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Poudel, Anish. "BOND STRENGTH EVALUATION IN ADHESIVE JOINTS USING NDE AND DIC METHODS." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/dissertations/1010.
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Adhesive bonding of graphite epoxy composite laminates to itself or traditional metal alloys in modern aerospace and aircraft structural applications offers an excellent opportunity to use the most efficient and intelligent combination of materials available thus providing an attractive package for efficient structural designs. However, one of the major issues of adhesive bonding is the occasional formation of interfacial defects such as kissing or weak bonds in the bondline interface. Also, there are shortcomings of existing non-destructive evaluation (NDE) methods to non-destructively detect/characterize these interfacial defects and reliably predicting the bond shear strength. As a result, adhesive bonding technology is still not solely implemented in primary structures of an aircraft. Therefore, there is a greater demand for a novel NDE tool that can meet the existing aerospace requirement for adhesive bondline characterization. This research implemented a novel Acoustography ultrasonic imaging and digital image correlation (DIC) technique to detect and characterize interfacial defects in the bondline and determine bond shear strength in adhesively bonded composite-metal joints. Adhesively bonded Carbon Fiber Reinforced Plastic (CFRP) laminate and 2024-T3 Aluminum single lap shear panels subjected to various implanted kissing/weak bond defects were the primary focus of this study. Kissing/weak bonds were prepared by controlled surface contamination in the composite bonding surface and also by improperly mixing the adhesive constituent. SEM analyses were also conducted to understand the surface morphology of substrates and their interaction with the contaminants. Morphological changes were observed in the microscopic scale and the chemical analysis confirmed the stability of the contaminant at or very close to the interface. In addition, it was also demonstrated that contaminants migrated during the curing of the adhesive from CFRP substrate which caused a decrease of bond shear strength in single lap shear test samples. Through-transmission ultrasonics (TTU) Acoustography at 3.8 MHz showed promising results on the detectability of bondline defects in adhesively bonded CFRP-Al lap shear test samples. A correlation between Acoustography ultrasonic attenuation and average bond shear strength in CFRP-Al lap shear panels demonstrated that differential attenuation increased with the reduction of the bond shear strength. Similarly, optical DIC tests were conducted to identify and quantify kissing bond defects in CFRP-Al single lap shear joints. DIC results demonstrated changes in the normal strain (εyy) contour map of the contaminated specimens at relatively lower load levels (15% ~ 30% of failure loads). Kissing bond regions were characterized by negative strains, and these were attributed to high compressive bending strains and the localized disbonding taking placed at the bondline interface as a result of the load application. It was also observed that contaminated samples suffered from more compressive strains (εyy) compared to the baseline sample along the loading direction and they suffered from less compressive strains (εxx) compared to the baseline sample perpendicular to the loading direction. This demonstrated the adverse effect of the kissing bond on the adhesive joint integrity. This was a very significant finding for the reason that hybrid ultrasonic DIC is being developed as a faster, more efficient, and more reliable NDE technique for determining bond quality and predicting bond shear strength in adhesively bonded structures.
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Luz, Andre Miguel Godinho da. "Predictive modelling and multiscale NDE methods in failure assessment of thermal barrier coatings." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9065.
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The use of thermal barrier coatings (TBCs) allows advanced gas turbine engines to operate at a temperature higher than the incipient melt temperature of the superalloy from which the engine components are made, thereby enhancing the performance and efficiency of the engine. However, delamination cracks initiated in these coatings during service limit their applications. This investigation analysed the effects of thermal cycling on the structure, thermo-mechanical properties and lifetime of Ni-based superalloy samples coated with a TBC. The results indicate that the coating system exhibits substantial changes during its life, with the thermo-mechanical properties of the TBC layers being highly sensitive to temperature and cyclic oxidation. The current study also presents a new finite element model that describes the evolution of the stress state within a thermal barrier coating subjected to thermal cycling loading. This computational framework was used to identify the optimal design parameters through a newly proposed sensitivity index, so that TBCs can be engineered with improved lifetime. Photoluminescence piezo-spectroscopy has been used to identify non-destructively the onset of microcracks and monitor their propagation through a proposed local damage factor that combines spectral shape evolution with peak shift. The computational spectral simulation was based on coupling the finite element model for the calculation of stress with an external routine for the prediction of luminescence spectra. A new non-destructive multi-sensor diagnostics procedure based on the combination of imaging- and laser-based techniques was presented. It has been demonstrated that it can accurately determine the remaining life of high-temperature coatings, and therefore it represents an important development direction for improving the reliability of TBCs. It is concluded that the results obtained in this research were quite satisfactory, which suggests that further model development and field testing of the non-destructive methodology are warranted for predictive failure assessment of thermal barrier coating systems. Keywords Thermal barrier coating Material properties Finite element modeling Photoluminescence piezo-spectroscopy Non-destructive evaluation
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Knopp, Jeremy Scott. "Modern Statistical Methods and Uncertainty Quantification for Evaluating Reliability of Nondestructive Evaluation Systems." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1395942220.
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MINDA, ELISE. "SENSITIVITY STUDIES ON NONDESTRUCTIVE EVALUATION (NDE) METHODS FOR MONITORING FATIGUE AND THERMAL EMBRITTLEMENT IN AUSTENITIC AND FERRITIC STEEL NUCLEAR REACTOR PLANT (NRP) COMPONENTS." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1195611890.
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Hodé, Romain. "Development of laser ultrasonic methods for the nondestructive evaluation of bonded aeronautical assemblies." Thesis, Le Mans, 2020. http://cyberdoc-int.univ-lemans.fr/Theses/2020/2020LEMA1030.pdf.
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Actuellement, l'allègement des structures aéronautiques est un enjeu industriel majeur afin de réduire la consommation en carburant des moteurs et diminuer les émissions polluantes. L'assemblage par collage répond à ce besoin d'allègement et possède de nombreux avantages comparé aux techniques plus conventionnelles comme le soudage ou le rivetage. En effet, cette méthode ne nécessite pas l'ajout de rivets et permet d’'assembler des matériaux composites ayant un rapport résistance/masse élevé. Néanmoins, aucune méthode d'évaluation non destructive (END) ne permet à ce jour de certifier la tenue mécanique des assemblages collés. Lever ce dernier verrou technologique permettrait un déploiement important du collage dans l'industrie. L'objectif de cette thèse est de développer des méthodes ultrasons-laser pour l'END des assemblages collés. Cette technique optique pour générer et détecter des ultrasons dans un matériau offre l'avantage d'être totalement sans contact. Un modèle semi-analytique permettant de simuler la propagation d'ondes générées par laser dans un multicouche est tout d'abord présenté. Puis, deux méthodes de contrôle capables de distinguer expérimentalement des collages industriels avec et sans défauts sont introduites. La première porte sur la résolution d'un problème inverse à partir d'ondes planes synthétisées et réfléchies par le collage. La seconde est basée sur l'atténuation de résonances locales des modes de Lamb à vitesse de groupe nulle (ZGV). Ces deux méthodes permettent d'identifier des paramètres quantitatifs pour distinguer des collages structuraux ayant des tenues mécaniques différentes<br>Currently, the weight lightening of aircraft structures is a major industrial issue in order to reduce engine fuel consumption and greenhouse gas emissions. Adhesive bonding addresses this need for lighter structures and has many advantages compared to more conventional techniques such as welding or riveting. Indeed, this method does not require the addition of rivets and allows to assemble composite materials with a high strength-to-weight ratio. However, to date there is no nondestructive evaluation (NDE) method to certify the mechanical strength of bonded assemblies. Overcoming this last technological limitation would enable a significant deployment of adhesive bonding in the industry. The objective of this thesis is to develop laser ultrasonic methods for the NDE of bonded assemblies. This optical technique to generate and detect ultrasound in a material has the advantage of being fully contactless. A semi-analytic model to simulate the propagation of laser generated waves in a multilayer structure is first presented. Then, two control methods which can experimentally discriminate between industrial bonds with and without defects are introduced. The first one concerns the resolution of an inverse problem using synthesized plane waves reflected from the bonding. The second one is based on the attenuation of local resonances of zero-group-velocity (ZGV) Lamb modes. These two methods allow the identification of quantitative parameters to distinguish structural bonds of different mechanical strengths
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Hamze, Alaa. "Détection et localisation de changements dans une structure : application numérique et expérimentale." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00934435.
