TY - CONF A1 - Rhode, Michael A1 - Schaupp, Thomas A1 - Muenster, C. A1 - Mente, Tobias A1 - Boellinghaus, Thomas A1 - Kannengießer, Thomas T1 - "On how to influence your results" - A review on carrier gas hot extraction parameters for hydrogen determination in welded specimens N2 - Carrier gas hot extraction (CGHE) is a commonly applied technique for determination of hydrogen in welded joints using a thermal conductivity device (TCD) for quantitative measurement. The CGHE is based on the accelerated hydrogen effusion due to thermal activation at elevated temperatures. The ISO 3690 standard suggests different specimen geometries as well as necessary minimum extraction time vs. temperature. They have the biggest influence on precise hydrogen determination. The present study summarizes the results and experience of numerous test runs with different specimen temperatures, geometries and factors that additionally influence hydrogen determination. They are namely: specimen surface (polished/as-welded), limited TCD sensitivity vs. specimen volume, temperature measurement vs. effects of PID-furnace controller as well as errors due to insufficient data assessment. Summarized, the temperature is the driving force of the CGHE. Two different methods are suggested to increase the heating rate up the reach the desired extraction temperature without changing the experimental equipment. Suggestions are made to improve the reliability of hydrogen determination depended on the hydrogen signal stability during extraction accompanied by evaluation of the recorded data. Generally, independent temperature measurement with calibration specimens is useful for further data analysis, especially if this data is used for calculation of trapping kinetics by thermal desorption analysis (TDA). T2 - IIW Annual Assembly and International Conference 2018, Meeting of Commission II-E CY - Nusa Dua, Bali Island, Indonesia DA - 15.07.2018 KW - Carrier gas hot extraction (CGHE) KW - Welding KW - ISO 3690 KW - Hydrogen KW - Experimental design PY - 2018 AN - OPUS4-45520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - von Oertzen, Alexander T1 - 12. Tagung zur Sicherheit bei Sprengarbeiten (Bezpieczeństwo robót strzałowych) in Polen JF - Sprenginfo N2 - Das polnische Bergbauinstitut GIG richtet alle zwei Jahre eine Fachtagung mit dem Thema „Sicherheit bei Sprengarbeiten“ im kleinen Bergstädtchen Ustroń (Polen) aus. Die Tagung hat eine internationale Ausrichtung und bietet Vorträge und Themen sowohl in englischer als auch polnischer Sprache. Es werden Ergebnisse anwendungsorientierter Forschung sowie aus der Praxis der Sprengarbeit vorgestellt. Teilnehmer und Beiträge kommen sowohl von großen Bergbaubetrieben und in Polen tätigen Herstellern als auch von Instituten und Behörden. Im Jahr 2018 war auch die BAM vertreten und der Autor möchte hiermit von den vielfältigen Themen berichten. Es gibt eine gewisse Ähnlichkeit zu der jährlich in Siegen stattfindenden „Informationstagung Sprengtechnik“ des Deutschen Sprengverbandes, wobei bisher wenig inhaltlicher Austausch stattfindet. KW - Explosivstoffe KW - Konferenzbericht KW - Sprengarbeiten PY - 2018 SN - 0941-4584 VL - 40 IS - 3 SP - 6 EP - 7 PB - Deutscher Sprengverband CY - Siegen AN - OPUS4-46900 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni T1 - 2D and 3D imaging chracterization techniques for porous ceramics N2 - The combination of microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on porous material properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of porosity in ceramics. Moreover, I will show how not-so-novel 2D characterization techniques, based X-ray refraction, can allow a great deal of insights in the damage evolution in microcracked (and porous) ceramics. I will show how X-ray refraction can detect objects (e.g. microcracks) below its own spatial resolution. Finally, I will discuss the link between the microstructural findings and the mechanical properties of porous microcracked ceramics. T2 - CIMTEC 2018 CY - Perugia, Italy DA - 04.06.2018 KW - Orientation KW - Cordierite KW - Beta-eucrytite KW - Porosity KW - Microcracking KW - Computed tomography KW - X-ray refraction PY - 2018 AN - OPUS4-45119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, B. A1 - Marko, A. A1 - Petrat, T. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - 3D laser metal deposition: process steps for additive manufacturing JF - Welding in the World N2 - Laser metal deposition (LMD) is an established technology for two-dimensional surface coatings. It offers high deposition rates, high material flexibility, and the possibility to deposit material on existing components. Due to these features, LMD has been increasingly applied for additive manufacturing of 3D structures in recent years. Compared to previous coating applications, additive manufacturing of 3D structures leads to new challenges regarding LMD process knowledge. In this paper, the process steps for LMD as additive manufacturing technology are described. The experiments are conducted using titanium alloy Ti-6Al-4Vand Inconel 718. Only the LMD nozzle is used to create a shielding gas atmosphere. This ensures the high geometric flexibility needed for additive manufacturing, although issues with the restricted size and quality of the shielding gas atmosphere arise. In the first step, the influence of process parameters on the geometric dimensions of single weld beads is analyzed based on design of experiments. In the second step, a 3D build-up strategy for cylindrical specimen with high dimensional accuracy is described. Process parameters, travel paths, and cooling periods between layers are adjusted. Tensile tests show that mechanical properties in the as-deposited condition are close to wrought material. As practical example, the fir-tree root profile of a turbine blade is manufactured. The feasibility of LMD as additive technology is evaluated based on this component. KW - Laser metal deposition KW - Build-up strategy KW - Deposition rate KW - Additive manufacturing PY - 2018 DO - https://doi.org/10.1007/s40194-018-0590-x SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 4 SP - 877 EP - 883 PB - Springer Berlin Heidelberg CY - Heidelberg AN - OPUS4-44868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gollwitzer, Christian A1 - Ulbricht, Alexander A1 - Scholz, Philipp A1 - Joshi, Yogita A1 - Weidner, Steffen T1 - 3D printing material filled with metal organic frameworks analyzed by synchrotron based absorption edge tomography N2 - Absorption edge tomography, also known as differential tomography at absorption edges, is a method which exploits the sudden change of the attenuation coefficient, when the photon energy crosses the absorption edge of an element. Synchrotron radiation is the best source for absorption edge tomography, because of its small bandwidth, high intensity and easily adjustable photon energy. The synchrotron beamline BAMline at the synchrotron radiation facility BESSY II in Berlin, which is operated by the Bundesanstalt für Materialforschung und -prüfung (BAM), provides a monochromatized beam in a photon energy range from 5 keV up to 80 keV with a bandwidth of 2%, when the double multilayer monochromator is used. Together with the microtomography setup, this enables differential tomography with submicron resolution at the K edge of the elements from chromium up to the lanthanides, and up to uranium, when the L edges are used as well. In this work, metal organic frameworks (MOFs) embedded in polymer are characterized using differential tomography. MOFs are microporous structures of metal ions, coordinated by organic linker molecules, that can be used in a broad field of applications, especially in gas storage and catalysis. In this work, polymer embedded MOFs were extruded into filaments, which could be used for 3d-printing to profit from the specific properties of the MOFs in polymeric materials combined with the arbitrary shapes provided by 3d-printing. For the extrusion, different polymer classes like ABS, polyester- and polyetherurethanes, as well as different MOFs (ZIF-8, ZIF-67, HKUST-1) were used to create MOF containing filaments with a nominal diameter of 3.0 mm. Differential tomography at the edges of the Zn, Co, and Cu was then used to find the distribution of the corresponding MOF in the filament and to analyze the shape of the inclusions. T2 - MSE 2018 CY - Darmstadt, Germany DA - 26.09.2018 KW - Absorption edge KW - Tomography KW - Metal organic framework KW - Synchrotron PY - 2018 AN - OPUS4-46429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günster, Jens A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Acchar, W. T1 - 3D printing of porcelain by layerwise slurry deposition JF - Journal of the European Ceramic Society N2 - The Layerwise Slurry Deposition is a technology for the deposition of highly packed powder layers. A powder bed is achieved by depositing and drying layers of a ceramic suspension by means of a doctor blade. This deposition technique was combined with the binder jetting technology to develop a novel Additive Manufacturing technology, named LSD-print. The LSD-print was applied to a porcelain ceramic. It is shown that it was possible to produce parts with high definition, good surface finish and at the same time having physical and mechanical properties close to those of traditionally processed porcelain, e.g. by slip casting. This technology shows high future potential for being integrated alongside traditional production of porce-lain, as it is easily scalable to large areas while maintaining a good definition. Both the Layerwise Slurry Deposition method and the binder jetting technologies are readily scalable to areas as large as > 1 m2. KW - Binder jetting KW - Additive Manufacturing KW - 3D printing KW - Porcelain PY - 2018 DO - https://doi.org/10.1016/j.jeurceramsoc.2018.03.014 SN - 0955-2219 VL - 38 IS - 9 SP - 3395 EP - 3400 PB - Elsevier Ltd. AN - OPUS4-45713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chi, Jinchun A1 - Zocca, Andrea A1 - Agea Blanco, Boris A1 - Melcher, J. A1 - Sparenberg, M. A1 - Günster, Jens T1 - 3D Printing of Self-Organizing Structural Elements for Advanced Functional Structures JF - Advanced Materials Technologies N2 - A shape evolution approach based on the thermally activated self-organization of 3D printed parts into minimal surface area structures is presented. With this strategy, the present communication opposes currently established additive manufacturing strategies aiming to stipulate each individual volumetric element (voxel) of a part. Instead, a 3D structure is roughly defined in a 3D printing process, with all its advantages, and an externally triggered self-organization allows the formation of structural elements with a definition greatly exceeding the volumetric resolution of the printing process. For enabling the self-organization of printed objects by viscous flow of material, functionally graded structures are printed as rigid frame and melting filler. This approach uniquely combines the freedom in design, provided by 3D printing, with the mathematical formulation of minimal surface structures and the knowledge of the physical potentials governing self-organization, to overcome the paradigm which strictly orrelates the geometrical definition of 3D printed parts to the volumetric resolution of the printing process. Moreover, a transient liquid phase allows local programming of functionalities, such as the alignment of functional particles, by means of electric