TY - JOUR A1 - Reusch, Frederik A1 - Klingbeil, Dietmar A1 - Svendsen, B. T1 - A non-local extension of Gurson-based ductile damage modeling JF - Computational materials science N2 - The purpose of this work is the development and numerical implementation of a non-local extension of existing Gurson-based modeling for isotropic ductile damage and attendant crack growth. In the current work, this extension is based on a generalization of Gurson-based ductile damage modeling formally analogous to that of Needleman and Tvergaard as based on a (local) effective damage parameter f* which accounts in their case in an effective fashion for the effect of void coalescence on yield behaviour. Here, the corresponding generalized effective damage parameter ? is introduced in order to delocalize the model damage process. To this end, ? is modeled in this work as a scalar-valued continuum microstructural field or generalized phase field via a recent thermodynamic approach to the modeling of such fields. In the last part of the work, the complete model for coupled damage-deformation is implemented numerically using the finite element method and utilized to investigate the damage behaviour of an inhomogeneous steel block in simple tension. The corresponding simulation results demonstrate in particular that delocalization of the model damage process also leads to minimization of mesh-dependence. For simplicity, the current formulation is restricted to the case of small strain and isothermal conditions. PY - 2003 DO - https://doi.org/10.1016/S0927-0256(02)00402-0 SN - 0927-0256 VL - 26 SP - 219 EP - 229 PB - Elsevier CY - Amsterdam AN - OPUS4-2863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reusch, Frederik A1 - Klingbeil, Dietmar A1 - Svendsen, B. T1 - Fortschritte bei der nicht-lokalen Modellierung duktiler Schädigung T2 - 35. Tagung des DVM-Arbeitskreises Bruchvorgänge - Fortschritte der Bruch- und Schädigungsmechanik - Simulationsmethoden der Bruchmechanik (DVM-Bericht 235) T2 - 35. Tagung des DVM-Arbeitskreises Bruchvorgänge CY - Freiburg, Deutschland DA - 2003-02-18 KW - Duktile Schädigung KW - Nicht-lokale Materialmodellierung KW - Gurson-Modell KW - Große Deformationen KW - Stabilitätsuntersuchung PY - 2003 SN - 0943-3473 SN - 1616-4687 IS - 235 SP - 49 EP - 58 PB - DVM CY - Berlin AN - OPUS4-2854 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klingbeil, Dietmar A1 - Reusch, F. A1 - Svendsen, B. T1 - Fortschritte bei der Zuverlässigkeit rechnerischer Methoden der Schädigungsmechanik zur Auslegung sicherheitsrelevanter Bauteile T2 - 29. MPA-Seminar Sicherheit und Verfügbarkeit in der Energietechnik T2 - 29. MPA-Seminar Sicherheit und Verfügbarkeit in der Energietechnik ; RIMAP Power Workshop ; ECOPRESS Seminar CY - Stuttgart, Deutschland DA - 2003-10-09 PY - 2003 VL - 1 SP - 1.1 EP - 1.20 PB - MPA CY - Stuttgart AN - OPUS4-2855 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reusch, Frederik A1 - Klingbeil, Dietmar A1 - Svendsen, B. T1 - Local and non-local Gurson-based ductile damage and failure modelling at large deformation JF - European journal of mechanics A N2 - The purpose of this work is the formulation, numerical implementation and initial application of a non-local extension of existing Gurson-based modelling for isotropic ductile damage and attendant crack growth. It is being carried out under the premise that void coalescence results not only in accelerated damage development (e.g., Needleman and Tvergaard, 1984), but also in damage delocalisation (i.e., via interaction between neighbouring Gurson RVE's). To this end, we proceed by analogy with the approach of Needleman and Tvergaard (1984) who replaced the Gurson void volume fraction f with a (local) effective damage parameter f* in the Gurson yield condition to account for the effect of void coalescence on the material behaviour. In the current case, the role of f* is taken over and generalised by an effective continuum damage field ?. A field relation for ? is formulated here in the framework of continuum thermodynamics. In the simplest case, the resulting relation is formally analogous to the inhomogeneous temperature equation in which void nucleation and growth represent (local) sources for ? and in which void coalescence takes place in a process zone whose dimension is determined by a characteristic material lengthscale. Analogous to temperature, then, ? represents an additional continuum degree-of-freedom here, resulting in a coupled deformation-damage field model. In the last part of the work, the complete model for coupled damage-deformation is implemented numerically using the finite-element method on the basis of backward-Euler integration and consistent linearisation. Using this implementation, the behaviour of the current extended Gurson-based damage model is investigated for the case of simple tension of an inhomogeneous steel block. In particular, the corresponding simulation results document quantitatively the dependence of the delocalisation of the model damage process and minimisation of mesh-dependence on the characteristic dimension of the damage process zone. KW - Thermodynamic formulation KW - Gurson-based damage modelling KW - Non-local modelling PY - 2003 DO - https://doi.org/10.1016/S0997-7538(03)00070-6 SN - 0997-7538 SN - 1873-7285 VL - 22 IS - 6 SP - 779 EP - 792 PB - Elsevier CY - Paris AN - OPUS4-2862 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 - Reusch, Frederik A1 - Klingbeil, Dietmar A1 - Svendsen, B. ED - Habraken, A. M. T1 - Local and non-local Gurson-based models for ductile damage and failure T2 - Proceedings of the 4th International ESAFORM Conference on Material Forming T2 - 4th International ESAFORM Conference on Material Forming CY - Liège, Belgium DA - 2001-04-23 KW - Ductile damage and failure KW - Finite elements KW - Gradient type material models PY - 2001 VL - 2 SP - 511 EP - 514 CY - Liège AN - OPUS4-1133 LA - eng 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 - Klingbeil, Dietmar A1 - Svendsen, B. A1 - Reusch, F. T1 - Advances in the application of non-local damage models in the simulation of ductile crack-extension T2 - Advanced fracture mechanics for life and safety assessments N2 - Local damage models usually have the disadvantage that results are strongly mesh dependent. The reason is that the type of the underlying partial differential equations changes under quasi-static conditions from elliptic to hyperbolic. Non-local damage models do not exhibit such behaviour under certain conditions. The usage of such non-local damage models in finite element analyses opens the possibility for preserving the ellipticity of the partial differential equations and thus avoiding mesh dependence of numerically obtained results. The loss of ellipticity for local models and its preservation for non-local models are demonstrated for a wide variety of examples enclosing ductile damage. In the present investigation, the non-local damage model is applied to the simulation of ductile crack extension in fracture mechanics specimens. The type of the underlying differential equations is permanently analysed and controlled. T2 - 15th European Conference on Fracture (ECF-15) CY - Stockholm, Sweden DA - 2004-08-11 KW - Duktile Schädigung KW - Bruchmechanik KW - Nicht-lokal PY - 2004 SP - 1 EP - 8(?) CY - Stockholm AN - OPUS4-4066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Flatten, Arnd A1 - Klingbeil, Dietmar A1 - Svendsen, B. T1 - Nicht-lokale, dehnratenabhängige Modellierung adiabatischer Scherbänder an Proben und Bauteilen JF - DVM-Bericht T2 - 39. Tagung des DVM-Arbeitskreises Bruchvorgänge - Bruchmechanik und Bauteilsicherheit CY - Dresden, Deutschland DA - 2007-02-13 KW - Bauteilsicherheit KW - Hochgeschwindigkeitsbelastung KW - Finite-Elemente-Methode KW - Gradienten-Plastizität KW - Adiabatische Scherbänder KW - Componentsafety KW - Highspeed-Loading KW - Finite-Element-Method KW - Gradient Plasticity KW - Adiabatic Shear Bands PY - 2007 SN - 1434-257X VL - 239 SP - 277 EP - 283 CY - Berlin AN - OPUS4-15934 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 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 - Klingbeil, Dietmar A1 - Svendsen, B. A1 - Reusch, F. T1 - Gurson-based modelling of ductile damage and failure during cyclic loading processes at large deformation JF - Engineering Fracture Mechanics N2 - Purpose is the formulation, numerical implementation, identification and application of a material model for ductile damage and failure during cyclic and non-proportional loading. The authors combined a hyperelasticity-based elasto-plastic model for non-linear isotropic as well as kinematic hardening with a modified Gurson model. Evolution strategy helped identify the model parameters for the high-strength steel 10MnMoNi5-5. The simulation of ductile failure in fracture mechanics specimens verified the model with respect to cyclic loading at two temperatures. The simulation of additional fracture mechanics applications validated the model as to the development of residual stresses at the crack tip under cyclic loads. KW - Ductile damage KW - Combined non-linear hardening with cyclic loading KW - Finite-element simulation KW - Material parameter identification KW - Residual stresses PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0013794416301138 DO - https://doi.org/10.1016/j.engfracmech.2016.03.023 SN - 0013-7944 VL - 160 SP - 95 EP - 123 PB - Pergamon-Elsevier Science Ltd. CY - Oxford, UK AN - OPUS4-36121 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 -