TY - CONF A1 - Eberle, Arno A1 - Sievert, Rainer A1 - Schubert, A. ED - Winkler, T. ED - Schubert, A. T1 - On the influence of two different underfill materials on the inelastic thermo-cyclic response of a flip-chip solder bump N2 - The finite element method was used to simulate the thermo-mechanical behaviour of a solder bump configuration on Al2O3 substrate under thermo-cyclic loading between -55 °C and 125 °C. Chaboche's viscoplastic material model was used to describe the Bauschinger effect and the creep/plasticity interaction for the tin-lead solder material. The influence of two different viscoelastic underfill materials (Epoxy+50 % SiO2, Epoxy+70 % SiO2) on the inelastic deformation of the tin-lead solder was analyzed and compared. It may be shown that the thermally matched 'hard' underfiller (Epoxy+70 % SiO2) significantly reduces the accumulated inelastic strain in the bump compared to 'soft' underfiller or no underfill material. On the other hand, the maximum lateral normal stress will increase slightly. PY - 2015 SP - 471 EP - 480 AN - OPUS4-33859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eberle, Arno A1 - Sievert, Rainer ED - Michel, B. ED - Winkler, T. T1 - Viscoplastic analysis of a solder-bump-configuration at thermo-cyclic loading T2 - Micro Mat '97 - International conference and exhibition micro materials CY - Berlin, Germany DA - 1997-04-16 KW - Hardening and creep KW - Constitutive modeling KW - Determination of material parameters KW - Hysteresis loops KW - Relaxation behaviour PY - 1997 SN - 3-932434-05-6 SP - 283 EP - 286 AN - OPUS4-33714 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eberle, Arno A1 - Sievert, Rainer A1 - Schiller, Wolfgang Arno T1 - Flip-Chip-Lotbumps thermisch-zyklisch belastet - Einfluß des Substratmaterials auf das viskoplastische Verhalten von Flip-Chip-Lotbumps PY - 1998 SN - 0025-5300 VL - 40 IS - 9 SP - 350 EP - 352 PB - Carl Hanser Verlag CY - München AN - OPUS4-33715 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eberle, Arno A1 - Sievert, Rainer A1 - Schiller, Wolfgang Arno T1 - Numerical investigation on the influence of different substrate materials on the viscoplastic behaviour of flip chip solder bumps N2 - The finite element method was used to simulate the thermo-mechanical behaviour of a flip chip under thermocyclic loading between -55°C (-67°F) and 125°C (257°F). In order to simulate realistically the inelastic material response of the solder bump, Chaboche's viscoplastic material model instead of a classical ORNL-theory was implemented into the finite element code ABAQUS and applied to a flip chip configuration. This so-called unified constitutive model is able to describe the Bauschinger effect as well as the creep/plasticity interaction. Herewith the influence of the substrate material on the inelastic deformation behaviour of a tin-lead solder bump was analysed. A comparison is given with respect to the influence of the two substrate materials namely Al2O3 and our self-developed Low Temperature Co-fired Ceramics (LTCC) on the inelastic response of the Sn60Pb40 eutectic solder material. It may be shown that the thermoelastic behaviour of the LTCC substrate significantly reduces the cyclic stresses in the bump compared to Al2O3 as well as the cumulative inelastic strain which is responsible for the development of damage and hence flip chip failure T2 - International symposium on advanced packaging materials 2000 CY - Braselton, Georgia, USA DA - 06.03.2000 PY - 2000 SN - 0-930815-59-9 DO - https://doi.org/10.1109/ISAPM.2000.869253 SP - 112 EP - 117 AN - OPUS4-33716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sommitsch, C. A1 - Sievert, Rainer A1 - Wlanis, T. A1 - Redl, C. T1 - Lifetime evaluation of two different hot work tool steels in aluminium extrusion N2 - During aluminium extrusion, the die experience cyclic thermo-mechanical loads that