Simulated defect growth avalanches during deformation of nanocrystalline copper
S Tiwari and GJ Tucker and DL McDowell, PHILOSOPHICAL MAGAZINE, 93, 478-498 (2013).
In this work we introduce a method to capture the proliferation of material defects that carry inelastic deformation, in microstructures simulated through isobaricisothermal molecular dynamics. Based on the premise that inelastic dissipation is accompanied by a local temperature rise, our method involves analyzing the response of a chain of NoseHoover thermostats that are coupled to the atomic velocities, while the microstructure deforms under the influence of a ramped external stress. We report results obtained from the uniaxial deformation of two nanocrystalline copper microstructures and show that our analysis allows the dissipative signal of a variety of inelastic events to be effectively unified via an avalanche of dissipation. Based on this avalanche, we quantitatively compare dissipation for inelastic deformation under tension vs. compression, observing a significant tensioncompression asymmetry in this regard. It is concluded that the present method is useful for discerning critical points that correspond to collective yield and inelastic flow.
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