TY - CONF A1 - Eberle, Arno A1 - Sievert, Rainer T1 - Numerical analysis of an electronic structure bearing deep cracks N2 - The successive fatigue failure process, i.e. crack initiation and growth up to electrical failure, has been investigated for a flip chip configuration. A cracked and uncracked solder bump was analysed using an unified viscoplastic constitutive model (Chaboche). The electrical failure of a bump seems to be reached in general not before a deep crack has grown into the bump. In order to update the actual loading situation two different cracked structures were calculated. T2 - MicroMat 2000 - 3rd International conference and poster exhibition Micro Materials CY - Berlin, Germany DA - 17.04.2000 PY - 2000 SN - 3-932434-15-3 SP - 582 EP - 585 AN - OPUS4-33827 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 -