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Made available in DSpace on 2014-10-09T12:35:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:55Z (GMT). No. of bitstreams: 0 / Os tubos de Geradores de Vapor em Reatores Nucleares do tipo PWR são submetidos a diferentes níveis de tensões e carregamento em altas temperaturas, reduzindo sua vida útil devido o surgimento de defeitos e corrosão. A inspeção por Correntes Parasitas é um ensaio não destrutivo usado para diagnosticar defeitos de corrosão e descontinuidades na superfície externa e interna em tubos de trocadores de calor. Esses tubos estão sujeitos a danos por diferentes mecanismos de degradação mecânica e química, tais como trincas por fadiga e corrosão sob tensão. Os sinais de inspeção por Correntes Parasitas são afetados por diferentes ruídos dificultando sua análise pelo inspetor. Esse trabalho apresenta os resultados da análise dos sinais de Correntes Parasitas usando a Transformada de Hilbert-Huang (THH) funcionando como filtro de ruídos (De-noising), como uma técnica alternativa de processamento e análise de sinais. A Transformada de Hilbert-Huang teve esse nome atribuído pela agência espacial norte-americana (NASA) para o resultado da reunião de dois processos, um método de decomposição empiricamente modal (Empirical Mode Decomposition EMD), seguido da análise espectral de Hilbert (Hilbert Spectral Analysis HSA). Os sinais de inspeção por correntes parasitas possuem características de transiente, não estacionário e não linear. A transformada de Hilbert-Huang aplicada neste trabalho forneceu dois recursos alternativos em processamento de sinais; o pré-processamento que funcionou como filtro de ruídos, e outro de análise de sinais, responsável pela identificação das características tempo-frequência-energia do sinal. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Carbonfaserverstärkten Kunststoffen (CFK) erzielen ihre herausragende Festigkeit und Steifigkeit durch exakte Anpassung der Faserverläufe im Bauteil an die im Einsatz wirkenden Belastungen. Für eine Qualitätskontrolle und eine Optimierung der Fertigungsverfahren ist daher ein Verfahren notwendig, das in der Lage ist, die Faserorientierung in 3D-Preforms (mehrlagigen, drapierten Vorformlingen aus trockenen Carbonfasern) und 3D-CFK zerstörungsfrei zu messen und mit der Soll-Faserorientierung zu vergleichen. Die derzeit für die Faserorientierungsmessung eingesetzten optischen bzw. Röntgen-CT-Verfahren sind hierfür nur beschränkt geeignet, da optische Verfahren auf die oberste Lage und Röntgen-CT-Verfahren auf Kleinproben beschränkt sind. In dieser Arbeit wird daher ein Verfahren entwickelt, das die Faserorientierung in mehrlagigen 3D-Carbonfaserpreforms und -CFK zerstörungsfrei messen kann. Grundlage hierfür ist die Hochfre-quenz-Wirbelstromprüfung, die eine Darstellung der Verläufe der leitfähigen Carbonfäden in den einzelnen, übereinander gestapelten Lagen des CFK erlaubt. Um hierauf aufbauend eine vollauto-matische Faserorientierungsmessung zu schaffen, wird in einem ersten Schritt ein Roboter-Bahnplanungsverfahren zur vollständigen Erfassung komplex geformter 3D-Oberflächen entwi-ckelt. Aus dem erhaltenen 3D-Wirbelstrombild der Oberfläche wird anschließend über einen auf lokaler Abwicklung und Fouriertransformation beruhenden Algorithmus die lokale Faserorientie-rung in den einzelnen Lagen gemessen und die 3D-Verläufe einzelner Fäden werden rekonstruiert. Die Messunsicherheit des Verfahrens wird anhand systematischer experimenteller Untersuchungen an 2-, 4-, 6- und 8-lagigen 2D-Gelegestapeln quantifiziert. Untersucht wird hierbei auch der Einfluss der Materialparameter (Gelegetyp) sowie der Messparameter (Spulenanordnung, Spulendurch-messer, Sensororientierung, Messfrequenz) auf die sich ergebende Messunsicherheit, woraus Empfehlungen für die Wahl von Sensor und Messfrequenz abgeleitet werden. Das entwickelte Messverfahren wird anschließend an zwei 3D-Anwendungsfällen validiert. Als erster Anwendungsfall wird ein vierlagiges, komplex geformtes CFK-Bauteil betrachtet. Es wird gezeigt, wie mithilfe des entwickelten Messverfahrens die Faserorientierung aller vier Lagen zerstörungsfrei erfasst werden kann. Verschiedene Exemplare desselben Bauteils werden hinsicht-lich der Faserorientierung verglichen. Anschließend wird im zweiten Anwendungsfall ein automati-scher Drapierprozess zu einer Halbkugel betrachtet, bei dem verschiedene, ein-, zwei und vierlagi-ge textile Halbzeuge hinsichtlich der sich ausbildenden Faserorientierung nach der Drapierung verglichen werden, mit dem Ziel, das Verformungsverhalten mehrlagiger Strukturen besser zu verstehen und Empfehlungen für die Halbzeugauswahl abzuleiten. In einem abschließenden Schritt werden Schnittstellen geschaffen, um die Faserorientierungsmes-sung in den CFK-Entwicklungsprozess zu integrieren. Zum einen wird durch eine Schnittstelle zur Drapiersimulation ein quantitativer Vergleich zwischen vorausgesagter und Ist-Faserorientierung möglich, zum anderen wird gezeigt, wie die gemessenen Faserorientierungen der Einzellagen direkt zur Parametrierung von Struktursimulationen verwendet werden können. Das entwickelte Verfah-ren ermöglicht damit eine fundierte Festigkeits- und Steifigkeitsanalyse mit den zerstörungsfrei gemessenen Faserorientierungen nach dem Umformprozess.:1 Einleitung 2 Grenzen bestehender Verfahren zur Faserorientierungsmessung bei der CFK-Herstellung 3 Stand der Technik zur Wirbelstromprüfung von Carbonfasermaterialien 4 Entwicklung einer Roboter-Bahnplanung zur vollständigen Erfassung einer 3D-Oberfläche 5 Entwicklung einer Faserorientierungsmessung aus 3D-Wirbelstromdaten 6 Experimentelle Untersuchung der Messunsicherheit an 2D-Gelegestapeln 7 Verfahrenserprobung an mehrlagigen 3D-Preforms und CFK 8 Integration der Faserorientierungsmessung in den CFK-Entwicklungsprozess 9 Zusammenfassung und Ausblick / The superior strength and stiffness of carbon fiber reinforced plastics (CFRP) results from an exact adaptation of the component’s fiber orientation to the external loads during service. Quality control, as well as development and optimization of the production processes, thus require a method to non-destructively measure the fiber orientation in 3D preforms (draped multilayer stacks made of dry carbon fibers) and CFRP. Currently, this fiber orientation measurement is done by optical or X-ray computer tomography methods, which are limited, however to the uppermost, optical visible fabric layer (optical methods) or to small sample sizes (X-ray computer tomography). Therefore, this thesis develops a method to non-destructively measure the 3D fiber orientation in multi-layer 3D preforms and CFRP. The starting point for this development is the technique of high-frequency eddy current testing, which allows an imaging of the individual carbon yarn courses in multiple stacked textile layers. In order to develop a fully-automated fiber orientation measure-ment process with this technique, in a first step a robot path planning is developed that allows the complete scanning of a complexly-shaped 3D surface with an eddy current sensor. From the resulting 3D eddy current image of the surface, the local fiber orientation of the individual layers is measured by local development (flattening) of the surface and a Fourier transformation. The uncertainty of measurement for this method is quantified from experiments with 2-, 4-, 6- and 8-layer 2D non-crimp fabric stacks. The influence of the material parameters (type of fabric) as well as of the measurement parameters (sensor type, coil diameter, sensor orientation, measure-ment frequency) is evaluated. Recommendations for the choice of sensor and measurement frequency are derived. The developed measurement method is subsequently validated with two different 3D application cases. As a first application case, a four-layer, complexly-shaped CFRP component is analyzed. It is shown how the developed measurement method can be used to non-destructively measure the fiber orientation of all four layers. Different specimen of the same CFRP component are compared regarding fiber orientation. The second application case is an automated draping process to a hemispherical shape, for which one-, two- and four-layer textile fabrics are compared regarding the fiber orientation after draping, in order to better understand the forming properties of multi-layer structures and derive recommendations for the choice of textile. In the final step, software interfaces are developed to integrate the fiber orientation measurement into the CFRP design and development process. It is integrated with a draping simulation, to allow a quantitative comparison of the predicted and the measured fiber orientations. Furthermore, it is shown how the measured fiber orientation of the individual fabric layers can be used for the parametrization of finite element structural simulations. The developed measurement method thus lays the base for a substantiated strength and stiffness analysis based on the component’s actual as-is fiber orientation after the draping process.:1 Einleitung 2 Grenzen bestehender Verfahren zur Faserorientierungsmessung bei der CFK-Herstellung 3 Stand der Technik zur Wirbelstromprüfung von Carbonfasermaterialien 4 Entwicklung einer Roboter-Bahnplanung zur vollständigen Erfassung einer 3D-Oberfläche 5 Entwicklung einer Faserorientierungsmessung aus 3D-Wirbelstromdaten 6 Experimentelle Untersuchung der Messunsicherheit an 2D-Gelegestapeln 7 Verfahrenserprobung an mehrlagigen 3D-Preforms und CFK 8 Integration der Faserorientierungsmessung in den CFK-Entwicklungsprozess 9 Zusammenfassung und Ausblick

Le contrôle non destructif (CND) par Courants de Foucault (CF) de défauts de fissuration est l’une des techniques les plus répandues dans de nombreux secteurs industriels. L’utilisation d’outils de modélisation adaptés permet d’améliorer les procédés de contrôle et la compréhension des données expérimentales observées. Ce travail de thèse, réalisé au CEA LIST et sous la direction de D. Lesselier (Laboratoire des Signaux et Systèmes), a pour objectif de proposer une approche de modélisation semi-analytique dédiée à la simulation du CND CF de défauts fins ou très fins dans une pièce plane conductrice composée de plusieurs couches. Il a fait l’objet d’une collaboration, dans le cadre du projet CIVAMONT, avec l’équipe Meander de l’University of Western Macedonia (Grèce), dirigée par le professeur T. Theodoulidis.Du point de vue de la simulation, la complexité du problème à traiter est liée aux particularités des défauts de fissuration : une ouverture très fine, un profil complexe et la possibilité d’avoir des ponts de conductivité entre les deux faces latérales du défaut. Ces caractéristiques expliquent la difficulté qu’ont les méthodes de simulation classiques, semi-analytiques ou purement numériques, à traiter efficacement ce type de configuration. Pour ces raisons, une approche dédiée aux défauts fins, fondée sur la méthode des éléments de frontière, a été développée. Elle présente l’avantage majeur de ne requérir qu’une discrétisation surfacique du défaut, en traitant analytiquement le calcul dans la direction de son ouverture. Après la résolution, avec la Méthode des Moments, de l’équation intégrale décrivant les interactions entre le champ d’excitation et le défaut, la réponse de la sonde est calculée en appliquant le théorème de réciprocité. Les développements théoriques réalisés dans cette thèse ont abouti à la mise en place d’une formulation générale permettant la prise en compte d’un nombre quelconque de défauts fins, d’orientations et des géométries différentes, pouvant être situés dans des couches différentes de la pièce. Par la suite, cette méthode innovante a été implémentée au sein de la plateforme de simulation CIVA, développée au CEA LIST, et a été validée expérimentalement à plusieurs reprises. Une extension de cette méthode a également permis la mise en place d’une approche la couplant à une modélisation volumique standard pour la simulation de configurations complexes comme le contrôle de fissures au voisinage d’un alésage. Ce travail, qui a fait l’objet d’une diffusion internationale affirmée, a permis de lever avec succès un certain nombre de difficultés théoriques et pratiques liées à la modélisation du CND CF de défauts fins. / Non Destructive Testing (NDT) with Eddy Current (EC) techniques are is widely employed in several industrial sectors for cracks detection. Numerical simulation tools are largely used in order to design sensors, understand the signals collected during the measurements process and to provide a support in expertise. This work has been accomplished inside CEA LIST in collaboration with L2S-Supélec. It is also a part of the CIVAMONT 2012 project, with the active participation of MEANDER laboratory members from University of Western Macedonia (Greece) and Technological Educational Institute of Western Macedonia (Greece). The main goal of our work has consisted in to developing a semi-analytical modeling approach, devoted to Eddy Current Testing (ECT) of multiple narrow cracks in planar multilayered structures. From the numerical point of view, simulation of multiple narrow cracks problems is a difficult task for classical methods, like for example the Volume Integral Method (VIM) or the Finite Element Method (FEM). The main issues reside in geometrical characteristics of narrow crack themselves. Indeed, a narrow crack presents a small opening as well as complex profile and a complex shape, with possible electrical contacts inside it. All these features increase enormously, with classical methods, the difficulty to simulate in rapid and/or precise way problems involving narrow cracks. We have tackled the narrow crack issue by developing a Boundary Element Method (BEM) dedicated to ECT signal modeling, starting from an approach presented in literature. Then, we have extended its capability to more realistic and challenging cases, such as the ECT of multilayered structures affected by complex narrow cracks. The principle of this method is to introduce additional assumptions, leading to the description of the crack perturbation as the effect of a dipole distribution, oriented toward the crack opening. Numerically speaking, such a description makes it possible to largely reduce, compared to the VIM, the number of unknowns that one needs to properly solve the problem. A particular attention has been devoted to the analytical formulation, in order to achieve generality, accuracy and efficiency. A precise derivation of the spectral-domain Dyadic Green Function (DGF) associated to our problem has first been developed. In this work, analytical expressions of the spectral-domain DGF have been obtained via the Discrete Complex Image Method (DCIM). Then, an accurate approximation of the spectral-domain DGF has been achieved via the Generalized Pencil of Function (GPOF) method. Therefore, the closed-form of the spectral-domain DGF, expressed under the form of Sommerfeld Integrals (SIs), has been calculated analytically. Finally, the integral equation(s) associate to the electromagnetic problem is solved by applying the Method of Moments (MoM).Validations with respect to experiments and commercial simulation software have been performed to test the model. A large set of configurations have been chosen in order to address realistic configurations involving multiple narrow cracks embedded in different layers of a given multilayered structure. The model proposed has shown its promising performance in terms of computational time compared with the VIM and the FEM. Moreover, a very good agreement with respect to the experimental data has always been observed. In the last and very recent part of our work, a coupled approach between BEM and VIM has been studied and developed in order to address, in a efficient way, problems where narrow cracks appear in the vicinity of with volumetric flaws (for example the simulation of fastener sites inspections). Comparisons with experimental measures have shown that the coupled approach is capable to achieve, overall, better results than the VIM and saves a lot of computational time.

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La thèse a mis en œuvre deux méthodes inverses pour l’évaluation non destructive d’un milieu multicouche anisotrope : la microscopie acoustique et les courants de Foucault. Pour la microscopie acoustique, nous avons adapté un modèle de propagation de l'onde acoustique dans un milieu multicouche, en calculant les coefficients de réflexion et de transmission d’un revêtement multicouche sur un substrat et en modélisant la réponse acoustique V(z) propre à la microscopie acoustique. Une méthode inverse utilisant l’algorithme de Levenberg-Marquardt donne accès à l’épaisseur, au module de Young et à la densité du revêtement. Pour les courants de Foucault, une méthode inverse similaire basée sur le formalisme de Tree a été mise au point, qui donne accès à l’épaisseur, à la conductivité électrique et à la perméabilité magnétique du revêtement. Après des vérifications de l’algorithme sur des matériaux massifs de référence, nous avons appliqué ces méthodes à un métal revêtu pour tuyauteries de centrale thermique : de l’acier inoxydable austénitique type 304 revêtu par pulvérisation thermique de superalliage Hastelloy C22 à base de nickel. La corrosion sèche sous l’effet des gaz chauds (air contenant du gaz SO2) amincit graduellement la paroi des tubes, ce qui peut les rendre dangereux. Il a fallu tenir compte de l’effet du grenaillage préalable à la pulvérisation, qui crée une mince couche de martensite à laquelle les courants de Foucault sont très sensibles : un modèle à trois couches substrat / martensite / revêtement a été utilisé. Nous avons caractérisé des échantillons de métal avant et après exposition à l’air avec ou sans SO2 à 650°C. Les deux méthodes d’évaluation non destructive permettent une détermination très satisfaisante de l’épaisseur de revêtement et se complètent bien. L’évaluation des caractéristiques physiques (acoustiques et électromagnétiques) met en évidence des hétérogénités du revêtement liées à son mode d’élaboration et des évolutions au cours du temps. Des pistes d’amélioration des méthodes sont proposées. / In the current work, we investigate the nondestructive evaluation of a thermal sprayed coating (Hastelloy C22 Ni-based alloy) on substrate (type 304 austenitic stainless steel) using acoustic microscopy and ECT method. Two models were built for the evaluation of this kind of material: one is for acoustic V(z) measurement and the other is for swept eddy current measurement. The implementation of these two models is used for the evaluation and properties measurement of the thermal sprayed coatings, such as elastic properties, electromagnetic properties. In particular, the main achievements and results are as follows: 1. Acoustic wave propagation in an anisotropic multilayered medium was investigated. The formula for calculating the reflection and transmission coefficients of the multilayered medium on or without a substrate were derived, which is necessary for the modeling of acoustic V(z) measurement of the thermal sprayed coating on substrate. 2. A model was built for the acoustic V(z) measurement of the thermal sprayed coatings on substrate, which can deal with anisotropic multilayered media. Specifically, we used a model of multilayered coatings with graded properties on substrate to calculate the acoustic reflection coefficient of our sample. Treating the thermal sprayed coating, deposited on a 304 steel substrate, as FGMs, we evaluated the coating thickness and the Young’s modulus evolution along the depth of the coating. 3. A model was built for the swept eddy current measurement of the thermal sprayed coatings. Since before the spraying process, the surface of the substrate is usually shot-peened (SP), the coated material is considered as a three-layer medium. The coating thickness and electromagnetic properties of each of the 3 layers were determined by an effective reverse process. 4. The thermal sprayed coated material after exposure in different conditions, i.e., as-received, heat-treated in air and heat-treated in SO2 environment, and after different exposure time was evaluated by the integrity of acoustic microscopy and ECT method. The coating thickness and the electromagnetic properties of the coated material under different conditions were measured.

<p>I både kvalitets- och kontrollarbete finns det behov att kunskapsmässigt komma så nära verkligheten som möjligt vid fastställande av defektparametrar för oförstörande provning (OFP). Orsaken är att olika acceptanskrav och bedömningsgränser är svåra att klarlägga när man inte kan förlita sig på att uppgifter är realistiska. I projektet har olika erfarenheter använts för att få en bättre helhetsbild i området för defektparametrar och oförstörande provning.</p><p>Denna rapport redovisar den inledande delen av forskning och utvecklingsprojektet PLANT 2, där olika defektparametrar kartlagts och en teoretisk bedömning utförts med avseende på hur signalsvaret påverkas för OFP-metoderna virvelström (ET) och ultraljudsprovning (UT) i form av puls-eko (PE) och ”time-of-flight-diffraction” (TOFD).</p><p>Definitionen av redovisade defektparametrar följer i stort SKI-rapport 95:70 [1]. Defektparametrar i denna rapport redovisas i bilaga 1.</p><p>Vid bedömningen av defektparametrarnas inverkan på OFP-tekniker, har drift¬inducerande defekter och tillverkningsdefekter hanterats separat. För de driftinducerande defekterna delades bedömningen upp i en generell och en specifik bedömning. De defektparametrar som bedöms specifikt och klassats att påverka signalsvaret betydligt bör vara av mest intresse i nästkommande etapp. Följande defektparametrar bedömdes påverka signalsvaret betydligt:</p><p>• Form i ytan, antal sprickor och avstånd i gatstensmönster</p><p>(vid termisk ut¬mattning)</p><p>• Form i djupled</p><p>• Sprickbredd vid sprickspets och sprickspetsradie</p><p>För tillverkningsdefekter bedömdes defektparametrarnas form i djupled och geometri påverka signalsvaret betydligt för defekttyperna slagg och bindfel.</p><p>Vid utvärdering av UT-PE och UT-TOFD teknikerna överensstämde resultatet helt med den teoretiska bedömningen. För ET-tekniken stämde endast en av tre defektparametrar överens med den teoretiska bedömningen.</p> / <p>In quality control of defect parameters for Non-Destructive Testing (NDT) it’s essential to have good knowledge about the defects. The reason is that different acceptance criteria and assessments must be based on defects that correspond to real defects. In this project different experience has been analyzed to get a better overview between defect parameters and non-destructive testing.</p><p>This report shows the beginning of the research & development project PLANT 2. There are different flaw parameters that have been mapped and a theoretical assessment has been performed with regard to how the signal response is influenced by the NDT techniques eddy current, ultrasonic pulse echo and ultrasonic time-of-flight-diffraction.</p><p>The definition of the reported flaw parameters does in general follow the one presented in SKI-report 95:70 [1]. The actual flaw parameters in this report are presented in appendix 1.</p><p>In the assessment of the influences on the NDT techniques with regard to flaw parameters, service-induced flaws and manufactured flaws have been separated in to two categories. The service-induced flaws have further on been separated in a general and a specific assessment. Those flaw parameters that have been assessed to be specific and classified to influence the signal response considerably should be the ones of most interest in future studies. The following flaw parameters were assessed to affect the signal response considerably:</p><p>• Macroscopic shape in the surface direction, number of cracks</p><p>and cobblestone stone pattern distance (for thermal fatigue)</p><p>• Macroscopic shape in the through thickness direction</p><p>• Crack width at the crack tip and the crack tip radius</p><p>For flaws caused by the manufacturing process, type slag and lack of fusion, the flaw parameters “Macroscopic shape in the through thickness direction” and “the geometry” were influenced by the signal response considerably.</p><p>In the evaluation of signal response with the UT pulse echo and UT TOFD techniques, the result corresponded to the theoretical assessment. For the eddy current technique only one of three flaw parameters corresponded to the theoretical assessment.</p>

I både kvalitets- och kontrollarbete finns det behov att kunskapsmässigt komma så nära verkligheten som möjligt vid fastställande av defektparametrar för oförstörande provning (OFP). Orsaken är att olika acceptanskrav och bedömningsgränser är svåra att klarlägga när man inte kan förlita sig på att uppgifter är realistiska. I projektet har olika erfarenheter använts för att få en bättre helhetsbild i området för defektparametrar och oförstörande provning. Denna rapport redovisar den inledande delen av forskning och utvecklingsprojektet PLANT 2, där olika defektparametrar kartlagts och en teoretisk bedömning utförts med avseende på hur signalsvaret påverkas för OFP-metoderna virvelström (ET) och ultraljudsprovning (UT) i form av puls-eko (PE) och ”time-of-flight-diffraction” (TOFD). Definitionen av redovisade defektparametrar följer i stort SKI-rapport 95:70 [1]. Defektparametrar i denna rapport redovisas i bilaga 1. Vid bedömningen av defektparametrarnas inverkan på OFP-tekniker, har drift¬inducerande defekter och tillverkningsdefekter hanterats separat. För de driftinducerande defekterna delades bedömningen upp i en generell och en specifik bedömning. De defektparametrar som bedöms specifikt och klassats att påverka signalsvaret betydligt bör vara av mest intresse i nästkommande etapp. Följande defektparametrar bedömdes påverka signalsvaret betydligt: • Form i ytan, antal sprickor och avstånd i gatstensmönster (vid termisk ut¬mattning) • Form i djupled • Sprickbredd vid sprickspets och sprickspetsradie För tillverkningsdefekter bedömdes defektparametrarnas form i djupled och geometri påverka signalsvaret betydligt för defekttyperna slagg och bindfel. Vid utvärdering av UT-PE och UT-TOFD teknikerna överensstämde resultatet helt med den teoretiska bedömningen. För ET-tekniken stämde endast en av tre defektparametrar överens med den teoretiska bedömningen. / In quality control of defect parameters for Non-Destructive Testing (NDT) it’s essential to have good knowledge about the defects. The reason is that different acceptance criteria and assessments must be based on defects that correspond to real defects. In this project different experience has been analyzed to get a better overview between defect parameters and non-destructive testing. This report shows the beginning of the research &amp; development project PLANT 2. There are different flaw parameters that have been mapped and a theoretical assessment has been performed with regard to how the signal response is influenced by the NDT techniques eddy current, ultrasonic pulse echo and ultrasonic time-of-flight-diffraction. The definition of the reported flaw parameters does in general follow the one presented in SKI-report 95:70 [1]. The actual flaw parameters in this report are presented in appendix 1. In the assessment of the influences on the NDT techniques with regard to flaw parameters, service-induced flaws and manufactured flaws have been separated in to two categories. The service-induced flaws have further on been separated in a general and a specific assessment. Those flaw parameters that have been assessed to be specific and classified to influence the signal response considerably should be the ones of most interest in future studies. The following flaw parameters were assessed to affect the signal response considerably: • Macroscopic shape in the surface direction, number of cracks and cobblestone stone pattern distance (for thermal fatigue) • Macroscopic shape in the through thickness direction • Crack width at the crack tip and the crack tip radius For flaws caused by the manufacturing process, type slag and lack of fusion, the flaw parameters “Macroscopic shape in the through thickness direction” and “the geometry” were influenced by the signal response considerably. In the evaluation of signal response with the UT pulse echo and UT TOFD techniques, the result corresponded to the theoretical assessment. For the eddy current technique only one of three flaw parameters corresponded to the theoretical assessment.