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La détection d'endommagements et de changements des propriétés élastiques dans des structures, utilisant les variations des paramètres dynamiques, fait l'objet d'une attention particulière depuis plusieurs années dans les domaines du génie mécanique et du génie civil. Le principe général repose sur le fait que la variation des propriétés physiques (e.g. rigidité, masse, module d'Young, conditions aux limites) entraîne une variation des caractéristiques dynamiques de la structure (e.g. fréquences de résonance, amortissements modaux et déformées modales). La présence d'endommagement provoque ainsi une diminution de la rigidité de la structure, c'est-à-dire une augmentation de sa flexibilité et de son amortissement que l'on retrouve dans la forme des modes et les valeurs des fréquences. Utilisant le changement de ces informations entre un état sain et un état endommagé, plusieurs méthodes non-destructives ont été proposées dans la littérature afin d'identifier et de localiser ces endommagements. Ces pratiques et ces activités sont d'une importance considérable puisqu'elles permettent en premier lieu d'anticiper et donc d'éviter des ruptures dans les structures, toujours catastrophiques, et plus généralement de mettre en place des plans de maintenance prédictives, en lien avec le suivi sur le long terme de leur intégrité (Structural Health Monitoring). Ces méthodes de surveillance se popularisent également du fait de la réduction des coûts des instrumentations, liés à l'apparition de nouveaux équipements à bas coût, ayant des performances satisfaisantes. L'objectif de ce travail est de tester les différentes solutions permettant la détection, la localisation et la quantification des changements dans des structures simples. Plusieurs méthodes ont été testées et une approche nouvelle a été proposée basée sur l'utilisation de la méthode des perturbations. Trois approches ont été suivies: une modélisation par éléments finis (analyse modale), une simulation numériques par éléments finis (analyse temporelle) et enfin des analyses expérimentales sur des poutres en Plexiglas au laboratoire, les trois volets de ce travail ayant permis de tester la sensibilité des méthodes non-destructives (NDE) globales et locales pour la détection et la localisation. Les changements ont été associés à une variation locale du module de Young (E), numériquement pour les solutions numériques et par chauffage local sur des sections de la poutre dans le volet expérimental. Dans tous les cas, nous sommes en situations réelles afin de proposer l'identification des caractéristiques modales par des méthodes opérationnelles (Operative Modal Analysis) telles que la méthode du décrément aléatoire et la méthode de décomposition dans le domaine fréquentiel (Frequency Domain Decomposition). Les résultats d'identification ont montré une très bonne corrélation entre les valeurs numériques et les valeurs expérimentales obtenues : fréquences de résonance et déformés modale. Pour identifier l'endommagement, les méthodes de localisation basées sur la courbure des déformées propres, la matrice de flexibilité, la courbure de flexibilité et enfin sur la méthode d'inversion des modes ont été employées. D'après les résultats obtenus, la méthode d'inversion se montre efficace dans le cas de variations modales faibles et transitoires, alors que la méthode de la courbure de flexibilité donne généralement de bons résultats et apparait robuste lorsque les variations sont plus prononcées.
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Kiriakidis, Alejandro C. "Implementation and application of NDE on ceramic candle filters." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=2831.
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Thesis (Ph. D.)--West Virginia University, 2003.<br>Title from document title page. Document formatted into pages; contains xiv, 185 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 170-176).
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Miller, Richard A. "NDE method for carbon-carbon composite disk brakes using infrared thermography /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1650510601&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Ismatullah. "Analysis of space-borne antennas by higher-order method of moments and inverse equivalent current methods." kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=977261.
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Chitti, Abhishek. "ASSESS MATERIAL PROPERTIES OF CONCRETE USING COMBINED NDT METHODS." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2490.
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The aim of this research is to assess the material properties of concrete like modulus of elasticity, compressive strength, and Poisson’s ratio using various nondestructive Testing (NDT) methods like Ultrasonic Pulse Velocity (UPV) and Rebound Hammer (RH). Assessment of material properties of concrete is very important as they are used for structural design process. Various NDT methods are applied to ensure the quality of concrete specimens but they can also be used to find material properties. UPV is a NDT method which is used to test the internal condition of the concrete specimen. RH is a surface hardness testing method and can be used to test the homogeneity of the specimen. For this study, several batches of concrete samples with three different design strengths of 6000 psi, 8000 psi, and 12000 psi were casted. Modulus of elasticity and Poisson’s ratio were calculated from UPV P-wave and S-wave velocities. A Nomogram was developed by combining the longitudinal ultrasonic pulse velocities, rebound numbers, and compressive strengths measured from UPV, RH, and compressive strength tests respectively. This combined NDT correlation curve (Nomogram) can be used to estimate compressive strength of concrete if UPV and rebound values are known. The accuracy of these NDT methods were determined by comparing estimated strength to the actual strength. Furthermore, the effect of moisture content on UPV and rebound values was reviewed and also studied dynamic modulus of elasticity and its relation with static modulus of elasticity of the concrete was investigated for better understanding.
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Poggi, Francesco. "Bending properties of commercial wood-based panels by NDT methods." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-66162.
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This thesis work focuses mainly on the application of non-destructive testing (NDT) methods on wood-based panels (WBP) in order to estimate the bending properties. To prove the accuracy and applicability of these methods on WBP, their results are correlated with results from a standardized static bending test. The behavior in different climate conditions and the application on panels of larger sizes is also questioned to provide an indication about strong points and boundaries of NDT methods applied on WBP.The bending properties are of major importance, especially for materials suited to bear loads. Bending stiffness, represented by the modulus of elasticity (MOE), is an expression of the deflection rate of a material under load. The bending strength, represented by the modulus of rupture (MOR), is an expression of the maximum load withstood by a material before rupture.Before testing, the material is acclimatized in three climate conditions: dry (20°C, 35% RH), standard (20°C, 65% RH) and wet (20°C, 85% RH), to understand the bending properties variation and how the NDT methods are affected by the variation in moisture content.The materials used are seven types of WBP, in particular four types of particleboards (PB), one type of high-density fiberboard (HDF), one type of dual density PB (with high and low density areas along the production direction) and one type of light-weight panel (Board-on-stiles, a composite panel of HDF, PB and paper honeycomb).To test the bending properties the following NDT methods are considered: transversal resonance vibration and longitudinal resonance vibration with the use of the BING system and the time-of-flight with the use of Fakopp Ultrasonic Timer and Silvatest Trio. The resonance vibration methods, transversal and longitudinal, are based on the relation between resonance vibration properties and bending properties of a material. The relation with bending properties also exists for the stress wave velocity (SWV) through a material, calculated with the time-of-flight method. The dynamic MOE resulting from these tests is then correlated with the static MOE and MOR from the static bending test.The NDT methods resulted to be reliable on WBP, with generally high levels of correlation between dynamic MOE and static MOE and MoR. The highest correlation value for MoE is with the transversal resonance vibration while the highest for MOR is with the longitudinal resonance vibration. The results of the dynamic MOE for all the NDT methods are higher than the static MOE, as confirmed also in the literature; the average ratio between the dynamic and the static MOE is, for example, up to 1,6 for WBP in standard climate condition, tested with Fakopp U.T.. These results are extremely higher than values suggested by previous studies. Moreover, the ratio increases with increasing relative humidity of the climate condition. The results from the tests on larger sizes suggest a possible application in this field. The time-of-flight method is suitable for in-plane uniform materials, like the PB and HDF, while the transversal resonance methods give also a good representation of the properties of the dual density PB and the light-weight panel.
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Olsson, Johan. "Managing clearinghouse risk for NDF cleared contracts : Validating the HS/VaR method for NDF FX CCP Clearing risk." Thesis, KTH, Matematisk statistik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168635.
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In this thesis we describe and discuss the reality for a central clearing party clearinghouse. The importance of sound risk management is discussed. We specifically validate the usage of a Historical Simulation/VaR approach for managing the risk when acting as a CCP for the Non Delivery Forward FX instrument. The method is back tested and some alternative approaches are proposed.<br>Sedan finanskrisen 2008 har regelverken för central clearing av OTC handlade produkter stärkts. I Europa tvingar EMIR regelverket in de OTC handlade financiella produkter att clearas på ett så kallad CCP Clearinghus. Mer och mer av dessa finansiella produkter kommer nu cleareas på clearinghusen. Clearinghusen blir därmed mer och mer riskabla och ett antal studier har gjorts angående vad denna komplexa miljö kan innebära i form av spridningseffekt etc. Därför är det av stor vikt att clearinghusen kan hantera risken som det innebär att clearea dessa nya produkter. Ett exempel på sådan centralt clearad produkt är FX instrument som tex NDF. På NASDAQ Clearing så är förslaget att använda Historical Simultion/VaR för att räkna ut de säkerheter som ska tas in från medlemmarna. ESMA ställer vissa krav på denna modell men är i övrigt positivt inställda till just HS/VaR. Jag har i detta arbete redogjort för hur ett clearinghus fungerar, hur ett FX instrument som NDF fungerar och slutligen gjort en Back test av HS/VaR som riskmått för en NDF portfölj. Speciellt fokuserar jag på hur denna modell skulle ha klarat den turbulenta perioden under 2008/2009 med efterföljande lugna period. Back testet visar att den inte skulle vara lämplig under denna period och avslutningsvis diskuterar jag runt några alternativa adaptioner för att modellen skulle vara bättre anpassad till karakteristiken i FX tidsserien.
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Schleip, Christoph. "Climate change detection in natural systems by Bayesian methods." kostenfrei, 2009. http://mediatum2.ub.tum.de/node?id=805580.
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MALIK, MUHAMMAD SOHAIL. "Reliability Analysis of LASER ULTRASONICS as an NDT method for surface defect detection in High Speed Hollow Train Axles using Experimental and Numerical Methods." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243060.
