Computational Fluid–Structure Interaction Analysis of Piston Pin Multiphase Elastohydrodynamic Lubrication With Unsteady Flow Channel Variation

Abstract

This research focuses on the multiphase oil film tribology between the piston pin and the connecting rod in an internal combustion engine and establishes a new computational approach for thin-film lubrication with unsteady flow channel variation. First, the pin and the connecting rod are considered as rigid bodies, and 3D numerical analysis of the cavitating lubricating oil flow is performed when combustion load is applied to the pin. We find that dynamic pressure does not increase around the connecting rod edge and that pressure is potentially insufficient to support the load. In the second numerical analysis, the pin and the connecting rod are considered to be elastically deformable structures, and coupled 3D multiphase fluid–structure interaction simulation is performed. The boundary lubrication area is detected using a statistical Greenwood–Tripp model as unevenness of the contacted metal surface. The results show that pressure distribution spreads more widely than in the result for rigid bodies and that the film was thicker as well. Also, the pin deformed like a bow, but the deformation of the connecting rod was quite small, suggesting a potential mechanical contact at the edge of the connecting rod with the pin. By comparison with an actual operationally used piston pin, we find that the fluid–structure coupled analysis qualitatively predicted the seizure location.