can lead to materials degradation and failure. For a process optimization and a comparison of different hot work tool steels, the finite element method is an appropriate means. Local inelastic strains result from the interaction of the applied temperature and stress loading and can be computed by suitable inelastic constitutive equations. Stress amplitudes and dwell times during extrusion result in creep-fatigue damage. A lifetime consumption model sums increments of a damage variable over time and defines materials failure as the accumulation of the resulting damage variable to a critical value. The procedure for the identification of the material parameters for both the constitutive and the damage model is described in detail, including the material parameters for the description of time-effects, and applied to the hot work tool steel Böhler W300 ISOBLOC (EN 1.2343). The lifetime consumption for two different hot work tool steels is compared on the basis of an example in aluminium extrusion. KW - Extrusion KW - Creep KW - Fatigue KW - Viscoplasticity KW - Aging KW - Failure PY - 2008 DO - https://doi.org/10.1016/j.commatsci.2007.07.054 SN - 0927-0256 VL - 43 IS - 1 SP - 82 EP - 91 PB - Elsevier CY - Amsterdam AN - OPUS4-17585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krumphals, F. A1 - Wlanis, T. A1 - Sievert, Rainer A1 - Wieser, V. A1 - Sommitsch, C. T1 - Damage analysis of extrusion tools made from the austenitic hot work tool steel Böhler W750 N2 - During hot extrusion of copper alloys, extrusion tools have to withstand cyclic thermal and mechanical loads. To enhance the service life of the tools, materials with high temperature strength are designed as well as an optimised process control is performed. To characterise the tool damage evolution during service and to improve process guiding, modelling and simulation are appropriate means. The extrusion process of copper billets at three different temperatures was simulated by an FE-program to obtain the temporal boundary conditions, i.e. stress and temperature distributions at the interface billet-liner. Those boundary conditions were used to simulate the elastic–viscoplastic behaviour of the tool steel Böhler W750 in service by means of Abaqus Standard™ v.6.8-3 software in conjunction with Z-Mat package. A lifetime rule was added in order to compute the lifetime consumption and the cycles to failure. KW - Hot work tool steel KW - Damage evolution KW - Lifetime prediction KW - Copper extrusion PY - 2011 DO - https://doi.org/10.1016/j.commatsci.2010.04.022 SN - 0927-0256 VL - 50 IS - 4 SP - 1250 EP - 1255 PB - Elsevier CY - Amsterdam AN - OPUS4-23215 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Simulation von Alterung und Ermüdungs-Lebensdauer bei Hochtemperatur-Beanspruchung mit einem viskoplastischen Modell T2 - Arbeitskreis "Stoffgesetze" CY - Munich, Germany DA - 2008-05-09 PY - 2008 AN - OPUS4-17457 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Simulation von Scherbandbildung beim Hochgeschwindigkeits-Spanen T2 - AK "Stoffgesetze", Otto-von-Guericke Universität Magdeburg CY - Magdeburg, Germany DA - 2002-07-05 PY - 2002 AN - OPUS4-6144 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Analyse der Makroriss-Initiierung an Kerben und von Rissfortschritt in einer einkristallinen Superlegierung bei Hochtemperaturermüdung T2 - DVM-AG "Verformungs- und Versagensverhalten bei komplexer thermisch-mechanischer Beanspruchung", MTS Systems CY - Berlin, Germany DA - 2002-03-22 PY - 2002 AN - OPUS4-6112 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Modellierung duktilen Schädigungsverhaltens bei Hochgeschwindigkeitverformung T2 - Arbeitsgruppen des DFG-Schwerpunktprogramms "Spanen metallischer Werkstoffe mit hohen Geschwindigkeiten" CY - Berlin, Germany DA - 2002-02-01 PY - 2002 AN - OPUS4-6145 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Simulation