Influence of strain-induced crystallization on the crack driving force in fracture behavior of rubber

Natural rubber exhibits interesting properties due to strain-induced crystallization: for instance, fatigue lifetime is known to be modified by this microstructural evolution which dissipates energy. Fatigue crack propagation studies show that, under uniaxial tension loading, fatigue crack growth resistance increases with the loading ratio, even if the peak stress increases. Strain induced crystallization is believed to play an important role in this reinforcement process. It can be due to dissipation by crystallization and/or to accumulation of crystallites. We have already proposed an anisotropic constitutive model for strain-induced crystallization rubber. Moreover, recent experiments have allowed determination of the strain-induced crystallization distribution around a crack tip during uninterrupted fatigue tests. The purpose of this work is to compare spatial distributions of crystallinity in a cracked sample at different elongations between one experiment and simulation results. We then compare the experimental and computed shape of the crack.