Cell model simulation of void growth in nodular cast iron under cyclic loading

Rabold, Frank; Kuna, Meinhard

doi:10.1016/j.commatsci.2004.09.016

Cited by 37 publications

(23 citation statements)

References 7 publications

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“…This phenomenon was first evidenced in micromechanical finite element simulations performed by Gilles et al (1992) under conditions of constant overall triaxiality (in absolute value), and later confirmed by several authors Besson and Guillemer-Neel, 2003;Brocks and Steglich, 2003;Rabold and Kuna, 2005;Steglich et al, 2005;Mbiakop et al, 2015;Lacroix et al, 2016). As explained by Lacroix et al (2016), the ratcheting of the porosity is fundamentally tied to two features of the material behaviour, namely strain hardening and elasticity.…”

Section: Accepted Manuscriptmentioning

confidence: 79%

A Gurson-type layer model for ductile porous solids with isotropic and kinematic hardening

Morin

Michel

Leblond

2017

International Journal of Solids and Structures

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The aim of this work is to propose a Gurson-type model for ductile porous solids exhibiting isotropic and kinematic hardening. The derivation is based on a "sequential limit-analysis" of a hollow sphere made of a rigid-hardenable material. The heterogeneity of hardening is accounted for by discretizing the cell into a finite number of spherical layers in each of which the quantities characterizing hardening are considered as homogeneous. A simplified version of the model is also proposed, which permits to extend the previous works of Leblond et al. (1995) andLacroix et al. (2016) for isotropic hardening to mixed isotropic/kinematic hardening. The model is finally assessed through comparison of its predictions with the results of some micromechanical finite element simulations of the same cell. First, the numerical and theoretical overall yield loci are compared for given distributions of isotropic and kinematic pre-hardening. Then the predictions of the model are investigated in evolution problems in which both isotropic and kinematic hardening parameters vary in time. A very good agreement between model predictions and numerical results is found in both cases.

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Section: Accepted Manuscriptmentioning

confidence: 79%

A Gurson-type layer model for ductile porous solids with isotropic and kinematic hardening

Morin

Michel

Leblond

2017

International Journal of Solids and Structures

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“…Later papers on the subject included the works of Besson and Guillemer-Neel (2003), Brocks and Steglich (2003), Rabold and Kuna (2005), Steglich et al (2005) and Mbiakop et al (2014). They were essentially devoted to further micromechanical simulations along the lines initiated by Gilles et al (1992) and Devaux et al (1997), sometimes for more complex (cubical) elementary cells.…”

Section: Accepted Manuscript 1 Inmentioning

confidence: 99%

Numerical study and theoretical modelling of void growth in porous ductile materials subjected to cyclic loadings

Lacroix

Leblond

Perrin

2016

European Journal of Mechanics - A/Solids

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Experiments have shown that in porous ductile materials, cyclic loadings lead to lower fracture strains than monotone ones. The effect has been tentatively ascribed to a continued increase of the mean porosity during each cycle with the number of cycles ("ratcheting of the porosity"). In this work, we first perform finite-element-based micromechanical simulations of elementary hollow cells. These cells are initially spherical, contain an initially spherical void and are loaded cyclically through conditions of homogeneous boundary strain rate; the triaxiality is held constant throughout in absolute value. These simulations fully confirm the interpretation of the reduced fracture strains under cyclic loadings just mentioned. The modelling of the ratcheting of the porosity is then discussed. Gurson (1977)'s classical model is shown not to be able to predict such an effect, the evolution of the porosity being stabilized right from the first semicycle. The so-called LPD model due to Leblond et al. (1995), an improved variant of Gurson (1977)'s model with a more refined description of strain hardening, makes a better job but fails to accurately reproduce the results of the micromechanical simulations. One explanation of the discrepancy is the assumption of positively proportional straining made in this model, which is basically inadequate for cyclic loadings. An improved version of the LPD model is introduced; this version discards this assumption, at the expense of introduction and radial discretization of an underlying spherical "microcell" at each material point. It is not significantly more computationally expensive than the old one and permits a satisfactory reproduction of the results of the micromechanical simulations. This paves the way to simulations of ductile rupture under cyclic loadings within the framework of Gurson-like models.

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“…An early debonding observed in uniaxial tension tests supports this assumption. Several studies investigate DCI with unit cell models [27][28][29][30][31][32][33]. These models are suitable to investigate material parameters and models.…”

Section: Introductionmentioning

confidence: 99%

Influence of graphite morphology on static and cyclic strength of ferritic nodular cast iron

et al. 2018

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Abstract. High silicon alloyed nodular cast iron consists of a purely ferritic matrix and graphite nodules, mainly. Varying wall thicknesses and manufacturing conditions result in different graphite morphologies throughout a structural component. From an experimental point of view, axial fatigue and tensile tests were carried out on specimens with differently degraded graphite. From a numerical point of view, the microstructure has been modelled using a finite element (FE) approach with representative volume elements (RVE). The RVE models were built according to micrographs of fatigue specimens. The generated RVEs determine effective material properties through elasto-plastic homogenization and were subsequently analysed using a shakedown approach. In shakedown theory, the material re-enters the elastic regime after a few cycles of initial plastic deformation. This work uses the shakedown theorem to derive a lower bound estimation of the endurance limit from a non-incremental simulation. Here, the material has to be modelled elastic-perfectly plastic. The major challenge in modelling nodular cast iron is to determine suitable material parameters for the graphite and ferrite phase, revealed by parameter studies on the static and cyclic model. By using reasonable material parameters, fundamental effects, observed in the fatigue tests, were reproduced on the model level.

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Cell model simulation of void growth in nodular cast iron under cyclic loading

Cited by 37 publications

References 7 publications

A Gurson-type layer model for ductile porous solids with isotropic and kinematic hardening

A Gurson-type layer model for ductile porous solids with isotropic and kinematic hardening

Numerical study and theoretical modelling of void growth in porous ductile materials subjected to cyclic loadings

Influence of graphite morphology on static and cyclic strength of ferritic nodular cast iron

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