Memory in 3D cyclically driven granular material

TL;DR

This study investigates how dense granular materials under cyclic compression exhibit memory effects, showing that translational and rotational displacements encode different types of memory influenced by friction.

Contribution

The paper combines experimental and numerical methods to demonstrate that dense granular systems can store history of compression, with distinct effects on translation and rotation.

Findings

Translational displacements encode memory dependent on static friction.

Rotational displacements encode memory unaffected by friction.

Simulations accurately reproduce grain displacements under cyclic compression.

Abstract

We perform experimental and numerical studies of a granular system under cyclic-compression to investigate reversibility and memory effects. We focus on the quasi-static forcing of dense systems, which is most relevant to a wide range of geophysical, industrial, and astrophysical problems. We find that soft-sphere simulations with proper stiffness and friction quantitatively reproduce both the translational and rotational displacements of the grains. We then utilize these simulations to demonstrate that such systems are capable of storing the history of previous compressions. While both mean translational and rotational displacements encode such memory, the response is fundamentally different for translations compared to rotations. For translational displacements, this memory of prior forcing depends on the coefficient of static inter-particle friction, but rotational memory is not altered by the level of friction.