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Recently, automotive engines have been operating under harsh conditions of high-power, low viscosity oil and increase of start-stop (e.g. idling stop). In plain bearing used within engine, as oil film thickness decreases, the frequency of direct contacts on the sliding surfaces between the shaft and the bearing are gradually increasing. In fact, the plain bearings for engines would tend to be used under mixed lubrication and the contacts of the surface roughness asperities sometimes occur between the shaft and the bearing. As a result, the bearing wear on the sliding surfaces is accelerated by the contacts of the roughness asperities. In order to predict the bearing performance exactly, it is very important to understand the change progress of the geometric shape of sliding surfaces caused by the wear.

Modern engine bearings have been operating under very harsh conditions. Consequently, a bearing wear propagates for a short time and a fatigue sometimes occurs on high loaded region. To reproduce the bearing damage in actual engines, the operating conditions of engine bearing were simulated on a rig test machine. The bearing wear was measured until the fatigue crack occurred in the simulation test. The wear progressed at the edges of the bearing length and the crack also was observed near the edges. The bearing damage is influenced by the bearing design and operating conditions. The experiment was conducted to change the design parameters in conditions. The experimental results were compared to the calculated results based on the elastohydrodynamic lubrication (EHL) theory. The correlation between bearing damage and bearing performance by theoretical analysis were investigated on effects of the design parameters.

The possibility of predicting engine bearing durability by elastohydrodynamic lubrication (EHL) calculations was investigated with the aim of being able to improve durability efficiently without conducting numerous confirmation tests. This study focused on the connecting rod big-end bearing of an automotive engine. The mechanisms of wear and fatigue, which determine bearing durability, were estimated by comparing the results of EHL analysis and experimental data. This comparison showed the possibility of predicting the wear amount and the occurrence of fatigue by calculation.

Engine bearings today are operating under very harsh conditions. Consequently, a wear propagates for a short time and a fatigue sometimes occurs on the bearings. In present study, on the rig test machine, the operating conditions of engine bearing were simulated to reproduce the bearing damage. The bearing wear was measured until the fatigue crack occurred. The bearing wear increased at the edges of the bearing length and the crack also was observed near the edges. The experimental results were compared to the calculated results based on the elastohydrodynamic lubrication (EHL) theory. The correlations between the bearing damage and the bearing performances by the theoretical analysis were investigated.