Controlling Strain Bursts and Avalanches at the Nano- to Micrometer Scale

Abstract

We demonstrate, through three-dimensional discrete dislocation dynamics simulations, that the complex dynamical response of nano- and microcrystals to external constraints can be tuned. Under load rate control, strain bursts are shown to exhibit scale-free avalanche statistics, similar to critical phenomena in many physical systems. For the other extreme of displacement rate control, strain burst response transitions to quasiperiodic oscillations, similar to stick-slip earthquakes. External load mode control is shown to enable a qualitative transition in the complex collective dynamics of dislocations from self-organized criticality to quasiperiodic oscillations.

Dislocations and Plastic Deformation in MgO Crystals: A Review

“…Therefore, while atomistic simulations commonly refer to the nm-scale, DD simulations allow modeling volumes up to a few hundreds of µm 3 including large populations of dislocations. Many DD applications exist for the cases of nano-indentation [108], precipitation hardening [109][110][111], fatigue [112] or micropillar compression [113][114][115], all applied whatever the crystalline materials. Mainly, all DD codes follow similar calculation steps.…”

Universality Class of Nanocrystal Plasticity: Localization and Self-Organization in Discrete Dislocation Dynamics

“…We in-terpret the phenomenon in terms of a spatial integration of avalanche behaviors across slip planes [41]. This is a generic mechanism in bifurcation processes such as the Frank-Read nucleation of a single dislocation, and thus we argue that the proposed effect should extend to 3D-DDD models [32,44].…”

“…Fig. 2(d)): In SC, event size is defined as S = i ∈ {δ i > threshold } δ i ; in DC, an event is characterized by stress drops δσ which lead to temporary displacement overshoots -thus, in order to compare the two loading conditions, a DC strain burst event size is defined as S = i ∈ {−δσ i >σ threshold } δ i [44].…”

“…(d): Events (strain jumps) statistics for different loading protocols, different point size represents different w. blue: DC, red: SC. Strain jump in DC mode is calculated according to the method in [44]. between SC and DC disappears at high stress loading rates: Fig.…”

Effects of Rate, Size, and Prior Deformation in Microcrystal Plasticity

“…In contrast, in DC, an event is characterized by stress drops δσ which lead to temporary displacement overshoots -thus, in order to compare the two loading conditions, a DC strain burst event size is defined as S = ∑ i ∈ {−δσ i >σ threshold } δ i (Cui et al 2016).…”