der Span-Segmentierung unter Berücksichtigung duktiler Schädigung T2 - Arbeitsgruppen des DFG-Schwerpunktprogramms "Spanen metallischer Werkstoffe mit hohen Geschwindigkeiten" CY - Aachen, Germany DA - 2002-07-03 PY - 2002 AN - OPUS4-6132 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 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 - GEN A1 - Sievert, Rainer A1 - Hamann, Andreas A1 - Noack, Hans-Dieter A1 - Löwe, Peter A1 - Singh, Kai A1 - Künecke, Georgia ED - Tönhoff, K. T1 - Simulation der Spansegmentierung einer Nickelbasislegierung unter Berücksichtigung thermischer Entfestigung und duktiler Schädigung KW - Hochgeschwindigkeitsbeanspruchung KW - Viskoplastisches Deformationsverhalten KW - Thermische Entfestigung KW - Duktile Schädigung PY - 2005 SN - 3-527-31256-0 SP - 446 EP - 469 PB - Wiley-VCH CY - Weinheim AN - OPUS4-7306 LA - deu 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 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 - 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 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. ED - Portella, Pedro Dolabella T1 - Simulation of Low Cycle Fatigue Failure of FCC Single Crystals 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 - TY - CONF A1 - Sievert, Rainer A1 - Österle, Werner A1 - Olschewski, Jürgen A1 - Ziebs, Josef T1 - Physical interpretation of a viscoplastic model applied to high temperature performance of a nickel-base superalloy T2 - 7th International Conference on Mechanical Behaviour of Materials CY - The Hague, Netherlands DA - 1995-01-01 PY - 1995 SP - 557 EP - 558 CY - Den Haag AN - OPUS4-2507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sievert, Rainer A1 - Österle, Werner A1 - Olschewski, Jürgen A1 - Ziebs, Josef T1 - Physical interpretation of a viscoplastic model applied to high temperature performance of a nickel-base superalloy PY - 1997 SN - 0179-4841 SN - 0044-3093 VL - 88 SP - 416 EP - 424 PB - Hanser CY - München AN - OPUS4-2547 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Forest, S. A1 - Sievert, Rainer A1 - Aifantis, E. C. T1 - Strain gradient crystal plasticity: Thermomechanical formulations and applications PY - 2002 SN - 0334-8938 VL - 13 IS - 3-4 SP - 219 EP - 232 PB - Freund Publ. CY - London AN - OPUS4-2858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sievert, Rainer A1 - Noack, Hans-Dieter A1 - Hamann, Andreas A1 - Löwe, Peter A1 - Singh, Kai A1 - Künecke, Georgia A1 - Clos, R. A1 - Schreppel, U. A1 - Veit, P. A1 - Uhlmann, E. A1 - Zettier, R. T1 - Simulation der Spansegmentierung beim Hochgeschwindigkeits-Zerspanen unter Berücksichtigung duktiler Schädigung PY - 2003 UR - http://www.uni-magdeburg.de/ifme/techmech.html SN - 0232-3869 VL - 23 IS - 2-4 SP - 216 EP - 233 PB - Institut für Mechanik CY - Magdeburg AN - OPUS4-2859 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Singh, Kai A1 - Hamann, Andreas A1 - Klingbeil, Dietmar A1 - Sievert, Rainer A1 - Künecke, Georgia A1 - Clos, R. A1 - Schreppel, U. A1 - Veit, P. T1 - Versagenssimulation dynamisch belasteter Proben mit unterschiedlichen Mehrachsigkeitszuständen unter Verwendung des Johnson-Cook-Versagensmodells für eine Nickelbasislegierung KW - Mehrachsigkeit KW - Simulation KW - Versagen KW - Johnson-Cook KW - Dynamisch KW - Nickelbasislegierung PY - 2003 UR - http://www.uni-magdeburg.de/ifme/techmech.html SN - 0232-3869 VL - 23 IS - 2-4 SP - 205 EP - 215 PB - Institut für Mechanik CY - Magdeburg AN - OPUS4-2861 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Forest, S. A1 - Boubidi, Pascal A1 - Sievert, Rainer T1 - Strain Localization Patterns at a Crack Tip in Generalized Single Crystal Plasticity KW - Crack KW - Single crystal KW - Crystal plasticity KW - Cosserat medium KW - Strain localization PY - 2001 DO - https://doi.org/10.1016/S1359-6462(00)00684-9 SN - 1359-6462 SN - 1872-8456 VL - 44 IS - 6 SP - 953 EP - 