TY - CONF A1 - Pfennig, Anja A1 - Wolf, Marcus A1 - Gröber, Andre A1 - Böllinghaus, Thomas A1 - Kranzmann, Axel T1 - Corrosion fatigue of 1.4542 exposed to a laboratory saline aquifer water CCS-environment N2 - X5CrNiCuNb16-4 has been proven to be sufficient resistant in corrosive environments, but shows rather unusual corrosion behaviour in CCS environment. Therefore a series of 30 specimens was tested at stress amplitudes between 150 MPa and 500 MPa (sinusoidal dynamic test loads, R=-1; resonant frequency ∼ 30 Hz). Due to the rather heterogeneous fine machined surfaces (Rz=4) the specimens are comparable with prefabricated parts. X5CrNiCuNb16-4 reached the maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa and lies 60% below the stress amplitude measured in air. The scatter range TN = 1:34 is disproportionately large. Although the fracture surface exhibited the typical striations and corroded surface areas no significant differences were found. The hardness was found to be homogeneous in all specimens tested at 335 HV10. Non-metallic inclusions were found within the microstructure, but no correlation could be found between the inclusions and early rupture. Still specimens that showed inclusions at the fracture surface and its cross section endured lower number of cycles. Additionally Aluminium was analysed in specimens with low number of cycles and may be cause for early rupture during corrosion fatigue tests. These findings reveal a very high sensitivity on a homogeneous microstructure upon the corrosion and corrosion fatigue behaviour of X5CrNiCuNb16-4 and needs to be taken into account when regarding this steel as pipe steel during injection of CO2 into saline aquifers. T2 - 13th International Conference on Greenhouse Gas Control Technologies CY - Lausanne, Switzerland DA - 14.11.2016 KW - Steel KW - Corrosion fatigue KW - Electrochemistry KW - Reliability KW - CCS KW - CO2-storage PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418525 DO - https://doi.org/10.1016/j.egypro.2017.03.1678 SN - 1876-6102 VL - 114 SP - 5219 EP - 5228 AN - OPUS4-41852 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Stolpe, Heiko A1 - Kruschwitz, Sabine ED - Schumann, R. T1 - Correlation between the electric impedance and the water layer thickness in partially saturated screed samples N2 - The moisture content of screed samples is monitored by means of embedded sensors. Relative humidity sensors and multi-ring-electrodes are used to measure the spatial moisture distribution during desorption. Based on the humidity data and the pore volume distribution, the moisture and the water layer thickness within the pore space are predicted. Slit shape as well as cylindrical pores are evaluated. Finally, the measured real part of the electrical impedance and the calculated water layer thickness are correlated. Based on the available data, a significant trend change of the impedance is documented at a water layer thickness of approximately 3 nm. This water layer thickness corresponds to a relative humidity of 88.3%. T2 - 10. CMM Tagung CY - Ettlingen, Germany DA - 10.10.2019 KW - Material moisture KW - Screed KW - Embedded sensors KW - Electric impedance KW - Water layer thickness PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-494636 VL - 10 SP - 79 EP - 102 PB - CMM, Karlsruher Institut für Technologie CY - Karlsruhe AN - OPUS4-49463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Müller, Bernd R. T1 - Correction of diffuse X-ray detector based background N2 - A novel approach to strongly suppress artifacts in radiography and computed tomography caused by the effect of diffuse background Signals (“backlight”) of 2D X-ray detectors is suggested. Depending on the detector geometry the mechanism may be different, either based on the optical scattering of the fluorescent screen materials into optical detection devices or Compton or X-ray fluorescence scattering by the detector components. Consequently, these erroneous intensity portions result in locally different violations of Lambert Beer’s law in single projections (radiographs). When used as input data for computed tomography these violations are directly observed via modulation of the projected mass as a function of the rotation Phase and the sample’s aspect ratio (dynamics). The magnitude of the diffuse Background signal depends on the detector area covered by the projected sample. They are more pronounced the smaller the shaded area and the stronger the total attenuation. Moreover, the local intensity mismatch depends on the attenuation of the sample. We present very basic reference data measured with multiple metal foils at a synchrotron radiation source. Beam hardening artifacts can be excluded due to the monochromatic radiation. The proposed correction procedure