Modeling of Grain Shape Effect on Multiaxial Plasticity of Metallic Polycrystals

Abstract

A simplified nonincremental interaction law is used describing the nonlinear elasticinelastic behavior of FCC polycrystals proposed recently (AbdulLatif and Radi, 2010, “Modeling of the Grain Shape Effect on the ElasticInelastic Behavior of Polycrystals with SelfConsistent Scheme,â€‌ 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 (خ±â€‰= a/b). An aggregate of grains of ellipsoidal shape is supposed to be randomly distributed with a distribution of aspect ratios having a lognormal 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 elasticinelastic cyclic behavior of this alloy is quantitatively described by the model. As a conclusion, the model can successfully describe the elastoinelastic at the overall and local levels.