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MULTIAX: Multiaxial and Multiscale Plasticity in Metals (MULTIAX)
Date du début: 1 mars 2014, Date de fin: 28 févr. 2019 PROJET  TERMINÉ 

"Our ambition is to probe the influence of non-proportional multiaxial straining on the multiscale aspects of metal plasticity with focus on three deformation mechanisms: dislocation plasticity in bcc metals, mechanical twinning in fcc metals and the martensitic phase transformation. These mechanisms play a key role in modern TWIP and TRIP steels, yet about their response to multiaxial loading not much is known.The underlying hypothesis of this research project is that by performing biaxial deformation tests at the micro-, meso- and macro-scale meanwhile following the microstructure insitu, ground-breaking insight can be obtained on how a second strain path, a change in strain path with or without prior unloading affects the operation of the deformation mechanism, the defect accumulation and as a consequence, the evolving microstructure.The expected outcome of the research will help the formulation of criteria to be implemented in micromechanical models, for which constitutive equations are now relying solely on a knowledgebase derived from uniaxial testing.Operationally, the project contains a development phase and a research phase. First a micro- and meso-scale biaxial test rig will be developed, allowing deforming small samples in two orthogonal directions independently, compatible to be installed at various Xray beamlines of synchrotron facilities in Europe and in SEMs. The research phase will be multiscale: the response of each deformation mechanism will be investigated at the level of the mechanism itself, at the level of an oligocrystal focusing on transmission of strain across grain boundaries and at the macrosopic level focussing on the evolution of the microstructure. Experimental research will be accompanied by synergetic computational simulations."