  Cavitation is a common damage mechanism in soft solids. Here, we study this
using a phase-separation technique in stretched, elastic solids to controllably
nucleate and grow small cavities by several orders of magnitude. The ability to
make stable cavities of different sizes, as well as the huge range of
accessible strains, allows us to systematically study the early stages of
cavity expansion. Cavities grow in a scale-free manner, accompanied by
irreversible bond breakage that is distributed around the growing cavity,
rather than being localized to a crack tip. Furthermore, cavities appear to
grow at constant driving pressure. This has strong analogies with the
plasticity that occurs surrounding a growing void in ductile metals. In
particular we find that, although elastomers are normally considered as brittle
materials, small-scale cavity expansion is more like a ductile process. Our
results have broad implications for understanding and controlling failure in
soft solids.
