No description available.

[pt] A termografia infravermelha tem sido usada como uma técnica de avaliação não destrutiva para detectar falhas nos componentes estruturais, desempenhando um papel importante nos programas de inspeção de fabricação, inspeção em serviço e manutenção. Um programa de investigação foi lançado com o objetivo de apresentar combinações de métodos analíticos, experimentais e numéricos para prever e monitorar o início da fadiga e a progressão dos danos à fadiga em equipamentos como vasos de pressão, tanques, tubulações e dutos com mossas ou anomalias complexas. O monitoramento do início e propagação da fadiga nas amostras reais utilizou técnicas de inspeção por infravermelho não destrutivo. Análise termoelástica de tensão (TSA), correlação tridimensional de imagem digital (3D-DIC) e strain gages de fibra óptica Bragg (FBSG) foram utilizados para determinar deformações em locais de fadiga em pontos críticos. Os campos de deformação determinados a partir das medições experimentais e do método de elementos finitos (MEF) foram combinados com a equação de vida-de-fadiga de Coffin-Manson e a regra de dano por fadiga de Miner para prever a vida de fadiga (N). Os resultados das amostras tubulares testadas de 3 m de comprimento contendo mossas de formato complexo foram relatados e analisados completamente. Este trabalho confirmou que os métodos infravermelhos de avaliação rápida de fadiga são ferramentas práticas e eficientes que podem fornecer resultados confiáveis, não destrutivos e rápidos acerca do comportamento à fadiga dos materiais. Uma boa concordância entre as estimativas de vida em fadiga e a vida real de mossas com geometria complexas em dutos só pode ser atingida se medições precisas ou determinações numéricas das deformações circunferenciais que atuam nos pontos de interesse forem acopladas a curvas de fadiga deformação-vida adequadas. Acoplando uma técnica experimental para determinar com precisão a geometria das mossas com uma técnica de análise numérica de deformações fará com que sejam obtidas boas estimativas de deformação das posições críticas que serão combinadas com as curvas de fadiga baseadas na relação deformação-vida. As presentes conclusões podem ser aplicadas a outras estruturas que podem apresentar mossas, como tanques e vasos de pressão. / [en] Infrared thermography has been used as a nondestructive evaluation (NDE) technique to detect flaws in structural components, playing an important role in manufacturing inspection, in-service inspection and maintenance programs. An investigation program was launched with the objective of presenting combinations of analytical, experimental and numerical methods to predict and monitor fatigue initiation and fatigue damage progression in equipment such as pressure vessels, tanks, piping and pipelines with dents or complex-shaped anomalies. The monitoring of fatigue initiation and propagation in the actual specimens used nondestructive inspection techniques such as thermoelastic stress analysis (TSA), three-dimensional digital image correlation (3D-DIC) and fiber optic Bragg strain gages (FBSG) to determine strains at fatigue hot spots locations. Strain fields determined from the experimental measurements and from the finite element method (FEM) were combined with the fatigue Coffin-Manson strain-life equation and the Miner s fatigue damage rule to predict fatigue life (N). Results from tested 3m long tubular (with nominal dimensions: 324mm external diameter and 6.35mm wall thickness) specimens containing complex-shaped dents were reported and fully analyzed. This work confirmed that infrared rapid fatigue assessment methods are practical and efficient tools that can provide a reliable, non-destructive and faster results about the fatigue behavior of materials. Good agreement among fatigue life estimations and actual fatigue lives of complex dent shapes in pipeline specimens can only be achieved if accurate measurements or numerical eterminations of the circumferential strains actuating at the dent hot-spots were coupled with suitable fatigue strain-life curves. Coupling an experimental technique for accurately determining dent shapes to a numerical strain analysis technique will lead to good hot-spot strain estimations to be combined with the strain-life fatigue curves. The present conclusions can be applied to other structures that may present dents such as tanks and pressure vessels.

