Shear modulus and reversible particle trajectories of frictional granular materials under oscillatory shear

TL;DR

This paper numerically investigates how frictional granular materials respond mechanically under oscillatory shear, revealing how particle trajectories and moduli depend on friction and scale with trajectory areas.

Contribution

It introduces a detailed analysis of reversible particle trajectories and their relation to mechanical moduli in frictional granular materials under oscillatory shear.

Findings

Storage modulus softens with small friction coefficients.

Residual loss modulus decreases as friction increases.

Scaling laws relate moduli to loop trajectory areas and grain size.

Abstract

In this study, we numerically investigated the mechanical responses and trajectories of frictional granular particles under oscillatory shear in the reversible phase where particle trajectories form closed loops below the yielding point. When the friction coefficient is small, the storage modulus exhibits softening, and the loss modulus remains finite in the quasi-static limit. As the friction coefficient increases, the softening and residual loss modulus are suppressed. The storage and loss moduli satisfy scaling laws if they are plotted as functions of the areas of the loop trajectories divided by the strain amplitude and diameter of grains, at least for their small values.