Mixed-mode (I/II) failure assessment of rubber materials using the effective stretch criterion

The main aim of the present study is to extend the application of the effective stretch (ES) criterion from pure mode-I to the general in-plane mixed-mode (I/II) loading in cracked rubber specimens. The ES criterion, which was previously proposed by the present authors for mode-I loading conditions, has been formulated using the well-known eight-chain model which is based on the statistical mechanics approach of rubber elasticity. The key point in the generalization of the criterion is the nearly uniaxial nature of the stress fields in proximity of the crack tip in rubber-like materials. Furthermore and in order to validate the accuracy of the criterion in mixed-mode (I/II) loading, two sets of experimental data available in the literature have been analyzed and the corresponding predictions of the suggested criterion have been obtained. Very good agreement has been found between the experimental results and the predictions of the ES criterion which confirms the accuracy of the criterion in the case of cracked-rubbers under in-plane mixed-mode (I/II) loading.