Experimental study and model on the low-cycle fatigue behavior of thermoplastic vulcanizates

Thermoplastic vulcanizates (TPVs) is composed of crosslinked rubber and plastic and have recently been used to replace traditional rubber. To investigate their constitutive behavior throughout the fatigue life, a series of tensile fatigue tests were carried out. The experimental results show significant fatigue softening of TPV, which can be regarded as the joint action of fatigue damage and fatigue creep. After many cycles, the viscous flow can also be restored; thus, the fatigue creep was eliminated by the cyclic-pause-cyclic experiment. The cyclic curves were obtained when the fatigue damage was the only effect. Based on a visco-hyperelastic constitutive model, the evolution rate of the constitutive model parameters during fatigue damage was obtained using the network alteration theory. Considering fatigue damage and fatigue creep effect together, a fatigue-softening constitutive model is proposed. The model can predict the constitutive behavior of TPVs over their entire fatigue life.