The use of infrared thermography for boundary layer detection was evaluated for use in the Cal Poly Low Speed Wind Tunnel (LSWT) and recommendations for the successful use of this technique were developed. In cooperation with Joby Aviation, an infinite wing model was designed, manufactured and tested for use in the LSWT. The wing was designed around a custom airfoil profile specific for this project, where the nearly-flat pressure gradient at a zero pitch angle would delay the chordwise onset of boundary layer transition. Steady-state, RANS numerical simulations predicted the onset of transition to occur at 0.75 x/c for the design Reynolds Number condition of 6.25x105. The wing was manufactured from 3D printed aluminum, with a wall thickness of 0.125 inches and a chord length of 13.78 inches. Two central rows of static pressure taps were used, each with 12 functional chordwise locations. The taps were able to generate strong correlation to the numerically predicted pressure coefficient distribution. The use of an infrared camera visualized and confirmed the presence of boundary layer transition at the chordline location anticipated by the early simulations. To do so, the model was pre-heated such that the differential cooling properties of laminar and turbulent flow would generate a clear temperature gradient on the surface correlating to boundary layer transition. Adjustment of the model’s pitch angle demonstrated a change in the onset location of boundary layer transition during the infrared testing. The change of onset location was seen to move forward along the chordline as the aerodynamic angle of attack was increased. Testing with a Preston Tube system allowed for the interpolation of local skin friction coefficient values at each static tap location. Application of both laminar and turbulent empirical assumptions, when compared to numerical expectations, allowed for the qualitative assessment of boundary layer transition onset. Overall, the wing model developed for this research proved capable of producing quality and repetitive results for the experimental goals it was designed to meet. The model will next be used in continued tests which will further explore the use of infrared thermography.

The railroad industry is pivotal in the United States to ensure that the supply chain does not shut down for the American people. Non-Destruction Evaluation (NDE) approaches are preferred and performed on the railways to ensure the safety of the population that is exposed to the railway industry. When damage occurs on the rail base, there is an increased risk derailment of the train cars. Due to the nature of the railroad industry, there are challenges with developing a quick and reliable inspection method, along with the improvement of current NDE methods. The load, speed, and cycles of trains have increased the load that track sections endure over time. Some railways that were originally built in the early 20th century are still utilized today, designed for trains that are not nearly as heavy or fast as used today. Defects and damage on the railways lead to the need of development of an NDE approach utilizing Line Scan Thermography approaches. One of the most common defects that are formed are on the rail base is known as “base nicks” and “half-moon cracks”, these types of defects can occur over time. This research aims to study the feasibility of applying this NDE technique to detect defects that can occur on a rail base, both internal and external. For this research, a heat source up to 6000 W and tested velocities up to 447.1 mm/s (1.0 mph) are used to study the effects of line scanning thermography on various samples. In total, 10 samples are employed to test for feasibility: each one having a unique set of defects. Some defects fabricated on these samples are internal, such as bottom drilled holes (BDH) and side drilled holes (SDH); some of these samples are fabricated from actual rail samples. From tests conducted for internal defects, it can be concluded that defects with diameters of 6.35 mm (0.25”) can be detected at a remaining thickness from the observation surface of 6.35 mm. Along with internal defects, there are also external defects employed on the samples; these defects include simulated base nicks, fractures, and half-moon cracks. For surface defects tests from this research, it is found that the anomalies can be detected visually. The results from the experimental studies provide insight and limitations of LST for the possibility of a future commercial application.

No description available.

Les enjeux économiques et sécuritaires majeurs portant sur l'évaluation de la pérennité des systèmes de précontrainte dans les ouvrages d'art conduisent au développement de nouvelles méthodes d'auscultation. Ces travaux représentent la contribution du LGCgE au programme national de recherche ANR ACTENA sur l'auscultation des câbles tendus non-accessibles. Les objectifs de ce travail sont la détermination du tracé des câbles de précontrainte et la détection des zones de défauts d'injection par thermographie infrarouge active. Le premier chapitre rappelle le contexte de cette étude, ainsi que les travaux antérieurs. L'introduction d'un mode de chauffage par induction conduit à une indétermination sur la présence éventuelle de défaut. Afin de lever cet artefact, le deuxième chapitre introduit une méthode originale de traitement fréquentiel des thermogrammes bruts basée sur une approche systémique dans le domaine fréquentiel. Une modélisation par éléments finis des spécimens expérimentaux permet d'étudier la diffusion et d'élaborer les paramètres expérimentaux. Le troisième chapitre expose les résultats expérimentaux obtenus sur trois spécimens de poutres. La procédure de traitement fréquentiel est appliquée aux séries de thermogrammes bruts obtenus. Les résultats sont discutés et mettent en avant l'intérêt des images de phase. Une approche quantitative est appliquée aux résultats de thermographie infrarouge dans le quatrième chapitre. La méthode d'inversion présentée permet la détermination de la diffusivité thermique du béton d'enrobage ainsi que son épaisseur. / The economical and security aspects of the durability of the prestressed concrete construction works lead to develop new non destructive testing methods. This work was developed within the framework of the ANR ACTENA French research project. The main arms are to contribute to the localization of prestressed tendon ducts or rebars and also to the detection of the poor filling defects. The context of this study and previous works are described in the chapter I. The introduction of an inductor heating provides a non uniformity of the heating. In order to avoid any misinterpretation of thermograms, a frequential method based on transfer functions is proposed in chapter II. A 3D numerical model of the experimental specimens is performed by finite element method. Chapter III shows experimental results for three concrete beam specimens. The frequential procedure is applied to the raw thermograms. The results are discussed and highlighted the interest of phase images. A quantitative approach is applied to infrared thermographical results in the chapter IV. Finally, an inverse method is proposed and allowed to the determination of thermal diffusivity and the thickness of the cover concrete.

