Multiscale coupling between experimental measurement and numerical simulations. How to applied experimental boundary conditions to mechanical microstructure simulation

GRACIELA BERTOLINO; JEROME CREPIN; MARIE DEXET; EVA HERIPRE

Canada

Simposio; PLASTICiTY'06, International Symposium on Plasticity 2006; 2006

Plasticity

<!-- @page { size: 8.5in 11in; margin: 0.79in } P { margin-bottom: 0.08in } --> To optimize mechanical parameters of constitutive law such as critical resolved shear stress, strain hardening and local toughness, coupling methods have been developed based on multiscale measurements and simulations. On one hand, experimental characterization of microstructures are performed by using Orientation Imaging Microscopy thanks to EBSD and mechanical tests are carried out measuring intragranular strain field thanks to microextensometry techniques and SEM analysis. On the other hand, finite element (F.E.) simulations are performed on a mesh that represents this microstructure under experimental investigation [1-2]. However, even if the in situ local displacement field measurement allows to determine the local boundaries conditions at a time t, the evolution of these local field during the mechanical test for quasi-static strain rate (typically 10-4 s-1) are still often unknown due to the difficulties with SEM analysis to obtain images with a good resolution (4000x4000 pixels) in less that 15 minutes. So a linearization procedure between the different steps of the test has to be performed, that can conduct locally but also macroscopically to a wrong loading path of the microstructure [3]. So, we present in this paper, an in situ test performed under optical microscope with digital high resolution camera, that allows local intragranular measurement of the displacement and strain fields but also to obtain the evolution of these fields during the loading path (typically 1 second for each image). In the following, the effect of the different ways to apply boundary conditions in the F.E. calculations are discussed.