958 PB - Elsevier CY - Oxford AN - OPUS4-3972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer A1 - Hamann, Andreas T1 - Weiterentwicklung der Simulation der Span-Segmentierung unter Berücksichtigung duktiler Schädigung T2 - Arbeitsgruppen des DFG-Schwerpunktprogramms "Spanen metallischer Werkstoffe mit hohen Geschwindigkeiten" CY - Hamburg, Germany DA - 2003-04-04 PY - 2003 AN - OPUS4-3993 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Zur Bestimmung der Materialparameterwerte viskoplastischer Stoffgesetze für die Modellierung von Hochtemperatur-Ermüdung T2 - Eröffnungsveranstaltung des Christian Doppler Laboratoriums für Werkstoffmodellierung und Simulation, Montanuniversität Leoben CY - Leoben, Austria DA - 2006-06-27 PY - 2006 AN - OPUS4-12454 LA - deu 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 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 - JOUR A1 - Forest, S. A1 - Sievert, Rainer T1 - Nonlinear microstrain theories N2 - A hierarchy of higher order continua is presented that introduces additional degrees of freedom accounting for volume changes, rotation and straining of an underlying microstructure. An increase in the number of degrees of freedom represents a refinement of the material description. In addition to available nonlinear Cosserat and micromorphic theories, general formulations of elastoviscoplastic behaviour are proposed for microdilatation and microstretch continua. A microstrain theory is introduced that is based on six additional degrees of freedom describing the pure straining of the microstructural element. In each case, balance equations and boundary conditions are derived, decompositions of the finite strain measures into elastic and plastic parts are provided. The formulation of finite deformation elastoviscoplastic constitutive equations relies on the introduction of the free energy and dissipation potentials, thus complying with requirements of continuum thermodynamics. Some guidelines for the selection of a suitable higher order model for a given material close the discussion. KW - Continuum mechanics KW - Higher order continua KW - Micromorphic KW - Cosserat KW - Elastoviscoplasticity KW - Finite deformation PY - 2006 DO - https://doi.org/10.1016/j.ijsolstr.2006.05.012 SN - 0020-7683 VL - 43 IS - 24 SP - 7224 EP - 7245 PB - Elsevier CY - New York, NY AN - OPUS4-13734 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sommitsch, C. A1 - Sievert, Rainer A1 - Wlanis, T. A1 - Günther, Burkhard A1 - Wieser, V. T1 - Modelling of creep-fatigue in containers during aluminium and copper extrusion N2 - During hot extrusion of aluminium alloys, extrusion dies experience cyclic temperature changes as well as multiaxial loadings. To improve the service life of the dies, cleaner and high hot strength materials are designed as well as an optimised process control is performed. For the improvement of the process guiding and a comparison of lifetime behaviour of different hot work tool steels, modelling and simulation are appropriate means. The extrusion process has been simulated using the FE-program Deform to find the stress and temperature history at the inner diameter of the liner, i.e. the boundary conditions for the subsequent cyclic simulation of the container during service. Inelastic constitutive equations have been implemented into Abaqus Standard to describe strain hardening and time recovery effects. They include the Norton viscoplastic flow rule, thermo-mechanical isotropic hardening and two non-linear kinematic hardening laws. A damage-rate model predicts failure and thus the lifetime of the container. The procedure for the identification of material parameters for both the constitutive and the damage model is described in detail for the hot work tool steel Böhler W400 VMR (EN 1.2343). KW - Extrusion KW - Hot work tool steels KW - Creep-fatigue KW - Lifetime KW - Damage PY - 2007 SN - 0927-0256 VL - 39 IS - 1 SP - 55 EP - 64 PB - Elsevier CY - Amsterdam AN - OPUS4-14530 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sievert, Rainer T1 - Zur Bestimmung der Materialparameterwerte eines viskoplastischen Verformungs- und Lebensdauer-Modells für die Simulation von Hochtemperatur-Ermüdung T2 - DGM-Arbeitskreis "Mechanisches Werkstoffverhalten bei hoher Temperatur" CY - Mülheim an der Ruhr, Germany DA - 2007-10-11 PY - 2007 AN - OPUS4-16286 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sievert, Rainer T1 - A geometrically nonlinear elasto-viscoplasticity theory of second grade N2 - A general concept for the consideration of the influence of strain gradients on elasto-viscoplastic material behaviour at finite deformation is presented that does not need to account for an additional flow rule for the plastic strain gradient. The balance of momentum including the representation of the stresses, the power of work at contact for the formulation of boundary conditions as well as the nonlocal form of the total power of deformation are derived via the dissipation inequality for the investigated nonpolar continuum model of second grade. In addition to the gradient of the elastic strain tensor, energy storage with gradients of different internal variables is considered: gradient of (i) the plastic strain Tensor itself, (ii) an internal strain tensor induced by viscoplastic straining, by which energy due to hardening is stored also with ist gradient, and (iii) scalar internal variables like the accumulated viscoplastic strain or an internal time variable of damage. Finally, for the simulation of the damage behaviour during a strain hold-time period at a crack tip the responses of a ratedependent and a quasi-rate-independent gradient-enhanced damage model are compared in finite element studies. KW - Viscoplasticity KW - Plasticity KW - Strain-gradient KW - Finite deformation PY - 2011 UR - http://www.uni-magdeburg.de/ifme/zeitschrift_tm/2011_Heft2/01_Sievert.pdf SN - 0232-3869 VL - 31 IS - 2 SP - 83 EP - 111 PB - Institut für Mechanik CY - Magdeburg AN - OPUS4-24166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Boubidi, Pascal A1 - Sievert, Rainer ED - Fuentes, M. T1 - Analysis of low-cycle fatigue at notches in a single crystal superalloy at high temperature T2 - 13th European Conference on Fracture CY - San Sebastián, Spain DA - 2000-09-06 KW - LCF KW - Kerben KW - Einkristalle KW - Turbinenschaufeln PY - 2000 SN - 0-08-043699-4 SN - 1566-1369 N1 - Serientitel: ESIS publication – Series title: ESIS publication IS - 26 PB - Elsevier CY - Amsterdam AN - OPUS4-1074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Boubidi, Pascal A1 - Sievert, Rainer ED - Biallas, G. T1 - Experimental and Numerical Investigations of Macro-Crack Initiation under Low-Cycle Fatigue Loading at Notches in a Single Crystal Superalloy at High Temperature T2 - CAMP 2002 CY - Bad Lippspringe, Germany DA - 2002-04-03 KW - Single crystal KW - Notched specimens KW - Cracks KW - Lifetime KW - Turbine blades PY - 2002 SN - 3-00-009254-4 SP - 127 EP - 141 PB - Inst. für Prozess- und Werkstofftechnik CY - Paderborn AN - OPUS4-1436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Forest, Samuel A1 - Sievert, Rainer T1 - Elastoviscoplastic constitutive frameworks for generalized continua N2 - A unifying thermomechanical constitutive framework for generalized continua including additional degrees of freedom or/and the second gradient of displacement is presented. Based on the analysis of the dissipation, state laws, flow rules and evolution equations are proposed for Cosserat, strain gradient and micromorphic continua. The case of the gradient of internal variable approach is also incorporated by regarding the nonlocal internal variable as an actual additional degree of freedom. The consistency of the continuum thermodynamical framework