TY - CONF A1 - Bente, Klaas T1 - The thermoacoustic effect and its application in air-coupled testing of composite structures N2 - Airborne ultrasonic testing of lightweight, structured composite materials enables fast and contact-free non-destructive testing in aerospace and avoids material degradation due to contact with a coupling liquid. Established resonant air-coupled transducers consist of piezocomposite materials and several matching layers or more advanced materials like charged cellular polypropylene. The relaxation time and the specific frequency of such mechanical ultrasound emitters limit the spectrum of applications for each device. A short pulse length is key for reliable defect detection and each component at test can be best characterized at material- and geometry-specific frequencies. Here we show that focused thermoacoustic transducers are suited for testing lightweight, structured composite plates. Since the ultrasound is generated in air, these transducers show no resonance behavior and emit a broadband acoustic spectrum between 1.2 kHz and 1 MHz. Composite specimens of 3 mm to 9 mm thickness made of polylactide with a honeycomb structure were tested. Flat bottom holes were introduced to quantify the spatial resolution of the imaging method inside the strongly anisotropic specimen. As no broadband receivers are available yet, cellular polypropylene transducers were used as receivers, which limits the bandwidth of the method towards the bandwidth of the receiver. Nevertheless, we demonstrate the competitiveness of the thermoacoustic transducer compared to mechanical emitters at their respective resonance frequencies. Because a thermoacoustic transmitter features a nearly ideal pulse width, a single transmitter can be coupled with receivers with different resonance frequencies. With the development of broadband ultrasound receivers, air-coupled ultrasound spectroscopy will likely be possible in the near future. The analysed transducer holds the potential to speed up testing during production and maintenance in aerospace and automotives. Its combination with a broadband receiver could also expand the application field of air-coupled ultrasonic testing from a qualitative error detection towards a quantitative, spatially resolved analysis of mechanical material properties. T2 - 10th International Symposium on NDT in Aerospace CY - Dresden, Germany DA - 24.10.2018 KW - Thermoacoustics KW - Ultrasonic Testing KW - Broadband KW - Ultrasound Emission PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464677 SN - 978-3-940283-96-2 SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin AN - OPUS4-46467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Lima Vasconcelos, S. A1 - Sattler, M. A1 - Müller, B. A1 - Plehn, W. A1 - Horn, Wolfgang T1 - The Influence of textile floor coverings on the indoor air quality N2 - Textile floor coverings are often used in offices and residential buildings. Large areas like meeting rooms, cinemas, theaters and hotels are often equipped with such coverings. They contribute to the comfort of the users as they provide high pedaling comfort and sound absorption. The weakness of these building materials is due to the odor emission that is released from the floor covering, which affects the comfort of the users. A bad air quality and the resulting dissatisfaction can lead to lower employee productivity. The research project of the Hochschule für Technik und Wirtschaft Berlin (HTW-Berlin) is promoted by the German Environment Agency (UBA). The project has the following title: Low-emission and low-odor building products for energy-efficient buildings - Development of requirements and concepts for the Blue Angel from a climate protection perspective; investigates the emission and odor behavior of textile floor coverings (Emissions- und geruchsarme Bauprodukte für energieeffiziente Gebäude - Entwicklung von Anforderungen und Konzepten für den Blauen Engel aus Klimaschutzsicht; untersucht das Emissions- und Geruchsverhalten textiler Bodenbeläge). T2 - Clima 2019 Congress CY - Bucharest, Romania DA - 26.05.2019 KW - VOC Emissionen KW - Geruch KW - Bodenbelag KW - AgBB Bewertung PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-487341 DO - https://doi.org/10.1051/e3sconf/201911102051 SN - 2267-1242 VL - 111 SP - 02051-1 EP - 02051-6 PB - EDP Sciences AN - OPUS4-48734 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Talebi, Elnaz A1 - Korzen, Manfred A1 - Espinós, A. A1 - Hothan, Sascha ED - Albero, Vicente T1 - The effect of damage location on the performance of seismically damaged concrete filled steel tube columns at fire N2 - In this paper, a nonlinear three-dimensional finite element (FE) model was developed and validated to study the effect of seismic damage location on the response of concrete filled tube (CFT) columns at fire after earthquakes. Three analyses were conducted consecutively in the modelling, namely, cyclic, thermal and structural. Results of the cyclic loading analysis comprising residual deformations were applied as the Initial condition to the thermal-stress model, replicating the seismic performance of column. Following, a nonlinear sequentially coupled-thermal stress Analysis was carried out to investigate the fire response of CFT columns after the seismic event. Three damage scenarios were contemplated, considering any possible potential damages that could be generated by the earthquake loading on CFT columns. The accuracy of the proposed FE model was examined by comparing the numerical results with that of available tests on fire and cyclic loading. By means of the validated model, the performance of damaged CFT columns was then investigated under fire after earthquakes. The level of damage was assumed as a high damage level, presuming that the column reached 50% of ist lateral resistance while still maintaining its overall stability after the earthquake. The results were presented broadly, including the axial deformation history as well as the fire resistance time for CFT columns. To have a comprehensive insight on the influence of damage location in columns, the fire response of damaged specimens was compared with that of an intact one. T2 - 12th International Conference on Advances in Steel-Concrete Composite Structures (ASCCS 2018) CY - Valencia, Spain DA - 27.06. 2018 KW - Fire after earthquake KW - Concrete filled tube (CFT) column KW - Finite element model KW - Seismically damaged column KW - Damage location KW - Fire performance PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457694 SN - 978-84-9048-601-6 DO - https://doi.org/10.4995/ASCCS2018.2018.8534 SP - 835 EP - 842 PB - Editorial Universitat Politècnica de València CY - València AN - OPUS4-45769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robens-Radermacher, Annika A1 - Unger, Jörg F. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram ED - Biondini, F. ED - Frangopo, D. M. T1 - Temperature dependent modelling approach for early age behavior of printable mortars N2 - Structural build-up describes the stability and early-age strength development of fresh mortar used in 3D printing. lt is influenced by several factors, i.e. the composition of the print­ able material, the printing regime, and the ambient conditions. The existing modelling approaches for structural build-up usually define the model parameters for a specific material composition with­ out considering the influence of the ambient conditions. The goal of this contribution is to explicitly include the temperature dependency in the modelling approach. Temperature changes have signifi­ cant impact on the structural build-up process: an increase of the temperature leads to a faster dissol­ ution of cement phases and accelerates hydration. The proposed extended model includes temperature dependency using the Arrhenius theory. The new model parameters are successfully calibrated based on Viskomat measurement data using Bayesian inference. Furthermore, a higher impact of the temperature in the re-flocculation as in the structuration stage is observed. T2 - The Eighth International Symposium on Life-Cycle Civil Engineering (IALCCE 2023) CY - Milano, Italien DA - 02.07.2023 KW - 3D concrete printing KW - Material characterization KW - Structural build-up KW - Thixotropy KW - Model calibration PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-582175 SN - 978-1-003-32302-0 DO - https://doi.org/10.1201/9781003323020-146 SN - 978-1-003-32302-0 VL - 1st Edition SP - 1193 EP - 1200 PB - CRC Press AN - OPUS4-58217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Britzke, Ralf A1 - Bruno, Giovanni A1 - Mueller, Bernd R. A1 - Hentschel, Manfred P. T1 - Talbot- Lau interferometry with a non- binary phase grating for non-destructive testing N2 - Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect. At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems. We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes. Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries. T2 - WCNDT2016 CY - Munich, Germany DA - 13.06.2016 KW - Phase-contrast X-ray imaging KW - Talbot- Lau interferometry KW - Phase grating KW - Visibility KW - Synchrotron radiation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365987 SN - 978-3-940283-78-8 VL - BB 158 SP - Tu.3.G.2., 1 EP - 9 AN - OPUS4-36598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Britzke, Ralf A1 - Bruno, Giovanni A1 - Müller, Bernd R. A1 - Hentschel, M. P. T1 - Talbot- Lau interferometry with a non- binary phase grating for non-destructive testing N2 - Grating interferometric set-ups have been established in the last decade. They are promising candidates to obtain enhanced image contrast from weakly absorbing micro and nano structures. They are based on X-ray refraction and near-field diffraction using the Talbot effect. At the expense of taking multiple images, Talbot-Lau grating interferometry allows separating the absorption, refraction, and scattering contributions by analysing the disturbances of a phase grating interference pattern. Contrary to other refraction enhanced methods, this technique can be applied using conventional X-ray tubes (divergent, polychromatic source). This makes it attractive to solve typical non-destructive testing problems. We investigated the efficiency of phase gratings, i.e. the visibility (the amplitude of oscillations) upon variation of propagation distance and phase grating rotation around an axis parallel to the grid lines. This grating rotation changes the grating shape (i.e. the distributions of phase shifts). This can yield higher visibilities than derived from rectangular shapes. Our study includes experimental results obtained from synchrotron radiation, as well as simulations for monochromatic radiation. The advantages of Talbot-Lau interferometry are demonstrated at the example of glass capillaries. T2 - 19th World Conference on Non-Destructive Testing 2016 CY - Munich, Germany DA - 13.06.2016 KW - Talbot- Lau interferometry KW - Phase grating KW - Non-destructive testing PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-383163 SP - Tu_3_G_2, 1 EP - 9 AN - OPUS4-38316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krankenhagen, Rainer A1 - Ziegler, Mathias A1 - Maierhofer, Christiane ED - Maldague, X. T1 - Systematic errors in the evaluation of uncorrected data from thermographic lock-in measurements N2 - Lock-in thermography (LT) is based on the correct evaluation of phase differences between the temperature oscillations at different surface regions of the object under test during periodic heating. Since the usual heating procedures contain a DC component, the actual heating pattern achieved is not harmonic. This causes systematic deviations when phase differences are determined by means of harmonic analysis, e.g. with FFT analysis. The resulting errors depend clearly on the ratio between DC and AC amplitude, which is demonstrated at simulated and experimentally recorded temperature transients. Further experimental LT data obtained by different oscillating energy inputs showed a variety of possible shapes of transients with different DC components. T2 - 14th QIRT Conference CY - Berlin, Germany DA - 26.06.2018 KW - NDT KW - Lock-in Thermography KW - FFT PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-453768 SP - 539 EP - 547 PB - QIRT Council AN - OPUS4-45376 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sproesser, G. A1 - Schenker, S. A1 - Pittner, Andreas A1 - Borndörfer, R. A1 - Rethmeier, Michael A1 - Chang, Y.