TY - CONF A1 - Stajanca, Pavol A1 - Krebber, Katerina ED - Webb, D. J. ED - Scully, P. ED - Sugden, K. T1 - Radiation induced attenuation in perfluorinated polymer optical fibres for dosimetry applications N2 - Real-time measurement of radiation-induced attenuation (RIA) in a commercial perfluorinated polymer optical fibre (PF-POF) is performed with regard to on-line Radiation monitoring purposes. Spectral character and dose dependence of fibre’s RIA is measured in 450-900 nm spectral region. Fibre exhibited high radiation sensitivity in the visible region with strong increase towards the UV wavelengths. Good linearity and high sensitivity reaching up to 130 dBm-1/kGy was demonstrated in the VIS region for a low-dose range. This of-the-shelf PF-POF could be therefore interesting for on-line remote dosimetry applications. T2 - POF 2016: 25th International Conference on Plastic Optical Fibres CY - Birmingham, UK DA - 13.09.2016 KW - Perfluorinated polymer optical fibers KW - Gamma radiation monitoring KW - Radiation induced attenuation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-403221 SN - 978-1-85449-408-5 SP - 167 EP - 170 CY - Birmingham AN - OPUS4-40322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krietsch, Arne A1 - Krause, U. A1 - Gabel, D. A1 - Abbas, Z. A1 - Dufaud, O. T1 - Quasi-static dispersion of dusts for the determination of lower explosion limits of hybrid mixtures N2 - Knowledge of explosion limiting concentration of explosible materials is necessary for the design of explosion protection measures. Currently employed methods of testing MEC of a dust cloud or LEL of a hybrid mixture are based on arbitrary assumptions and possess technical limitations that often lead to values of MEC/LEL, which are unrealistically low or poorly reproducible. This contribution presents an improved method for experimental determination of MEC of a combustible dust cloud or LEL of a flammable gas or hybrid mixture. The new set-up operates under laminar conditions and allows a uniform suspension of dust particles in an open top acrylic glass tube. Dust concentration is measured with the help of infrared sensors installed a few centimeters above and below the ignition source. In order to evaluate the dependence of MEC on flow front velocity, MEC of lycopodium was determined at four flow velocities. The results show that the flow field intensity does not significantly influence the MEC of lycopodium for the flow ranges tested in this work. Moreover, LEL of hybrid mixtures of lycopodium and methane was also tested at flow velocities of 4.7 cm/s, 5.8 cm/s, 7 cm/s and 11 cm/s and compared with the values obtained from other sources. The results suggest that the requirement of high energy pyrotechnical igniter may be relinquished, provided that a truly homogeneous suspension of dust particles could be achieved. Moreover, the effect of relative amount of dust and gas, on the course of ignition and flame propagation in hybrid mixtures at their LEL, was studied by the help of high speed videos. For hybrid mixtures of carbonaceous dusts (like lycopodium) at their LEL, ignition occurs in the gas phase, however, flame propagation is only possible through a two-way interaction of dust and gas during the course of combustion. T2 - 13th Symposium International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions (ISHPMIE) CY - Online meeting DA - 27.07.2020 KW - Dust explosions KW - Gas explosions KW - Lower explosion limit KW - Hybrid mixtures PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-540955 DO - https://doi.org/10.7795/810.20200724 SP - 750 EP - 764 PB - Physikalisch-Technische Bundesanstalt AN - OPUS4-54095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jaenisch, Gerd-Rüdiger A1 - Kolkoori, Sanjeevareddy A1 - Bellon, Carsten T1 - Quantitative simulation of back scatter X-ray imaging and comparison to experiments N2 - X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood. In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations. T2 - 19th World Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Radiology KW - Back-scatter techniques KW - Simulation KW - Monte Carlo methods KW - Measurements PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365897 SN - 978-3-940283-78-8 VL - 158 SP - 1 EP - 11 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung (DGZfP) CY - Berlin, Germany AN - OPUS4-36589 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Götschel, S. A1 - Maierhofer, Christiane A1 - Müller, Jan P. A1 - Rothbart, Nick A1 - Weiser, M. T1 - Quantitative defect reconstruction in active thermography for fiber-reinforced composites N2 - Carbon-fiber reinforced composites are becoming more and more important in the production of light-weight structures, e.g., in the automotive and aerospace industry. Thermography is often used for non-destructive testing of These products, especially to detect delaminations between different layers of the composite. In this presentation, we aim at methods for defect reconstruction from thermographic measurements of such carbon-fiber reinforced composites. The reconstruction results shall not only allow to locate defects, but also give a quantitative characterization of the defect properties. We discuss the simulation of the measurement process using finite element methods, as well as the experimental validation on flat bottom holes. Especially in pulse thermography, thin boundary layers with steep temperature gradients occurring at the heated surface need to be resolved. Here we use the combination of a 1D analytical solution combined with numerical solution of the remaining defect equation. We use the simulations to identify material Parameters from the measurements. Finally, fast heuristics for reconstructing defect geometries are applied to the acquired data, and compared for their accuracy and utility in detecting different defects like back surface defects or delaminations. T2 - 19th World Conference on Non-Destructive Testing 2016 CY - München, Germany DA - 13.06.2016 KW - Active thermography KW - Numerical simulation KW - Time-resolved thermogram KW - Thermal wave PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366644 UR - https://www.wcndt2016.com/Programme/show/Th-4-C-4 VL - 2016 SP - Th.4.C.4-1 EP - Th.4.C.4-10 AN - OPUS4-36664 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Maierhofer, Christiane A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gower, M. A1 - Lodeiro, M. A1 - Baker, G. T1 - Quantitative comparison of different non-destructive techniques for the detection of artificial defects in GFRP N2 - In order to test their suitability different non-destructive methods were performed to inspect a GFRP plate with artificial defects. These defects were manufactured by means of thin PTFE sheets inserted between two plies in three different depth. The inspection methods were microwave reflection, flash thermography and phased array ultrasonics, all applied to the same specimen. Selected results are shown for all methods demonstrating opportunities and limits of the particular inspection methods. The achieved detection limits and further application aspects are compared directly to provide a useful information for the planning of inspection tasks. T2 - ECNDT CY - Gothenburg, Sweden DA - 11.06.2018 KW - Fiber resisted polymers KW - Non-destructive testing KW - Thermographic testing KW - Ultrasonic testing PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-453728 SP - ECNDT-0247-2018 AN - OPUS4-45372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maierhofer, Christiane A1 - Krankenhagen, Rainer A1 - Röllig, Mathias A1 - Heckel, Thomas A1 - Brackrock, Daniel A1 - Gaal, Mate T1 - Quantification of impact damages in CFRP and GFRP structures with thermography and ultrasonics N2 - The extent of damage caused by impacts in fibre reinforced composites depends on the energy of the impacts, on the velocity and the shape of the impacting body, on the material and structure of the composite and on the geometry of the structure. Here, mainly the thickness of the component is essential. The non-destructive evaluation of these damages can be carried out using both ultrasound and active thermography methods. A comparison of the detection sensitivity of these methods for the different damages is carried out in this paper depending on the fibre composite material used (CFRP and GFRP), the thickness of the material and the impact energy. The NDT methods used after the damage are supplemented by thermographic measurements with high temporal resolution, which were already recorded during the impact. T2 - 14th Quantitative InfraRed Thermography Conference CY - Berlin, Germany DA - 25.06.2018 KW - Active thermography KW - Passive thermography KW - Ultrasonics KW - CFRP KW - GFRP KW - Impact PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454952 UR - http://www.qirt.org/archives/qirt2018/papers/126.pdf DO - https://doi.org/10.21611/qirt.2018.126 SP - 933 EP - 940 PB - DGZfP e. V. AN - OPUS4-45495 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Hentschel, M. P. A1 - Lange, A. A1 - Trappe, Volker A1 - Laquai, René A1 - Shashev, Yury A1 - Evsevleev, Sergei A1 - Bruno, Giovanni T1 - Progress survey of X-Ray refraction imaging techniques N2 - The most substantial innovations in radiographic imaging techniques of the last two decades aim at enhanced image contrast of weakly absorbing micro and nano structures by taking advantage of X-ray refraction effects occurring at outer and inner surfaces. The applications range from fibre reinforced plastics to biological tissues. These techniques comprise, among others, X-ray refraction topography, diffraction enhanced imaging, phase contrast imaging, Talbot-Lau grating interferometry, and refraction enhanced imaging. They all make use of selective beam deflections up to a few minutes of arc: the X-ray refraction effect. In contrast to diffraction, this type of interaction has a 100 % scattering cross section, as shown experimentally. Since X-ray refraction is very sensitive to the orientation of interfaces, it is additionally a tool to detect, e.g., fibre or pore orientation. If the detector resolution exceeds the size of (small) individual features, one detects the integral information (of inner surfaces) within the gauge volume. We describe the above-mentioned techniques, and show their experimental implementation in the lab and at a synchrotron source. We also show strategies for data processing and quantitative analysis. T2 - 19th World Conference on Non-Destructive Testing CY - Munich, Germany DA - 13.06.2016 KW - grating KW - topography KW - refraction KW - X-ray PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366194 SN - 978-3-940283-78-8 VL - 2016/158 SP - We.3.B.2, 1 EP - 9 AN - OPUS4-36619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Guhl, Svetlana A1 - Meyer, Klas A1 - Kern, Simon A1 - Gräßer, Patrick A1 - Maiwald, Michael ED - Maiwald, Michael T1 - Process monitoring of an intensified continuous production unit with compact NMR spectroscopy N2 - Monitoring chemical reactions is the key to chemical process control. Today, mainly optical online methods are applied. NMR spectroscopy has a high potential for direct loop process control. Compact NMR instruments based on permanent magnets are robust and relatively inexpensive analyzers, which feature advantages like low cost, low maintenance, ease of use, and cryogen-free operation. Instruments for online NMR measurements equipped with a flow-through cell, possessing a good signal-to-noise-ratio, sufficient robustness, and meeting the requirements for integration into industrial plants (i.e., explosion safety and fully automated data analysis) are cur-rently not available off the rack. Recently, promising benchtop NMR instruments with acceptable performance came to market and process integrated sensors developed on basis of such laboratory instruments are on their way. T2 - 12. Kolloquium des Arbeitskreises Prozessanalytik CY - Berlin, Germany DA - 28.11.2016 KW - Online NMR spectroscopy KW - Modular production units KW - Low field NMR spectroscopy PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-383646 SP - P17, 75 EP - 77 AN - OPUS4-38364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Stefan A1 - Küttenbaum, Stefan A1 - Niederleithinger, Ernst T1 - Practical procedure for the precise measurement of geometrical tendon positions in concrete with ultrasonic echo N2 - Existing concrete structures were usually designed for lifetimes of several decades. The current and urgently required efforts to increase sustainability and protect the environment will likely result in extended service lives up to 100 years. To achieve such objectives, it is required to assess structures over their entire lifecycles. Non-destructive testing (NDT) methods can reliably support the assessment of existing structures during the construction, operational, and decommissioning phases. One of the most important and safety-relevant components of a prestressed concrete structure are the tendons. NDT methods such as the ultrasonic echo method are suitable for both the detection and the localization of the tendons, i.e., the measurement of their geometrical position inside the component. The uniqueness of structures, concrete heterogeneity, and varying amounts of secondary components such as the reinforcement represent obstacles in the application of these methods in practice. The aim of this contribution is to demonstrate a practicable procedure, that can be used in the field to determine the parameters required for the measuring data analysis without extensive knowledge about the investigated components. For this purpose, a polyamide reference specimen is used to show which steps are required to obtain reliable imaging information on the position of tendons from the measurement data. The procedure is then demonstrated on a concrete test specimen that covers various relevant and practice-oriented test scenarios, such as varying tendon depths and component thicknesses. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2022) CY - Cape Town, South Africa DA - 03.10.2022 KW - Validation KW - Non-destructive testing KW - Ultrasonic KW - Reconstruction KW - Concrete KW - Tendon duct PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-559979 DO - https://doi.org/10.1051/matecconf/202236403007 SN - 2261-263X SP - 1 EP - 8 AN - OPUS4-55997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winkelmann, Aimo A1 - Nolze, Gert A1 - Voss, M. A1 - Salvat-Pujol, F. A1 - Werner, W. S. M. T1 - Physics-based simulation models for EBSD: advances and challenges N2 - EBSD has evolved into an effective tool for microstructure investigations in the scanning electron microscope. The purpose of this contribution is to give an overview of various simulation approaches for EBSD Kikuchi patterns and to discuss some of the underlying physical mechanisms. T2 - EMAS 2015 - 14th European Workshop on MODERN DEVELOPMENTS AND APPLICATIONS IN MICROBEAM ANALYSIS CY - Portoroz, Slovenia DA - 03.05.2015 KW - Electron backscatter diffraction KW - Simulation KW - Dynamical theory KW - Kinematic theory PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-377469 DO - https://doi.org/10.1088/1757-899X/109/1/012018 VL - 109 SP - 012018-1 EP - 012018-13 AN - OPUS4-37746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -