Dynamic interactions of surface wear and tooth crack in gear transmission systems: An investigation of progressive-degradation mechanisms

Gear transmission systems are essential components in numerous industrial applications due to their efficient power transmission, precise ratios and smooth operation. However, under complex operating conditions and extended use, gear pairs, particularly those bearing the main load, are susceptible to faults that probably jeopardize the entire system. While extensive research has been conducted on gear faults, most studies focus on isolated fault types, overlooking the inevitable surface wear during the mid-to-late operation stages. Wear often interacts with other faults, leading to system instability and reducing the reliability of current analysis. Neglecting the interaction between wear and other failures can result in inaccurate evaluations of gear system performance and unreliable assessments of overall gear transmission health. To address these challenges, this paper proposes a framework for the dynamics analysis of gear systems over their lifespan, accounting for the coupling effects of surface wear and root crack. Specifically, an enhanced model based on the potential energy method is developed to calculate mesh stiffness as faults progress. During model construction, the variation in multi-tooth meshing is carefully considered, as it is influenced by factors such as tooth profile deviation, static transmission error, deformation and fluctuating meshing forces. Furthermore, the dynamic interactions between wear and crack are thoroughly examined. To predict system degradation, a new model updating scheme is introduced considering the coupled faults. Moreover, the vibration response is analyzed, with the results validated through finite element analysis and run-to-failure experiments, demonstrating the effectiveness of the developed scheme in predicting coupled fault progression.