Strain localization and percolation of stable structure in amorphous solids

Area of Science:

• Materials Science
• Computational Materials Science
• Solid Mechanics

Background:

• Amorphous solids lack long-range atomic order, leading to complex mechanical behaviors.
• Spontaneous strain localization is a critical phenomenon influencing material failure.
• Understanding the factors controlling localization is essential for designing robust materials.

Purpose of the Study:

• To investigate the influence of structural relaxation on strain localization in a model amorphous solid.
• To explore the relationship between strain rate, structural relaxation, and the onset of localization.
• To identify potential microstructural features governing mechanical response.

Main Methods:

• Simulations of a model amorphous solid using molecular dynamics.
• Systematic variation of the quenching rate to control structural relaxation.
• Mechanical testing at different strain rates.
• Analysis of atomic structure and topological order (k-core percolation).

Main Results:

• Strain localization is observed during simulated mechanical tests.
• The degree of localization is dependent on the extent of prior structural relaxation.
• A transition in strain rate dependence of localization occurs, linked to k-core percolation.
• Evidence for a relevant microstructural length scale is inferred.

Conclusions:

• Structural relaxation significantly impacts strain localization in amorphous solids.
• The k-core percolation of quasi-crystalline short-range order marks a transition in mechanical behavior.
• A microstructural length scale likely governs the mechanical response of these materials.