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The objective of the research is to find a methodology to test the train axle for possible surface defects using non-contact laser ultrasonic technique and then studying the reliability of this non-destructive test (NDT) method by considering a large set of defects with varying sizes to build Probability of Detection (POD) curve. Generally, this NDT technique has three parts: laser beam generation and impingement on a point over the test object surface, ultrasound propagation within the material of the test object and reception of the ultrasound wave propagated at a certain distance from the laser source position. The wave propagation will be influenced by the path where it propagates through and specifically it will be modified in presence of a defect. The part of methodology covered in this research is more concentrated on the laser beam incidence and ultrasound generation within the material and its behavior as it moves through the train axle under study. Laser ultrasonics is being considered a replacement of conventional ultrasonic testing method as it eliminates many limitations of conventional method and has advantages of its own. In case of train axles preventive maintenance is a challenge using conventional method as once mounted it is very difficult to reach all areas of axle and dismounting is never a good idea with respect to time and economy. Though rotating probe method needs only small elements to be removed to reach the central bore in case of hollow axles but there was still an urge to use a non-contact method which is feasible for hard to reach areas and does not require dismounting of the axle completely. Laser ultrasonics if found feasible in future not only kills this issue but it is also quicker and if used properly can detect wider range of surface defects. As a starting point it is necessary to know the behavior of ultrasonic waves in the material which is steel in our case. The steel axle under research is being used in high speed train ETR 460. It becomes harder to see the behavior of the waves when there is a hollow axle with various abrupt variations in cross section along the length. Surface acoustic waves (SAW) which are precisely Rayleigh surface waves in our case are the most important for detecting surface defects. These waves are almost half in speed to longitudinal waves and so are with smaller wavelengths for a given frequency to become more sensitive to any hurdles in their way. It also leads to many reflections in the detected signals due to central hole and fillets present on each variation of the cross section. A section of the axle with two fillets is selected initially to study all of the above behavior. 2D model of this section is numerically analyzed using COMSOL multi-physics code. A series of experiments is also carried on selected section using the lab equipment available to produce Nd: YAG (neodymium-doped yttrium aluminum garnet) laser in the infrared region with a short pulse of about 16 Megawatt (maximum power) for 12 nanoseconds duration. It theoretically causes about 5 nanometer of penetration in the steel to cause thermo-elastic regime. This value also varies on the basis of surface quality and frequency of laser beam used. Due to this phenomenon, a transient increase in temperature in a small volume of material causes a thermal stress which in turn propagates three types of waves: longitudinal waves, transverse waves and Rayleigh surface waves. The reception signal was read by using Laser Doppler Vibrometer (LDV). Another option may also be considered by using air-coupled ultrasonic transducer making the method a hybrid Laser Ultrasonic system. Behavior of the stated waves studied numerically and experimentally by measuring vertical displacement of a point at different locations by simulating defect of varying size and position is what can help in finalizing the objective. Along with this sensitivity and efficiency of the NDT method against different range of defect sizes is also important. It can be achieved by measuring POD curve of the system. This curve tells us about the largest probable size of defect which can be missed by the technique under consideration. Parametric studies run for different defect sizes give a curve against RMS of the signal and the amplitude of the Rayleigh wave. For example to study change in RMS of the vertical displacement of a point when measured after defect of a constant width and varying depth from no crack to a maximum crack depth showing a variable behavior with a small incremental step each time gives a probability measure of the detection of the defect. The Rayleigh Surface wave attenuation was one of the main changing factors considered due to the inclusion of the defects. The important information is extracted using POD Curve to look for the minimum size of defect to be seen by the method with required level of probability. It also helps to define the inspection interval of a train axle under service. First of all a range of crack sizes is to be defined in which the inspection system under question cannot determine if the object is defected or not. Then a large number of specimen are required in this range of defects to do further analysis. Linear regression analysis of these results is used to get the conventional POD curve. This type of POD curve built with inputs from numerical models is termed as Model Assisted POD curve or MAPOD curve. MAPOD curve avoids the expensive real building of test specimen for different defect sizes. A large number of trial experiments were done on the real axle without defect to incorporate natural noise of the inspection method in the numerical readings. The model to be used was refined multiple times to get a fully qualified model fulfilling all the real requirements and avoiding as much as possible the stochastic behavior of numerical methods involved. A generalized alpha time stepping algorithm was used in the time domain study of all the experiments. Direct Solver used was the famous MUMPS solver and Newton method was used for the iterative non-linear solution. At the end MAPOD curve for the specific settings used showed that the Laser-Ultrasonics is fairly suitable to detect the typical crack sizes and if a suitable configuration is found it is quite efficient to serve the purpose of in service inspection of train axles without using any conventional contact techniques.
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Bale, Jefri Semuel. "The damage observation of composite using non destructive testing (NDT) method." Thesis, Paris 10, 2014. http://www.theses.fr/2015PA100067/document.
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L'objectif de ce travail de thèse est d'étudier le comportement de l'endommagement des matériaux composites sous chargement statique et fatigue par contrôle non destructif (C.N.D) thermographie et soutenu par émission acoustique et la tomographie (CT scan). Pour cela, ce unidirectionnels composite à fibres de verre (GFRP) et discontinue composite à fibres de carbone (DCFC) ont été utilisés comme les éprouvettes qui ont fourni par PSA peugeot citröen, France. Une série d'essais mécaniques a été réalisée pour déterminer le comportement de l'endommagement sous chargement statique et fatigue. Pendant tout des essais mécanique, la thermographie a été utilisé pour l'observation en temps réel pour suivre l'évolution des températures sur la surface de l'éprouvette et supporté par émission acoustique dans certaines conditions. Cette étude a utilisé une forme rectangulaire et se compose d'éprouvettes trouées et non trouées au centre de l'éprouvette. La vitesse de déplacement constante est appliquée pour observer l'effet sur le comportement de l'endommagement sous chargement de traction statique. Sous les essais de fatigue, le paramètre constant de la fréquence et de l'amplitude de stress a été étudiée pour chaque niveau de charge pour avoir les propriétés de fatigue et l'évolution de l'endommagement de l'éprouvette. La tomographie a été utilisée pour confirmer l'apparition de l'endommagement et l'etat du matériau après l'essai de fatigue. L'analyse des résultats de l'expérimentation et de l'observation NDT montré le bon accord entre les résultats mechnical et NDT thermographie avec prise en charge par l'observation de l'émission acoustique en détecter l'apparition et la propagation de l'endommagement de GFRP PRV et DCFC sous chargement de statique en traction. Les essais en fatigue montrent que la dissipation thermique est liée à l'évolution de l'endommagement et également thermographie et peut être utilisé avec succès pour déterminer la limite d'endurance (HCFS) et la courbe de Wöhler du matériau composite. Les résultats par CT scan ont mesurée avec succès les endommagements et l'état du matériau après essai de fatigue du matériau composite<br>The aim of this study is to investigate the damage behaviour of composite material in static and fatigue condition with non destructive testing (NDT) thermography method and supported by acoustic emission and also computed tomography (CT) scan. Thermography and acoustic emission are used in real-time monitoring techniques during the test. On the other hand, NDT observation of tomography is used for a post-failure analysis. In order to achive this, continuous glass fiber composite (GFRP) and discontinuous carbon fiber composite (DCFC) have been used as the test specimens which supplied by PSA Company, France. A series of mechanical testing was carried out to determine the damage behaviour under static and fatigue loading. During all the mechanical testing, thermography was used in real-time observation to follow the temperature change on specimen surface and supported by acoustic emission in certain condition. This study used rectangular shape and consist of specimen with and without circular notches (hole) at the center. The constant displacement rate is applied to observe the effect on damage behaviour under tensile static loading. Under fatigue testing, the constant parameter of frequency and amplitude of stress was explored for each load level to have the fatigue properties and damage evolution of specimen. The tomography was used to confirm the appearance of damage and material condition after fatigue testing. The analysis from the experiment results and NDT observation shown the good agreement between mechnical results and NDT thermography with supported by acoustic emission observation in detect the appearance and propagation of damage for GFRP and DCFC under static loading. Fatigue testing shows that thermal dissipation is related to the damage evolution and also thermography and can be successfully used to determine high cycle fatigue strength (HCFS) and S-N curve of fiber composite material. From post failure analysis, CT scan analysis successfully measured and evaluated damage and material condition after fatigue test for fiber composite material. v
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Usner, Brian C. "Generalized hybrid methods for modeling complex electromagnetic structures." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1135004394.
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Schrader, Andy. "Methods to improve bond on FRP wrapped piles." [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001914.
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Britt, Olivia Grace. "Assessing the Suitability of Typical Timber Testing Methods for Australian Heritage Timber Structures." Thesis, Sydney School of Architecture, Design and Planning, 2023. https://hdl.handle.net/2123/30017.
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This research aims to examine the applicability of conventional inspection methods for timber structures where structures have recognised heritage value. The research seeks to understand the appropriateness of inspection methodologies typically prescribed for timber in heritage applications. A literature review of current inspection methods utilised by engineers, architects and others within the heritage structures field has been undertaken, and the appropriateness of timber structural inspection methods used in practice (destructive testing, semi-destructive testing, and non-destructive testing methods) reviewed in light of heritage aims for Australian structures, and interviews conducted with practicing industry professionals to discuss uptake of these methods in practice.
A review of current literature indicates that non-destructive technologies present significant potential for further analysis of timbers in-situ without damage to the fabric itself, and represent a particular opportunity for heritage sites, as analysis can be conducted with minimal invasiveness. Interviews with practicing professionals within this industry indicates that currently, such methods have been incorporated only minimally into standard professional practice methodologies. While a lack of familiarity with many available methods is evident, the reasons behind the limited uptake are complex, including but not limited to a lack of pre-defined Australian guidelines prescribing their use, a perception of high associated costs, and an unwillingness on the part of clients to request the use of these methods.
It is found that significant opportunity exists for an improvement in the uptake of non-destructive methods as preferential over semi-destructive test methods. Indicative processes of example best-practice methods incorporating non-destructive testing into a typical assessment regime are presented.
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Komárková, Tereza. "NDT kontrola zabudovaných kotev do betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225571.
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Non-destructive inspection using ultrasonic anchoring method is the only possible way to detect inadequate anchorage length. For rescue roads systems inadequate anchoring can have fatal consequences. Therefore, control anchoring bridge barriers should be carried out every installation of crash barriers.
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Wassouf, Ziad. "Die Mortar Methode für Finite Elemente hoher Ordnung." kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=821650.
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Luttenberger, Michael. "Solving polynomial systems on semirings : a generalization of Newton's method." kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=796584.
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Kostan, Mario. "Design and fabrication of GaPO4 ultrasonic transducer for NDT at high temperatures." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17228.
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There is a critical need for inspection and condition monitoring of high temperature critical components such as pipelines and welds in electrical power generation and other plants operating at temperatures as high as 580°C. The high temperatures and pressures experienced in these pipelines, particularly for ageing plants lead to creep, fatigue and corrosion type defects. Safety of these plants is of paramount importance, and regular maintenance is carried out during planned outages at ambient temperatures. Ultrasonic non-destructive testing can be used to detect defects in the weld at ambient temperatures. However, at high operational temperatures, this technique cannot be applied due to the lack of high temperature transducers. This research has achieved significant advances towards enabling ultrasonic inspection and condition monitoring of high temperature critical points, by developing an ultrasonic transducer around an advanced piezoelectric single crystal material, called Gallium Orthophosphate (GaPO4), which can operate at the required temperature of 580°C. Based on its reported piezoelectric and other properties, and its commercial availability, GaPO4 was chosen as a candidate active material for application in a prototype high temperature transducer. In a series of confidence building tests with the selected piezoelectric material (electrical characterisation via the impedance method), it has been demonstrated that the GaPO4 piezoelectric elements are stable when subjected to 580°C for more than 600 hours. Ultrasonic thickness gauging has shown that GaPO4 works as a functional transducer generating and receiving ultrasound waves at 580°C for at least 360 hours. Furthermore, the sensitivity of the GaPO4 transducer to detect defects with simple geometry was successfully tested through measurements on steel blocks containing artificial defects (side-drilled holes) up to the same high temperatures. Based on the characterisation results from the impedance and ultrasonic measurements, a prototype ultrasonic transducer for operation at high temperatures has been designed and manufactured. The new ultrasonic transducer was tested in a laboratory environment using a steel calibration block, high temperature couplant, SONO 1100, and an electric furnace. In the range from ambient temperatures up to the target of 580°C, the ultrasonic transducer kept a signal-to-noise (SNR) level sufficiently high, above the threshold of 6 dB, which is high enough for practical non-destructive testing and condition monitoring.
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Dulay, Didar Singh. "The application of electromagnetic NDT method to the inspection of non-ferrous cast materials." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/4175.
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Inspection of non-ferrous cast material is routinely carried out looking for casting defects inherent for the manufacturing process. The NDT methods employed are Radiography and Ultrasonics, primarily for sub-surface or internal defects and Penetrants fo r surface breaking defects. Electromagnetic techniques have not been used on cast material except maybe for conductivity determination. This limitation resulting fi7om the surface roughness normally associated with cast surfaces and the fact the other techniques mention above have been very successful in finding and evaluating the discontinuities sought. The possible application of Electromagnetic techniques on surfaces in the as-cast condition of non-ferromagnetic material came about because of specific problems experienced by industry. Two major investigations were offered namely; 1) Investigation of CNC material - CuNiCr [1.6%Cr] castings exhibiting oxide entrapment in the form of networks. 2) Investigation of NAB - Nickel Aluminium Bronze exhibiting selective phase corrosion on immersion in seawater. The detection and measurement of both oxide entrapment and phase selective corrosion was difficult and in cases impossible with conventional NDT methods employed for quality control of these material/component types. Time of Flight DiMaction Ultrasonics did give some 50% detectability of phase selective corrosion, but the method was found to be expensive and very time consuming. The metallurgical properties of the material and morphology of the defects have been studied for both Cupro Nickel Chromium and Nickel Aluminium Bronze cast alloys. An investigation was then conducted to study the effects of eddy current signals and their potential in detecting, both linear and cluster type defects which were predominantly interdendritic with some reported as intergranular in nature. For inspecting Cupro Nickel Chromium castings two successful eddy current methods have been developed. Detection of surface flaws was achieved by high frequency [2MHzj examination and subsurface flaws by using low frequencies [1--'IKHz] but using specifically developed sensors that provided good penetration but maintained sensitivity to the fine defects. In the case of Nickel Aluminium Bronze material, the investigation was to look at electromagnetic techniques, which best utilizes the inherent feature of permeability/conductivity associated with this non- ferromagnetic material and any changes that phase selective corrosion may produce. Some meaningful results were obtained using a combination of edd'y current excitation with detection via magneto -re s istive sensors. Testing through 30-40mm of material to detect small magnetic variation produced by only 1-2 mm of corrosion penetration was difficult to quantify. Detection and assessment however appeared hopeful when examination was carried out from the corroded surface. With quantifiable samples a meaningful technique using eddy current excitation and magneto-resistive sensor for detection can be developed.
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Gerik, Axel M. "Modification and automation of fractal geometry methods : new tools for quantifying rock fabrics and interpreting fabric-forming processes." kostenfrei, 2009. http://mediatum2.ub.tum.de/node?id=683825.
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Mao, Jinchao. "Implémentation of the Analytic Nodal Method in the NDF code and applications to CANDU reactors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/MQ57418.pdf.
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Chehade, Samar. "Modelling of the 3D scattering of elastic waves by complex structures for specimen echoes calculation. Application to ultrasonic NDT simulation." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS273/document.
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Le sujet de la thèse s’inscrit dans le cadre du développement de modèles pour la simulation du contrôle non-destructif (CND) par ultrasons. L'objectif à long terme est la mise au point, par une méthode de rayons, d’un outil complet de simulation des échos issus de la géométrie (surfaces d’entrée, de fond…) ou des structures internes des pièces inspectées. La thèse vise plus précisément à intégrer le phénomène de diffraction par les dièdres à un modèle existant dérivant de l’acoustique géométrique et qui prend uniquement en compte les réflexions sur les faces.Pour cela, la méthode dite des fonctions spectrales, développée initialement pour le cas d'un dièdre immergé, est développée et validée dans un premier temps dans le cas des ondes acoustiques pour des conditions aux limites de type Dirichlet ou Neumann. La méthode est ensuite étendue à la diffraction des ondes élastiques par des dièdres infinis à faces libres et d'angles quelconques, pour une incidence 2D puis pour une incidence 3D. Cette méthode est semi-analytique puisque les solutions recherchées s'écrivent sous la forme d'une somme d'une fonction singulière, qui est déterminée analytiquement à l'aide d'un algorithme récursif, et d'une fonction régulière, qui est approchée numériquement.Les codes correspondants sont validés par comparaison à une solution exacte dans le cas acoustique et par comparaison à d'autres codes (semi-analytiques et numériques) dans le cas élastique. Des validations expérimentales du modèle élastodynamique sont également proposées<br>This thesis falls into the framework of model development for simulation of ultrasonic non-destructive testing (NDT). The long-term goal is to develop, using ray methods, a complete simulation tool of specimen echoes (input, back-wall surfaces...) or echoes of inner structures of inspected parts. The thesis aims more specifically to integrate the phenomenon of diffraction by wedges to an existing model derived from geometrical acoustics, which only accounts for reflections on the wedge faces.To this end, a method called the spectral functions method, which was initially developed for immersed wedges, is developed and validated as a first step in the case of acoustic waves with Dirichlet or Neumann boundary conditions. The method is then extended to elastic wave diffraction by infinite stress-free wedges of arbitrary angles, for 2D and 3D incidences. This method is semi-analytic since the unknown solutions are expressed as the sum of a singular function, determined analytically using a recursive algorithm, and a regular function which is approached numerically.The corresponding codes are validated by comparison to an exact solution in the acoustic case and by comparison to other codes (semi-analytic and numerical) in the elastic case. Experimental validations of the elastodynamic model are also proposed
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Kollmannsberger, Stefan. "ALE-type and fixed grid fluid-structure interaction involving the p-version of the finite element method." kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=811715.
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Sturesson, Claes. "Nondestructive testing (NDT) of Norway spruce with respect to infection by root and butt rot using ultrasound and acoustic methods." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-15753.
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Brashear, Kyle Thomas. "The Assessment of Sonic Waves and Tracer Gases as Non-Destructive Testing (NDT) Methods for In-Situ Underground Mine Seals." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50519.
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Since the MINER Act of 2006, the minimum static load of in-situ underground mine seals has been increased from 20-psi to either 50-psi if monitoring is conducted or 120-psi if left unmonitored. These minimum strength requirements in seals must be designed, built, and maintained throughout the lifetime of the seal. Due to this, it has become necessary to assess the effectiveness of non-destructive testing (NDT) technologies to determine seal integrity, which in this case, are explored using sonic waves and tracer gases. Through both small and large scale testing, two NDT methods were evaluated on their abilities to determine integrity of the seal. A sonic wave technique to observe a change in wave velocity to identify faults within the seal material. As a NDT method, tracer gases may be used as a potential indicator of a connection between both sides of the seal material through a series of faults and cracks within the material itself. This paper reviews the history of underground mine seals and discusses the overall assessment of sonic waves and tracer gases to serve as NDT methods for estimating the integrity of these seals.<br>Master of Science
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Shromáždil, Petr. "Teplotní závislost elektronického šumu piezokeramických snímačů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218064.
