Finite element simulations of the plastic behaviour of crystallin aggregates, potential applications to salt and calcite

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Finite element simulations of the deformation of bcc aggregates using a crystal plasticity model

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Finite element simulation of the deformation of b.c.c. aggregates using a crystal plasticity model - local orientation effects

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Porosity reduction by the action of pressure solution

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The influence of grain orientation on the stored energy during cold rolling of steels - experimental evidence and finite element simulations

In order to understand the role of the stored energy within individual grains of a deformed polycrystal during the nucleation step of recrystallization, a finite element code has been used to characterise in some details the deformed state of an aggregate of grains after rolling. This code takes explicitly into account the crystallographic nature of the material, and includes a physically-based hardening law of individual slip systems, enabling us to calculate an average dislocation density within each grain after each deformation step. The presented simulations of large plane strain deformation have been performed on an aggregate of 343 cubic grains, asociated with 343 initially randomly distributed orientations. It is thus possible to follow during deformation the global texture and deformation evolutions and also to get more local information within deformed grains, such as reorientations, average intra and intercrystalline misorientations and dislocation densities. It is thus found that the predicted texture evolution is in good agreement with the experimental one measured after various rolling strains; also, at the end of the simulated rolling process, the so-called γ orientations are predicted to be the hardest, i. e. associated with maximum dislocation density. This result is finally discussed, together with preliminary calculations of intragranular misorientations in the context of nucleation

The influence of grain orientation on the stored energy during cold rolling of steels. Experimental study and finite element simulation

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Hydro-mechanical properties of chemically altered limestones using 2D and 3D full-field multi-scale investigations

International audienc

Deformation of aluminum in situ SEM and full field measurements by digital image correlation: evidence of concomitant crystal slip and grain boundary sliding

International audienceMechanical testing in situ scanning electron microscopy (SEM) has become a standard technique for multiscale micromechanical investigation of polycrystalline materials. Direct observation of developing strain heterogeneities allows identification of the active mechanisms and quantification of their respective contributions to the overall strain. We developed a novel experimental setup for thermomechanical testing in situ SEM, especially suited to full strain field measurements. These are based on digital image correlation (DIC), from the sample scale to the scales of the aggregate and the single grain. We present results obtained during simple compression, at controlled displacement rates and at temperatures up to 400°C, of nearly pure polycrystalline aluminum exhibiting randomly oriented coarse grains (ca. 300 m in size). Electron microlithography was applied to produce specific surface marking patterns appropriate for the different scales of interest. Full surface strain fields were obtained by digital image correlation (DIC) analysis. The localization patterns evidenced dominant crystal slip plasticity, but also substantial simultaneous and continuous activity of grain boundary sliding (GBS), the contribution of which increased with temperature. We therefore advocate that experiments such as these here presented are necessary to go beyond a description in terms of deformation mechanism maps, which attribute deformation to a single mechanism