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Autor

  • Rethmeier, Michael (27)
  • Hodoroaba, Vasile-Dan (26)
  • Maiwald, Michael (26)
  • Bäßler, Ralph (24)
  • Ebell, Gino (19)
  • Neumann, Patrick P. (18)
  • Niederleithinger, Ernst (17)
  • Auersch, Lutz (16)
  • Bartholmai, Matthias (16)
  • Heckel, Thomas (16)
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Erscheinungsjahr

  • 2019 (1630) (entfernen)

Dokumenttyp

  • Vortrag (888)
  • Posterpräsentation (301)
  • Beitrag zu einem Tagungsband (248)
  • Zeitschriftenartikel (122)
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  • Sonstiges (11)
  • Forschungsbericht (10)
  • Dissertation (6)
  • Monografie (4)
  • Beitrag zu einem Sammelband (4)
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Sprache

  • Englisch (1135)
  • Deutsch (487)
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  • Russisch (1)

Referierte Publikation

  • nein (1630) (entfernen)

Schlagworte

  • Corrosion (45)
  • Korrosion (42)
  • Additive Manufacturing (36)
  • Fluorescence (25)
  • LIBS (22)
  • Ultrasound (20)
  • Ultraschall (19)
  • Additive manufacturing (18)
  • Concrete (18)
  • Nanoparticles (18)
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Organisationseinheit der BAM

  • 8 Zerstörungsfreie Prüfung (318)
  • 7 Bauwerkssicherheit (292)
  • 1 Analytische Chemie; Referenzmaterialien (265)
  • 6 Materialschutz und Oberflächentechnik (213)
  • 4 Material und Umwelt (164)
  • 3 Gefahrgutumschließungen (143)
  • 9 Komponentensicherheit (134)
  • 7.6 Korrosion und Korrosionsschutz (106)
  • 2 Chemische Sicherheitstechnik (102)
  • 5 Werkstofftechnik (101)
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1630 Treffer

