Numerical modelling of the cavitation damage in the conrod big end bearing of a high-performance internal combustion engine

Abstract

In this contribution a complementarity formulation for the solution of the elastohydrodynamic problem in the presence of cavitation is employed to investigate the tribological behaviour of the conrod big end bearing in a high-performance internal combustion engine. The continuous effort towards higher engine efficiencies, poses new challenges related to the increased specific loads to which engine components are subjected. In particular, the connecting rod big end bearing is subjected to both high loads and high relative velocity of the mating surfaces. Therefore, its tribological behaviour plays a crucial role. In fact, on one side, possible asperity contact pressures can produce wear of the interested components, and on the other side, a parallel possible cavitation of the lubricant can additionally damage the mating interfaces. Unfortunately for quantifying the cavitation damage, a universally established theory does not exist, even if it is well accepted that it is related to the sudden rapid implosion of the vapour bubbles near the surface. The precise investigation of this damage mechanism is usually neglected in big end bearing analysis since the implosion of the bubbles is difficult to quantify and it is not a standard output of any commercial software. Thus, in this work, a quantitative index previously proposed is reviewed and adopted to quantify the cavitation damage in a connecting rod big end bearing.