Extreme cavity expansion in soft solids: Damage without fracture

Abstract

Cavitation is a common damage mechanism in soft solids. Here, we study this using a phaseseparation 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. arXiv:1811.00841v2 [cond-mat.soft]

Elastic stresses reverse Ostwald ripening

“…Then the inflating pressure plateaus to a constant value P c = aE, where a is a constant close to one, describing the cavitation process. 3,7,14,15 Thus, the difference in pressure between droplets in the two domains is DP = 2UDR/R 2 + aDE, where DE and DR are the differences in Young's modulus and droplet radii between the two domains. By comparing these terms, we find elasticdominated ripening when…”

“…To derive eqn (7) we assume that the gradients of f sat are small in the vicinity of x i and take only the leading order term. The conservation law for the solute in the dilute phase is given by 11 where the first term corresponds to fluxes driven by chemical potential differences according to eqn (1), and the chemical potential m is given by eqn (2).…”

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Growth of gas-filled penny-shaped cracks in decompressed hydrogels

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