TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Life Analysis of a fcc Single Crystal and Simulation of Crack Propagation by Blunting and Re-Sharpening T2 - International Conference on Computational and Experimental Engineering and Sciences (ICCES`03) T2 - International Conference on Computational and Experimental Engineering and Sciences (ICCES`03) CY - Corfu, Greece DA - 2003-07-25 PY - 2003 AN - OPUS4-3071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Life Analysis of a fcc Single Crystal and Simulation of Crack Propagation by Blunting and Re-Sharpening T2 - International Conference on Computational Engineering Science T2 - International Conference on Computational and Experimental Engineering and Science 2003 (ICCES '03) CY - Corfu, Greece DA - 2003-07-25 PY - 2003 CY - Tokyo AN - OPUS4-2619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Simulation of Low Cycle Fatigue Failure of FCC Single Crystals T2 - 5th International Conference on Low Cycle Fatigue T2 - 5th International Conference on Low Cycle Fatigue CY - Berlin, Germany DA - 2003-09-09 PY - 2003 AN - OPUS4-3991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Numerische Simulation von Lebensdauerverhalten und Rissfortschritt bei niederzyklischer Ermüdung kubisch-flächenzentrierter Einkristalle T2 - Seminar der Fachgruppe V.2 "Werkstoffmechenik" T2 - Seminar der Fachgruppe V.2 "Werkstoffmechenik" CY - Berlin, Germany DA - 2003-11-18 PY - 2003 AN - OPUS4-3992 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Svendsen, B. A1 - Sievert, Rainer T1 - Additional hardening in metals due to plastically inhomogeneous deformations T2 - Jahrestagung der Gesellschaft für Angewandte Mathematik und Mechanik (GAMM) T2 - Jahrestagung der Gesellschaft für Angewandte Mathematik und Mechanik (GAMM) CY - Luxembourg City, Luxembourg DA - 2005-03-28 PY - 2005 AN - OPUS4-7394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Noack, Hans-Dieter A1 - Levkovitch, Vladislav A1 - Sievert, Rainer T1 - Übersicht über Verformungsmechanismen, Modellierung und LCF Lebensdauervorhersage von Superlegierungen bei hoher Temperatur T2 - Berichte zur 28. FVW/FVHT-Vortragsveranstaltung T2 - FVHT-Vortragsveranstaltung DA - 2005-11-25 KW - Superlegierungen KW - LCF KW - Modellierung PY - 2005 SP - 10 Seiten PB - Arbeitsgemeinschaft für warmfeste Stähle (FVW) AN - OPUS4-11221 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Application of extended crystal plasticity to the modeling of glide and kink bands and of crack opening in single crystals JF - Computational materials science N2 - In this work, the influence of the development of geometrically necessary dislocations (GNDs) at a crack tip in single crystals on the hardening and crack propagation behaviour is investigated. In particular, we are interested in examining the effect of such additional hardening on the development of glide and kink bands at the crack tip as well as on the process of crack opening. To this end, following Nye and many others, local deformation incompatibility in the material is adopted as a measure of the density of GNDs. Their development results in additional energy being stored in the material, leading to additional kinematic-like hardening. A thermodynamic formulation of the model in the context of the dissipation principle facilitates the derivation of the corresponding hardening relation. Results suggest that this additional hardening retards kink-band development, but has little or no influence on glide-band development. It also influences the crack tip opening displacement (CTOD). It turns out that the simulated CTOD correlates well with experimentally determined crack-propagation rates for different crack growth direction in the crystal. KW - Thermodynamics KW - Single crystal plasticity KW - Geometrically necessary dislocations KW - Hardening KW - Glide and kink bands KW - Crack-opening displacement PY - 2005 SN - 0927-0256 VL - 32 IS - 3-4 SP - 426 EP - 434 PB - Elsevier CY - Amsterdam AN - OPUS4-7067 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fedelich, Bernard A1 - Noack, Hans-Dieter A1 - Levkovitch, Vladislav A1 - Sievert, Rainer T1 - Übersicht über Verformungsmechanismen, Modellierung und LCF-Lebensdauervorhersage von Superlegierungen bei hoher Temperatur T2 - Tagungsband der 28. VDEh Vortragsveranstaltung der Arbeitsgemeinschaft für warmfeste Stähle und der Arbeitsgemeinschaft für Hochtemperaturwerkstoffe "Langzeitverhalten warmfester Stähle und Hochtemperaturwerkstoffe" T2 - 28. VDEh Vortragsveranstaltung der Arbeitsgemeinschaft für warmfeste Stähle und der Arbeitsgemeinschaft für Hochtemperaturwerkstoffe "Langzeitverhalten warmfester Stähle und Hochtemperaturwerkstoffe" CY - Düsseldorf, Deutschland DA - 2005-11-25 KW - Superlegierungen KW - LCF KW - Modellierung PY - 2005 SP - 127 EP - 136 PB - Stahlinstitut VDEh CY - Düsseldorf AN - OPUS4-11526 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - On the influence of deformation incompatibility on the development of glide and kink bands at the crack tip and on crack opening in single crystals T2 - 13th International Workshop on Computational Mechanics of Materials (IWCMM 13); Otto-von-Guericke-University T2 - 13th International Workshop on Computational Mechanics of Materials (IWCMM 