Couple Stress Effects on the Dynamic Behavior of Connecting Rod Bearings in Both Gasoline and Diesel Engines

An isothermal hydrodynamic analysis of big end connecting rod bearings for both diesel and gasoline engines lubricated with couple stress fluids is undertaken. Based on the V. K. Stokes micro-continuum theory, an incompressible modified Reynolds equation is derived from the fluid motion and mass conservation equations using the assumptions of thin-film theory. The hydrodynamic performance and the crank pin center trajectories are determined numerically by means of the Booker mobility technique. Compared with the Newtonian lubricant case, the lubricants with couple stresses provide an increase of the minimum film thickness, and a drastic decrease of the power loss, peak pressure, and flow rate over one engine cycle for both engines.