TY - JOUR A1 - Vöse, Markus A1 - Fedelich, Bernard A1 - Owen, J. T1 - A simplified model for creep induced grain boundary cavitation validated by multiple cavity growth simulations N2 - Simulations of cavitation processes on a grain boundary under creep conditions have been carried out, taking into account nucleation, growth, coalescence and sintering of multiple cavities. Cavity growth rates have been calculated through a resolution procedure based on the use of holomorphic complex functions. Three dimensionless parameters have been identified that are responsible for the cavitation development. Parameter studies have been carried out in order to characterise the mechanisms that are responsible for the cavitation development. These studies have been used to develop a physically motivated, simplified model in order to describe the cavitation development of the simulations in terms of global state variables. The simplified model is able to reproduce the cavitation development for all considered combinations of the dimensionless parameters and allows the description of the thickening behaviour of a cavitating grain boundary. KW - Creep damage KW - Grain boundary diffusion KW - Cavitation KW - Simulation PY - 2012 DO - https://doi.org/10.1016/j.commatsci.2012.01.033 SN - 0927-0256 VL - 58 SP - 201 EP - 213 PB - Elsevier CY - Amsterdam AN - OPUS4-25630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dmitriev, A. I. A1 - Österle, Werner A1 - Kloß, Heinz A1 - Orts-Gil, Guillermo T1 - A study of third body behaviour under dry sliding conditions. Comparison of nanoscale modelling with experiment N2 - Automotive brake pads consist of many components but it is still not entirely clear which role each of the elements of this complex composition plays to provide the specified regimes of sliding. This is due to the mutual interaction of multiscale mechanisms, realized during the friction. In this work we have attempted to partly answer this question using computer simulations. Since the simulation allows us to consider various combinations of the structure of the system being simulated ceteris paribus, it becomes possible to understand the role of each constituent sequentially. The main attention is paid to the structure and composition of the thin film that forms on the surface of both bodies as a result of compaction of the wear product, its chemical composition and oxidation. This layer, also named a third body or friction film, differs in composition and microstructure from the two first bodies. We considered a single contact for the steady state sliding when the structure and composition of friction films already are formed. As a modelling tool we used the method of movable cellular automata, which has well proven itself in solving of such tasks. We investigated the influence of modification of the structure and composition of the third body on the features of system behaviour at friction. To assess the adequacy of the numerical model, experimental studies with an artificial third body were also carried out. The Simulation results are in good agreement with experimental data. KW - Third body KW - Dry sliding KW - Mechanically mixed layer KW - Computer simulation PY - 2012 DO - https://doi.org/10.3176/eng.2012.3.12 SN - 1736-6038 SN - 1736-7522 VL - 18 IS - 3 SP - 270 EP - 278 AN - OPUS4-38545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR T1 - Amts- und Mitteilungsblatt, Band 42, Heft 1 T3 - Amts- und Mitteilungsblatt der BAM - 1/2012 PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-129 SN - 0340-7551 VL - 42 IS - 1 SP - 1 EP - 49 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-12 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR T1 - Amts- und Mitteilungsblatt, Band 42, Heft 2 T3 - Amts- und Mitteilungsblatt der BAM - 2/2012 PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-119 SN - 0340-7551 VL - 42 IS - 2 SP - 1 EP - 151 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-11 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR T1 - Amts- und Mitteilungsblatt, Band 42, Heft 3 T3 - Amts- und Mitteilungsblatt der BAM - 3/2012 PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-109 SN - 0340-7551 VL - 42 IS - 3 SP - 1 EP - 375 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-10 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR T1 - Amts- und Mitteilungsblatt, Band 42, Heft 4 T3 - Amts- und Mitteilungsblatt der BAM - 4/2012 PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-97 SN - 0340-7551 VL - 42 IS - 4 SP - 1 EP - 187 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-9 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröter, Maria-Astrid A1 - Holschneider, M. A1 - Sturm, Heinz T1 - Analytical and numerical analysis of imaging mechanism of dynamic scanning electron microscopy N2 - The direct observation of small oscillating structures with the help of a scanning electron beam is a new approach to study the vibrational dynamics of cantilevers and microelectromechanical systems. In the scanning electron microscope, the conventional signal of secondary electrons (SE, dc part) is separated from the signal response of the SE detector, which is correlated to the respective excitation frequency for vibration by means of a lock-in amplifier. The dynamic response is separated either into images of amplitude and phase shift or into real and imaginary parts. Spatial resolution is limited to the diameter of the electron beam. The sensitivity limit to vibrational motion is estimated to be sub-nanometer for high integration times. Due to complex imaging mechanisms, a theoretical model was developed for the interpretation of the obtained measurements, relating cantilever shapes to interaction processes consisting of incident electron beam, electron–lever interaction, emitted electrons and detector response. Conclusions drawn from this new model are compared with numerical results based on the Euler–Bernoulli equation. KW - Electron microscopy KW - Scanning force microscopy KW - Cantilever motion KW - Modes KW - Harmonics KW - Mathematical model KW - Imaging theory PY - 2012 DO - https://doi.org/10.1088/0957-4484/23/43/435501 SN - 0957-4484 SN - 1361-6528 VL - 23 IS - 43 SP - 1 EP - 10 PB - IOP Publishing Ltd. CY - Bristol AN - OPUS4-27642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stoppel, Markus A1 - Taffe, Alexander A1 - Wiggenhauser, Herbert A1 - Kurz, J. H. A1 - Boller, C. ED - Grantham, M. ED - Mechtcherine, V. ED - Schneck, U. T1 - Automated multi-sensor systems in civil engineering for condition assessment of concrete structures N2 - Infrastructure is subject to continuous ageing. This has given life cycle management of infrastructure an important role. Therefore an increasing demand for reliable inspection and monitoring tools is noticeable. A combination of different non-destructive test methods is often necessary to receive reliable results for material characterization, flaw detection and the determination of component specific geometry Parameters. Regarding concrete structures thickness measurements are combined with flaw detection and additional Information about reinforcement and tendon ducts is required. Therefore, a multi-sensor measurement approach is necessary with a high degree of automation. Otherwise a time consuming succession of manual measurements has to be performed which would prevent practical applications. A modular control and data acquisition approach is described and the application of two different automated measurement devices is shown. The BetoScan System consists of a self-navigating mobile robot. The System is especially designed for the Investigation of reinforced concrete floors exposed to de-icing salts. The data acquisition of the OSSCAR System, a multi-sensor Scanner, is similar to the robot approach. These different applications are based on a similar kernel allowing the modular use of different contact and non-contact sensors. The described general concept of multi-sensor data acquisition and data analysis presented here is not limited to the field of civil engineering applications. T2 - Concrete Solutions 2011 - 4th International Conference on Concrete Repair CY - Dresden, Germany DA - 26.09.2011 KW - Multi sensor KW - Data aquisition KW - Assessment of concrete structures KW - Scanner KW - NDT PY - 2012 SN - 978-0-415-61-622-5 SP - 397 EP - 403 PB - Taylor & Francis CY - London AN - OPUS4-24659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hussung, D. R. A1 - Kurz, J. H. A1 - Stoppel, Markus T1 - Automatisierte, zerstörungsfreie Prüftechnik für großflächige Stahlbetontragwerke - Ein Anwendungsbeispiel T1 - Automated non-destructive inspection techniques for large reinforced concrete constructions - An example of use N2 - Eine Vielzahl zerstörungsfreier Prüfverfahren hat in den letzten Jahren Einzug in die Bauwerksuntersuchung gehalten. Um die Aussagekraft der Einzelverfahren zu erhöhen und den wirtschaftlichen Einsatz weiter voranzubringen, lag es nahe, die Verfahren kombiniert auf einer automatisierten Plattform zu montieren. Zu diesem Zweck wurde das BetoScan-System entwickelt. Um weitere Erfahrungen mit dem BetoScan-System zu erhalten, wurde ein langjährig genutztes Parkhaus aus Stahlbeton mit Gussasphaltfahrbahn als Untersuchungsobjekt ausgewählt. Bei der experimentellen Bauwerksuntersuchung wurden die Verfahren Wirbelstrom, Radar, Ultraschall und Mikrowelle zum Einsatz gebracht. Von der Anwendung des Systems und der Auswertung der Ergebnisse wird in diesem Beitrag berichtet. N2 - In recent years a variety of non-destructive evaluation methods are more and more used for the inspection of constructions. Increasing the information value of inspections and the economic aspects of applications leads to a combination of methods on an automated system. Therefore, the BetoScan robot was developed. Gaining more experience in applications was realized with the inspection of a car park which was unused for several years. The building was made of reinforced concrete with melted asphalt as floor coating. Within the frame of the inspections eddy current, radar, ultrasound and microwaves were used. The application of the BetoScan system and the results are presented in this article. KW - Automatisierte zerstörungsfreie Prüfung KW - Bauwesen KW - Kombination KW - Verfahren KW - Bauwerksüberwachung KW - BetoScan-System KW - Dauerhaftigkeit KW - Gussasphalt KW - Instandsetzung KW - Lebensdauer KW - Mikrowelle KW - Nachhaltigkeit KW - Qualitätssicherung KW - Radar KW - Ultraschall-Prüfung KW - ZfP-Verfahren KW - Bauwerkserhaltung/Sanierung KW - Allgemeines PY - 2012 DO - https://doi.org/10.1002/best.201200048 SN - 0005-9900 SN - 1437-1006 VL - 107 IS - 12 SP - 794 EP - 804 PB - Ernst CY - Berlin AN - OPUS4-27588 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Sievert, Rainer A1 - Klingelhöffer, Hellmuth A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. ED - Khan, A. S. ED - Kabirian, F. ED - Liu, J. T1 - Axial-torsional thermo-mechanical fatigue of a near-gamma TiAl-alloy N2 - The uniaxial, torsional and biaxial thermo-mechanical fatigue behavior of γ-TiAl alloy have been examined, at both in-phase (IP) and out-of-phase (OP). OP test conditions were most damaging and needed the lowest strain amplitudes. Pure torsional tests were found in between uniaxial IP and OP tests. The non-proportional multiaxial OP test showed a lower lifetime at the same equivalent mechanical strain amplitude compared to the other types of tests. The microstructure has been characterized applying electron microscopy. T2 - Plasticity '12 - 18th International Symposium on Plasticity and its Current Applications CY - San Juan, PR, USA DA - 03.01.2012 KW - TMF KW - Multiaxial fatigue KW - Titanium aluminides PY - 2012 SN - 0-9659463-0-4 SP - 187 EP - 189 PB - NEAT Press CY - Fulton, MD, USA AN - OPUS4-25325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -