TY - JOUR A1 - Prager, Jens A1 - Gravenkamp, Hauke A1 - Rahman, Mehbub-Ur A1 - Köppe, Enrico T1 - Einsatz geführter Wellen für die Ultraschallprüfung N2 - Der Einsatz geführter Wellen für die zerstörungsfreie Prüfung mit Ultraschall eröffnet neue Möglichkeiten, räumlich ausgedehnte Bauteile mit begrenzter Zugänglichkeit auf ihre Integrität zu prüfen und gewinnt daher zunehmend an Bedeutung. Dieser Artikel behandelt die physikalischen Grundlagen der Schallausbreitung. Deren Verständnis bildet die Grundlage für die Entwicklung geeigneter Prüfsysteme. An Beispielen werden verschiedene Möglichkeiten zur Simulation der Schallausbereitung vorgestellt. Aktuelle Lösungsansätze zur Prüfung von plattenförmigen Strukturen und von Rohrleitungen werden beschrieben, wobei besonders auf die Sensortechnik und die speziellen Anforderungen an die Prüfhardware eingegangen wird. N2 - Guided waves are widely used for non-destructive testing using ultrasound. Recently, the method has become increasingly important for integrity tests of spatially extended components with limited accessibility. This article discusses the basic physics of the sound propagation of guided waves. Their understanding forms the basis for the successful development of adapted inspection systems. Examples for simulating the wave propagation using different methods are presented. Current approaches for the inspection of plate-like structures and pipelines are described with focus on sensor technology and the specific requirement on the test hardware. KW - Zerstörungsfreie Prüfung KW - Geführte Wellen KW - Ultraschallprüfung KW - Non-destructive evaluation KW - Guided waves KW - Ultrasound PY - 2012 DO - https://doi.org/10.1524/teme.2012.0168 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 79 IS - 5 SP - 251 EP - 261 PB - Oldenbourg CY - München AN - OPUS4-26206 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Baer, Wolfram A1 - Chruscicki, Sebastian A1 - Habib, Abdel Karim A1 - Homann, Tobias A1 - Hussels, Maria-Teresa A1 - Prager, Jens A1 - Schmidt, Dirk A1 - Stajanca, Pavol A1 - Weltschev, Margit A1 - Wossidlo, Peter T1 - Feasibility study - Continuous monitoring of pipes using distributed acoustic and fibre optic sensors N2 - The feasibility study „AGIFAMOR. Ageing infrastructures – distributed acoustic monitoring of pipes” is an interdisciplinary research project at BAM internally financed from 2015 to 2018. Therefore, the quite young fibre optic sensing technology of distributed acoustic sensing (DAS) was investigated to possibly be extended towards a global condition monitoring system for pipelines operating in real time. DAS is a highly dynamic fibre optic sensing technology based on the method of coherent optical time domain reflectometry (C-OTDR). DAS allows capturing strain changes in the range of kHz. For the experimental work, the most suitable application yielding an optimum sensitivity was proven by wrapping a standard single-mode silica fibre around the pipe. The DAS sensitivity was investigated regarding the detection of 1) incidents that initiate propagation of acoustic waves in the pipe wall, 2) changes inside the pipeline causing altered flow and 3) damage development in the pipe wall. Therefore, several testing setups in laboratory as well as in real scale were realized. For comparison purposes, experiments were accompanied by acoustic emission analyses and by measurements with accelerometers. DAS was found to be very sensitive to gas ignition and its propagation across the pipe. Furthermore, the ability of DAS to detect and localize acoustic signals associated with pipeline leakage was demonstrated. The detection of crack formation and propagation within the pipe wall by means of DAS was studied during bending tests on several pipe segments, but was not proven so far with certainty. As expected, these studies turned out as the most difficult challenge due to the random occurrence and transient nature of microscopic damage phenomena. T2 - Proceedings of the International Symposium on Structural Health Monitoring and Nondestructive Testing CY - Saarbrücken, Germany DA - 04.10.2018 KW - Accelerometers KW - Acoustic emission KW - Fibre optic acoustic sensing KW - Continous monitoring KW - Bending tests on pipe segments KW - Leak detection PY - 2018 SP - Paper 21 AN - OPUS4-46375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Hussels, Maria-Teresa A1 - Chruscicki, Sebastian A1 - Baer, Wolfram A1 - Wossidlo, Peter A1 - Homann, Tobias A1 - Prager, Jens A1 - Schmidt, Dirk A1 - Weltschev, Margit A1 - Habib, Abdel Karim T1 - BAM-Projekt AGIFAMOR – Zustandsüberwachung von Rohrleitungen N2 - Rohrleitungssysteme sind aufgrund ihrer Funktion und Ausdehnung für den Betrieb, die Verfügbarkeit und die Sicherheit von Industrieanlagen von besonderer Bedeutung. Die bisher in definierten Intervallen durchgeführten, wiederkehrenden Prüfungen zur Sicherstellung leckagefreier Rohrleitungen sind kostenintensiv und mit einem erhöhten Aufwand verbunden. Mit dem interdisziplinären Forschungsprojekt AGIFAMOR (Ageing Infrastructures – Akustisches Monitoring von Rohrleitungen) arbeitet die BAM an der Entwicklung und Erprobung einer örtlich und zeitlich kontinuierlichen Zustandsüberwachung von Rohrleitungen basierend auf einem faseroptischen akustischen Messsystem, welches einen vergleichsweise geringen Installationsaufwand der Sensoren erfordert. Mit diesem Verfahren sollen vor allem betriebsbedingte Schädigungen infolge von Korrosion sowie daraus entstehende Pittings oder Risse erkannt und damit Leckagen verhindert werden. Im Rahmen einer Machbarkeitsstudie zum Teilaspekt „Detektion von Risswachstum“ wurde ein 2,5 m langes, definiert vorgekerbtes Stahlrohr mit der faseroptischen Sensorik (FOS) ausgestattet und quasistatisch unter 4-Punkt-Biegung belastet. Mit fortschreitender Belastung wächst, ausgehend vom vorhandenen Außenumfangskerb, ein Riss im Stahlrohr bis zum Erreichen der Leckage – in der Praxis ein gefährliches Schadensszenario. Parallel zur FOS erfolgten Messungen mit Schallemissionssensoren, Beschleunigungssensoren und Potentialsonden, deren Ergebnisse die Interpretation der FOS-Messergebnisse unterstützen sollen. T2 - 21. Kolloquium Schallemission CY - Fulda, Germany DA - 09.03.2017 KW - Beschleunigungssensoren KW - Faseroptische Sensorik KW - Schallemission KW - Monitoring KW - Rohrleitung PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-401811 SN - 978-3-940283-82-5 VL - DGZfP-BB 159 SP - Vortrag 17, 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-40181 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baensch, Franziska A1 - Baer, Wolfram A1 - Chruscicki, Sebastian A1 - Homann, Tobias A1 - Prager, Jens A1 - Schmidt, Dirk A1 - Stajanca, Pavol A1 - Weltschev, Margrit A1 - Wosidlo, Peter A1 - Habib, Abdel Karim T1 - AGIFAMOR: Anwendung der akustischer und faseroptischer Sensorik zur Überwachung von Rohrleitungen; Teil 3: Technische Hintergründe - Messmethoden N2 - Schäden an Rohrleitungen können zu hohen Umweltbelastungen und wirtschaftlichen Schäden führen. Um die dauerhafte Verfügbarkeit der Infrastruktur zu gewährleisten, wird im Rahmen des Projekts AGIFAMOR an der Bundesanstalt für Materialforschung und -prüfung (BAM) erprobt, inwiefern das Verfahren der verteilten akustischen faseroptischen Sensorik (Distributed acoustic sensing - DAS) zur kontinuierlichen Überwachung von Rohrleitungen verwendet werden kann. Neben der DAS werden erprobte Verfahren der zerstörungsfreien Prüfung wie Schallemissionsanalyse (SEA) und Beschleunigungssensoren eingesetzt. An dieser Stelle soll detailliert auf die unterschiedlichen Messverfahren und deren spezifischen Einsatz im Rahmen des Projektes eingegangen werden. KW - Verteilten akustischen faseroptischen Sensorik KW - Überwachung von Rohrleitungen KW - Zerstörungsfreie Prüfung KW - Schallemissionsanalyse KW - Beschleunigungssensorik PY - 2018 SN - 2191-0073 VL - 8 IS - 5 SP - 29 EP - 35 PB - Springer-VDI-Verl. CY - Düsseldorf AN - OPUS4-45933 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kolkoori, Sanjeevareddy A1 - Rahman, Mehbub-Ur A1 - Prager, Jens T1 - Effect of columnar grain orientation on ultrasonic plane wave energy reflection and transmission behaviour in anisotropic austenitic weld materials N2 - This article describes a comprehensive quantitative analysis on effect of columnar grain orientation on ultrasonic plane wave energy reflection and transmission behaviour in acoustically anisotropic austenitic weld materials. The quantitative results are presented for following general interfaces (a) Isotropic-Anisotropic, (b) Anisotropic-Isotropic, (c) Fluid-Anisotropic, (d) Anisotropic-Fluid, (e) Anisotropic-Anisotropic, (f) Anisotropic-Free surface occur during the ultrasonic non destructive evaluation of austenitic weld materials. Explicit analytical expressions are presented for energy reflection and transmission coefficients at an interface between two arbitrarily oriented transversely isotropic materials. By applying explicit analytical expressions for energy reflection and transmission coefficients, numerical results are presented for several columnar grain