Experimentally validated thermodynamic theory of metal fatigue

Fracture due to cyclic actuation occurs when the accumulated entropy generation reaches a critical threshold known as the fracture fatigue entropy (FFE). The accumulated entropy generation is directly related to the intrinsic dissipations such as the supplied work, damage energy, cold work, and internal friction. In this paper, we examine the contribution of these mechanisms to fatigue damage via an irreversible thermodynamic framework and provide experimental evidence for the validity of the formulations. The formulations properly capture the evolution of temperature and reveal that experimentally observed abrupt temperature rise just before fracture is due to the rapid increase in damage and can be predicted.