Unifying impacts in granular matter from quicksand to cornstarch

TL;DR

This paper investigates the transition between liquefaction and solidification in granular suspensions during impact, revealing a coupling mechanism between dilatancy and fluid pressure that explains diverse impact behaviors.

Contribution

It introduces a unified model linking impact responses in granular media, from quicksand to cornstarch, based on dilatancy-fluid pressure coupling.

Findings

Identifies a transition controlled by packing fraction and impact conditions.

Demonstrates the role of dilatancy and fluid pressure in impact response.

Provides a generic mechanism applicable across different particulate media.

Abstract

A sharp transition between liquefaction and transient solidification is observed during impact on a granular suspension depending on the initial packing fraction. We demonstrate, via high-speed pressure measurements and a two-phase modeling, that this transition is controlled by a coupling between the granular pile dilatancy and the interstitial fluid pressure generated by the impact. Our results provide a generic mechanism for explaining the wide variety of impact responses in particulate media, from dry quicksand in powders to impact-hardening in shear-thickening suspensions like cornstarch.