orientations of the transverse isotropic austenitic weld material including both real and complex domain of the reflected and transmitted normal component of slowness vectors. Valid domains of incident wave vector angles, angular dependency of energy reflection and transmission coefficients and critical angles for reflected and transmitted waves are discussed. The existence of a reflected (or) transmitted second branch of quasi shear vertical waves and its consequence to the ultrasonic non destructive testing of austenitic weld materials are investigated. The presented comprehensive quantitative evaluation provides an overview on the effect of anisotropic properties on energy reflection and transmission coefficients in columnar grained austenitic weld materials. KW - Anisotropy KW - Inhomogeneous waves KW - Austenitic weld material KW - Polarization vector KW - Energy skewing KW - Critical angle KW - Energy flux vector KW - Evanescent waves PY - 2012 DO - https://doi.org/10.1007/s10921-012-0140-1 SN - 0195-9298 SN - 1573-4862 VL - 31 IS - 3 SP - 253 EP - 269 PB - Plenum Press CY - New York, NY AN - OPUS4-27792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolkoori, Sanjeevareddy A1 - Rahman, Mehbub-Ur A1 - Chinta, P.K. A1 - Kreutzbruck, Marc A1 - Prager, Jens ED - Thompson, D. O. ED - Chimenti, D. E. T1 - Quantitative evaluation of ultrasonic sound fields in anisotropic austenitic welds using 2D ray tracing model N2 - Ultrasonic investigation of inhomogeneous anisotropic materials such as austenitic welds is complicated because its columnar grain structure leads to curved energy paths, beam splitting and asymmetrical beam profiles. A ray tracing model has potential advantage in analyzing the ultrasonic sound field propagation and there with optimizing the inspection parameters. In this contribution we present a 2D ray tracing model to predict energy ray paths, ray amplitudes and travel times for the three wave modes quasi longitudinal, quasi shear vertical, and shear horizontal waves in austenitic weld materials. Inhomogenity in the austenitic weld material is represented by discretizing the inhomogeneous region into several homogeneous layers. At each interface between the layers the reflection and transmission problem is computed and yields energy direction, amplitude and energy coefficients. The ray amplitudes are computed accurately by taking into account directivity, divergence and density of rays, phase relations as well as transmission coefficients. Ultrasonic sound fields obtained from the ray tracing model are compared quantitatively with the 2D Elastodynamic Finite Integration Technique (EFIT). The excellent agreement between both models confirms the validity of the presented ray tracing results. Experiments are conducted on austenitic weld samples with longitudinal beam transducer as transmitting probe and amplitudes at the rear surface are scanned by means of electrodynamical probes. Finally, the ray tracing model results are also validated through the experiments. T2 - 38th Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Burlington, VT, USA DA - 17.07.2011 KW - Ultrasonic sound field KW - Ray tracing KW - Ray directivity KW - Austenitic weld PY - 2012 SN - 978-0-7354-1013-8 DO - https://doi.org/10.1063/1.4716359 SN - 0743-0760 SN - 0094-243X N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1430 SP - 1227 EP - 1234 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolkoori, Sanjeevareddy A1 - Rahman, Mehbub-Ur A1 - Chinta, P.K. A1 - Boehm, Rainer A1 - Prager, Jens ED - Linde, B. B. J. ED - Paczkowski, J. ED - Ponikwicki, N. T1 - Simulation of ultrasonic fields in anisotropic materials using 2D ray tracing method N2 - Ultrasound propagation in inhomogeneous anisotropic materials is difficult to examine because of the directional dependency of elastic properties. Simulation tools play an important role in developing advanced reliable ultrasonic testing techniques for the inspection of anisotropic materials particularly austenitic cladded materials and dissimilar welds. A 2-D Ray tracing method is developed for evaluating ray path, amplitude and travel time for three wave modes namely quasi longitudinal wave (qP), quasi shear vertical wave (qSV) and shear horizontal waves (SH) in anisotropic materials such as austenitic cladded materials. The inhomogenity in the anisotropic material is represented by discretizing the anisotropic region into several homogeneous layers. The ray paths are traced during its propagation through the various interfaces between those layers. At each