Atomistic simulation of the inelastic yield and flow behavior of nanocrystalline Cu under multiaxial stress states
Shreevant Tiwari (Georgia Inst of Technology), David McDowell (Gerogia Tech)
From Atomistics to Reality: Spanning Scales in Simulations and Experiments Symposium A
Wed 10:45 - 12:15
CIT 165
Elasto-plastic deformation in nanocrystalline metals is known to be dominated by interface-mediated deformation mechanisms. Recent observations of non-Schmid effects in dislocations nucleated from interfaces, and competition between intragranular and intergranular deformation mechanisms in nanoscale grains have motivated questions regarding the appropriate form of the yield function and flow potential for metallic nanomaterials. In the present work, we have utilized molecular dynamics simulations to characterize inelastic yield and flow in nanocrystalline Cu under multiaxial stress states. We have chosen two distinct yield criteria: (a) the dissipation, as computed from ensemble-level thermometry, and (b) the inelastic strain tensor. Our results suggest that initial yield in nanocrystalline Cu ensembles is not driven solely by the deviatoric stress. Particularly, the yield strength under shear is increased under imposed compression and decreased under imposed dilatation.