Au cours des dernières années, l’essor spectaculaire des microsystèmes (ou MEMS), qui touche tous les domaines industriels, est à l’origine de nombreux et nouveaux progrès technologiques. Néanmoins, dans ce contexte prometteur de large envergure, la fiabilité des MEMS s’avère être la problématique à améliorer pour franchir la phase d’industrialisation à grande échelle. C’est dans le cadre de cette thématique de fiabilité des microsystèmes, que s’inscrit ce travail.La température étant un paramètre majeur entrant dans de nombreux mécanismes d’endommagement des MEMS, notre étude présente la conception et la réalisation d’un banc de thermographie infrarouge de haute résolution (2 µm), associé à la mise en œuvre d’une méthodologie d’analyse et de traitement des mesures infrarouges.Ce dispositif innovant permet un diagnostic in-situ, sans contact et rapide des défaillances des MEMS par mesures locales et quantitatives des pertes thermiques associées. Cet outil constitue une avancée importante pour détecter, mesurer et comprendre les mécanismes d’endommagement des MEMS. Il nous permet de reconstituer des images thermiques de tout type de microsystème en cours de fonctionnement ou soumis à des tests de vieillissement accéléré, et ceci afin de réaliser une analyse fine et rapide de leur fiabilité.Ce travail apporte de nouveaux résultats en ce qui concerne la détection des mécanismes de défaillance de différents types de MEMS-RF et tout particulièrement des MEMS-RF avec contact électrique. / Over the last few years, considerable effort has gone into the study of the failure mechanisms and reliability of MicroElectroMechanical Systems (MEMS). MEMS performance and reliability are affected by many parameters, such as the complex physical interactions between thermo-mechanical deformation, current flow, high power actuation and contact heating. In particular, temperature is a key issue for the design of a low loss and reliable MEMS. In order to improve device reliability it is essential to understand the thermal behaviours of RF-MEMS under standard or harsh current conditions. In this work, we present a new approach to investigate the failure mechanism of MEMS. An original set-up has been developed to localise and measure the heat loss of MEMS during actuation. Thermal characterization has been performed using infrared thermography to investigate the thermal sensitivity of MEMS. A brand new infrared bench was developed for temperature distribution measurement. An infrared camera, operating in the 1,5 - 5 µm bandwidth, was coupled to a new specific optic to reach an enhanced spatial resolution better than 2 µm/pixel. This work presents several results obtained on different advanced RF-MEMS including RF-MEMS switches where failure mechanism had been diagnosed.

La mesure de champs de température sans contact est un paramètre clé pour l'optimisation et le contrôle des procédés. Les systèmes actuels présentent des limitations, particulièrement sur des surfaces hétérogènes et/ou dans des conditions dynamiques pouvant entraîner une altération de la surface. Ces restrictions sont causées par la méconnaissance de l'émissivité de la surface qui est une fonction complexe de nombreuses grandeurs physiques (température, longueur d'onde, rugosité, direction de détection). La thèse présentée propose le développement complet d'une nouvelle méthode de mesure de champs de température vraie, dénommée THERMOREFLECTOMETRIE, applicable sur tout type de matériaux opaques, dans la gamme [300-1000]°C. Elle permet la mesure en ligne de l'émissivité par le couplage d'une étape classique de THERMOGRAPHIE avec une étape de REFLECTOMETRIE laser. La démarche adoptée consiste premièrement en l'analyse critique de la méthode et de ses facteurs d'influence, ainsi que du dimensionnement optimal des éléments par des études en simulations. Ensuite un prototype opérationnel est mis en oeuvre et ses défauts sont caractérisés, du point de vue d'un système de type CAMERA, et les corrections nécessaires sont mises en place. Enfin, les performances expérimentales sont évaluées sur des scènes thermiques complexes et hétérogènes qui mettent en évidence la bonne précision du prototype pour tous les échantillons testés / True temperature field measurement is a key parameter for the optimization and the control of industrial processes. Current systems present limitations, especially on heterogeneous surfaces and/or in dynamical conditions involving the surface's variation. These restrictions are due to the ignorance of the surface's emissivity, which is a complex function of many physical quantities (temperature, wavelength, roughness, direction of detection). This thesis presents the complete development of a new method of true temperature field measurement, called Thermoreflectometry, applicable on any kind of opaque material, in the range [300-1000]°C. It allows the on-line measurement of emissivity by mixing a step of classical THERMOGRAPHY with a step of laser REFLECTOMETRY. The approach of this work is, first, the critical analysis of the method and its influence quantities, and then the optimal dimensionment of the components by simulation studies. Thirdly, a prototype is built and its defaults are characterized, following a CAMERA-based point of view, and the possible corrections are implemented. Finally, the experimental performances are estimated on some complex heterogeneous thermal scenes which emphasize the prototype's precision for all the tested samples