assumes a constant (non-local) scattering mechanism. T2 - DIR 2011 - International symposium on digital industrial raidology and computed tomography CY - Berlin, Germany DA - 20.06.2011 KW - Backlight KW - X-ray detector KW - Fluorescence screen KW - Synchrotron radiography KW - Computed tomography PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-243589 SN - 978-3-940283-34-4 IS - DGZfP-BB 128 (Poster 24) SP - 1 EP - 7 PB - Deutsche Gesellscahft für Zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-24358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Construction and validation of a novel phased array borehole probe for ultrasonic investigations at sealing structures in radioactive repositories N2 - A new type of ultrasonic borehole probe is currently under development for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The goal is to examine the sealing structures made of salt concrete for possible cracks, delamination, and embedded objects. Earlier prototype probes use 12 or 16 individual dry point contact (DPC) horizontal shear wave transducers grouped into a transmitter and a receiver array, each made up of six or eight individual transducers. They are operated with a commercially available portable ultrasonic flaw detector used in the civil engineering industry. To increase the generated sound pressure of the borehole probe, the number of transducers in the novel probe is increased to 32. In addition, timed excitation of each probe is used to direct a focused sound beam to a specific angle and distance based on calculated time delays. Hence, the sensitive test volume is limited, and the signal-to-noise ratio of the received signals is improved. This paper presents the validation of the newly developed phased array borehole probe by beam computation in CIVA software and experimental investigations on a semi-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction techniques, an optimised radiation pattern of the probe is expected to improve the signal quality and thus increase the reliability of the imaging results. This is of great importance for the construction of safe sealing structures needed for the disposal of radioactive or toxic waste. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Borehole probe KW - Phased array technique KW - SealWasteSafe KW - Monitoring KW - Engineered barrier; PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-568016 SN - 1435-4934 SP - 1 EP - 4 PB - NDT.net AN - OPUS4-56801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Leinitz, Sarah ED - Diouri, A. ED - Boukhari, A. ED - Ait Brahim, L. ED - Bahi, L. ED - N., Khachani ED - Saadi, M ED - Aride, J. ED - Nounah, A. T1 - Concrete casting robustness improvement due to active rheology N2 - With ongoing innovation in process technology, the challenges of concrete technology are more and more focused on the rheological optimisation for these processes, since improper mixture stability or poor compaction ability negatively affect the concrete homogeneity and quality. However, along with the increasing complexity of today’s concrete mixture compositions, concrete becomes more prone to failure regarding the casting process. Variable properties of the raw materials typically cause changing workability. The reasons can be found among others in scattering water contents, physical or chemical properties of the cement or varying environmental temperatures. Robustness in the delicately adjusted rheology, however, is of utmost importance for modern and future process technology, from sprayed concrete over pumpable concrete towards 3D-printing, with regard to the long-term strength, the function and the durability. Typically, material induced changes cannot be identified easily due to the complex interactions of concrete constituents. Therefore, a precise and prompt counteraction is impossible. However, it is known that the yield stress can be controlled by addition of supplementary superplasticizer or stabilising agent. In combination with computerized process observation tools that can rapidly interpret and react on changes in the rheology, it is therefore thinkable, that only these two admixture types can adjust the rheology steadily and permanently, regardless of the actual root cause for observed macroscopic rheology change. The presentation will firstly give a comprehensive overview of effects at the interface between pore solution, particles and hydrates, which affect the rheology of fresh concrete. Secondly, ways are recommended how the rheology can be actively manipulated before eventually computerized methods are demonstrated that help to actively and rapidly assess and counteract performance scatter during steady casting processes. T2 - 2nd International Congress on Materials & Structural Stability (CMSS-2017) CY - Rabat, Morocco DA - 22.11.2017 KW - Cusum KW - Rheology KW - Control Chart KW - Concrete KW - Robustness PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-444317 DO - https://doi.org/10.1051/matecconf/201814901001 SN - 2261-236X VL - 149 SP - 01001-1 EP - 01001-7 PB - EDP Sciences CY - Les Ulis AN - OPUS4-44431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altenburg, Simon A1 - Maierhofer, Christiane A1 - Straße, Anne A1 - Gumenyuk, Andrey T1 - Comparison of MWIR thermography and high-speed NIR thermography in a laser metal deposition (LMD) process N2 - Additive manufacturing (AM) offers a range of novel applications. However, the manufacturing process is complex and the production of defect-free parts with high reliability and durability is still a challenge. Thermography is a valuable tool for process surveillance, especially in metal AM processes. The high process temperatures allow one to use cameras usually operating in the visible spectral range. Here, we compare the results of measurements during the manufacturing process of a commercial laser metal deposition setup using a mid-wavelength-IR camera with those from a visual spectrum high-speed camera with band pass filter in the near-IR range. T2 - Conference QIRT 2018 CY - Berlin, Germany DA - 25.06.2018 KW - Additive manufacturing KW - Laser metal deposition KW - ProMoAM KW - Thermography PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-454993 UR - http://www.qirt.org/archives/qirt2018/papers/p35.pdf DO - https://doi.org/10.21611/qirt.2018.p35 SP - 1 EP - 5 PB - QIRT Council CY - Quebec, Canada AN - OPUS4-45499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Thiele, Marc A1 - Hille, Falk A1 - Makris, Ruben ED - Helmerich, Rosemarie ED - Ilki, A. ED - Motavalli, M. T1 - Comparison of fatigue crack detection methods for high-cyclic loaded steel structures N2 - At present, to produce renewable energy offshore wind farms play an important role. The available space combined with the more valuable wind conditions make offshore locations very attractive for wind powered energy production. In Europe a significant number of offshore wind farms already exist, especially in the North and Baltic Sea. In future this trend will continue, and further offshore wind farms will be built. The majority of offshore wind turbines are mounted on steel foundation structures. Due to the high-cyclic loading by wind and waves fatigue stress plays a substantial role regarding structural safety. Besides the consideration of fatigue within the design process, to monitor existing steel structures for potential fatigue cracks during their life time is a major topic and a challenge. For the structures of the offshore wind turbines are large and partially under water effective reliable methods for the detection of fatigue cracks are required. This contribution presents investigations on different crack detection methods applied at high-cycle fatigue tests on small-scale welded steel samples as well as on large-scale welded steel components. The tests were conducted at the BAM laboratories. For crack detection mainly three different methods were used and compared. The first method regards to the measurement of strain by conventionally strain gauges. Secondly, the crack luminescence was used as a new and effective optical method for surface monitoring. And finally, crack detection by pressure differentials of the inner and outer section of tubular steel elements was investigated. A comparison study will emphasize the advantages and disadvantages of the different methods and show which of the described methods is potentially more suitable for an application on real offshore wind structures. T2 - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures CY - Potsdam, Germany DA - 27.08.2019 KW - Fatigue KW - Steel structures KW - Crack detection PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489433 SP - Th.2.A.1-1 EP - Th.2.A.1-8 AN - OPUS4-48943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hüsken, Götz A1 - Shamsuddoha, Md A1 - Thiele, Marc A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten T1 - Comparison of cracks formed in scaled grouted connection of offshore energy structures under static and cyclic loads N2 - Global energy consumption will increase in the future necessitating both fossil fuels and renewable energy choices - especially wind energy. Such high energy demand requires installation of offshore energy structures, rigs, platforms and towers, which are susceptible to adverse environmental conditions along with maintenances. Due to their large size and remote locations, cylindrical grouted joints are often adopted between substructure and foundation in these offshore platforms and wind structures such as monopiles. However, these connections are composite structures with exterior sleeve, interior pile and infill mortar. Degradation and settlements were reported inside similar connections, which were installed in last three decades. Besides, grouting in the offshore sites were proven difficult to obtain ideal load bearing capacity. In-situ loading conditions were also found to be affecting the failure mechanism inside such connections. This study aims at characterizing the nature of cracks generated in these grouted connections under both static and cyclic loading. Scaled grouted joints were manufactured using a novel reusable mold, and connections were loaded to failure to visualize the main failure patterns. An assessment between failure under these two types of load is drawn along with comparison to previously available literature. T2 - 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures CY - Potsdam, Germany DA - 27.08.2019 KW - Grouted connection KW - Crack formation KW - Crack pattern KW - Static load KW - Cyclic load PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-487961 SP - Th.2.A.1-1 EP - Th.2.A.1-9 AN - OPUS4-48796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ehrig, Karsten A1 - Goebbels, Jürgen A1 - Meinel, Dietmar A1 - Paetsch, O. A1 - Prohaska, S. A1 - Zobel, Valentin T1 - Comparison of crack detection methods for analyzing damage processes in concrete with computed tomography N2 - Analyzing damages at concrete structures due to physical, chemical, and mechanical exposures need the application of innovative non-destructive testing methods that are able to trace spatial changes of microstructures. Here, the utility of three different crack detection methods for the analysis of computed tomograms of various cementitious building materials is evaluated. Due to the lack of reference samples and standardized image quality evaluation procedures, the results are compared with manually segmented reference data sets. A specific question is how automatic crack detection can be used for the quantitative characterization of damage processes, such as crack length and volume. The crack detection methods have been integrated into a scientific visualization system that allows displaying the tomography images as well as presenting the results. T2 - DIR 2011 - International symposium on digital industrial raidology and computed tomography CY - Berlin, Germany DA - 20.06.2011 KW - Crack detection KW - Computed tomography KW - Data visualization PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-243569 SN - 978-3-940283-34-4 IS - DGZfP-BB 128 (Poster 2) SP - 1 EP - 8 PB - Deutsche Gesellscahft für Zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-24356 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Spitzer, Stefan A1 - Askar, Enis A1 - Krietsch, Arne A1 - Schröder, Volkmar T1 - Comparative study on standardized ignition sources used for explosion testing N2 - For the determination of safety characteristics of gases, vapors and dusts different types of ignition sources are used in international standards and guidelines. Table 1 compares technical relevant ignition sources with their main features. The paper presents test results of a comparative calorimetric and visual study between four different types of ignition sources. The ignition procedures were analyzed visually with a high-speed camera and electric recordings. In addition to that, the influence of the electrode-orientation, -distance as well as ignition energy on the reproducibility of the exploding wire igniter was tested. The exploding wire is already in use for standardized determination of safety characteristics of gases, first tests on the suitability of the exploding wire igniter for dust testing have been carried out by Scheid et al. Using the exploding wire, the ignition energy can be varied from 2 to 10 000 J (2 x 5 000 J) and thus it could be used for gases, vapors, dusts and hybrid mixtures. Moreover it can be used at high initial pressures and it is the only ignition source with an easily measurable ignition energy release. Furthermore, it does not introduce another chemical reaction into the system. Finally, a proposal for a standard ignition source for explosion tests on hybrid mixtures is derived from the test results. T2 - 13th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions CY - Online meeting DA - 27.07.2020 KW - Ignition source KW - Exploding Wire KW - Hybrid mixtures KW - Safety characteristics determination PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517908 UR - https://oar.ptb.de/files/download/5f3e662f4c93901010006dbf DO - https://doi.org/10.7795/810.20200724 VL - 13 SP - 864 EP - 875 PB - PTB Physikalisch-Technische Bundesanstalt Braunschweig AN - OPUS4-51790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -