Phase-Field Analysis of Bending Fatigue and Crack Growth in Carburized Gears

Gear tooth fracture represents a critical and hazardous failure mode in gear transmissions. To mitigate this risk, carburizing treatment is commonly employed to enhance the surface hardness and wear resistance of gear teeth while preserving the core’s high toughness. To investigate the fatigue crack propagation mechanisms in carburized gears and inform gear design optimization, a single-tooth bending fatigue test was conducted using the load-up and load-down method. The bending fatigue strength of the gear was subsequently determined through numerical analysis and calculation. A phase-field fracture model for gear fatigue was developed based on experimental data and fracture mechanics theory. The model also accounted for variations in gear hardness due to carburizing and simulated the failure evolution process under cyclic loading. The model effectively captured the initiation, propagation, and final failure stages of cracks. Its predictions were compared with experimentally observed crack behavior, thereby validating its accuracy in predicting fatigue crack propagation in carburized gears. Additionally, the model’s predicted maximum principal stress at gear fracture was compared with the experimentally determined fatigue bending strength, further corroborating the numerical prediction’s accuracy. The high consistency between experimental results and simulation data underscores the practicality and reliability of the phase-field model in fatigue crack propagation research. This study introduces novel methods and tools for predicting fatigue life and crack propagation.