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Autor*in

  • Kreutzbruck, Marc (201)
  • Brekow, Gerhard (26)
  • Maierhofer, Christiane (26)
  • Pelkner, Matthias (26)
  • Prager, Jens (23)
  • Gaal, Mate (21)
  • Bartusch, Jürgen (17)
  • Brackrock, Daniel (17)
  • Reimund, Verena (17)
  • Schlichting, Joachim (16)
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Erscheinungsjahr

  • 2018 (3)
  • 2017 (3)
  • 2016 (6)
  • 2015 (8)
  • 2014 (20)
  • 2013 (27)
  • 2012 (22)
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  • 2010 (24)
  • 2009 (35)
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Dokumenttyp

  • Beitrag zu einem Tagungsband (87)
  • Vortrag (56)
  • Zeitschriftenartikel (36)
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  • Deutsch (104)
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Referierte Publikation

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Schlagworte

  • GMR (18)
  • Ultrasonic testing (10)
  • Magnetic flux leakage (9)
  • Ferroelectret (8)
  • Reconstruction (8)
  • Thermography (7)
  • Cellular polypropylene (6)
  • Non-destructive testing (6)
  • Phased array (6)
  • Eddy current (5)
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Organisationseinheit der BAM

  • 8 Zerstörungsfreie Prüfung (20)
  • 8.4 Akustische und elektromagnetische Verfahren (19)
  • 5 Werkstofftechnik (7)
  • 5.2 Experimentelle und modellbasierte Werkstoffmechanik (6)
  • 8.5 Mikro-ZfP (5)
  • 9 Komponentensicherheit (5)
  • 5.1 Materialographie, Fraktographie und Alterung technischer Werkstoffe (4)
  • 9.3 Schweißtechnische Fertigungsverfahren (4)
  • 6 Materialchemie (2)
  • 6.7 Oberflächenmodifizierung und -messtechnik (2)
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201 Treffer

