Modeling of Grain Shape Effect on Multiaxial Plasticity of Metallic Polycrystals

A simplified nonincremental interaction law is used describing the nonlinear elastic-inelastic behavior of FCC polycrystals proposed recently (Abdul-Latif and Radi, 2010, “Modeling of the Grain Shape Effect on the Elastic-Inelastic Behavior of Polycrystals with Self-Consistent Scheme,” ASME J. Eng. Mater. Technol., 132(1), p. 011008). In this scheme, the elastic strain defined at the granular level based on the Eshelby's tensor is assumed to be isotropic, uniform and compressible. Hence, the approach considers that the inclusion (grain) has an ellipsoidal shape of half axes defining by a, b and c such as a ≠ b = c. The granular heterogeneous inelastic strain is locally determined using the slip theory. Both elastic and inelastic granular strains depend on the granular aspect ratio (α = a/b). An aggregate of grains of ellipsoidal shape is supposed to be randomly distributed with a distribution of aspect ratios having a log-normal statistical function. The effect of this distribution on the mechanical behavior is investigated. A host of cyclic inelastic behavior of polycrystalline metals is predicted under uniaxial and multiaxial loading paths. Using the aluminum alloy 2024, an original complex cyclic loading path type is proposed and carried out experimentally. After the model parameters calibration, the elastic-inelastic cyclic behavior of this alloy is quantitatively described by the model. As a conclusion, the model can successfully describe the elasto-inelastic at the overall and local levels.