Richard LeSar, John Graham, Laurent Capolungo

Iowa State University Department of Materials Science and Engineering Ames, IA US
Ames Laboratory Ames, IA US
Los Alamos National Laboratory Los Alamos, NM US

Discrete dislocation dynamics (DD) simulations have been widely used to gain a better understanding of the mechanisms involved in the deformation of metals. While there are a number of variants of DD simulations, they all involve the calculation of the stress at each dislocation, the resolving of that stress as a force, and solving the equations of motion. Sub-scale models are used to describe such processes as junction formation, cross-slip, and climb. In traditional DD approaches, the stresses are found by summing analytical expressions (usually based on isotropic elasticity). Recently we have shown that the stress calculation can be done using a fast Fourier transform (FFT) method based on an eigenstrain representation of the plasticity. The FFT-DD approach is faster than conventional methods and enables use of anisotropic elasticity with little change in computational time.  In addition, it is straightforward to include any type of additional eigenstrain, allowing us link the FFT-DD method directly within the FFT-polycrystal framework developed by Lebensohn, which enables direct simulations of dislocation-based plasticity in fully polycrystalline systems. In this talk, we will show recent applications of the FFT-DD-polycrystal method. We will also show how this same framework enables straightforward modeling of such phenomena as precipitate/inclusion/solute hardening, creep, etc., providing a unified approach for dealing with complex deformation phenomena.