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Magnetic response field of spherical defects within conductive components (2010)
Kreutzbruck, Marc ; Thomas, Hans-Martin ; Casperson, Ralf ; Reimund, Verena ; Blome, Mark ; Allweins, K. ; Lembke, G.
The determination of magnetic distortion fields caused by inclusions hidden in a conductive matrix using homogeneous current flow needs to be addressed in multiple tasks of electromagnetic non-destructive testing and materials science. This includes a series of testing problems such as the detection of tantalum inclusions hidden in niobium plates, metal inclusion in a nonmetallic base material or porosity in aluminum laser welds. Unfortunately, straightforward tools for an estimation of the defect response fields above the sample using pertinent detection concepts are still missing. In this study the Finite Element Method (FEM) was used for modeling spherically shaped defects and an analytical expression developed for the strength of the response field including the conductivity of the defect and matrix, the sensor-to-inclusion separation and the defect size. Finally, the results also can be useful for Eddy Current Testing problems, by taking the skin effect into consideration.
Advanced crack shape analysis using SAFT (2010)
Boehm, Rainer ; Brackrock, Daniel ; Kitze, Jessica ; Brekow, Gerhard ; Kreutzbruck, Marc
The spatial resolution in ultrasonic testing as a wave phenomenon in nature is limited to a certain fraction of the wavelength, usually defined to be close to the Rayleigh criterion. In case of complicated reflector surfaces – such as stress corrosion cracking - this limitation prevents an exact visualization of the defect shape. There exist a few approaches to improve the spatial resolution, whose reconstruction quality all in common also depend on the achieved signal-to-noise ratio of the raw data. In this work we present a specific SAFT analysis, in which a high number of different angles of incidence produce a sufficiently high number of different reflections at the crack edges resulting in an improved SNR. In doing so, we reconstruct a coherent crack structure. First investigations were made at artificially simulated crack configurations with different contours and curvatures in flat and cylindrical test blocks. The measurements results – visualized by representative scans – show details of crack design and crack orientation. We also will present a comparison of the SAFT analysis between modelling and phased array measurements.
Ultrasonic inspection system for automated round-bar-testing based on phased array technique (2010)
Schenk, Gottfried ; Brackrock, Daniel ; Brekow, Gerhard ; Kreutzbruck, Marc ; Deutsch, W.A.K. ; Joswig, M. ; Maxam, K. ; Schuster, V.
Within a know-how transfer project funded by the government conventional ultrasonic technique was replaced by phased array technique for automated round-bar testing. Instead of applying a great number of conventional probes to achieve acceptable volume coverage we used curved linear arrays. The benefits of phased array technique such as programmable skew angles, beamforming and beam positions, led not only to a significant decrease in inspection time, but also the number of probes could be substantially reduced . Finally, the testing parameters for a large range of bar-diameters could be adapted by software control instead of time-consuming mechanical replacement. The probe-design was carried out by a proprietary modelling program. Both the theoretical calculations as well as the latter experimental verifications revealed significant advantages of curved arrays versus the planar types. A radial oriented probe offers perfect adaption to the cylindrical shape of the specimen allowing wide variations of the sound field. Thus beam direction, beam size and beam position could be optimized with respect to a minimum of inspection cycles, as inspections have to be executed in-line during the production. A number of laboratory tests were carried out on special test components. In order to achieve an optimal performance of the reference rod we implemented three different types of reference reflectors: (i) flat-bottom-holes with diameters of 0.8 mm and 1.2 mm, (ii) side-drilled-holes with a diameter of 0.7 mm for the detection of volumetric flaws, and (iii) notches with a depth of 0.2 mm and 0.5 mm for the detection of surfaceoriented defects. All laboratory tests were carried out with the COMPAS-XXL inspection system, a proprietary development of BAM.
Nonlinear electromechanical response of the ferroelectret ultrasonic transducers (2010)
Döring, Joachim ; Bovtun, Viktor Petrovic ; Bartusch, Jürgen ; Erhard, Anton ; Kreutzbruck, Marc ; Yakymenko, Y.
The ultrasonic transmission between two air-coupled polypropylene (PP) ferroelectret (FE) transducers in dependence on the amplitude of the high-voltage exciting pulse revealed a strongly nonlinear electromechanical response of the FE transmitter. This phenomenon is described by a linear increase of the inverse electromechanical transducer constant t33(1) of the PP FE film with an increase of the exciting electrical pulse amplitude. Enlargement of t33(1) by a factor of 4 was achieved by application of 3500 V exciting pulses. The electrostriction contribution to t33(1) can be attributed to the electrostatic force between electrodes and the Maxwell stress effect. The nonlinear electromechanical properties of the PP FE result in a strong increase of its air-coupled ultrasonic (ACUS) figure of merit (FOM) under the high-voltage excitation, which exceeds results of the PP FE technological optimization. The FOM increase can be related to the increase of PP FE coupling factor and/or to the decrease of its acoustic impedance. A significant enhancement of the ACUS system transmission (12 dB) and signal-to-noise ratio (32 dB) was demonstrated by the increase of excitation voltage up to 3500 V. The nonlinear electromechanical properties of the PP FEs seem to be very important for their future applications.
Geometrische Charakterisierung von Fehlstellen mittels lokal angeregter aktiver Thermografie / Characterizing geometrical parameters of voids with locally excited active thermography (2010)
Schlichting, Joachim ; Kervalishvili, Guram N. ; Maierhofer, Christiane ; Kreutzbruck, Marc
Defect sizing by local excitation thermography (2010)
Schlichting, Joachim ; Maierhofer, Christiane ; Kreutzbruck, Marc
In this article, we present a measurement procedure to gain information about depth and angle of open surface cracks. The method is based on a local excitation with, e.g., a laser. The resulting surface temperature is recorded with an infrared camera. Based on this data, crack-caused anisotropies in the lateral heat flow can be detected and exploited to characterise the cracks. The experimental set-up is based on a Nd:YAG laser. The beam is focused on the test sample by using an optical scanner to generate the required lateral heat flow. The time resolved temperature distribution is recorded with a high-speed infrared camera (InSb FPA, 3 to 5 µm) providing a frame rate of up to 500 Hz. Up to now, only qualitative information was gained from measurements of this type. Whereas the local transient behaviour of temperature distribution provides also quantitative information of the crack parameters. The general concept of the method presented herein has already been published [1], but the mentioned publication is focused on the crack depth only. In this paper, we can show that it is possible to simultaneously resolve the angle and depth and, in particular, the depth of non-perpendicular cracks.
Microstructure and magnetoresistance of heterogeneous gold-rich Ag3Au1.1Te2 (2010)
Kienle, L. ; Duppel, V. ; Lembke, G. ; Mogwitz, B. ; Janek, J. ; Kreutzbruck, Marc ; Simon, A.
Dispersions of very small non-magnetic metal particles or inclusions in a non-magnetic semiconductor matrix are well known to produce unusually large and linear magnetoresistance effects. So far these materials were limited to the binary silver-rich chalcogenides Ag2Se and Ag2Te. In this contribution Ag3AuTe2 was selected as a first candidate for a ternary matrix material, thus offering enhanced capabilities for the generation of heterogeneous microstructure and spatially varying composition on the nanoscale. In gold-rich Ag3Au1.1Te2 two kinds of inhomogeneities are present, namely Au deposits with a size on the micron scale and an inhomogeneous distribution of Au and Ag within the matrix. The matrix consists of micron-sized grains with the structure type of Ag3AuTe2 as studied by electron microscopy. Like the binary silver chalcogenide phases, the material also shows a large and linear magnetoresistance effect. The transversal magnetoresistance effect was measured between 20 K and 270 K in magnetic fields up to B = 5 T. The results are discussed on the basis of existing models for a large and linear positive MR effect.
Magnetic Response Field of Spherical Cefects within Conductive Components (2010)
Kreutzbruck, Marc
Ultraschallverfahren - Bewährte Lösungen und neue Technologien in Forschung und Produktion (2010)
Kreutzbruck, Marc
Untersuchungen zur Anregung geführter Wellen in Platten mittels Gruppenstrahlertechnik (2010)
Prager, Jens ; Hoever, C. ; Kreutzbruck, Marc
Geführte Wellen breiten sich in Platten und Hohlzylindern über weite Entfernungen aus. Aus dieser Eigenschaft ergibt sich ein hohes Anwendungspotential dieser Wellenart für die zerstörungsfreie Prüfung ausgedehnter Bauteile und Strukturen mittels Ultraschall. Nachteilig für die Anwendung geführter Wellen sind ihr dispersives Verhalten und die zunehmende Anzahl ausbreitungsfähiger Wellenmoden bei hohen Frequenzen. Ziel des Einsatzes der Gruppenstrahlertechnik ist es, eine ausgewählte Wellenmode selektiv anzuregen bzw. zu empfangen. Durch die Änderung des Schwenkwinkels im Gruppenstrahlerprüfkopf wird eine definierte Spurwellenlänge auf dem Interface zwischen Prüfkopf und Struktur festgelegt, die zur Anregung einer Welle mit entsprechender Phasengeschwindigkeit führt. Da der Schwenkwinkel elektronisch verändert werden kann, lässt sich auch die angeregte Wellenmode elektronisch auswählen, worin der große Vorteil des vorgestellten Verfahrens liegt. In den vorgestellten Untersuchungen wurde die Anwendbarkeit der Methode experimentell demonstriert. Der Anregemechanismus wurde theoretisch beleuchtet und die Wellenausbreitung im Prüfkopf mit verschiedenen analytischen Ansätzen modelliert. Mit diesen Modellen können Fragen der Richtwirkung und der Effizienz der Anregung detailliert untersucht werden. Die modellierten Wellenfelder wurden mit den experimentellen Ergebnissen verglichen und die Anwendbarkeit der theoretischen Ansätze beurteilt, wobei die Ergebnisse der theoretischen Untersuchungen im Experiment verifiziert werden konnten.
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