13); Otto-von-Guericke-University CY - Magdeburg, Germany DA - 2003-09-22 PY - 2003 AN - OPUS4-7128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. T1 - Simulation of Fatigue Crack Propagation in Ductile Metals by Blunting and Re-Sharpening JF - International journal of fracture N2 - Laird and Smith [(1962). Philosophical Magazine 8, 847–857] proposed a plastic sliding-off mechanism for the stage II fatigue crack growth via striation formation. In their view, the fatigue crack extension results solely from the changing character of deformation at the crack tip during loading and unloading. In particular, the crack tip blunts during the loading stage and folds into a double notch during the unloading stage, resulting in striation formation. In order to verify Laird’s plastic blunting mechanism for ductile polycrystals as well as for ductile fcc single crystals, FE calculations were performed for a rectangular plate with an initially sharp crack under plane strain conditions. The plate was subjected to a fully reversed tension-to-pressure cyclic load perpendicular to the crack plane (Mode 1). In the single crystal case the crack propagation simulations were carried out for cracks with crack plane (001) for two different crack growth orientations [110] and [100]. No initial radius for the crack tip was assumed. The actual shape of the crack tip followed from an initially sharp crack by repeated remeshing. To model the constitutive behavior typical for polycrystalline ductile metals, J2 hypo-elasto-plasticity model with Armstrong–Frederick kinematic hardening was used. To model the constitutive behavior typical for ductile fcc single crystals, a geometrically nonlinear version of Cailletaud’s model based on the multiplicative elasto-plastic decomposition of the deformation gradient was implemented into the FE program ABAQUS. For simplicity, only octahedral slip systems were considered. Using repeated remeshing for severely distorted elements at the advancing crack tip, deformation patterns in the sense of Laird’s mechanism for fatigue crack propagation with striation formation were obtained in the case of the polycrystal simulation as well as in the case of the single crystal simulation for [110] crack growth direction. The simulation for [100] crack growth direction with the same stress level as for [110] direction also yielded crack extension by progressive large deformations but without striation formation. The dependence of the fatigue striation formation on the crack growth direction as predicted by the simulation of crack propagation in single crystals is verified by the experimental results of Neumann [(1974). Acta Metallurgica 22, 1155–1165] on pure copper single crystals. KW - Fatigue KW - Crack Propagation KW - Viscoplastic Constitutive Model KW - Finite-Element-Simulation KW - Fatigue KW - FE modeling KW - Laird KW - Plastic blunting and re-sharpening KW - Remeshing KW - Single crystal KW - Striations PY - 2005 SN - 0376-9429 SN - 1573-2673 VL - 136 IS - 1-4 SP - 207 EP - 220 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-10631 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, Robert F. T1 - Simulation of deformation and lifetime behavior of a fcc single crystal superalloy at high temperature under low-cycle fatigue loading JF - International Journal of Fatigue N2 - This work deals with the formulation of a three-dimensional crystallographic time-incremental lifetime rule for face-centered cubic (fcc) single crystals used for gas-turbine blade applications. The damage contribution rate of each slip system to the total damage is governed by the current values of the resolved shear stress and the slip rate on the corresponding slip system. The damage rule is combined with a crystallographic viscoplastic deformation model. For the nickel-base single-crystal superalloy CMSX4 at 950 °C, various strain- and stress-controlled uniaxial cyclic tests with and without hold-times can be described for different crystal orientations by one set of material parameters. For verification, simulation results for a single-crystal specimen with a notch have been compared with corresponding experimental results. The predicted lifetime is within the factor of two of the measured one. KW - Single crystal KW - High temperature KW - Viscoplastic constitutive model KW - Lifetime rule KW - Low-cycle fatigue KW - Superalloy PY - 2006 DO - https://doi.org/10.1016/j.ijfatigue.2005.12.006 SN - 0142-1123 VL - 28 IS - 12 SP - 1791 EP - 1802 PB - Elsevier CY - Oxford AN - OPUS4-13198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Levkovitch, Vladislav A1 - Sievert, Rainer A1 - Svendsen, B. ED - Portella, Pedro Dolabella T1 - Simulation of Low Cycle Fatigue Failure of FCC Single Crystals T2 - Fifth International Conference on Low Cycle Fatigue T2 - 5th International Conference on Low Cycle Fatigue (LCF-5) CY - Berlin, Germany DA - 2003-09-09 KW - Single crystal KW - Viscoplasticity KW - Simulation KW - Fatigue KW - Lifetime KW - Crack propagation KW - Blunting and resharpening KW - Laird KW - Striations KW - Re-meshing PY - 2003 VL - 5 SP - 415 EP - 420 PB - DVM, Deutscher Verband für Materialforschung und -prüfung CY - Berlin AN - OPUS4-3819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -