Contact Fatigue Strength Reliability Assessment of Transmission Gears Considering Assembly Uncertainty

Gears are extensively utilized in mechanical transmissions, where their reliability directly affects the operating efficiency of the whole mechanical system. Surface contact fatigue failure is the most common fault in transmission gears during their service, and therefore deserves key attention to ensure operational safety. During gear work processes, assembly uncertainty serves as an important influencing factor on power transmission performance, thereby inevitably exerting an impact on the reliability of contact fatigue strength (CFS). However, existing studies have not fully considered the effects of assembly uncertainty on the reliability assessment of CFS for gears. In this study, we focus on the reliability assessment issue of CFS for transmission gears with the consideration of multi-source uncertainties including concerned assembly uncertainty. Initially, multi-source uncertainties are introduced which include material dispersion, load randomness and assembly uncertainty, and the assembly parameters of concern are characterized. Thereafter, the performance function for CFS of gears and the corresponding reliability model are adopted, in which Monte Carlo method is employed for the reliability calculation. Then, a pair of spur gears is studied as an example, where stochastic finite element model of the gear pair is established to extract the maximum contact stress. Finally, the case-study results indicate the significant effect of assembly uncertainty on the reliability of gear CFS. Hence, the effect of assembly uncertainty cannot be ignored in gear reliability design.