-J. A1 - Finkbeiner, M. T1 - Sustainable welding process selection based on weight space partitions N2 - Selecting a welding process for a given application is crucial with respect to the sustainability of part manufacturing. Unfortunately, since welding processes are evaluated by a number of criteria, preferences for one or the other process can be contradictory. However, the prevalent procedure of weight assignment for each criterion is subjective and does not provide information about the entire solution space. From the perspective of a decision maker it is important to be able to assess the entire set of possible weightings and answer the question which welding process is optimal for which set of weights. This issue is investigated by means of a weight space partitioning approach. Two welding processes are considered with respect to three criteria that reflect their economic and environmental performance. In order to find the most sustainable welding process the underlying weight space partition is evaluated. T2 - 13th Global Conference on Sustainable Manufacturing – Decoupling Growth from Resource Use CY - Bình Dương New City, Vietnam DA - 16.09.2015 KW - Welding costs KW - Multi-criteria decision support KW - LCA KW - Welding process selection KW - GMAW KW - Multi-attribute decision method PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-353740 DO - https://doi.org/10.1016/j.procir.2016.01.077 SN - 2212-8271 VL - 40 SP - 127 EP - 132 PB - Elsevier B.V. AN - OPUS4-35374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Superplasticizer and Shrinkage Reducing Admixture Dosages for Microfine Cement in Grout Systems N2 - Grouts have numerous applications including crack repair as maintenance in construction industries. Microfine cements are intensively used for high strength mortar and grout products. They are ideal for injection grouting in structural repair. Such grouts should have suitable rheological properties to be injectable, especially those used in repair and rehabilitation. The use of superplasticizers (SP) in these products is thus becoming increasingly crucial to achieve favorable workability and viscosity properties. A difficulty in such grouts is the plastic shrinkage due to finer particles used. It is thus necessary to determine optimum SP and shrinkage reducing admixture (SRA) dosages for a microfine cement based grout. In this study, a saturation dosage was decided from two Polycarboxylate ether (PCE) based SPs in relation to neat cement using slump flow and rheological parameters. A range of grout mixtures was formulated containing micro silica (MS) and fly ash (FA), and tested for suitable rheological and mechanical parameters. Based on the results, a grout mixture with MS and FA was selected to determine optimum SRA content. According to the results, a SP dosage of 3% by weight of neat cement is sufficient to achieve saturation. The grout material including MS and FA can produce comparable properties to neat cement grout. MS is found to improve compressive strength within the range considered, whereas a higher FA content provides favourable rheological properties. Finally, a SRA dosage of 4%, which could reduce the shrinkage by about 43% after 28d days, is determined for the grout system. T2 - 2nd International Conference on Building Materials and Materials Engineering (ICBMM 2018) CY - University of Lisbon, Portugal DA - 26.09.2018 KW - Grout KW - Microfine Cement KW - Superplasticizer KW - Supplementary Cementitious Materials KW - Shrinkage Reducing Admixture PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-478319 DO - https://doi.org/10.1051/matecconf/201927801001 VL - 278 SP - Article Number 01001 PB - EDP Sciences AN - OPUS4-47831 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bellon, Carsten A1 - Zhukovskiy, M. A1 - Markov, M. A1 - Podolyako, S. A1 - Uskov, R. A1 - Jaenisch, Gerd-Rüdiger T1 - Supercomputing the cascade processes of radiation transport N2 - Modeling of the photon-electron cascade progress in multicomponent objects of complex geometrical structure by use of hybrid supercomputers is considered. An approach to computing the cascade processes is developed. The approach has three key properties allowing the effective use of heterogeneous structure of computers for solving the tasks of radiation transport in complex multi-scale geometries. Firstly, two different discreet geometrical description of an object being under radiation is used: triangulated model for photon transport and voxel model for electron transport. Secondly, small parameter of the problem is explicitly taking into account for modeling surface effects (for instance, electron emission). Thirdly, the effective calculation decomposition between CPU and GPU is developed for significant increasing the speed of calculations of processes in question. Modeling of experiment on researching the bremsstrahlung generated by electron beam in Ta target is carried out. Comparison of computing and experimental results shows satisfactory consent. T2 - 19th World Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Super somputing KW - Photon-electron transport KW - Monte Carlo methods KW - Modelling PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365932 SN - 978-3-940283-78-8 VL - 158 SP - 1 EP - 6 PB - DGZfP CY - Berlin, Germany AN - OPUS4-36593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -