Coarse graining atomistic simulations of plastically deforming amorphous solids

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Mechanics

Background:

• Disordered solids fail via localized shear bands, requiring accurate continuum theories.
• Continuum theories depend on precise modeling of amorphous structures.

Purpose of the Study:

• To develop a coarse-graining methodology for atomistic simulations of metallic glasses.
• To establish a strain criterion for distinguishing shear band regions.
• To evaluate the impact of coarse-graining length scales on shear band prediction.

Main Methods:

• Molecular dynamics simulations of metallic glass.
• Coarse-graining of atomistic quantities (e.g., potential energies).
• Signal-to-noise ratio analysis to quantify shear band signal strength.

Main Results:

• A strain criterion successfully identified shear band regions.
• Coarse-graining length scale significantly affects simulation accuracy.
• A lower bound for coarse-graining length was identified for agreement with atomistics.

Conclusions:

• The proposed coarse-graining method effectively analyzes shear bands in metallic glasses.
• Coarse-graining length scale is a critical parameter in shear transformation zone theory.
• Effective temperature concept requires appropriate coarse-graining scales to remain valid.