Viscoelastic properties of natural rubber with fatigue damage

The interplay of fatigue damage and inelasticity of elastomers is an open problem. A viscoelasticity-based constitutive equation's parameters were used to trace the evolution of elastomer inelasticity with fatigue damage. Contrary to the Continuum-damage-mechanics based hypothesis, the decay of stiffness of the equilibrium network was non-monotonic with fatigue life. The variation of the inelastic network parameters suggests interplay between damage and inelasticity. However, a trend suggestive of the effect of damage on viscoelasticity was not found. High-temperature fatigue demonstrated no permanent effect on stress–strain response. The results indicate that the degradation of stiffness is not an indicator of fatigue-induced damage.