Multiscale Crystal Plasticity Modeling for Metals

Series
GT-MAP Seminar
Time
Friday, December 2, 2016 - 3:00pm for 2 hours
Location
Skiles 006
Speaker
Prof. David McDowell and Shouzhi Xu – GT ME and MSE
Organizer
Sung Ha Kang

Please Note: Talk by Shuozhi Xu, Title: Algorithms and Implementation for the Concurrent Atomistic-Continuum Method. Abstract: Unlikemany other multiscale methods, the concurrent atomistic-continuum (CAC) method admits the migration of dislocations and intrinsic stacking faults through a lattice while employing an underlying interatomic potential as the only constitutive relation. Here, we build algorithms and develop a new CAC code which runs in parallel using MPI with a domain decomposition algorithm. New features of the code include, but are not limited to: (i) both dynamic and quasistatic CAC simulations are available, (ii) mesh refinement schemes for both dynamic fracture and curved dislocation migration are implemented, and (iii) integration points in individual finite elements are shared among multiple processors to minimize the amount of data communication. The CAC program is then employed to study a series of metal plasticity problems in which both dislocation core effects at the nanoscale and the long range stress field of dislocations at the submicron scales are preserved. Applications using the new code include dislocation multiplication from Frank-Read sources, dislocation/void interactions, and dislocation/grain boundary interactions.

Crystal plasticity modeling is useful for considering the influence of anisotropy of elastic and plastic deformation on local and global responses in crystals and polycrystals. Modern crystal plasticity has numerous manifestations, including bottom-up models based on adaptive quasi-continuum and concurrent atomistic-continuum methods in addition to discrete dislocation dynamics and continuum crystal plasticity. Some key gaps in mesoscale crystal plasticity models will be discussed, including interface slip transfer, grain subdivision in large deformation, shock wave propagation in heterogeneous polycrystals, and dislocation dynamics with explicit treatment of waves. Given the mesoscopic character of these phenomena, contrasts are drawn between bottom-up (e.g., atomistic and discrete dislocation simulations and in situ experimental observations) and top-down (e.g., experimental) information in assembling mesoscale constitutive relations and informing their parameters.