Stress hot spots in viscoplastic deformation of polycrystals

Abstract

The viscoplastic deformation of polycrystals under uniaxial loading is investigated to determine the relationship between hot spots in stress and their location in relation to the microstructure. A 3D full-field formulation based on fast Fourier transforms for the prediction of the viscoplastic deformation of poly-crystals is used with rate-sensitive crystal plasticity. Two measured polycrystalline structures are used to instantiate the simulations, as well as a fully periodic synthetic polycrystal adapted from a simulation of grain growth. Application of (Euclidean) distance maps shows that hot spots in stress tend to occur close to grain boundaries. It is also found that low stress regions lie close to boundaries. The radial distribution function of the hot spots indicates clustering. Despite the lack of texture in the polycrystals, the hot spots are strongly concentrated in 1 1 0 orientations, which can account for the observed clustering. All three microstructures yield similar results despite significant differences in topology.

Fourier-based schemes with modified Green operator for computing the electrical response of heterogeneous media with accurate local fields

“…The success of the method resides in its ability to cope with arbitrarily complex and often very large microstructures, supplied as segmented images of real materials, for example, multiscale [instead of 'multistage'] nanocomposites [8], austenitic steel [9], granular media [5] or polycrystals [instead of 'polycrystal'] [10,11,12]. This technique allows maps of the local fields to be computed in realistic microstructures.…”

Versatile algorithms for the computation of 2-point spatial correlations in quantifying material structure

“…Although a number of different measures of the spatial correlations in the microstructure are possible (e.g., lineal path functions [27][28][29][30] and radial distribution [30][31][32][33] functions), only the n-point spatial correlations (or n-point statistics) [15,16,18,19,30,[34][35][36][37][38][39] provide the most complete set of measures that are naturally organized by increasing amounts of structure information. For example, the most basic of the n-point statistics are the 1-point statistics, and they reflect the probability of finding a specific local state of interest at any randomly selected single point (or voxel) in the material structure.…”

Shock induced damage in copper: A before and after, three-dimensional study

“…[1][2][3] Recent advances in nondestructive characterization have allowed for some of the first direct comparisons between quasi-static models of plasticity in polycrystals [4][5][6][7] and experiment. [8][9][10] With the goal of linking to dynamic models, [11][12][13][14][15] we leverage these advances to study high strain-rate plasticity through shock loading of coarse-grained copper and discuss the first non-destructive characterization of dynamic damage nucleation in the bulk.…”