Cavitation in a swollen elastomer constrained by a non-swellable shell

Abstract

A small cavity inside a swollen elastomer may grow or shrink, depending on the external stresses applied onto the elastomer, surrounding humidity, and boundary constraints of the elastomer. In this article, we study the variation of the size of a small cavity inside a swollen elastomer when environmental humidity changes. In the model, the surface of the swollen elastomer is coated by a non-swellable but permeable elastomer shell. Our analysis shows that the cavity shrinks with the increase of humidity, while the cavity grows with the decrease of humidity. Interestingly, with the decrease of the humidity, the cavity grows slowly and continuously first; when the humidity is lower than a critical value, the cavity may grow discontinuously, jumping from a small one to a big one, which is analogous to first-order phase transition. In this paper, we explore the effects of initial swelling ratio and the boundary constraint of the swollen elastomer on its cavitation behavior.