Les ultrasons (US) thérapeutiques sont devenus un sujet d'intérêt croissant en ophtalmologie. Les ultrasons focalisés de haute intensité (HIFU) pour le traitement du glaucome et pour la délivrance de médicaments dans l'oeil sont les deux principaux domaines de recherche dans ce domaine. Cette thèse traite des deux sujets en deux parties distinctes : l'administration de médicaments ou drug delivery par d'ultrasons (USDD) à travers la sclère et la caractérisation par rayonnement infrarouge (IR) d'un dispositif HIFU ophtalmique pour le traitement du glaucome. Bien que plus perméable que la cornée, l'administration de médicaments efficace à travers la sclère reste un réel challenge. Dans ce travail, nous avons évalué l'effet d'une propagation d'us en mode pulsé sur l'administration de médicaments à travers la sclère. Parmi les mécanismes sous-jacents, la cavitation semble être un contributeur à une USDD renforcée. L'activité maximale de cavitation sous-jacente à une émission d'ultrasons en mode pulsé peut donc être une méthodologie viable pour l'amélioration de l'administration de médicaments à travers l'oeil. Dans la deuxième partie de la thèse, une nouvelle méthode de caractérisation ultrasonore de terrain a été développée pour un dispositif HIFU multi-éléments. Ce dispositif médical développé par Eyetechcare est destiné au traitement du glaucome réfractaire (Rillieux -la-pape, France). Une alternative basée sur la thermographie par infra-rouge a été développée pour une évaluation rapide et qualitative de la distribution d'intensité émise spécifiquement par ce dispositif à haute fréquence (19-21 mhz) constitué de multiéléments à focalisation en ligne. Cette méthodologie permettra de caractériser les sondes de thérapie à l'échelle industrielle / Therapeutic ultrasound has become a topic of growing interest in ophthalmology. High intensity focused ultrasound (HIFU) for the treatment of glaucoma and ultrasound (US) drug delivery are the two main areas of research in this field. This work addresses these domains in two separate parts: transscleral ultrasound drug delivery (USDD), and infrared (IR) field characterization of an ophthalmic HIFU device for glaucoma treatment. The sclera is a promising pathway for ocular drug delivery, since transscleral administration can address both the anterior and posterior segments of the eye. Due to the low permeability however, efficient drug delivery is challenging. In this study, HIFU was investigated as a potential modality for an enhanced transscleral drug delivery (in vitro). Among US effects, cavitation was shown to be the major contributor to an enhanced USDD. A pulsed US protocol designed to maximum cavitation activity may therefore be a viable method for enhancing ocular drug delivery. In the second part, a new method of ultrasonic field characterization was developed for a multi-element HIFU device. This system is designed and produced for glaucoma treatment by Eyetechcare Company (Rillieux-la-Pape, France). The traditional hydrophone method for field characterization was prohibitively slow on an industrial scale. An alternative modality for rapid qualitative assessment of the intensity distribution based on infra-red (IR) thermography was developed specific to this high frequency (19-21 MHz) device with line-focus US radiators. The second part of the study was aimed to expand the application of a R&D technique for ultrasonic field characterization to an industrial scale

