Athermal creep deformation of ultrastable amorphous solids

TL;DR

This study numerically explores how amorphous solids deform under shear stress, revealing different transient behaviors based on stability and identifying critical scaling near failure, with implications across soft and brittle materials.

Contribution

It provides a unified numerical framework to analyze creep deformation in amorphous solids of varying stability, highlighting the role of shear band formation and critical scaling.

Findings

Stable samples show non-monotonic strain rate curves.

Diverging timescales are associated with fluidization.

Results challenge existing theoretical models for brittle-like materials.

Abstract

We numerically investigate the athermal creep deformation of amorphous materials having a wide range of stability. The imposed shear stress serves as the control parameter, allowing us to examine the time-dependent transient response through both the macroscopic strain and microscopic observables. Least stable samples exhibit monotonicity in the transient strain rate versus time, while more stable samples display a pronounced non-monotonic S-shaped curve, corresponding to failure by sharp shear band formation. We identify a diverging timescale associated with the fluidization process and extract the corresponding critical exponents. Our results are compared with predictions from existing scaling theories relevant to soft matter systems. The numerical findings for stable, brittle-like materials represent a challenge for theoretical descriptions. We monitor the microscopic initiation of shear bands during creep responses. Our study encompasses creep deformation across a variety of materials ranging from ductile soft matter to brittle metallic and oxide glasses, all within the same numerical framework.