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Elastic criterion for shear-banding instability in amorphous solids.
1State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Physical Review. E
|May 20, 2022
Summary
Plastic flow in amorphous solids localizes into shear bands through shear-transformation (ST) avalanches. This study provides direct experimental evidence, revealing an elastic criterion for shear banding instability in colloidal glasses.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Rheology
Background:
- Amorphous solids exhibit plastic flow, often localizing into shear bands.
- This localization is attributed to avalanches of shear-transformation (ST) events.
- Direct experimental evidence for ST avalanches driving shear banding has been lacking.
Purpose of the Study:
- To provide direct experimental evidence of shear-transformation (ST) avalanches leading to shear banding in amorphous solids.
- To investigate the role of strain rates in controlling shear banding.
- To identify an elastic criterion for shear banding instability.
Main Methods:
- Utilized a 3D colloidal glass under shear as a model system.
- Studied avalanches of shear-transformation (ST) events and their correlation with shear banding.
- Analyzed elastic response fields, including shear and dilatation.
- Quantified spatial decay of elastic fields to determine correlation lengths.
Main Results:
- Demonstrated shear banding controlled by strain rates in colloidal glass.
- Observed loss of Eshelby-type spatial symmetry in elastic response fields during shear banding.
- Identified a preferential correlation along the banding direction.
- Established an elastic criterion: dilatation correlation length < shear correlation length.
Conclusions:
- ST-induced free volume confinement within the elastic shear domain is crucial for self-organization and shear banding.
- The study visually confirms the interplay between local dilatation and ST particles.
- Unifies free volume and ST mechanisms for a fundamental understanding of shear banding in amorphous solids.
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