N-site modeling of a 3D viscoplastic polycrystal using Fast Fourier Transform

We present a formulation to compute the local response of elastic and visco plastic anisotropic 3D polycrystals based on the Fast Fourier Transform (FF T) algorithm. This formulation is conceived for periodic heterogeneous micr ostructures and also for materials with random spatial distribution of hete rogeneities. The approach is of the n-site kind, provides an exact solution of the equilibrium equation and has better numerical performance than smal l-scale FEM. The viscoplastic FFT formulation combined with an ad-hoc micro structure updating scheme is used to predict local states, morphology and t exture evolution of ideal f.c.c. polycrystals. The model predicts strain lo calization, intragranular misorientation and subgrain formation and overall textures which are smoother than those obtained with classical 1-site sche mes, in better agreement with experiments. (C) 2001 Acta Materialia Inc. Pu blished by Elsevier Science Ltd. All rights reserved.