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Investigation of chemically modified ICIE16 bioactive glass, part II (2019)
Hmood, F. ; Schmidt, Franziska ; Görke, O. ; Günster, Jens
Chemically modified bioactive glasses based on ICIE16 were prepared with the melt-quenching method using water as a quenching medium. The sinterability of these bioactive glasses was investigated and is discussed in this article. The sintering experiments were conducted with different sintering temperatures, sintering times and heating rates. Those parameters are crucial for dense glass with an amorphous structure. The particle size (d50) of the starting glass powder was determined at 88 μm and kept constant. The pre-pressed glass pellets were cold-isostatically pressed at 300 MPa to a green density of around 63 %. Density development, phase identification, shrinkage behavior and the microstructure were investigated to determine the sinterability of the developed glasses. The glass powders were sintered at different temperatures inside the processing window while crystallization was monitored. The results have shown that the sinterability of the developed glasses strongly dependsonthe proposed chemical additions. The highest density reached was 96 %, which belongs to BP1 glass with sintering conditions of 20 K/min heating rate for 60 min at 750 °C.
Force distance curves (FDC) & contact resionance (CR) measurement modes for mechanical property measurements (2019)
Backes, Sebastian
At the Stakeholder meeting of the EMPIR project “Multifunctional ultrafast microprobes for on-the-machine measurements”, details about two measurement modes were presented. Force distance curves and contact resonance measurements are compared. The basic principles are explained and exemplary measurements concerning mechanical properties of polymers are shown.
Scanning characterization of polymer coating layers using contact resonance with piezoresistive microprobes (2019)
Backes, Sebastian
The motivation and the measurement setup for large fast-scanning piezoresistive cantilevers are presented. The theory behind the measurements of mechanical properties through contact resonance is explained. Results of such measurements on two kinds of polymer are compared to results from force distance curves. Noise, time-dependency and dependency of the results on the vibration mode are identified as challenges of contact resonance.
Neue Entwicklungen der Faseroptische Sensorik: von Infrastruktur-Monitoring zu neuronalen Netzen (2019)
Kowarik, Stefan
Der Vortrag gibt eine Einführung zu obigen Themen auf Niveau von Master Studierenden.
Smart materials and structures based on fiber optic sensing (2019)
Kowarik, Stefan
This talk gives an overview of basic techniques. Towards the end some applications of neural networks are discussed.
Fast fitting of reflectivity data of growing thin films using neural networks (2019)
Greco, A. ; Starostin, V. ; Karapanagiotis, C. ; Hinderhofer, A. ; Gerlach, A. ; Pithan, L. ; Liehr, Sascha ; Schreiber, Frank ; Kowarik, Stefan
X-ray reflectivity (XRR) is a powerful and popular scattering technique that can give valuable insight into the growth behavior of thin films. This study Shows how a simple artificial neural network model can be used to determine the thickness, roughness and density of thin films of different organic semiconductors [diindenoperylene, copper(II) phthalocyanine and alpha-sexithiophene] on silica from their XRR data with millisecond computation time and with minimal user input or a priori knowledge. For a large experimental data set of 372 XRR curves, it is shown that a simple fully connected model can provide good results with a mean absolute percentage error of 8–18% when compared with the results obtained by a genetic least mean squares fit using the classical Parratt formalism. Furthermore, current drawbacks and prospects for improvement are discussed.
Explicit dynamics in impact simulation using a NURBS contact interface (2019)
Otto, Peter ; Lorenzis, L. ; Unger, Jörg F.
In this paper, the impact problem and the subsequent wave propagation are considered. For the contact discretization an intermediate NURBS layer is added between the contacting finite element bodies, which allows a smooth contact formulation and efficient element‐based integration. The impact event is ill‐posed and requires a regularization to avoid propagating stress oscillations. A nonlinear mesh dependent penalty regularization is used, where the stiffness of the penalty regularization increases upon mesh refinement. Explicit time integration methods are well suited for wave propagation problems, but are efficient only for diagonal mass matrices. Using a spectral element discretization and the coupled FE‐NURBS approach the bulk part of the mass matrix is diagonal.
Numerical and Experimental Observation of the melt pool behaviour for laser beam welded thick plates in partial penetration mode (2019)
Bakir, Nasim
The geometry of the melt pool in laser beam welding plays a major role to understand the dynamics of the melt and its solidification behavior. In this study, a butt configuration of 20 mm thick structural steel and transparent quartz glass was used to observe the weld pool geometry in the partial penetration mode by means of a high-speed camera. The observations show that the dimensions of the weld pool vary depending on the depth. The areas close to the weld pool surface take a teardrop-shape. A bulge-region and its temporal evolution were observed approximately in the weld pool root. Additionally, a 3D transient thermal-fluid numerical simulation was performed to obtain the weld pool shape and to understand the formation mechanism of the observed bulging effect. The model considers the local temperature field, the effects of phase transition, thermo-capillary convection, natural convection and temperature-dependent material properties. The numerical results showed good accordance and were furthermore used to improve the understanding of the experimentally observed bulging effect.
Investigation of the mechanical properties of single-pass hybrid laser-arc welded thick X120 pipeline steel plates (2019)
Üstündag, Ömer
High heat input leads to grain coarsening and softening in WM and HAZ; the tensile strength is reduced. Low heat input leads to inadmissible hardening in the WM; the impact strength is reduced. The proposed t8/5-time of 3 s to 15 s could be achieved through the reduced welding velocity. The concept of electromagnetic weld pool support system allowed single-pass welds in flat position without gravity drop-outs even for reduced welding speeds; in this way the heat input can be controlled. The adaptation of the electromagnetic weld pool support system to laser and laser hybrid welding process can dramatically increase the potential field of application of these technologies for real industrial implementation.
Vermeidung von Schweißimperfektionen im Überlappbereich bei laserstrahlhybrid-geschweißten Rundnähten (2019)
Rethmeier, Michael
Schwerpunkte: Strategie zur Vermeidung von Schweißimperfektionen im Überlappbereich beilaserhybridgeschweißten Rundnähten für 9.5 mm dicke Rohre. Anpassung der Laserleistung in Kombination mit der Defokussierung des Laserstrahls sowie einer Endkraterfüllung am Ende der Schweißnaht führte zu einer besseren Nahtausbildung. Herausrampung der Energie des Schweißprozesses, sodass ein Übergang von Durchschweißung zu einer Einschweißung mit gewünschter kelchförmiger Nahtgeometrie stattfand. Einstellung eines Wärmestaus durch Defokussierung und Verschiebung des Laserstrahls führt zu einem gut ausgebildeten Überlappbereich ohne Poren, Risse. Schweißungen an Rohrabschnitten mit einer max. Wandstärke von 15 mm, bei gegebenenfalls weiteren Parameteranpassungen.
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