An Optimum Connecting Rod Design Study—A Lubrication Viewpoint

The effect of support structure on the performance of a connecting rod bearing is analyzed by elastohydrodynamic lubrication theory. The support structure is modified iteratively until an optimum design is obtained. With the connecting rod of a typical gasoline engine as an example, it was found that a 150 percent improvement in film thickness and a 34 percent reduction in peak pressure can be obtained by changing the structural design. This design, however, increases the peak octahedral shear stress in the rod. Structural design changes considered were found to have surprisingly little effect on the power loss of the bearing.