Abstract Accurately predicting the engagement performance of wet clutches under complex operating conditions remains challenging due to lubrication state transitions and multiple uncertainties. In particular, hydraulic pressure fluctuations directly affect system stability and transmission efficiency. This study proposes a stochastic tribodynamic model coupling lubrication and dynamics effects to quantify the influence of hydraulic pressure uncertainty on wet clutch engagement behavior. By adopting the LuGre friction model, a continuous description of friction behavior due to asperity contact in mixed and boundary lubrication is achieved, avoiding the additional stick slip transitions modeling required in conventional approaches. Uncertainty propagation is investigated using the Monte Carlo method. The influence of lubricant viscosity on statistical characteristics of friction torque and relative angular velocity is systematically analyzed. Results demonstrate good agreement between simulations and experimental trends. Furthermore, increasing lubricant viscosity prolongs the engagement process, which reduces torque impact but can lead to higher energy loss. However, it effectively suppresses uncertainty propagation, thereby enhances statistical stability. The proposed framework provides valuable theoretical support for dynamic design, control optimization, and reliability assessment of wet clutch systems in transmission.
Chen et al. (Wed,) studied this question.