On the constitutive modelling of fatigue damage in rubber-like materials

A finite-strain hyperelastic phenomenological constitutive damage model is proposed to model the rate-independent failure behavior of rubber-like materials under isothermal conditions. At large strain, non-local gradient-enhanced damage model has been formulated and numerically implemented to predict the initiation and propagation of damage in rubber-like materials. The theoretical framework is based on the Internal State Variables (ISV) approach and has been implemented in the commercial finite element code ABAQUS via User Element subroutine (UEL). Robustness of the model was systematically investigated by undertaking the parametric study on the influence of damage parameters, both local and non-local, on the overall constitutive behavior of the material. The veracity of the theoretical framework was tested by quantitatively comparing the capability of the model to predict the onset of damage, its propagation and the corresponding load-displacement response of nitrile butadiene rubber material under quasi-static condition. Finally, the mesh objectivity simulations from the non-local model are presented for rubber under fatigue loading.