Mechanical excitation and marginal triggering during avalanches in sheared amorphous solids
D Richard1,2,3, A Elgailani4, D Vandembroucq5
1Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Amsterdam, Netherlands.
Physical Review. E
|April 19, 2023
Summary
We studied plastic strain in amorphous solids using molecular dynamics (MD) and elastoplastic models (EPM). Similar spatial correlations in both models explain avalanche size distributions, despite differing dynamics.
Area of Science:
- Solid mechanics
- Materials science
- Computational physics
Background:
- Amorphous solids exhibit plastic deformation through avalanches.
- Understanding the spatial correlations of plastic activity is crucial for modeling these phenomena.
Purpose of the Study:
- To investigate and compare the spatial correlations of plastic strain during avalanches in molecular dynamics (MD) and elastoplastic models (EPM).
- To elucidate the reasons behind the success of EPMs in reproducing MD-derived avalanche size distributions.
Main Methods:
- Simulations of amorphous solids under shear in the athermal quasistatic limit.
- Analysis of plastic strain and spatial correlations at both particle-scale (MD) and mesoscale (EPM).
Main Results:
- Identified two distinct length scales in plastic activity correlations: a short, time-dependent scale and a longer, diffusively growing scale associated with marginally stable sites.
- Observed that mechanical excitation, not just proximity to instability, drives short-range correlations.
- Found that EPMs capture MD avalanche size distributions due to similar spatial correlations, despite differences in temporal dynamics.
Conclusions:
- Spatial correlations, particularly the longer-range ones, are key to understanding avalanche behavior in amorphous solids.
- Mesoscale elastoplastic models can effectively capture macroscopic features of plastic deformation in amorphous solids, even with simplified dynamics.
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