Crackling to periodic dynamics in granular media

Area of Science:

• Physics
• Materials Science
• Geophysics

Background:

• Granular materials exhibit complex behaviors, including stick-slip dynamics and avalanches.
• Understanding the transition between different dynamic regimes is crucial for predicting material response.

Purpose of the Study:

• To investigate the local and global dynamics of sheared granular materials.
• To map the dynamic phase diagram and associated scaling laws.
• To explore grain-scale stress evolution and microscopic behavior.

Main Methods:

• Utilizing a stick-slip experimental setup with a slider and spring.
• Monitoring global force on the slider during shearing.
• Employing photoelastic particles to capture grain-scale stress evolution.

Main Results:

• Observed crackling dynamics with intermittent slip avalanches, irregular, and periodic behaviors.
• Identified transitions between dynamic regimes influenced by shear rate and loading stiffness.
• Deduced a dynamic phase diagram and associated scaling laws.

Conclusions:

• The study provides a comprehensive understanding of granular material dynamics under shear.
• The dynamic phase diagram offers a framework for predicting material behavior.
• Microscopic stress evolution correlates with macroscopic dynamic regimes.