Softening and residual loss modulus of jammed grains under oscillatory shear in an absorbing state

TL;DR

This study theoretically investigates the mechanical response of jammed, frictionless, overdamped particles under oscillatory shear, revealing softening and residual loss modulus even without irreversible plastic deformation, with insights from Fourier analysis.

Contribution

It introduces a theoretical framework explaining softening and residual loss modulus in jammed materials in an absorbing state, distinguishing reversible and plastic deformations.

Findings

Material softens under oscillatory shear.

Residual loss modulus persists without plastic deformation.

Hysteresis loops observed in particle trajectories.

Abstract

From a theoretical study of the mechanical response of jammed materials comprising frictionless and overdamped particles under oscillatory shear, we find that the material becomes soft, and the loss modulus remains finite even in an absorbing state where any irreversible plastic deformation does not exist. The trajectories of the particles in this region exhibit hysteresis loops. We succeed in clarifying the origin of the softening of the material and the residual loss modulus with the aid of Fourier analysis. We also clarify the roles of the yielding point in the softening to distinguish the plastic deformation from reversible deformation in the absorbing state.