interface the problem of reflection and refraction is solved. The ray amplitudes are computed by taking into account the directivity and phase relations. Ray divergence variation and ray transmission coefficients at each refraction boundary are considered. The Ray tracing results for ultrasonic field profiles in austenitic cladded materials are validated quantitatively by 2-D Elastodynamic Finite Integration Technique (EFIT) results and by the experiments. T2 - International congress on ultrasonics CY - Gdansk, Poland DA - 05.09.2011 KW - Ray path KW - Energy vector KW - Austenitic cladded material KW - Ultrasonic beam profile PY - 2012 SN - 978-0-7354-1019-0 DO - https://doi.org/10.1063/1.3703288 SN - 0094-243X N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1433 SP - 743 EP - 746 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolkoori, Sanjeevareddy A1 - Rahman, Mehbub-Ur A1 - Prager, Jens T1 - 3D ray tracing model for ultrasound field evaluation in inhomogeneous anisotropic materials: model and experimental validation N2 - In this contribution a 3D ray tracing model for ultrasonic field evaluation in inhomogeneous anisotropic materials such as austenitic welds is presented. The inhomogenity of austenitic weld material is represented as several homogeneous layers. The general problem of energy reflection and transmission at the boundaries of the layers are solved resulting 3D amplitude and energy reflection and transmission coefficients. The directivity factor for the ray in general arbitrary oriented austenitic weld material (including lay back orientation) is determined based on Lamb's reciprocity theorem. The transducer excited ultrasonic fields are accurately evaluated by employing ray directivity factor, transmission coefficients, divergence of the ray bundle and density of rays. Finally, the comparison between theoretical and experimental results will be described. T2 - DAGA 2012 - 38. Jahrestagung für Akustik - Fortschritte der Akustik CY - Darmstadt, Germany DA - 19.03.2012 KW - Ultrasonic field KW - 3D ray tracing KW - Inhomogeneous KW - Austenitic weld PY - 2012 SP - 959 EP - 960 PB - Deutsche Gesellschaft für Akustik e.V. AN - OPUS4-26204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Prager, Jens T1 - Device concept for the generation of guided waves for early damage detection N2 - In this study a method for early damage detection is investigated based on the directed excitation and measuring of Lamb waves (guided waves). The objective is to make a statement about the practicability of a Lamb wave generator (LWG) and about the application relevant parameters (specimen materials and dimensions, wave characteristics, excitation, transmission und reflection). Guided waves enable an effective differentiation of structural and defective indications as well as a classification of different defect types. For the investigations, a LWG was developed which combines the advantages of the single excitation of a piezoelectric actuator and the possibility of a group excitation. Algorithms were developed to identify and analyze damage patterns (cracks, wholes, weakening). T2 - Eurosensors XXVI CY - Kraków, Poland DA - 09.09.2012 KW - Lamb wave KW - Guided wave KW - DDS KW - SHM KW - Early damage detection PY - 2012 DO - https://doi.org/10.1016/j.proeng.2012.09.363 SN - 1877-7058 VL - 47 SP - 1185 EP - 1188 PB - Elsevier AN - OPUS4-27552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Numerische Berechnung der Dispersionseigenschaften von Lambwellen in Platten mit beliebiger Materialzusammensetzung N2 - Für alle Anwendungen geführter Wellen, beispielsweise in der zerstörungsfreien Materialprüfung, ist die exakte und effiziente Berechnung von Dispersionseigenschaften erforderlich. Dabei müssen für eine gegebene Frequenz die Anzahl der ausbreitungsfähigen Moden und deren Wellenzahlen sowie Phasen- und Gruppengeschwindigkeiten berechnet werden. Für den Fall von Lambwellen in homogenen isotropen Platten existieren analytische Gleichungen für die Wellenzahlen, die sich mit numerischen Nullstellensuchverfahren lösen lassen. Für komplexere Strukturen oder dreidimensionale, nicht rotationssymmetrische Wellenleiter ist die Entwicklung numerischer Methoden erforderlich. In der vorliegenden Arbeit wird ein numerisches Verfahren, basierend auf der Scaled Boundary Finite Element Method (SBFEM) [1] vorgestellt. Mit diesem lassen sich Dispersionseigenschaften von beliebigen Wellenleitern sehr effizient berechnen. Ergebnisse werden für den Fall von Wellen in Platten mit komplexer Materialzusammensetzung