Fracture and healing of elastomers: Experiments, Theory, and numerical implementation*

The recent numerical analysis by Lefèvre et al. (Int. J. Frac., 2015) and experiments by Poulain et al. (Int. J. Frac., 2017) have provided a thorough qualitative picture of the phenomena of nucleation and the ensuing growth of internal cavities/cracks in elastomers. Inter alia, this qualitative picture has established that the nucleation of internal cavities/cracks, popularly called cavitation, is fundamentally a by-product of fracture and not solely of elasticity as popularly thought. Also the experiments have revealed that internally nucleated cracks in conventional elastomers may fully heal.
In this talk, I will review, describe, and explain the above recent experiments in light of a new macroscopic theory that views elastomers as solids capable to undergo finite elastic deformations and also to phase transition to another solid of vanishingly small stiffness: the forward phase transition models the nucleation and propagation of fracture while the reverse phase transition models the possible healing. Further, guided by the experiments, the phase transition is taken to be driven by the competition between a combination of strain energy and hydrostatic stress concentration in the bulk and surface energy on the created/healed new surfaces in the given elastomer.