The paper concerns the transient thermal behavior of a conrod bearing in an automotive engine subjected to various running conditions. The thermal model is oil shear and contact friction heat generation components. The first part of the paper covers some of the industrial and scientific aspects related to bearings seizure, and emphasizes the importance of removing this failure mechanism as early as the incipient development stages of new automotive engines. The second part concerns several of the broad array of factors that approximate a seizure mechanism. In the third and final part, the mathematical model for conrod bearings seizure is revealed. The objective of the paper is to confirm the conrod seizure model's utility, complementary with more refined approaches such as the thermo-elasto-hydrodynamic approach.

No abstract

For many years, bearing suppliers use efficiently the specific pressure to evaluate the fatigue risk of conrod bearings. However, modern engines have made the bearing more sensitive to various phenomena such as the thermal expansion or the elasticity of the conrod housing. These effects modify the stresses in the bearing layers and by the way the fatigue loading. In this paper, we analyze the elastic and plastic behavior of the bearing during the engine life. We detail and provide the analytical relationships, which determine stresses in the overlay and the substrate of the bearing. Various loadings are taken into account such as the thermal loading, the hydrodynamic pressure field, the fitting loading, the free spread loading. The knowledge of the relationships helps to understand the mechanical behavior of the bearing. Particularly, it allows demonstrating that plastic flow occurs in the substrate and in the overlay during the first combustion cycles and the first thermal cycles. Residual stresses are introduced by plastic flow and modify the stress tensor in the different layers. Therefore, the two layers are subject to high cycles fatigue (H.C.F.) with combustion cycles and low cycles fatigue (L.C.F.) with thermal loading. The high cycle fatigue analysis is performed with multiaxial criteria.