is ensured by the introduction of a viscoplastic pseudo–potential of dissipation, thus extending the classical class of so–called standard material models to generalized continua. Variants of the higher order and higher grade theories are also reported based on the explicit introduction of the plastic strain tensor as additional degree of freedom. Within this new class of models, called here gradient of strain models, one recognizes the fact that, in a second grade theory for instance, the plastic part of the strain gradient can be identified with the gradient of plastic strain. Simple examples dealing with bending and shearing of Cosserat or second grade media are given to illustrate two types of extensions of classical J 2-plasticity : single-criterion and multi-mechanism generalized elastoplasticity. Finally, formulations at finite deformation of the proposed models are provided focusing on proper decompositions of Cosserat curvature, strain gradient and gradient of micromorphic deformation into elastic and viscoplastic parts. PY - 2003 DO - https://doi.org/10.1007/s00707-002-0975-0 SN - 0001-5970 SN - 1619-6937 VL - 160 SP - 71 EP - 111 PB - Springer CY - Wien AN - OPUS4-1924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eberle, Arno A1 - Sievert, Rainer T1 - Verifizierung von Flip-Chip-Demonstratoren unter Verwendung belastbarer Materialkennwerte T2 - Öffentliches Status-Seminar "Projekt SIMIKO" CY - München, Deutschland DA - 2000-09-29 PY - 2000 AN - OPUS4-976 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Sievert, Rainer A1 - Meersmann, Jürgen A1 - Kühn, Hans-Joachim A1 - Bendig, Max A1 - Frenz, Holger A1 - Olschewski, Jürgen A1 - Ziebs, Josef ED - Lütjering, G. T1 - Lifetime investigations for low-cycle fatigue of a nickel-base superalloy under proportional and non-proportional loading at elevated temperatures T2 - 6th International Fatigue Congress CY - Berlin, Germany DA - 1996-05-06 KW - Lebensdauer KW - Ermüdung KW - Legierung KW - Superlegierung KW - Hochtemperatur PY - 1996 SN - 0-08-042268-3 VL - 2 IS - 2 SP - 837 EP - 842 PB - Pergamon CY - Oxford AN - OPUS4-666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer ED - Pohl, M. T1 - Axial-torsionale thermo-mechanische Ermüdung einer near-Gamma TiAl-Legierung T2 - Tagung "Werkstoffprüfung 2007" CY - Neu-Ulm, Deutschland DA - 2007-11-29 KW - Titanaluminide KW - Thermomechanische Ermüdung (TMF) KW - Mehrachsige Belastung KW - Axial-torsional Belastung KW - von Mises Vergleichsspannung KW - Spröd-Duktil-Übergangstemperatur PY - 2007 SN - 978-3-514-00753-6 SP - 249 EP - 254 PB - Verl. Stahleisen CY - Düsseldorf AN - OPUS4-16318 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. ED - Kim, Young-Won ED - David Morris, ED - Rui Yang, ED - Christoph Leyens, T1 - Axial-torsional thermo-mechanical fatigue of Ti-45 Al-5Nb-0.2B-0.2C T2 - TMS 2008 Annual Meeting & Exhibition, "Structural Aluminides for Elevated Temperatures - Gamma Titanium and Other Metallic Aluminides" CY - New Orleans, Louisiana, USA DA - 2008-03-09 KW - Titanium Aluminide KW - Thermo-mechanical Fatigue KW - Axial-torsional Loading PY - 2008 SN - 978-0-87339-7209 SP - 103 EP - 109 PB - TMS CY - Warrendale, Pa AN - OPUS4-17904 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 - 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 - 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 - 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 - GEN A1 - Sievert, Rainer A1 - Fedelich, Bernard A1 - Günther, Burkhard A1 - Klingelhöffer, Hellmuth ED - Borsutzki, M. T1 - Zur Vorgehensweise bei der Bestimmung der Materialparameterwerte von inelastischen Verformungs- und Lebensdauer-Modellen für die Simulation des Materialverhaltens bei Hochtemperaturbeanspruchung N2 - Für viskoplastische Stoffgesetze wird das prinzipielle Verfahren der Identifikation von Materialmodell-Parametern für das Spannungs-Verformungs- und Versagens-Verhalten metallischer Werkstoffe am Beispiel von Hochtemperatur-Ermüdung aufgezeigt. Dies betrifft zum Einen die Verwendung geeigneter und auch möglichst weniger Experimente zur Hervorbringung der zu beschreibenden Phänomene des Werkstoffverhaltens und deren gezielte Auswertung sowie zum Anderen die physikalisch kontrollierte Führung einer numerischen Optimierung zur Ermittlung vertrauenswürdiger Materialparameterwerte. Diese Vorgehensweise wurde erfolgreich auf Warmarbeitsstähle sowie poly- und einkristalline Superlegierungen angewendet. T2 - Fortschritte der Kennwertermittlung für Forschung und Praxis CY - Bad Neuenahr, Deutschland DA - 2006-12-07 KW - Viskoplastische Materialmodelle KW - Lebensdauer-Regeln KW - Materialidentifikation PY - 2006 SN - 3-514-00734-9 SP - 121 EP - 126 PB - Stahleisen CY - Düsseldorf AN - OPUS4-14410 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. T1 - Axial-torsional thermomechanical fatigue of a near-gamma TiAl-alloy N2 - The uniaxial, torsional and axial-torsional thermomechanical fatigue (TMF) behavior of the near-γ TiAl-alloy TNB-V5 was investigated. TMF tests were performed at 400-800 °C with mechanical strain amplitudes ranging from 0.15% to 0.7%. The tests were conducted thermomechanically in-phase (IP) and out-of-phase (OP). For the same lifetimes, uniaxial IP tests required the highest strain amplitudes, while OP test conditions were most damaging and needed the lowest strain amplitudes. The Mises equivalent mechanical strain amplitudes of pure torsional tests were found in between uniaxial in-phase and out-of-phase tests for the same lifetimes. The non-proportional multiaxial out-of-phase test showed a lower lifetime at the same equivalent mechanical strain amplitude compared to the other types of tests. The microstructure has been characterized applying electron microscopy and microstructural parameters such as fraction of twinned grains, grain size, lamellar distance and dislocation density have been quantified. KW - Gamma titanium aluminide KW - TNB-V5 KW - Thermomechanical fatigue (TMF) KW - Axial-torsional loading KW - Microstructure PY - 2010 DO - https://doi.org/10.1016/j.msea.2010.03.073 SN - 0921-5093 SN - 1873-4936 VL - 527 IS - 16-17 SP - 3829 EP - 3839 PB - Elsevier CY - Amsterdam AN - OPUS4-21289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer A1 - Pfetzing, J. A1 - Eggeler, G. ED - K. Maruyama, ED - M. Niinomi, ED - S. Akiyama, ED - M. Ikeda, ED - M. Hagiwara, T1 - Axial-torsional thermo-mechanical fatigue of Ti-45 Al-5Nb-0.2B-0.2C T2 - 11th World Conference on Titianium (JIMIC 5) CY - Kyoto, Japan DA - 2007-06-03 KW - Gamma titanium aluminide KW - Thermo-mechanical fatigue KW - TMF KW - Axial-torsional loadings KW - Microstructure PY - 2007 SN - 978-4-88903-406-6 VL - 1 SP - 679 EP - 682 PB - Japan Institute of Metals CY - Kyoto AN - OPUS4-16669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schicker, Johannes A1 - Sievert, Rainer A1 - Fedelich, Bernard A1 - Noack, Hans-Dieter A1 - Kazak, Fedor A1 - Matzak, Kathrin A1 - Kühn, Hans-Joachim A1 - Klingelhöffer, Hellmuth A1 - Skrotzki, Birgit T1 - Entwicklung von Rechenmodellen zur Lebensdauervorhersage von Werkstoffen für Abgasturbolader-Heißteile unter thermo-mechanischer Ermüdungsbeanspruchung und Übertragung für Anwendung auf Bauteile T2 - Informationstagung Turbomaschinen 2010 CY - Bad Neuenahr, Deutschland DA - 2010-04-15 PY - 2010 IS - R550 SP - 111 EP - 134 AN - OPUS4-21268 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skrotzki, Birgit A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Sievert, Rainer A1 - Klingelhöffer, Hellmuth A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. ED - Khan, A. S. ED - Kabirian, F. ED - Liu, J. T1 - Axial-torsional thermo-mechanical fatigue of a near-gamma TiAl-alloy N2 - The uniaxial, torsional and biaxial thermo-mechanical fatigue behavior of γ-TiAl alloy have been examined, at both in-phase (IP) and out-of-phase (OP). OP test conditions were most damaging and needed the lowest strain amplitudes. Pure torsional tests were found in between uniaxial IP and OP tests. The non-proportional multiaxial OP test showed a lower lifetime at the same equivalent mechanical strain amplitude compared to the other types of tests. The microstructure has been characterized applying electron microscopy. T2 - Plasticity '12 - 18th International Symposium on Plasticity and its Current Applications CY - San Juan, PR, USA DA - 03.01.2012 KW - TMF KW - Multiaxial fatigue KW - Titanium aluminides PY - 2012 SN - 0-9659463-0-4 SP - 187 EP - 189 PB - NEAT Press CY - Fulton, MD, USA AN - OPUS4-25325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brookes, Stephen-Peter A1 - Kühn, Hans-Joachim A1 - Skrotzki, Birgit A1 - Klingelhöffer, Hellmuth A1 - Sievert, Rainer A1 - Pfetzing, J. A1 - Peter, D. A1 - Eggeler, G. T1 - Multi-Axial Thermo-Mechanical Fatigue Of A Near-Gamma TiAl-Alloy N2 - A material family to replace the current superalloys in aeronautical gas turbine engines is considered to be that of gamma Titanium Aluminide (γ-TiAl) alloys. Structural components in aeronautical gas turbine engines typically experience large variations in temperatures and multiaxial states of stress under non-isothermal conditions. The uniaxial, torsional and bi-axial thermomechanical fatigue (TMF) behaviour of this γ-TiAl alloy have been examined at 400 – 800°C with strain amplitudes from 0.15% to 0.7%. The tests were conducted at both in-phase (IP) and out-ofphase (OP). The effects of TMF on the microstructure were also investigated. For the same equivalent mechanical strain amplitude uniaxial IP tests showed significantly longer lifetimes than pure torsional TMF tests. The non-proportional multiaxial OP test showed the lowest lifetimes at the same equivalent mechanical strain amplitude compared to the other types of tests. KW - Gamma-Titanium Aluminide KW - Thermo-mechanical Fatigue KW - Axial-torsional Loading PY - 2005 DO - https://doi.org/10.4028/3-908454-01-8.283 SN - 1022-6680 SN - 1662-8985 VL - 59 SP - 283 EP - 287 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-18720 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schicker, Johannes A1 - Sievert, Rainer A1 - Fedelich, Bernard A1 - Noack, Hans-Dieter A1 - Matzak, Kathrin A1 - Kazak, Fedor A1 - Kühn, Hans-Joachim A1 - Klingelhöffer, Hellmuth A1 - Skrotzki, Birgit T1 - Entwicklung von Rechenmodellen zur Lebensdauervorhersage von Werkstoffen für Abgasturbolader-Heißteile unter thermo-mechanischer Ermüdungsbeanspruchung und Übertragung für Anwendung auf Bauteile PY - 2008 IS - R 542 SP - 5 EP - 29 CY - Frankfurt am Main AN - OPUS4-18954 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Schicker, Johannes A1 - Sievert, Rainer A1 - Fedelich, Bernard A1 - Noack, Hans-Dieter A1 - Kazak, Fedor A1 - Matzak, Kathrin A1 - Kühn, Hans-Joachim A1 - Klingelhöffer, Hellmuth A1 - Skrotzki, Birgit T1 - TMF Lebensdauerberechnung ATL-Heißteile - Entwicklung von Rechenmodellen zur Lebensdauervorhersage von Werkstoffen für Abgasturbolader-Heißteile unter thermomechanischer Ermüdungsbeanspruchung und Übertragung für Anwendung auf Bauteile PY - 2010 IS - 902 SP - 1 EP - 156 CY - Frankfurt am Main AN - OPUS4-20931 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schicker, Johannes A1 - Sievert, Rainer A1 - Fedelich, Bernard A1 - Klingelhöffer, Hellmuth A1 - Skrotzki, Birgit T1 - Versagensabschätzung thermomechanisch belasteter Heissteile in Turboladern KW - Computersimulation KW - Materialmodell KW - Chaboche KW - Schädigung KW - Lebensdauerabschätzung PY - 2010 SN - 0024-8525 VL - 71 IS - 6 SP - 444 EP - 450 PB - Springer Automotive Media, GWV-Fachverl. CY - Wiesbaden AN - OPUS4-21290 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -