Comparison between experimental film thickness measurements and elastohydrodynamic analysis in a connecting-rod bearing

Abstract

This paper describes the experimental measurements and the theoretical calculations of oil-film thickness in a dynamically loaded connecting-rod big-end bearing. Four eddy current gap sensors for each bearing are used to measure the oil-film thickness and to deduce the bearing trajectories. Experimental data for crankshaft main bearings are easy to obtain but connecting-rod bearings are more difficult to control due to the difficulty of installing instrumentation on connecting-rods that are rotating and reciprocating. The solution uses a mechanical linkage fixed under the piston axis. The elastohydrodynamic model considers connecting-rod elastic deformations. The calculation process uses finite element and Newton-Raphson methods for the numerical analysis. Comparisons of both the load and crankshaft speed effects are made between experiment and the theory.