# The Intimate Relationship between Cavitation and Fracture

## TL;DR

This paper uncovers the close relationship between cavitation and fracture in soft materials using combined experimental and theoretical approaches, revealing predictable pressure-volume behavior and metastable states influencing failure.

## Contribution

It introduces a minimal theoretical framework integrating cavity expansion and crack propagation, successfully explaining experimental observations and metastable states in soft material failure.

## Key findings

- Pressure-volume response follows a predictable path.
- Cavitation and fracture are interconnected in driving failure.
- Fracture energy depends on strain stiffening.

## Abstract

Nearly three decades ago, the field of mechanics was cautioned of the obscure nature of cavitation processes in soft materials [Gent, A.N., 1990. Cavitation in rubber: a cautionary tale. Rubber Chemistry and Technology, 63(3)]. Since then, the debate on the mechanisms that drive this failure process is ongoing. Using a high precision volume controlled cavity expansion procedure, this paper reveals the intimate relationship between cavitation and fracture. Combining a Griffith inspired formulation for crack propagation, and a Gent inspired formulation for cavity expansion, we show that despite the apparent complexity of the fracture patterns, the pressure-volume response follows a predictable path. In contrast to available studies, both the model and our experiments are able to track the entire process including the unstable branch, by controlling the volume of the cavity. Moreover, this minimal theoretical framework is able to explain the ambiguity in previous experiments by revealing the presence of metastable states that can lead to first order transitions at onset of fracture. The agreement between the simple theory and all of the experimental results conducted in PDMS samples with shear moduli in the range of 25-246 [kPa], confirms that cavitation and fracture work together in driving the expansion process. Through this study we also determine the fracture energy of PDMS and show its significant dependence on strain stiffening.