Esse trabalho foi desenvolvido para avaliar a relação entre diferentes medidas de eficiência utilizadas na bovinocultura de corte e as características de desempenho, carcaça e termografia infravermelho (TIV) em bovinos Nelore confinados. Foram utilizados 111 bovinos Nelore, machos não-castrados contemporâneos, com idade aproximada de 16±2 meses, peso corporal médio de 420±55 kg. Os animais foram confinados por 91 dias, sendo 21 dias de adaptação às instalações e à dieta. A dieta foi a mesma para todos os animais e composta por 73% de concentrado e 27% de volumoso. O consumo de matéria seca (CMS) foi avaliado diariamente, enquanto o peso vivo, medidas de ultrassom para avaliação de características de carcaça e imagens de TIV foram realizadas a cada 28 dias até o dia 70. A partir dos dados de CMS foram calculados o consumo alimentar residual (CAR), ganho de peso residual (GPR), consumo e ganho residual (CGR). Após a obtenção dos dados foram realizadas análises de associação (correlação e regressão) visando à identificação de possíveis relações entre as diferentes características com as medidas de eficiência. Não houve correlação entre o GMD com o CAR (r=0,001), e com o CGR (r= 0,114), enquanto o GPR apresentou correlação com o GMD (r= 0,588). O CMS foi correlacionado com o CAR (r= 0,612) e com o CGR (r= -0,532) e não houve correlação com o GPR (r= -0,002). Não houve correlação entre as medidas de eficiência com as características de peso vivo inicial (PVI) e peso vivo final (PV70). Dentre as características de carcaça avaliadas ao abate, apenas o GPR apresentou correlação com a gordura renal pélvica e inguinal (GRPIkg), trato gastrintestinal (TGIkg) e peso de corpo vazio (PCVZkg) na ordem de (r= 0,240), (r= 0,226) e (r= 0,210), respectivamente. Entre as medidas de carcaça avaliadas por ultrassom, apenas a espessura de gordura subcutânea (EGS) final apresentou correlação com o CAR (r= 0,348), GPR (r= -0,188) e CGR (r= -0,340), enquanto a espessura de gordura da picanha (EGP) final apresentou correlação apenas com o CAR (r= 0,233) e CGR (r= -0,200). Houveram correlações entre o ganho de EGS e o CAR (r= 0,371) e CGR (r= 0,345), porém o ganho de EGP se correlacionou apenas com o CAR (r= 0,202). Não foram observadas correlações entre as medidas de eficiência e TIV, porém, esses resultados podem ter sido influenciados pelos fatores ambientais. A AOL não apresentou correlação com nenhuma das medidas de eficiência avaliadas. Dessa forma conclui-se que, o CAR é a medida que mais se aplica n seleção de animais de menor CMS, sem prejuízos as características de desempenho. Adicionalmente, o CAR e CGR selecionam animais mais eficientes em termos de menor consumo, enquanto que o GPR seleciona animais de maior GMD. / The aim of the present study was to evaluate the relationship between different efficiency indexes used in beef cattle and performance, carcass traits and thermography in Nellore cattle at the feedlot system. A total of 111 Nellore male, with around 16±2 months age and 420±55 kg of body weight, were used. The animals were confined for 91 days, with 21 days for adaptation to the facilities and diet. The diet was the same for all animals, and composed by 73% of concentrate and 27% of roughage. Dry matter intake (DMI) was evaluated daily, and performance, ultrasound measurements and infrared thermography images were performed every 28 days until day 70. From the DMI measurements, residual feed intake (RFI), residual weight gain (RWG), residual intake and body weight gain (RIG) were calculated. From the data obtained, association analysis (correlation and regression) were performed to identify the possibilities relationships between the different characteristics with the efficiency measures. The ADG showed no correlation with RFI (r= 0.001) and RIG (r= 0.114); however, the RWG was correlated with ADG (r= 0.588). DMI was correlated with RFI (r= 0.612) and RIG (r= -0.532) and there was no correlation with RWG (r= -0.002) There was no correlation between efficiency measures with initial body weight (IBW) and final body weight (BW70). For carcass traits, evaluated at slaughter, only the RWG showed correlation with pelvic renal and inguinal fat (PRIFkg), gastrintestinal tract (GITkg) and empty body weight (EBWkg) in order of the (r= 0.240), (r= 0.226) and (r= 0.210), respectively. For carcass measurements evaluated by ultrasound, the final backfat thickness (BFT) showed correlation with RFI (r= 0.348), RWG (r= -0.188) and RIG (r= -0.340), while final subcutaneous fat thickness on the Biceps femoris muscle (BFTP8) showed a correlation with RFI (r= 0.233) and RIG (r= -0.220). In addition, BFT gain has been also correlated with RFI (r= 0.371) and RIG (r= 0.345); however, the BFTP8 gain only showed correlation with the RFI (r=0.202). There was no correlation between efficiency measures and the infrared thermography (IRT). The rib eye area (REA) showed no correlation with any the efficiency measures evaluated. In conclusion, the RFI is the measure that most applies in the selection of animals of smaller DMI, without damage to the performance traits. In addition, the RFI and RIG can promoter the selection of more efficient animals by lower consumer, whereas the RWG selected great ADG animals.