X-Ray Tomography Investigation of Cyclically Sheared Granular Materials.

Area of Science:

• Physics
• Materials Science
• Geophysics

Background:

• Granular materials exhibit complex behaviors under stress.
• Understanding microscopic processes is key to explaining macroscopic responses.

Purpose of the Study:

• To investigate the relationship between microscopic structural evolution and macroscopic shear force in cyclically sheared granular systems.
• To elucidate the role of particle rearrangement and frictional contacts in transient granular behaviors.

Main Methods:

• Combined X-ray tomography and shear force measurements.
• Cyclic shearing of granular systems.
• Analysis of particle-level structural rearrangement and contact friction.

Main Results:

• Observed evolution of microscopic structures and macroscopic shear force during shear cycles.
• Demonstrated that contact friction induces significant structural fluctuations and shear dilatancy.
• Developed an empirical constitutive relationship for macroscopic shear force.

Conclusions:

• Macroscopic behaviors of granular materials are directly linked to microscopic particle dynamics.
• Friction is a critical factor governing structural changes and dilatancy in granular systems.
• The developed constitutive relationship provides a framework for predicting granular material response.