or magnetic fields. KW - Additive Manufacturing KW - Self-Assembly KW - 3D-Printing KW - Polymeric Materials PY - 2018 DO - https://doi.org/10.1002/admt.201800003 SN - 2365-709X VL - 3 IS - 5 SP - 1800003-1 EP - 1800003-7 PB - Wiley-VCH CY - Weinheim AN - OPUS4-45714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Titscher, Thomas A1 - Unger, Jörg F. T1 - A Fourier transformation-based method for gradient-enhanced modeling of fatigue JF - International journal for numerical methods in engineering N2 - A key limitation of the most constitutive models that reproduce a Degradation of quasi-brittle materials is that they generally do not address issues related to fatigue. One reason is the huge computational costs to resolve each load cycle on the structural level. The goal of this paper is the development of a temporal Integration scheme, which significantly increases the computational efficiency of the finite element method in comparison to conventional temporal integrations. The essential constituent of the fatigue model is an implicit gradient-enhanced formulation of the damage rate. The evolution of the field variables is computed as amultiscale Fourier series in time.On a microchronological scale attributed to single cycles, the initial boundary value problem is approximated by linear BVPs with respect to the Fourier coefficients. Using the adaptive cycle jump concept, the obtained damage rates are transferred to a coarsermacrochronological scale associated with the duration of material deterioration. The performance of the developedmethod is hence improved due to an efficient numerical treatment of the microchronological problem in combination with the cycle jump technique on the macrochronological scale. Validation examples demonstrate the convergence of the obtained solutions to the reference simulations while significantly reducing the computational costs. KW - Accelerated temporal integration KW - Fourier series KW - Gradient-enhanced fatigue model PY - 2018 DO - https://doi.org/10.1002/nme.5740 SN - 1097-0207 SN - 0029-5981 VL - 114 IS - 2 SP - 196 EP - 214 PB - Wiley AN - OPUS4-44008 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oesch, Tyler A1 - Landis, E. A1 - Kuchma, D. ED - Lura, P. T1 - A methodology for quantifying the impact of casting procedure on anisotropy in fiber-reinforced concrete using X-ray CT JF - Materials and Structures N2 - Fiber-reinforced concretes (FRCs) offer significant improvements in tensile strength and durability compared to most other concrete mixes. However, for safe and efficient use of FRC in large structures, anisotropy of fiber orientation needs to be understood and properly controlled. In this project, both cored samples extracted from a FRC slab and FRC samples cast individually in molds were assessed using X-ray computed tomography (CT) and measurements of fiber orientation were extracted from the resulting CT images. These results showed that fibers within the slab were highly anisotropic in orientation while fibers in individually cast samples showed a much more heterogeneous distribution of orientations. This indicates that fiber orientation is highly dependent on the casting process and suggests that FRC can only be safely and efficiently utilized if anisotropic fiber orientation is properly accounted for during design and optimized casting methods are used during construction. KW - Anisotropic fiber orientation KW - Computed tomography KW - Fiber-reinforced concrete KW - UHPC KW - Hessian analysis KW - Order parameter PY - 2018 UR - https://rdcu.be/OR6k DO - https://doi.org/10.1617/s11527-018-1198-8 SN - 1359-5997 SN - 1871-6873 N1 - xxx VL - 51 IS - 3 SP - Article 73, 1 EP - 13 PB - Springer Netherlands CY - Dordrecht, Niederlande AN - OPUS4-45045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Artinov, Antoni A1 - Bachmann, Marcel A1 - Karkhin, V. A1 - Rethmeier, Michael T1 - A novel approach for calculating the thermal cycle of a laser beam welding process using a stationary CFD model N2 - This work aims to find the thermal cycles during and after fusion welding through simulation by first calculating the resulting local temperature field in the quasi-stationary part of the process. Here complete-penetration keyhole laser beam welding with a laser power of 18 kW on a 15 mm thick slab of a low-alloyed steel at a welding speed of 2 m/min is considered. In order to physically depict the laser material interaction a multi-physics numerical model including the effects of phase transformation, thermo-capillary convection, natural convection and temperature-dependent material properties up to evaporation temperature is developed. It uses a fixed keyhole geometry with a right truncated circular cone shape to introduce the laser beam energy to the workpiece. In a subsequent study, the resulting local temperature field is then used as an equivalent heat source in order to predict the unsteady thermal cycle during and after fusion welding. The translational movement of the laser beam through the workpiece is represented by a moving mesh approach. For the simulation, stationary heat transfer and fluid dynamics are described by a system of strongly coupled partial differential equations. These are solved with the commercial finite element software COMSOL Multiphysics 5.0. The results of the numerical simulation are validated by experiments, where the weld bead shapes and the thermal cycles show good correlation. T2 - 12th International Seminar "Numerical Analysis of Weldability" CY - Graz-Seggau, Austria DA - 23.09.2018 KW - Equivalent volumetric heat source KW - Process simulation KW - Laser beam welding KW - Transient heat transfer KW - Moving mesh PY - 2018 AN - OPUS4-46037 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -