@inproceedings{ReyVillazonKuehhornWeiss, author = {Rey Villaz{\´o}n, Jos{\´e} Maria and K{\"u}hhorn, Arnold and Weiß, Thomas}, title = {A Parametric Impact Study of the Geometry, Air System and Thermal Boundary Conditions on the Life of a Two-Stage High Pressure Turbine}, series = {Proceedings of the ASME Turbo Expo 2012, presented at The ASME 2012 Turbo Expo, June 11-15, 2012, Copenhagen, Denmark, Vol. 7, part A}, booktitle = {Proceedings of the ASME Turbo Expo 2012, presented at The ASME 2012 Turbo Expo, June 11-15, 2012, Copenhagen, Denmark, Vol. 7, part A}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-4473-1}, pages = {373 -- 382}, language = {en} } @misc{BolzOehringLindemannetal., author = {Bolz, Sebastian and Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine and Schr{\"u}fer, Susanne}, title = {Microstructure and mechanical properties of a forged beta-solidifying gamma TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, pages = {71 -- 83}, language = {en} } @misc{HirschZharnikovShaporenkoetal., author = {Hirsch, Thomas and Zharnikov, Michael and Shaporenko, Andrey and Stahl, Joachim and Weiss, Dieter and Wolfbeis, Otto S. and Mirsky, Vladimir M.}, title = {Size-controlled electrochemical synthesis of metallic nanoparticles on molecular templates}, series = {Angewandte Chemie International Edition}, volume = {44}, journal = {Angewandte Chemie International Edition}, number = {41}, issn = {1521-3773}, doi = {10.1002/anie.200500912}, pages = {6775 -- 6778}, abstract = {Reduction on the spot: Planarly adsorbed thiolated porphyrin molecules (purple) incorporated in an insulating alkanethiol monolayer (blue) function as nanoelectrodes for the local reduction of metals (gray). This approach was applied for the in situ synthesis of nanoparticles of a predetermined size.}, language = {en} } @misc{ShapovalovShapovalovaOssenbrinketal., author = {Shapovalov, Oleg and Shapovalova, Mariia and Ossenbrink, Ralf and Heckel, Thomas and Michailov, Vesselin and Weiß, Sabine and Gaal, Mate}, title = {Verbessern der Korrosionsbest{\"a}ndigkeit eines hochtemperaturbest{\"a}ndigen Ultraschalld{\"a}mpfungsk{\"o}rpers mittels Laserstrahl-Auftragschweißen}, series = {DVS Berichte 2021}, journal = {DVS Berichte 2021}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-147-1}, pages = {370 -- 377}, abstract = {W{\"a}hrend in einem konventionellen Ultraschallpr{\"u}fkopf ein Kunststoffd{\"a}mpfungsk{\"o}rper mit Kleber oder {\"O}l an einen Piezoschwinger angekoppelt ist, werden als Hochtemperaturl{\"o}sung feinpor{\"o}se sintermetallische D{\"a}mpfungsmaterialien mit einer Fl{\"u}ssigglasankopplung eingesetzt. Um dabei das Sintermetall vor dem korrosiven Angriff der Glasschmelze zu sch{\"u}tzten, wird am D{\"a}mpfungsk{\"o}rper gegenw{\"a}rtig Gold- oder Platinfolie zeit- und kostenaufwendig appliziert. In der aktuellen Arbeit wurde eine Methode zum Korrosionsschutz der sintermetallischen Oberfl{\"a}che aus rostfreiem Stahl mittels Laser-Pulverauftragschweißen entwickelt. Im Laufe einer Schweißparameterstudie auf dem Substratmaterial aus massivem rostfreiem Stahl wurde die Eignung unterschiedlicher Auftragsmaterialien auf Nickel- und Kobaltbasis untersucht. Dabei wurde zun{\"a}chst der Einfluss verschiedener Schweißparameter wie Laserleistung, Vorschubgeschwindigkeit und Pulvermenge auf die Auftragsqualit{\"a}t (Nahtform, Vermischungsgrad, Porosit{\"a}t) metallografisch bewertet. Anschließend wurden die aufgetragenen Schichten hinsichtlich ihrer Korrosionsbest{\"a}ndigkeit getestet. Der Kontakt mit einer fl{\"u}ssigen Glasmischung bei 500 °C hat bei keiner der beschichteten Proben sichtbare Korrosionswirkung gezeigt. Als Resultat der Schweißparameterstudie haben sich besonders die nickelbasierten Pulver als gut geeignete Materialien f{\"u}r den Prozess gezeigt. Die identifizierten Schweißparameter wurden im n{\"a}chsten Schritt erfolgreich an das sintermetallische Substrat angepasst.