The Edwards volume ensemble in cyclically sheared granular experiments.
Aile Sun1, Yinqiao Wang1, Yangrui Chen1
1School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China. jiezhang2012@sjtu.edu.cn.
Soft Matter
|April 22, 2022
Summary
The Edwards volume ensemble accurately describes cyclically sheared disk packings, even with friction. Free volume is directly proportional to compactivity, independent of friction.
Area of Science:
- Physics
- Materials Science
- Statistical Mechanics
Background:
- Cyclically sheared granular materials exhibit complex behaviors like anisotropy and hysteresis.
- Understanding the statistical mechanics of jammed matter is crucial for predicting material properties.
Purpose of the Study:
- To investigate the applicability of the Edwards volume ensemble to cyclically sheared bidisperse disks.
- To analyze the geometric and statistical properties of Voronoi cells in these systems.
- To determine the relationship between free volume, compactivity, and inter-particle friction.
Main Methods:
- Experimental investigation of bidisperse disks with varying friction coefficients (μ ≈ 0.3 and μ → ∞).
- Application of cyclic shear with varying shear amplitudes (γm).
- Comprehensive analysis of Voronoi cell geometry, anisotropy, and free volume spatial correlations.
Main Results:
- The Edwards volume ensemble provides an excellent statistical description of disk packings, despite anisotropy and hysteresis.
- Voronoi cell anisotropy is weak across tested shear amplitudes and independent of friction.
- Free volume and orientation correlations are short-ranged and weakly anisotropic, independent of friction.
Conclusions:
- The Edwards volume ensemble is a robust model for sheared granular systems.
- Free volume is directly proportional to compactivity, offering a simplified physical picture.
- Inter-particle friction has a limited impact on key geometric and statistical properties of the packings.
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