Rubber fatigue life under multiaxial loading: Numerical and experimental investigations

Numerical and experimental aspects of rubber fatigue crack initiation are investigated in this study. A parameter based on the strain energy density (SED) and predicting the onset of primary crack and its probable orientation was identified for such materials according to the investigations of Mars and Fatemi [1]. In a last work, we have analytically developed this criterion for simple tension (UT), biaxial tension (BT) and simple shear (SS) loadings in the framework of finite strains. The results denote the possibility to predict the orientation plane in which the primary crack would be expected to occur in a material. Then, it was implemented in a finite elements (FE) program. FE and analytical results for the usual strain states were compared and perfect agreement was highlighted. In this study, the load history dependence of the criterion is also pointed out and discussed. Finally, to evaluate life time up to crack nucleation, we have achieved a set of experimental fatigue tests using uniaxial tension (UT) and pure shear (PS) test specimens containing a hole in order to localise the crack initiation. We have also exploited a literature database issued from uniaxial and torsion fatigue tests. The obtained results prove the efficiency of the criterion to describe the fatigue life of rubbers under multiaxial loading.