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The main objective of the thesis „Electronic noise temperature dependence of piezoceramic sensors“ is to design the measuring set-up for the measurement of the piezoceramic sensor noise temperature dependence. The application for the control of the measurement process is realized. The theoretic chapter is focused on the properties of materials for the production of piezoceramic sensors. The basic effects related to the piezoceramic properties and the material structure is described in this part. Next chapter is focused on the technology of production of used piezoceramic. The properties of solid solutions as PbZrO3 – PbTiO3, and the non-destructive methods of the material testing are discussed. Our attention is concentrated to methods of acoustic emission. The next chapter is concerned on the realization of the measuring set-up and program equipment. The tested sample is the acoustic emission sensor made of piezoceramic material PCM-51. It is placed in the cylinder chest which is heated by the DC current source. The temperature measurement is realized by the data acquisition switch unit. The results of measurements are saved in PC and they are analyzed using MATLAB program. As a result we receive the frequency spectra of the electric noise voltage spectral density SU. The temperature dependencies of resonant peak value and frequency are determined from these spectra.
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Darrell, Leopold Augustus. "Development of an NDT method to characterise flaws based on multiple eddy current sensor integration and data fusion." Thesis, Leeds Beckett University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245778.
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Gränne, Fredrik. "Air and Water Tightness in Building Envelopes - Evaluation of Methods for Quality Assurance." Doctoral thesis, KTH, Building Sciences and Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3264.
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<p>The purpose of this work is to contribute to a process formaking buildings with good function and to avoid prematurefaults.</p><p>The design, construction and installation of low-slopedroofs are important parts of creating a durable building. Mostof the leakages in low-sloped roofs occur where materials withdifferent thermomechanical properties are joined together. Withbetter knowledge about these joints, the expected service lifecould better be estimated. Common roofing materials onlow-sloped roofs are roof membranes.</p><p>To avoid damages and to minimise energy consumption thedetection of air and water leaks is essential. It can bedifficult to localise a leak in e.g. a roof since water canflow far within the construction. Leakage detection can beapplied both as a quality assurance method after installationof low-sloped roofs and as field inspection methods. Theleakage detection can also be extended to terrace slabs and thewhole building envelope.</p><p>To investigate the strength of jointsbetween sheet metaland roofing membranes, several small-scale tests and somelarge-scale tests were performed. The test methods weredeveloped to match the loads that can be expected on this kindof joints.</p><p>A number of water leak-detection methods were evaluatedthrough application on test roofs. Some of the methods todetect leaks on low-sloped roofs can also be used to detect airleakage in other parts of the building envelope. To develop andevaluate air leak-detection procedures, selected methods wereused in two case studies.</p><p>The circumstances regarding welding of the material jointswere found to have great impact on the strength. The roofshould be designed so no long-term strain will appear since acomparatively low stress may damage the joint over time.</p><p>The performance of the leak-detection methods depends on theroofing material. All methods tested were an improvementcompared to visual inspections. Different recommendedapproaches for leakage detection and quality control is given.The case studies show that air leakage detection could beperformed with good accuracy. The potential difference methodcould without doubt be a tool for leakage localisation inwaterproofing layers both on roofs and in terrace slabs.</p><p><b>Keywords:</b>Roofing, roof membrane, durability,waterproofing, leakage, wind-load, non-destructive testing,NDT, BSL4, BSL3, air leakage, building envelope</p>
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Kellerer, Thomas Georg. "Entwicklung von immunochemischen und PCR-Methoden zum qualitativen Nachweis von Tilletia-Arten und Ustilago nuda in Saatgut." kostenfrei, 2009. https://mediatum2.ub.tum.de/node?id=739743.
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Ozturk, Emre. "Estimation Of The Height Of Surface Breaking Cracks Using Ultrasonic Timing Methods." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607176/index.pdf.
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In this thesis, two ultrasonic timing methods are used in order to investigate the accuracy and reliability of measurements for surface breaking cracks having different orientations and heights. Also the best applicable measurement technique is searched by comparing the received test results. These methods are the Time of Flight Diffraction (TOFD) Method using diffraction of longitudinal waves and another method using the reflection of shear waves from the crack tips. In order to simulate and measure the height of surface breaking cracks three sets of test blocks from steel, and two sets of wedges from plexiglas material are manufactured. Also several probes having frequencies of 2Mhz, 4Mhz, 5Mhz and angles of 45o and 70o are used.
Some test procedures are created to make realistic comparisons between the test results and the ones found by previous studies in literature. The results are compared according to the standard deviations of errors in crack height
measurements and it is found that the depth, orientation of defects and the frequency of probes have considerable affect on the results. With wider probe angles and higher frequencies of probes to some extent the errors are observed
to be running low and the height of cracks could be measured closer to the original size. The amount of the errors is increased in measurements with the increasing angle of cracks. The results of both methods are found to be very
satisfactory. A range of ±<br>0.5 mm for means of error from the original vertical crack heights is determined. The results agree with the previous studies.
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Cruz, Simone Ferreira de Almeida. "Crescimento e caracterização de monocristais de BaY2F8:TR onde TR = Nd3+, Pr3+, Er3+, Tb3+, Dy3+." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-13102011-103049/.
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Foram realizados estudos da síntese e do crescimento de cristais de BaY2F8:TR (TR= Nd3+; Pr3+; Er3+; Tb3+; Dy3+) simplesmente dopados e codopados (Nd3+:Dy3+ ; Nd3+:Pr3+) por meio do método de fusão por zona (FZ). Os cristais crescidos foram caracterizados quanto a sua estrutura por Difração de raios-x (DRX) e Difração de nêutrons (DN) com análise pelo método de Rietveld. Foi também estudado o comportamento na fusão deste material puro e dopado com elementos terras raras trivalentes através de: microscopia eletrônica de varredura (MEV) e espectroscopia dispersiva de raios-x (EDS). A concentração final de dopantes, bem como, sua distribuição nos cristais crescidos foi estimada e, quando possível, foi ainda calculado o coeficiente de segregação de cada dopante nesta matriz. Os cristais foram também analisados por espectroscopia de absorção e emissão no caso dos materiais duplamente dopados, sendo observada evidencias de transferência de energia Nd-Pr na região UV. Foram obtidos cristais com dimensões da ordem de 40 mm x 10mm com boa qualidade óptica e estrutural adequados para estudos espectroscópicos e testes de ação laser com bombeamento por laser de diodo. Experiências preliminares de crescimento de fibras monocristalinas desta matriz pura e dopada com Tb3+, pelo método de crescimento de micro-pulling down, foram também realizadas visando uma avaliação do método aplicado a este fluoreto. Foram obtidas apenas fibras translúcidas com diâmetro constante sendo necessária maior investigação sobre o crescimento de fibras deste material puro ou dopado.<br>Synthesis and Growth process of single crystals of BaY2F8:TR (TR= Nd3+; Pr3+; Er3+; Tb3+;Dy3+) single-doped and co-doped (Nd3+ :Dy3+ ; Nd3+:Pr3+) were performed by Zone Melting method (ZM). The grown crystals were characterized by X-ray diffraction (XRD) and Neutron Diffraction (ND) and analyzed by the Rietveld Method. The melting behavior of this pure and trivalent rare earth doped-fluoride was investigated also by scanning electron microscopy (MEV) and X-ray energy dispersive spectroscopy (EDS). The concentration and distribution of the dopants in the grown crystals were measured, and when feasible, the segregation coefficient was estimated. The single crystals were also analyzed by absorption spectroscopy and emission spectroscopy in the case of the co-doped crystals. Evidences of the occurrence of energy transfer process in the UV for Nd-Pr were detected. From the study of the growth process single crystals of 40mm x 10mm in size, with good optical and structural quality were obtained for spectroscopy studies and tests of laser emission. Initial experiments were also performed in the growth of single crystalline fibers of this host doped with Tb3+, by the micro-pulling down method aiming a preliminary evaluation of the use of this growth process. Only semi-transparent fibers were obtained. Additional studies are necessary to improve the growth of single crystalline fibers of this fluoride.
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Thekedar, Bhushan. "Investigations on the use of breath gas analysis with Proton Transfer Reaction Mass Spectrometry (PTR-MS) for a non-invasive method of early lung cancer detection." kostenfrei, 2009. https://mediatum2.ub.tum.de/node?id=821780.
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Shan, Yixing. "Decision making study : methods and applications of evidential reasoning and judgment analysis." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/17330.
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Decision making study has been the multi-disciplinary research involving operations researchers, management scientists, statisticians, mathematical psychologists and economists as well as others. This study aims to investigate the theory and methodology of decision making research and apply them to different contexts in real cases. The study has reviewed the literature of Multiple Criteria Decision Making (MCDM), Evidential Reasoning (ER) approach, Naturalistic Decision Making (NDM) movement, Social Judgment Theory (SJT), and Adaptive Toolbox (AT) program. On the basis of these literatures, two methods, Evidence-based Trade-Off (EBTO) and Judgment Analysis with Heuristic Modelling (JA-HM), have been proposed and developed to accomplish decision making problems under different conditions. In the EBTO method, we propose a novel framework to aid people s decision making under uncertainty and imprecise goal. Under the framework, the imprecise goal is objectively modelled through an analytical structure, and is independent of the task requirement; the task requirement is specified by the trade-off strategy among criteria of the analytical structure through an importance weighting process, and is subject to the requirement change of a particular decision making task; the evidence available, that could contribute to the evaluation of general performance of the decision alternatives, are formulated with belief structures which are capable of capturing various format of uncertainties that arise from the absence of data, incomplete information and subjective judgments. The EBTO method was further applied in a case study of Soldier system decision making. The application has demonstrated that EBTO, as a tool, is able to provide a holistic analysis regarding the requirements of Soldier missions, the physical conditions of Soldiers, and the capability of their equipment and weapon systems, which is critical in domain. By drawing the cross-disciplinary literature from NDM and AT, the JA-HM extended the traditional Judgment Analysis (JA) method, through a number of novel methodological procedures, to account for the unique features of decision making tasks under extreme time pressure and dynamic shifting situations. These novel methodological procedures include, the notion of decision point to deconstruct the dynamic shifting situations in a way that decision problem could be identified and formulated; the classification of routine and non-routine problems, and associated data alignment process to enable meaningful decision data analysis across different decision makers (DMs); the notion of composite cue to account for the DMs iterative process of information perception and comprehension in dynamic task environment; the application of computational models of heuristics to account for the time constraints and process dynamics of DMs decision making process; and the application of cross-validation process to enable the methodological principle of competitive testing of decision models. The JA-HM was further applied in a case study of fire emergency decision making. The application has been the first behavioural test of the validity of the computational models of heuristics, in predicting the DMs decision making during fire emergency response. It has also been the first behavioural test of the validity of the non-compensatory heuristics in predicting the DMs decisions on ranking task. The findings identified extend the literature of AT and NDM, and have implications for the fire emergency decision making.
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Landvogt, Niclas. "Nicht- invasive Darstellung der Peritonealkarzinose im Mausmodell mittels PET und Biolumineszenz : Imaging sowie Bewertung der beiden Methoden hinsichtlich ihrer Sensitivität." kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=797074.
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Pipis, Konstantinos. "Eddy-current testing modeling of axisymmetric pieces with discontinuities along the axis by means of an integral equation approach." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS176/document.
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Le contrôle non destructif (CND) de pièces pour des applications dans l'industrie a mené au besoin de modèles rapides et précises. Tels modèles servent au développement des méthodes d'inspection, à l'optimisation des capteurs utilisés aux essais, à l'évaluation des courbes de Probabilité de Detection (POD) ainsi qu'à la caractérisation de défauts. Cette thèse se focalise au CND par Courants de Foucault (CF) de pièces cylindriques avec des discontinuités selon z et contenant un défaut fin. Un modèle pour l'inspection de telles pièces a été développé afin de traiter des applications comme l'inspection des pièces alésées trouvées en aéronautique et des tubes des générateurs de vapeur utilisés dans l'industrie nucléaire. Ce modèle est basé sur une formulation d'équation intégrale. Plus précisément, la variation de l'impédance du capteur, dit signal CF, est calculée à partir d'une équation intégrale sur la surface du défaut. La formulation suivie est basée sur la méthode d'intégration surfacique (SIM). Cette formulation nécessite, d'un côté, le calcul du champ électrique en absence du défaut et, de l'autre côté, l'expression d'une fonction de Green qui correspond à la géométrie de la pièce sans défaut. Les deux problèmes électromagnétiques sont résolus en utilisant la méthode Truncation Region Eigenfunction Expansion (TREE). La méthode TREE est un outil performant pour la résolution des problèmes électromagnétiques qui prend en compte la décroissance rapide de l'intensité du champ afin de tronquer le domaine d'intérêt à une distance, où le champ est négligeable.Le modèle est validé en comparant le signal CF calculé avec des résultats obtenues par une approche combinant la méthode d'intégration volumique (VIM) et SIM, dite l'approche VIM-SIM (implémentée dans la plateforme CIVA) ainsi qu'avec le modèle d'éléments finis (FEM). Nous avons traité trois configurations différentes : un demi-espace conducteur alésé avec un défaut fin, une plaque conductrice avec un alésage et un défaut, et un tube semi-infini avec un défaut fin à la proximité de son bord. La comparaison des résultats montre un très bon accord entre les trois modèles. Le temps de calcul avec le modèle SIM est considérablement inférieur aux temps de calcul des autres modèles. En outre, le modèle SIM donne la possibilité d'effectuer le balayage du capteur dans le tube ou l'alésage dans le cas des pièces alésées<br>Nondestructive Testing (NDT) of parts for industrial applications such as in nuclear and aeronautical industry has led to the need for fast and precise models. Such models are useful for the development of the inspection methods, the optimisation of probes, the evaluation of the Probability of Detection (POD) curves or for the flaw characterisation.This PhD thesis focuses on the eddy-current NDT of layered cylindrical pieces with discontinuities in the z direction and containing a narrow crack. A model for the inspection of such pieces is developed in order to be applied on the inspection of fastener holes met in aeronautics and of steam generator tubes in nuclear sector.The model is based on an integral equation formalism. More precisely, for the calculation of the impedance change one needs to solve an integral equation over the surface of the narrow crack, which is represented by a surface electric dipole distribution. This is the method known as surface integration method (SIM). This formulation requires, on the one hand, the calculation of the electric field in the absence of the flaw, the so-called primary field, and, on the other hand, the Green's function expression corresponding to the geometry of the flawless piece. Both electromagnetic problems are solved by means of the Truncation Region Eigenfunction Expansion (TREE) method. The TREE method is a powerful tool for the solution of electromagnetic problems which uses the rapid decrease of the field in order to truncate the region of interest at a distance where the field is negligible.The model is validated by comparing the results of the coil impedance variation with those obtained by an approach that combines the volume integral method (VIM) with SIM, known as VIM-SIM method, implemented in the commercial software CIVA and the finite element method (FEM) implementation in COMSOL software. Three different configurations have treated. The more general geometry of a conducting half-space with a borehole, a conducting plate with a borehole and a crack and a conducting semi-infinite tube with a crack near the edge. The results of the three models show good agreement between them. The computational time of the SIM model is significantly lower compared to previous models. Furthermore, another advantage of the SIM model is that it provides the possibility of a scan inside the borehole
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Kermani, Behnoud. "Application of P-wave Reflection Imaging to Unknown Bridge Foundations and Comparison with Other Non-Destructive Test Methods." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/234113.
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Civil Engineering<br>M.S.C.E.<br>Proper design of bridge structures requires an appreciation for the possible failure mechanisms that can develop over the lifetime of the bridge, many of which are related to natural hazards. For example, scour is one of the most common causes of bridge failures. Scour occurs due to the erosion of soil and sediment within a channel with flowing water. During a flood event, the extent of scour can be so great that it can destabilize an existing bridge structure. In order to evaluate the scour potential of a bridge, it is necessary to have information regarding the substructure, particularly the bridge foundations. However, as of 2011 there are more than 40,000 bridges across United States with unknown foundations. Generally for these bridges there are no design or as-built plans available to show the type, depth, geometry, or materials incorporated into the foundations. Several non-destructive testing (NDT) methods have been developed to evaluate these unknown foundations. The primary objective of this research is to identify the most current and widely used NDT methods for determining the embedment depth of unknown bridge foundations and to compare these methods to an ultrasonic P-wave reflection imaging system. The ultrasonic P-wave reflection system has tremendous potential to provide more information and address several short-comings of other NDT methods. A laboratory study was initiated to explore various aspects related to the P-wave system performance, in order to characterize the limitations of the system in evaluation of unknown foundations prior to deployment in field studies. Moreover, field testing was performed using the P-wave system and a number of the current NDT methods at two selected bridge foundations to allow comparison between the results.<br>Temple University--Theses
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Färnqvist, Christian. "”Närmast i tiden är det ju blåssidan som gått ned.” : En studie om musiklärares och rektorers syn på barns instrumentval och kommunala musik- och kulturskolors rekryteringsmetoder." Thesis, Karlstad University, Division for Ingesund College of Music, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1673.
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<p>The purpose of this study is, on one hand, to obtain an understanding of how children in municipal music- and culture schools choose instruments and what forms of recruitment methods they are subjected to, and on the other hand, how you can make them continue to play once they have begun.</p><p>To acquire this information, I have interviewed five music teachers and two principals at municipal music- and culture schools in Värmland. The questions treated, among other things, what affects children’s instrument preferences, recruitment methods and what you can do to keep interest for the chosen instrument alive.</p><p>The result of the study shows some apparent tendencies. Even though some of the instruments have trouble recruiting students and other instruments have trouble keeping them, the old methods, which obviously do not work in a satisfactory manner, are still being used. Instead, increased commitment at the occasion of recruitment, more group teaching which strengthens the social bonds through role models and a will to have the courage to change the organization when it does not work, is required.</p>
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Liu, Danny Xin. "Characterization of Next Generation Lithium-ion Battery Materials Through Electrochemical, Spectroscopic, and Neutron-Based Methods." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437746661.
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Van, der Westhuizen Nicolé. "Gradient calculations of non-orthogonal meshes in the finite volume method / N. van der Westhuizen." Thesis, North-West University, 2013. http://hdl.handle.net/10394/9722.
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The handling of gradient calculations on non-orthogonal meshes in the Finite Volume Method (FVM) is important in the modelling of complex geometries, since different implementation methods have an influence on the accuracy and the stability of the solution. The application in the current study is the numerical solution of heat conduction in a complex geometry. It finds relevance in many engineering applications such as the Micro-Channel Heat Exchanger (MCHE) that acts as a recuperator in a High Temperature Reactor (HTR) power generation cycle. A program based on the FVM was developed in Excel for the solution of the diffusion equation on a non-orthogonal mesh. A test case of heat conduction in a rectangular block, meshed with a tetrahedral mesh, was solved with the Excel code. The same test case was solved with OpenFOAM. The results of the two codes were compared. Small differences were found and their origins were traced to slightly different implementation methods. Knowledge of the differences in implementation between the two codes resulted in a better understanding of the aspects that influenced accuracy and stability. Computations on meshes with the presence of mesh skewness and non-orthogonal mesh lines at boundaries were performed and an accompanying decrease in accuracy was observed. The results showed that the standard FVM as implemented in the Excel code and in OpenFOAM will need advanced methods to compensate for mesh skewness and non-orthogonality found at boundaries. During the study, a deeper knowledge and understanding was gained of the challenge of obtaining accurate solutions of heat conduction on non-orthogonal meshes. This knowledge may lead to the overall improvement of the simulation of heat transfer models in general and for the MCHE specifically.<br>Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013.
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BU, JLDAIN HAFETH. "Behaviour and Inspection of Novel Non-Crimp Dry Thick Reinforcement Fabrics." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32383.
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Aerospace structural components made from polymer matrix composites (PMCs) offer numerous advantages. Their high stiffness and high strength combined with low densities enable lower fuel consumption coupled with higher payloads. As a result, PMCs provide an important economic advantage over typical metallic airframes. Textile reinforcements for PMCs are made by assembling reinforcement fibres, typically carbon. Then, the textile reinforcements are typically cut into smaller pieces, stacked, draped and assembled into a dry assembly called a preform, the shape of which generally approaches that of the PMC part to be made. This manufacturing process is labour intensive and expensive.
Novel thick, net-shape, drapable, high vf textile reinforcements used toward manufacturing aerospace PMCs are being developed at the University of Ottawa. The technology enables the manufacturing of flat, drapable multilayered near net-shape preforms. The bending and in-plane shear behaviours of such novel thick reinforcement textiles was investigated to understand and define the behaviour of such thick fabric reinforcements when formed into required shapes. A bending apparatus was developed for investigating the bending behaviour of these novel thick reinforcement fabrics and an articulated frame shear rig was used for investigating the in-plane shear behaviour. A non-destructive inspection method using infrared imaging was used for investigating and identifying flaws and defects in these thick, dry textile reinforcements, aiming at increasing the quality and reproducibility of the final PMC parts made from these reinforcements.
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Lopresti, Mattia. "Non-destructive X-ray based characterization of materials assisted by multivariate methods of data analysis: from theory to application." Doctoral thesis, Università del Piemonte Orientale, 2022. http://hdl.handle.net/11579/143020.
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X-ray based non-destructive techniques are an increasingly important tool in many fields, ranging from industry to fine arts, from medicine to basic research. Over the last century, the study of the physical phenomena underlying the interaction between X-rays and matter has led to the development of many different techniques suitable for morphological, textural, elementary, and compositional analysis. Furthermore, with the development of the hardware technology and its automation thanks to IT advancements, enormous progress has been made also from the point of view of data collection and nowadays it is possible to carry out measurement campaigns by collecting many GigaBytes of data in a few hours. Already huge data sets are further enlarged when samples are analyzed with a multi-technique approach and/or at in situ conditions with time, space, temperature, and concentration becoming additional variables. In the present work, new data collection and analysis methods are presented along with applicative studies in which innovative materials have been developed and characterized. These materials are currently of high application interest and involve composites for radiation protection, ultralight magnesium alloys and eutectic mixtures. The new approaches have been grown up from an instrumental viewpoint and with regard to the analysis of the data obtained, for which the use and development of multivariate methods was central. In this context, extensive use has been made of principal component analysis and experimental design methods. One prominent topic of the study involved the development of in situ analysis methods of evolving samples as a response to different types of gradients. In fact, while in large structures such as synchrotrons carrying out analyzes under variable conditions is now consolidated practice, on a laboratory scale this type of experiments is still relatively young and the methods of data analysis of data sets evolving systems have large perspectives for development especially, if integrated by multivariate methods.
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Jansson, Adam. "Master thesis within light warhead for support weapon : Investigation of defects, methods and requirement specifications in order to get a shell body shatter free." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-45443.
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At launching the shell body, especially the backplane of the shell body, will be exposed to very high stresses due to acceleration, pressure and increased temperature from the propellant combustion. Defects in the shell body could in worst case for example result in high temperature gas leakage into the warhead and thereby ignite the explosives before exiting the launcher. This kind of explosion results in serious damages and can seriously injure both the gunner and other people in the surroundings. According to earlier study, carbon fibre reinforced epoxy with filament winding manufacturing method was the primary focus. The purpose of this master thesis was to investigate requirements and testing methods on a shell body manufactured in composite that will guarantee the safety of the gunner and surroundings in the launch phase. The pre-study conducted in this project showed that matrix cracks and fibre breakages are most common defects in the shell body that occur during launching affected by burst pressure. Matrix crack is the less dangerous defect among the impact damage types. Discussion with composite manufacturing companies showed that fibre breakage is a very serious type of defect since more breakage of fibres leads to the shell body have reduced stresses and cannot built-up the fully potential burst pressure during launching. Two requirement specifications were carried out, one for the shell body and another for the detection methods. These were created by own research and ideas according to found information, telephone- and e-mail contact with experts in areas and with personnel at Saab Dynamics AB. Some requirements for the shell body were that it should be fully usable after drop tests from different heights, vibration and transportation tests yield no cyclic damage after a long transport. Furthermore, the shell body should always use a fully isolated driving band to not have hot explosive gases penetrated into critical sections which results in detonation already in the launcher barrel. The most important requirements for the detection methods were to have depth analysis, high reliability and in-field inspection. Elimination- and decision matrices were made to find which detection methods should be the final selections in order to find the defects in a shell body. The detection methods which did not fulfil the criteria from each separate matrix were eliminated and did not proceed further as a concept. Eliminations were performed in concept generation phase (elimination matrix) and concept selection phase (decision matrix). In final selection phase a couple of methods were chosen that together found as many defects as possible. By using both acoustic emission and shearography all the critical defects and a wide range of other defects can be detected with very high reliability and resolution at an acceptable cost. These two methods “interact” perfectly with each other. Acoustic emission is the best method to find fibre breakage and matrix cracks, which are the most commonly occurring defects during launching. But shearography does not have a good detectability of fibre breakage and matrix cracks. On the other hand, shearography has good detectability of both planar- and volumetric defects. It is concluded that only two inspection methods, i.e. acoustic emission and shearography are needed to detect all of the possible defects in the grenade shell body. This is more economical solution requiring smaller space and fewer operators compared to one separate NDT method for detecting each type of defect.<br>Vid utskjutning av granathylsan utsätts framförallt bakplanet, för mycket höga påfrestningar genom acceleration, tryck och förhöjd temperatur från krutförbränningen. Vid en genombränning av granatskalet skulle sprängämnet i verkansdelen kunna tändas redan i eldröret och orsaka en vapensprängning. Den här typen av explosion resulterar i allvarliga skador både för skytten samt folk i dess omgivning. Med hänsyn till tidigare studier har det varit fokus på kolfiberförstärkt epoxi som är tillverkad av fiberlindning. Syftet var att utreda kravställningar och metoder för provning, som garanterar skyttens och omgivningens säkerhet i utskjutningsfasen av en granat tillverkad av kompositmaterial. Från förstudien i denna rapport visade sig att matrissprickor och fiberbrott är de vanligaste defekter som uppstår i granathylsan under utskjutningsfasen där den största påverkan är ifrån explosionstrycket. Matrissprickor är de mindre farliga defekter av de som uppstår under intryckning. Diskussion med komposittillverkande företag visade att fiberbrott är en väldigt farlig typ av defekt eftersom fibrerna står för styrkan och brott av fibrer leder till att granathylsan klarar av att utsättas för lägre påfrestningar och kan inte hjälpa till att bygga upp det önskvärda trycket som önskas under utskjutningen. Två kravspecifikationer utfärdades, en för granathylsan och en annan för detekteringsmetoderna. Dessa två skapades genom egen studie och idéer med hänsyn till hittad information, ifrån telefon- samt email kontakt med experter inom områdena samt med hjälp av personal på Saab Dynamics AB. Några krav som valdes för granathylsan var att den ska vara fullt användbar efter fallskärmsprovning från olika höjder, vibration- och transport tester för att inte få cykliska skador efter en lång transportering samt att alltid ha en fullt isolerad gördel så att inte de heta gaserna från explosivorna tänds redan i eldröret vilket orsakar vapensprängning. Några krav för detekteringsmetoder var att de ska kunna göra mätningar/analyser på djupet, ha hög trovärdighet samt vara portabel. Eliminering- och beslutsmatriser gjordes för att hitta vilka detekteringsmetoder som skulle bli de slutliga valen i jakten på att finna defekterna i granathylsan. De metoder som inte uppfyllde kriterierna från respektive matris blev eliminerade. Elimineringen utfördes i faserna för konceptgenerering och konceptval. I slutliga valet valdes ett par lämpliga metoder som tillsammans hittar så många defekter som möjligt. Genom att använda akustisk emission samt shearografi hittades samtliga kritiska defekter plus många andra som inte anses vara kritiska med väldigt hög trovärdighet och upplösning till ett mer acceptabelt pris. Metoderna samverkar väldigt bra med varandra eftersom akustisk emission är bästa metoden att hitta fiberbrott och matrissprickor vilket är vanligt förekommande i utskjutningsfasen. Shearografi har inte samma detekterbarhet på dem två defekterna men de har å andra sidan istället väldigt god detekterbarhet på både volymetriska- och plana defekter. Slutsatsen är att endast två metoder behövdes för att finna alla defekter vilket blir mer ekonomiskt, tar mindre plats och behöver färre certifierade operatörer jämfört med om man ska ha en detekteringsmetod för att finna respektive defekt.
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Murphy, Michael W., and Michael E. Barkenhagen. "The Sunset Supply Base long term COTS supportability, implementing affordable methods and processes." Thesis, Monterey, California. Naval Postgraduate School, 2003. http://hdl.handle.net/10945/1154.
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Approved for public release; distribution in unlimited.<br>This thesis represents a cross Systems Command (NAVSEA/NAVAIR) developed product. The product - the Sunset Supply Base (SSB) system - provides a complete system for addressing the risks and supportability issues involved with Commercial Off the Shelf (COTS) products in Navy combat and support systems. The SSB system was implemented on three Navy combat weapon systems at various phases of the product development life cycle. The main body provides to the Program Management Offices (PMO) and other decision makers, a high level summary of performance expectations. Appendix A - The Sunset Supply Base Architecture - identifies at a high level of abstraction a collaborative architecture providing a roadmap for design and development of the SSB system. Appendix B - The Systems Engineering Development and Implementation (SEDI) plan - is a prescriptive or "How to" manual describing activities that have been used to successfully implement the SSB system. Appendix C - Business Case Analysis (BCA) - presents the data collected as a result of SEDI plan implementation then addresses the business/programmatic attributes showing the viability and value proposition possible through the SSB system. Appendix D - The Marketing Plan for the SSB system - defines methods and practices necessary to establish the SSB system as the alternative of choice.<br>Chemical Engineer, United States Navy<br>Systems Engineer, United States Navy
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Ghodhbani, Nacef. "Contrôle et suivi des propriétés visco-élastiques d'un composite en cours de fabrication." Thesis, Le Havre, 2016. http://www.theses.fr/2016LEHA0008/document.
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Les transducteurs ultrasonores font l'objet de nombreux développements en contrôle non-destructif (CND) industriel. Utilisé ponctuellement et périodiquement, le CND ultrasonore permet d'établir des diagnostics sur la santé des matériaux. La caractérisation ultrasonore en temps réel constitue un outil de surveillance de l'évolution des propriétés physiques lors de la fabrication des matériaux composites. Dans ce contexte, des études sont menées au LOMC pour optimiser le procédé de fabrication des matériaux composites par RTM (Resin Transfer Molding) afin d’améliorer la qualité du produit. Ce travail de thèse consiste à développer des méthodes ultrasonores pour le suivi des propriétés viscoélastiques d’un composite pendant la phase de production. Les propriétés viscoélastiques sont étudiées à l’aide de modèles théoriques, de simulations numériques et de résultats expérimentaux. Des études de calibration ont été menées afin d’étudier les facteurs d’influence sur le suivi de propriétés ultrasonores lors de la mise en oeuvre d’un procédé RTM. Le suivi des paramètres viscoélastiques de résines époxy est effectué dans un premier temps à basse température au cours d'une polymérisation isotherme et d’une post-cuisson. Ensuite, une approche basée sur la méthode de caractérisation en émission/transmission a été développée afin d’étudier le comportement à haute température. La modélisation de la réponse électroacoustique par série de Debye (DSM) a été effectuée en se basant sur des approches analytiques. L’utilisation des transducteurs multiéléments permet la localisation et le dimensionnement de défauts lors du déplacement de fibres de carbone dans une résine liquide, entre des moules<br>The developments based on ultrasonic transducers are nowadays numerous in the industrial non-destructive testing (NDT). Used punctually and periodically, the ultrasonic NDT is used for health diagnostics of materials. Ultrasonic characterization in real time allows a physical properties monitoring during the manufacturing of composite materials. In this context, studies are conducted in LOMC in view to optimize the manufacturing process of composite materials using RTM (Resin Transfer Molding) in order to improve the product quality. This work consists to develop ultrasonic methods for the monitoring of viscoelastic properties during the production phase of composites. The viscoelastic properties are studied using theoretical models, numerical simulations and experimental measurements. Calibration studies were carried out to study the influencing factors on the monitoring of ultrasonic properties during the RTM process. The monitoring of viscoelastic parameters of epoxy resins is performed in a first time at low temperature during an isothermal polymerization and a post-curing. Then, an approach based on the transmission mode characterization was developed to study high-temperature behavior. Based on analytical approaches, the electroacoustic response was simulated by Debye series method (DSM). The use of phased array transducers was investigated for the location and sizing of defects during the movement of the carbon fiber in a liquid resin between the molds
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Björling, Linnéa, and Gardell Alicia Diaz. "Reparation av inbyggda stålbalkar : Ekonomiska och tidseffektiva förstärkningsmetoder med låg klimatpåverkan." Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259636.
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CE-märkta stålbalkar byggdes in i två konstruktioner innan det upptäcktes att det fanns porer i hattbalkarnas svets. Den defekta svetsen innebar att byggnadernas bärförmåga inte kunde garanteras. Kunskapen kring inbyggt stål stommaterial med defekt svets är liten. Det är dessutom svårt att reparera och undersöka stålbalkarnas svets när de är inbyggda i konstruktionen. Syftet med examensarbetet är att hitta förstärkningsmetoder och därmed främja kortare hanteringstid vid händelse av att defekta stålbalkar byggs in i en konstruktion. Metoden består av litteraturstudie och intervjuer. Först granskas litteratur för att förstå problematiken med defekt svets i stål stommaterial. Därefter utförs intervjuer med personer erfarna inom stål och byggteknik. Examensarbetets resultat är ett flertal förstärkningsmetoder för inbyggda stålbalkar med defekt svets. Några av förstärkningsmetoderna är möjliga att utföra med den kunskap som finns idag medan andra behöver undersökas och värderas innan de kan implementeras. Förstärkningsmetoderna som är möjliga att utföra med dagens kunskap är: att svetsa om balken från insidan eller att placera en balk/fackverksbalk under den befintliga balken. De metoder som behöver undersökas och värderas vidare är: skruvförband genom balken, efterspänna balken med vajrar eller GWS-stag och sedan fylla den med betong, föra in en balk inne i balken och fylla balken med betong och att kolfiberförstärka svetsen. Slutsatsen är att den här studien kan ligga till grund för framtagning av åtgärder för inbyggda stålbalkar med defekt svets med mål att uppnå den dimensionerade hållfastheten och en lösning som är tidseffektiv, kostnadseffektiv och har låg klimatpåverkan.<br>Before the discovery of pores in the weld, CE-certified steel beams were embedded in two constructions. Since the weld was defective, the carrying capacity of the two buildings was questioned. There is a lack of knowledge about embedded steel beams with a damaged weld. It is difficult to repair and analyze the weld when the beams are embedded in the construction. The aim of the study is to find reinforcement methods for steel beams. The expectation is to shorten time in the production in case that defective steel beams are detected in the construction. The method consists of a literature study complemented by interviews. Literature is examined to understand the problem of defective welding in the steel framework. Subsequently, interviews are conducted with professionals within steel and building technology. The result of the report is multiple reinforcement methods for embedded steel beams with a defective weld. Some of the methods are possible to implement with the knowledge available today. Other methods need to be examined and assessed before executed. The reinforcement methods that are possible to perform are: weld the beam from the inside or place a beam underneath the existing beam. The methods that need further analysis are: drill a screw joint through the beam, strain the beam with steel-wires and fill the inside with concrete, place a beam inside the existing beam and fill the inside with concrete and last to reinforce the weld with carbon fibers. The conclusion is that this study can be used when reinforcement methods are needed for embedded steel beams with a defective weld. The objective with these methods is to restore the load-bearing capacity as well as finding a solution that is time efficient, economic and has low climatic influence.
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Haïat, Guillaume. "Étude d'une méthode d'inversion basée sur la simulation pour la caractérisation de fissures détectées par ultrasons dans un composant revêtu." Phd thesis, Université Paris-Diderot - Paris VII, 2004. http://tel.archives-ouvertes.fr/tel-00007345.
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Le travail effectué au cours de cette thèse porte sur l'inversion de données ultrasonores. Le contexte industriel en est le contrôle non destructif des cuves de réacteurs à eau pressurisée. Ces contrôles visent à détecter et caractériser des fissures. Les données ultrasonores se présentent sous la forme d'échographies obtenues à l'aide d'un capteur fonctionnant en émission-réception. Les fissures sont détectées par diffraction de leurs arêtes. L'analyse des données obtenues est rendue difficile du fait de l'existence d'un revêtement dont la surface est irrégulière et dont le matériau diffère du matériau constitutif de la cuve. Une méthode est ici proposée pour localiser avec précision les arêtes diffractantes et donc permettre un dimensionnement des fissures à partir des échographies ultrasonores obtenues. Cette méthode s'appuie sur l'application d'outils de modélisation de la propagation et de la diffraction des ultrasons prenant en compte à la fois le caractère irrégulier de la surface et la nature hétérogène du composant. La méthode développée a fait l'objet d'une implémentation informatique et a pu être testée sur un ensemble de cas représentatifs. En particulier, ses performances ont été évaluées à partir de l'analyse de résultats expérimentaux. La précision obtenue en laboratoire sur les cas expérimentaux traités est conforme à la demande industrielle qui a motivé cette étude.