Fatigue reliability assessment of TBM disc cutter bearings using multi-dimensional interference model

Disc cutter bearings served as pivotal components in Tunnel Boring Machines (TBM), providing essential support, friction reduction, and precision transmission. During tunneling operations, these main bearings endured substantial alternating impact loads while demanding extended service life and operational reliability. Current research on bearing reliability remained constrained due to challenges in accurate load simulation and the prohibitive resource expenditure required for comprehensive reliability testing. This study employed a disc cutter structural model to investigate load transmission characteristics within the cutterhead system, establishing input conditions for bearing load spectrum analysis. Through numerical simulations, the maximum stress distribution and critical failure zones under unit loading conditions were identified. The quasi-static methodology was subsequently applied to derive stress histories at these critical regions, particularly the primary thrust roller–outer raceway interface. By integrating the stress-strength interference model with statistical theory, a dimensionless interference model was developed for reliability prediction under specified operational parameters. Analytical results demonstrated that stress amplitude distribution at critical zones followed a Weibull distribution (shape parameter = 0.67, scale parameter = 349.41), while service life adhered to a log-normal distribution. The established reliability curve revealed an inverse correlation between reliability and operational cycles, exhibiting rapid decline before 10⁵ cycles followed by gradual reduction. Beyond 10⁶ cycles, reliability diminished below 0.85. These findings provided theoretical foundations for rock fragmentation mechanics and fatigue reliability analysis of TBM rolling bearings.