A direct link between active matter and sheared granular systems

Area of Science:

• Physics
• Materials Science
• Complex Systems

Background:

• The mechanical properties of dense active matter and sheared amorphous solids exhibit striking similarities.
• A rigorous understanding of the underlying mechanisms driving this observed equivalence is lacking.

Purpose of the Study:

• To develop a theoretical model explaining the shared critical behavior of dense active matter and sheared amorphous solids.
• To validate mean-field predictions in lower dimensions and identify unifying principles for disordered materials.

Main Methods:

• Development of a mean-field model predicting critical behavior equivalence based on avalanche statistics.
• Numerical simulations using an "athermal quasistatic random displacement" protocol in two dimensions.
• Identification of a general class of perturbations bridging different force regimes.

Main Results:

• The mean-field model accurately predicts equivalent critical behavior (avalanche statistics) in infinite dimensions, up to a rescaling factor.
• These predictions show surprising accuracy in two-dimensional simulations, validating the model in low dimensions.
• A perturbation framework was identified that smoothly connects localized forces in active matter to system-spanning displacements in sheared solids.

Conclusions:

• Dense active matter and sheared amorphous solids share a universal framework governing their flow, deformation, and failure.
• The developed mean-field model provides a powerful tool for predicting the behavior of diverse disordered materials.
• This research bridges the gap between active and passive disordered systems, offering new insights into material mechanics.