(312c) Early-Time Dynamics of Fluid-Driven Cracks

Pressure-driven fluid propagation inside a soft target media can result in a planar rupture formation, referred to as a “penny-crack”. The radial and width profile of such cracks can be estimated using scaling laws depending on the balance of the viscous forces offered by the injected fluid and the mechanical properties of the soft hydrogel media. Although fluid driven cracks have been studied in the past over a large time scale and for both viscous and toughness regimes, early time dynamics of formation of penny cracks is still not well understood. Here, we study the early time dynamics of fluid driven cracks using high-speed videography. We attempt to elucidate the physical mechanism behind the transition of crack shapes with time. Universal scaling laws are developed to validate the experimental radial and width profiles of cracks formed for viscous and toughness regimes of fluid-driven cracking.