Mechanism of high-frequency deviation from kinetic-theory scaling in PAM rheology

Ascertain the physical mechanism responsible for the high-frequency deviation from kinetic-theory power-law scaling in the complex viscosity of polycatenated architected materials (PAMs) under oscillatory torsion, clarifying whether tensile contacts and the breakdown of the mapping between mean contact number (Z) and packing density p account for the observed departure.

Background

Rheology experiments and LS-DEM simulations of J-4-ring and T-6-ring PAMs show an inflection from shear-thinning to shear-thickening as frequency increases. Before the inflection, normalized viscosity follows a power-law consistent with kinetic theory when expressed versus Zc−Z; after the inflection, results systematically deviate.

Understanding the cause of this deviation is crucial to extend rheophysical theories to catenated granular systems where tensile contacts and non-standard contact networks may influence flow regimes.