Abstract: The wheel reducer driving system is the core component of the wheel hub drive system, which reliability directly affects the operating reliability and working life of the entire drive system. In view of the deficiency that only single tooth surface failure or tooth root failure is considered in the reliability evaluation of the existing wheel reducer transmission system, a dynamic reliability calculation method considering the correlation between the two failures is proposed. Firstly, a stochastic model of the strength degradation of tooth surface and tooth root is established respectively on the premise of considering the strength degradation of gear material. Secondly, based on the stress-strength interference theory and the Monte Carlo method, the dynamic reliability curve of the gear considering the strength degradation is calculated for both types of failures. Thirdly, a mathematical model of the dynamic reliability of a single gear is derived based on Copula function. Finally, the theorem of Sklar is applied to describe the correlation of part failure processes to obtain a mathematical model of the dynamic reliability of the wheel reducer driving system. The results of verification by calculation example show that this method can reveal the relationship between the fatigue life of the system and that of each component under multiple failure modes and factors. This method can provide a theoretical basis for the reliability evaluation and prediction of the wheel reducer driving system.

Key words: driving system, strength degradation, failure correlation, dynamic reliability mathematical model