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 -