präsentiert. T2 - DAGA 2012 - 38. Jahrestagung für Akustik - Fortschritte der Akustik CY - Darmstadt, Deutschland DA - 19.03.2012 KW - Ultraschall KW - Lambwellen KW - Dispersion KW - Scaled boundary finite element method PY - 2012 SP - 1 EP - 2 PB - Deutsche Gesellschaft für Akustik e.V. AN - OPUS4-25978 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Harrer, Andrea A1 - Daschewski, Maxim A1 - Prager, Jens A1 - Kreutzbruck, Marc A1 - Guderian, Matthias A1 - Meyer-Plath, Asmus T1 - Thermoacoustic generation of airborne ultrasound using carbon materials at the micro- and nanoscale N2 - The generation of airborne ultrasound is presented using the thermoacoustic principle applied to carbon materials at the micro- and nanoscale. Such materials are shown to be capable of emitting ultrasound when being fed by an alternating current. We tested the acoustic performance of carbon fibers, bucky papers and electrospun polyacrylonitrile-derived carbon nanofibers and determined the sound pressure for frequencies up to 350 kHz. A comparison between the experimental results and the theoretical prediction showed remarkable agreement for frequencies up to 150 kHz. Beyond 150 kHz, we found slight deviations from the expected sound pressure dependence on the square root of the frequency. KW - Thermoacoustic KW - Airborne ultrasound transducer KW - Sound pressure PY - 2012 DO - https://doi.org/10.3233/JAE-2012-1440 SN - 1383-5416 SN - 0925-2096 VL - 39 IS - 1-4 SP - 35 EP - 41 PB - IOS Press CY - Amsterdam, The Netherlands AN - OPUS4-26737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - A numerical approach for the computation of dispersion relations for plate structures using the scaled boundary finite element method N2 - In this paper, a method is presented for the numerical computation of dispersion properties and mode shapes of guided waves in plate structures. The formulation is based on the Scaled Boundary Finite Element Method. The through-thickness direction of the plate is discretized in the finite element sense, while the direction of propagation is described analytically. This leads to a standard eigenvalue problem for the calculation of wave numbers. The proposed method is not limited to homogeneous plates. Multi-layered composites as well as structures with continuously varying material parameters in the direction of thickness can be modeled without essential changes in the formulation. Higher-order elements have been employed for the finite element discretization, leading to excellent convergence for complex structures. It is shown by numerical examples that this method provides highly accurate results with a small number of nodes while avoiding numerical problems and instabilities. KW - Scaled boundary finite element method KW - Lamb waves KW - Dispersion KW - Non-destructive testing KW - Composites KW - Functionally graded materials PY - 2012 DO - https://doi.org/10.1016/j.jsv.2012.01.029 SN - 0022-460X SN - 1095-8568 VL - 331 IS - 11 SP - 2543 EP - 2557 PB - Academic Press CY - London AN - OPUS4-25743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Saputra, A. A. A1 - Song, C. T1 - The simulation of Lamb waves in a cracked plate using the scaled boundary finite element method N2 - The scaled boundary finite element method is applied to the simulation of Lamb waves for ultrasonic testing applications. With this method, the general elastodynamic problem is solved, while only the boundary of the domain under consideration has to be discretized. The reflection of the fundamental Lamb wave modes from cracks of different geometry in a steel plate is modeled. A test problem is compared with commercial finite element software, showing the efficiency and convergence of the scaled boundary finite element method. A special formulation of this method is utilized to calculate dispersion relations for plate structures. For the discretization of the boundary, higher-order elements are employed to improve the efficiency of the simulations. The simplicity of mesh generation of a cracked plate for a scaled boundary finite element analysis is illustrated. KW - Lamb waves KW - Scaled boundary finite element method KW - Dispersion KW - Structural dynamics KW - Cracks PY - 2012 DO - https://doi.org/10.1121/1.4740478 SN - 0001-4966 SN - 1520-8524 VL - 132 IS - 3 SP - 1358 EP - 1367 PB - AIP CY - Melville, NY, USA AN - OPUS4-27115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc A1 - Prager, Jens A1 - Boehm, Rainer A1 - Kitze, Jessica A1 - Brekow, Gerhard T1 - Progress in acoustical defect sizing NDT methods for the inspection of power-plant components N2 - The demand of improved NDT methods with proper visualization and sizing capabilities is a persistent trend in maintenance and manufacturing quality inspection. Especially when dealing with high quality standards in conjunction with safety-critical components in the sector of energy and transportation quantitative NDT techniques are vital to provide reliable quality control systems and a corresponding deeper insight into the component structure for a further fracture-mechanical estimation. The paper thus focuses the progress of the defect sizing capabilities of modern Ultrasonic Testing (UT). In Ultrasonic Testing the SAFT-algorithm (Synthetic Aperture Focusing Technique) currently experiences a renaissance. The method is based on combining the data of different transducer positions with their corresponding varied propagating time and it is currently applied in several industrial applications. SAFT enhances the SNR and the spatial resolution and is thus a valuable tool when it comes to improved defect detection and sizing. A tomographic-like data mapping is illustrated on several examples, where adapted phased array systems were used for the inspection of turbine components and also for a cladded mock-up of a nuclear reactor pressure vessel. In a statistical investigation we also performed a comparison with other defect sizing methods like TOFD (Time of flight diffraction). T2 - 18th WCNDT - World conference on nondestructive testing CY - Durban, South Africa DA - 16.04.2012 KW - SAFT KW - TOFD KW - Cracks KW - Phased Array PY - 2012 SN - 978-0-620-52872-6 SP - 1 EP - 8 (Paper 497) AN - OPUS4-26350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Höhne, Christian A1 - Boehm, Rainer A1 - Prager, Jens T1 - Anwendung multidimensionaler analytischer Signale mit Single-Orthant-Spektren zur Aufbereitung von SAFT-Daten in der Ultraschallprüfung N2 - Die Rekonstruktion von Materialfehlern aus gemessenen HF-Bildern mit Hilfe der Synthetic Aperture Focussing Technique (SAFT) ist ein bildgebendes Verfahren der zerstörungsfreien Werkstoffprüfung. Die Auswertbarkeit der gewonnenen Ergebnisse wird dabei maßgeblich durch die Darstellung der mittels SAFT-Rekonstruktion zusammengestellten Daten bestimmt, welche zunächst nur in Form positiver und negativer Amplitudenwerte vorliegen. Die Aufbereitung dieser Daten erfolgt durch Bildung der Einhüllenden der Amplituden aus dem zugehörigen analytischen Signal. Die Erweiterung dieses, nur im eindimensionalen Fall eindeutig definierten, Konzepts auf zweidimensionale Signalverläufe erfolgt dabei in Form einer Mittelung über die Betragsquadrate aller möglichen mit Single-Orthant-Spektren (SO-Spektren) zu bildenden analytischen Signale. Es wird gezeigt dass dies der Verwendung einer Approximation als separables Signal entspricht und für den zweidimensionalen Fall eine Möglichkeit vorgeschlagen Signale anhand ihrer partiellen und totalen Hilberttransformationen auf Separabilität und damit Anwendbarkeit dieser Näherung zu testen. Die Ergebnisse der so durchgeführten Bildverbesserung werden am Beispiel einer zweidimensionalen SAFT-Rekonstruktion an verschiedenen Reflektorarten dargestellt. T2 - DAGA 2012 - 38. Jahrestagung für Akustik - Fortschritte der Akustik CY - Darmstadt, Deutschland DA - 19.03.2012 PY - 2012 VL - II SP - 957 EP - 958 PB - Deutsche Gesellschaft für Akustik e.V. AN - OPUS4-25977 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Numerical simulation of ultrasonic guided waves using the scaled boundary finite element method N2 - The formulation of the Scaled Boundary Finite Element Method is applied for the computation of dispersion properties of ultrasonic guided waves. The cross-section of the waveguide is discretized in the Finite Element sense, while the direction of propagation is described analytically. A standard eigenvalue problem is derived to compute the wave numbers of propagating modes. This paper focuses on cylindrical waveguides, where only a straight line has to be discretized. Higher-order elements are utilized for the discretization. As examples, dispersion curves are computed for a homogeneous pipe and a layered cylinder. T2 - 2012 IEEE International Ultrasonics Symposium (IUS) CY - Dresden, Germany DA - 07.10.2012 KW - Guided waves KW - Simulation KW - Dispersion KW - Scaled boundary finite element method PY - 2012 SN - 978-1-4673-4562-0 DO - https://doi.org/10.1109/ULTSYM.2012.0673 SN - 1948-5719 SP - 2686 EP - 2689 AN - OPUS4-29665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -