Concurrent AtC coupling based on a blend of the continuum stress and the atomistic force

    A concurrent atomistic to continuum (AtC) coupling method is presented in this paper. The problem domain is decomposed into an atomistic sub-domain where fine scale features need to be resolved, a continuum sub-domain which can adequately describe the macroscale deformation and an overlap interphase sub-domain that has a blended description of the two. The problem is formulated in terms of equilibrium equations with a blending between the continuum stress and the atomistic force in the interphase. Coupling between the continuum and the atomistics is established by imposing constraints between the continuum solution and the atomistic solution over the interphase sub-domain in a weak sense. Specifically, in the examples considered here, the atomistic domain is modeled by the aluminum embedded atom method (EAM) inter-atomic potential developed by Ercolessi and Adams [F. Ercolessi, J.B. Adams, Interatomic potentials from first-principles calculations: the force-matching method, Europhys. Lett. 26 (1994) 583] and the continuum domain is a linear elastic model consistent with the EAM potential. The formulation is subjected to patch tests to demonstrate its ability to represent the constant strain modes and the rigid body modes. Numerical examples are illustrated with comparisons to reference atomistic solution. &nbsp

Cohesive and XFEM evaluation of adhesive failure for dissimilar single-lap joints

AbstractCohesive Zone Modelling (CZM) and eXtended Finite Element Modelling (XFEM) available in Abaqus® are used together to simulate the behaviour and strength of dissimilar single-lap adhesively bonded joints. A distinct CZM model is also used. Single-lap joints made of aluminium and carbon fibre adherends of different thickness are tested to understand better the behaviour of such dissimilar joints. Local deformation fields are monitored by using the digital image correlation method (DIC). Peeling and shearing strains are investigated, emphasizing that peeling is important in the region where failure is initiated, towards an extremity of the overlap region. The use of dissimilar adherends is reducing the strength and stiffness of the joints as the delamination and pull-out of the carbon fibres reduces the integrity of the joint. The experimental evidence given by DIC is not to be obtained by numerical simulations

Investigation of the Performance of Flow Models for TWIP Steel

WOS: 000440433900058Modeling of metal processing requires constitutive laws able to represent the experimental material behavior. Of the large number of available empirical constitutive equations, only a subset may be fitted accurately to given experimental data. The present work is aimed at identifying the equations that can be used to model the ambient temperature mechanical behavior of high Mn twinning-induced plasticity (TWIT') steels. These are fitted to experimental data for TWIP900 and further compared in terms of their ability to predict springback. The reference springback value is determined experimentally for the same material. The study provides guidelines for the selection of the constitutive model in forming simulations for this type of steel