On the micromechanical modelling of the viscoplastic behavior of single crystal superalloys

A micro-macro modeling of the single crystal viscoplasticity behavior is discussed, based on a composite approach and continuum mechanics based constitutive equations at the level of the precipitate gamma' and matrix gamma. It is shown how such an approach cannot simulate correctly both the tensile and shear loading conditions. An attempt is done that reconciliate the two loading conditions, by introducing a volumetric term in the gamma viscoplastic strain in order to redistribute the hydrostatic pressure in the matrix channels.