Tribo-dynamic performance analysis of engine main bearings with provision for wear progression and dynamic misalignment

The journal main bearings in internal combustion (IC) engines are susceptible to wear and journal misalignment, which causes more lubrication failure and frictional loss. This study proposes a novel tribo-dynamic model which is coupled with the dynamic misalignment and wear progression under the transient mixed lubrication regime, along with elastic deformation, surface roughness and cavitation boundary condition. The tribo-dynamic performance is evaluated by simultaneously solving translational and angular motion equations. Numerical simulation results reveal that the misalignment deflection angles decrease first and then increase with the increasing wear depth, and the wear angular displacement along with the rotational direction can restrain the misalignment degree and improve tribological lubrication properties. Therefore, the asperity contact possibilities can be reduced in the early stage of wear progression considering dynamic misalignment. In addition, the performance divergences between the static and dynamic misalignment are investigated considering different wear progression, surface roughness and load magnitudes, noting that the lubrication performance has a nonlinear relationship with dynamic misalignment, which generally intensifies the asperity contact and lubrication failure behaviors under most circumstances. The findings of the present work provide critical guidance for the lubrication failure analysis and condition monitoring of the engine main bearings.