Fatigue damage evolution analysis of drive shaft considering residual stress and hardness gradient

The service environment of the transmission shaft is complex, and it is frequently subjected to impact load. Impact fatigue is the main cause of its fatigue failure. In this study, a fatigue damage evolution analysis method of transmission shaft considering residual stress and hardness gradient is proposed under the framework of damage irreversible thermodynamics. Firstly, combined with the wave theory, the wave effect of impact stress wave is analyzed, the evolution equation of stress wave fluctuation behavior is established, and the evolution law of stress and strain field under the action of stress wave is analyzed. Then, based on the irreversible thermodynamic framework of damage, the thermodynamic state potential and dissipation potential of the damage process are studied, and the coupling characteristics of the damage evolution dynamic response and the intrinsic damage dissipation of the damaged material are analyzed. The damage evolution model of fatigue performance degradation considering residual stress and hardness gradient is established to identify the critical condition of intrinsic damage dissipation and describe the fatigue damage failure behavior. Finally, the cohesive element of the coupled damage constitutive is defined to simulate the damage evolution behavior of the substructure, and the influence of residual stress and hardness gradient on the damage evolution is explored. The results show that different initial crack forms have an important influence on the stress wave propagation behavior. The existence of residual tensile stress accelerates the process of fatigue damage accumulation, and the improvement of surface hardness can improve the fatigue resistance of the body.