}, language = {de} } @misc{ShapovalovHeckelGaaletal., author = {Shapovalov, Oleg and Heckel, Thomas and Gaal, Mate and Weiß, Sabine}, title = {External Acoustical Damping on a Metallic Angle Wedge in a High Temperature Resistant Ultrasonic Probe}, series = {Acoustics Australia}, volume = {50}, journal = {Acoustics Australia}, number = {3}, issn = {1839-2571}, doi = {10.1007/s40857-022-00270-9}, pages = {343 -- 353}, abstract = {Ultrasonic probes for high-temperature applications are provided with metallic wedges, which can withstand the contact with the high temperature of the inspected structure. The ultrasonic signal travels within the wedge and gets reflected from its boundaries, causing interference signals called "ghost echoes". The current work presents an investigation of the additional damping effect provided by porous sintered metal plates applied onto the surface of the wedge. In particular, the study evaluates the effect of damping plate thickness on the interference signal level at different transmission frequencies. Damping plates made of sintered metal SIKA-R 15 AX were attached to a wedge prototype made of steel 1.4301. The study revealed, that the most effective thickness of damping plates in the selected frequency interval of 1 to 4 MHz is equal to 4 mm. The evaluation of the interference signal has shown that the application of such damping plates to the wedge surface contributes to an additional attenuation of an interference signal of 10 to 30 dB after 500 µs of signal propagation.}, language = {en} } @misc{OehringLindemannPyczaketal., author = {Oehring, Michael and Lindemann, Janny and Pyczak, Florian and Paul, Jonathan and Stark, Andreas and Lippmann, Thomas and Schr{\"u}fer, Susanne and Roth-Fagaraseanu, Dan and Schreyer, Andreas and Weiß, Sabine}, title = {Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions}, series = {Intermetallics}, volume = {2015}, journal = {Intermetallics}, number = {58}, issn = {0966-9795}, doi = {10.1016/j.intermet.2014.11.008}, pages = {71 -- 83}, abstract = {In the cast condition g titanium aluminide alloys that solidify completely through the b phase are characterized by fine and homogeneous microstructures, weak textures and low segregation. For these reasons such alloys have a relatively good workability and can be closed-die forged without preceding ingot breakdown even if the alloys contain no large fractions of the b phase at the working temperature. The present work was devoted to a combined study of the constitution and microstructural morphologies that develop in various two-step heat treatments of a single-step forged b solidifying alloy. The study included high-energy X-ray diffraction for in situ investigations of the constitution at the heat treatment temperature. It was observed that the phase ransformations are quite sluggish in the material which results in fine microstructures and some conditions that significantly deviate from thermodynamic equilibrium. Further, tensile and creep testing was carried out on the different material conditions in order to identify the range in which the properties can be varied. It is found that this easily forgeable material exhibits comparable strength, ductility and creep strength as more conventional peritectically solidifying alloys.}, language = {en} } @misc{ShapovalovGaalHoenigetal., author = {Shapovalov, Oleg and Gaal, Mate and H{\"o}nig, Gerald and Gradt, Thomas and Weiß, Sabine}, title = {Temperature dependence of the propagation speed of a longitudinal wave in different solids for use as a wedge material in an extreme-temperature-resistant ultrasonic transducer}, series = {Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany}, volume = {2019}, journal = {Proceedings of the 23rd International Congress on Acoustics : integrating 4th EAA Euroregio 2019 : 9-13 September 2019 in Aachen, Germany}, editor = {Ochmann, Martin and Vorl{\"a}nder, Michael and Fels, Janina}, address = {Aachen}, isbn = {978-3-939296-15-7}, issn = {2226-7808}, doi = {10.18154/RWTH-CONV-239953}, pages = {4754 -- 4760}, abstract = {In special cases of angle beam ultrasonic measurement - e.g. defect detection in hot solids as well as flow measurement of liquid gases or energy storage mediums [1] - the applied transducer has to withstand extreme temperatures. Since the irradiation angle into the specific material is determined not only by wedge design, but also by the speed of sound in both the wedge material and the tested object, the developer must take into account the speed of the wave propagation in a wedge material over the whole temperature range of transducers application. In this study we investigate the temperature dependence of the speed of longitudinal wave propagation in 10 different materials in the range from -200 °C to 400 °C. The investigated materials belong to different material classes (ceramics, glass, as well as ferrous and non-ferrous metals) and are all temperature-resistant up to at least 600 °C, and therefore applicable as wedge materials in an ultrasonic transducer for use at extreme temperatures.}, language = {en} } @misc{WagnerKuehhornWeissetal., author = {Wagner, Frank and K{\"u}hhorn, Arnold and Weiss, Thomas and Otto, Dierk}, title = {Influence of different parametrizations on the optimum design of a high pressure turbine blade firtree}, series = {ASME Turbo Expo 2016, Turbomachinery Technical Conference and Exposition, Volume 7A, Structures and Dynamics, Seoul, South Korea, June 13-17, 2016}, journal = {ASME Turbo Expo 2016, Turbomachinery Technical Conference and Exposition, Volume 7A, Structures and Dynamics, Seoul, South Korea, June 13-17, 2016}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-4983-5}, doi = {10.1115/GT2016-56749}, pages = {11}, abstract = {Today the design processes in the aero industry face many challenges. Apart from automation itself, a suitable parametric geometry setup plays a significant role in making workflows usable for optimization. At the same time there are tough requirements against the parametric model. For the lowest number of possible parameters, which should be intuitively ascertainable, a high flexibility has to be ensured. Within the parameter range an acceptable stability is necessary. Under these constraints the creation of such parametric models is a challenge, which should not be underestimated especially for a complex geometry. In this work different kinds of parametrization with different levels of complexity will be introduced and compared. Thereby several geometry elements will be used to handle the critical regions of the geometry. In the simplest case a combination of lines and arcs will be applied. These will be replaced by superior elements like a double arc construct or different formulations of b-splines. There will be an additional focus on the variation of spline degree and control points. To guarantee consistency a set of general parameters will be used next to the specific ones at the critical regions. The different parameter boundaries have a influence on the possible geometries and should therefore be tested separately before an optimization run.}, language = {en} } @misc{JurischkaDinterEfimovaetal., author = {Jurischka, Christoph and Dinter, Franziska and Efimova, Anastasia and Weiss, Romano and Schiebel, Juliane and Schulz, Christian and Fayziev, Bekzodjon and Schierack, Peter and Fischer, Thomas and R{\"o}diger, Stefan}, title = {An explorative study of polymers for 3D printing of bioanalytical test systems}, series = {Clinical Hemorheology and Microcirculation}, volume = {75}, journal = {Clinical Hemorheology and Microcirculation}, number = {1}, issn = {1875-8622}, doi = {10.3233/CH-190713}, pages = {57 -- 84}, abstract = {Background: The 3D printing is relevant as a manufacturing technology of functional models for forensic, pharmaceutical and bioanalytical applications such as drug delivery systems, sample preparation and point-of-care tests. Objective: Melting behavior and autofluorescence of materials are decisive for optimal printing and applicability of the product which are influenced by varying unknown additives. Methods: We have produced devices for bioanalytical applications from commercially available thermoplastic polymers using a melt-layer process. We characterized them by differential scanning calorimetry, fluorescence spectroscopy and functional assays (DNA capture assay, model for cell adhesion, bacterial adhesion and biofilm formation test). Results: From 14 tested colored, transparent and black materials we found only deep black acrylonitrile-butadiene-styrene (ABS) and some black polylactic acid (PLA) useable for fluorescence-based assays, with low autofluorescence only in the short-wave range of 300-400 nm. PLA was suitable for standard bioanalytical purposes due to a glass transition temperature of approximately 60°C, resistance to common laboratory chemicals and easy print processing. For temperature-critical methods, such as hybridization reactions up to 90°C, ABS was better suited. Conclusions: Autofluorescence was not a disadvantage per se but can also be used as a reference signal in assays. The rapid development of individual protocols for sample processing and analysis required the availability of a material with consistent quality over time. For fluorescence-based assays, the use of commercial standard materials did not seem to meet this requirement.}, language = {en} }