integrating the Corona poling technique to either maintain or repair a network of on-site installed FUTs. The development of these techniques had started with the use of UV to replace the heating of the sol-gel composite film necessary during Corona poling. It was however found that under the same conditions, neither heat nor UV was required for the poling o f the film. Nonethless, this prompted optical studies with respect to some semiconductor and ferroelectric properties of these sol-gel films. Non-bonded FUTs are also presented as dry contact and momentary FUTs. The spray technique used with a shadow mask and other techniques was used to fabricate different devices such as ultrasonic phased-arrays and unimorph, piezoelectric vibrational energy harvesters, meant to be integrated with a battery network of NDT, SHM FUTs as an intermittent, self-sustained power source. These demonstrated an amplification in charge generation with a pre-stressed configuration, allowable by the flexible film and substrate. With such high piezoelectric performance inherent in the sol-gel film, a study into some ferroelectric properties of the film was performed, in particular by the optical approach using UV. The results demonstrated PZT-c films were absorbant between 200 and ~400 nm both before and after crystallization from HT treatment with an approximated bandgap of 2.8-3.1 eV. A photoconductivity of 0.0205 Ω-1cm-1 was measured for a 5 μm thick PZT-c film. An effect in which a lowering of the Curie temperature (Tc) was observed demonstrates that study in relation to the field of photoferroelectrics with such composite films may be of scientific interest. Lastly, the poling of the film in nanoscale using Piezo Force Microscopy (PFM) was demonstrated.<br>Dans cette thèse, des capteurs flexibles ultrasonores (CFU) à haute température (HT) ont été développés pour des applications dans le domaine de l'évaluation non destructive (END) et celui de la surveillance de la santé structurelle (SSS). Alors que les capteurs intégrés (CIU) qui peuvent être fabriqués sur site et qui ne nécessitent pas de couplant sont des solutions attrayantes dans ces domaines, la fabrication sur site peut souvent être difficile ou infaisable selon les conditions. Par contre, les CFUs qui sont petits et légers peuvent être fabriqués à part et installés sur site. Les couches composées piézo-électriques, avec lesquelles les capteurs ultrasoniques à haute température (CUHT) sont fabriqués, sont développés à partir de la technique sol-gel. Ces couches constituées de zirconate titanate de plomb (PZT-c), ou de titanate de bismuth (BIT-c) sont déposées sur des substrats métalliques d'épaisseurs de 75 m ou de 38 m. À la température de la pièce, ces CFUs démontrent une performance piézo-électrique comparable aux capteurs commerciaux lors des mesures d'épaisseur sur des surfaces plates. L'avantage de ces CFUs est que ceux-ci peuvent se conformer à des surfaces courbes. De plus, les CFUs peuvent être fabriqués à part et installés sur-site. De plus, des moyens pour attacher ces capteurs aux structures courbes comme les tuyaux ont été essayés. Des techniques de collage et de brasage ont été démontrées, avec les CFUs opérationnels à ces hautes températures jusqu'à 490ºC, offrant une solution conformable, HT, moyennement permanente, en plus de l'avantage de l'installation sur site. Les techniques de polarisation Corona à température de la pièce qui permettent une polarisation sélective ou à grande surface ont été développées, permettant de polariser des motifs. Le développement de ces techniques avait débuté avec l'utilisation d'ondes UV pour remplacer le chauffage qui était nécessaire durant la polarisation Corona, permettant une polarisation des couches piézo-électriques sol-gel à température de la pièce. Il a cependant été découvert que sous ces conditions, ni le chauffage, ni l'UV n'étaient nécessaires, ce qui a néanmoins motivé des études optiques vis-à-vis ces couches sol-gel par rapport à leurs propriétés semi-conductrices et ferroélectriques. La méthode de sol-gel utilisée avec un masque ainsi que d'autres techniques ont aussi été utilisées pour fabriquer des capteurs de configurations différentes comme le capteur à éléments en phase ou le capteur à contact momentané. Le sol-gel a aussi été utilisé pour fabriquer un capteur d'énergie vibratoire unimorphe dans le but d'être intégré avec un système de batteries et avec le réseau de CFU pour END et SSS come source d'énergie de façon discontinue mais autonome. Ces capteurs démontrent une augmentation de charge générée lorsqu'ils sont mis sous une tension pré-courbée, une configuration possible avec la couche et le substrat flexible. Les résultats optiques ont démontré une absorbance envers les ondes UV (~200-400 nm) dans l'état sol-gel des couches ainsi qu'après cristallisation à HT, avec une structure de bande de 2.8-3.1 eV. Une photoconductivité de 0.0205 Ω-1cm-1 a été mesurée pour une couche de PZT-c d'épaisseur de 5 μm. Un effet où une baisse en température du point Curie (Tc) a été observée sous ondes UV pour les couches de PZT-c démontre que des études dans le domaine de la photoferroélectricité avec ces couches seraient d'intérêt scientifique. La polarisation d'une couche de PZT-c sur une surface 500 nm x 500 nm utilisant la microscopie à force piezo (MFP) a aussi été démontrée.
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Borazjani, Ehsan. "Inverse Heat Conduction Approach for Infrared Non-destructive Testing of Single and Multi-layer Materials." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22919.
Full textAbstract:
The focus of this thesis is to derive analytical tools for the design of infrared nondestructive tests in single and multi layer material bodies. This requires the predetermination of the parameters of the experiment such that the infrared image has the required resolution for defect detection. Inverse heat conduction in single and multi-layer materials is investigated to determine the required frequency of excitation in order to obtain a desired temperature at the observation point. We use analytical quadrupole representation to derive a polynomial relation to estimate the frequency of the periodic excitation as a function of the temperature amplitude at a given observation point within the body. The formula includes characteristic geometric and material parameters of the system. The polynomial formula can be an e ective design tool for quick frequency predetermination in the design of non-destructive testing experiments with infrared thermography. The convergence and accuracy of the formula is assessed by comparison with the analytical thermal quadrupole solution and experimental results. We also investigate the e ect of the nite length of the material domain in order to establish the range of applicability of a simpli ed formula based on semi-in nite domain assumption. The e ect of nite length is investigated analytically by using (i) Fourier series which accounts for transients and (ii) Time varying solution associated to the steady state solution when a purely periodic excitation is applied. These results are also compared with numerical solution obtained with commercial nite element software ANSYSTM.
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Luggar, Russell David. "Rayleigh scattered photons for substance identification." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844418/.
Full textAbstract:
Rayleigh scattering, that is the elastic and coherent scattering of photons from bound atomic electrons, has been investigated for use as an active probe for substance identification. An angular dispersive scattering system has been developed for materials identification utilising the 22 keV Kalpha X-ray line from a low power (25 Watt) silver anode X-ray tube. Differential scattering cross-sections have been measured for a wide range of low- to high-Z materials and compared with free atom theoretical predictions. Experimental results compare favourably with theory and evidence has been found to suggest that inter-atomic and inter-molecular interference effects have little or no effect upon the total scattering cross-section. The potential of Rayleigh scattering for detection of inclusions of low-Z media within extended objects of similar atomic constitution has been investigated with particular emphasis on the detection of potential contaminants in food products. The contrasts obtained with scatter techniques are substantially in excess of those achievable with conventional transmission measurements. By exploiting the ratio of the scattering in two regions of momentum space as the scatter parameter the contrast between inclusion and matrix may be increased to over five times that of transmission methods. This technique may be used in many situations where alternative photon interrogation methods such as X-ray transmission or X-ray fluorescence are unsuitable and a wide range of potential applications including quality control, sorting of plastics, security screening and oil/water discrimination have been considered.