| Seizure failure of engine crankshaft bearings has been investigated through experiments and analysis. Test bearing materials include aluminum-tin, aluminum-lead-silicon, aluminum-tin-silicon, and copper-lead with lead-tin-copper overlay. Shaft materials include nodular cast iron and mild steel. Effects of different materials and surface texture of the bearing and shaft on their seizure loads have been studied. The results suggested that seizure may occur at micro, local, and failure scales. Both the material and surface texture of the bearing and shaft have significant effects on the seizure resistance of the bearing-shaft system.; The failure mechanism of aluminum-tin bearings is proposed to be melting and depletion of the tin in the alloy at high temperature. A failure model of aluminum-tin bearings, which is based on the melting temperature of tin, is presented. Effects of silicon particles in aluminum-lead-silicon and aluminum-tin-silicon bearing alloys on seizure resistance have been investigated. It is suggested that there might be an optimum size of silicon particles to achieve the best seizure resistance. Lead-tin-copper overlay on the copper-lead bearing has good tribological properties and seizure usually occurs between the shaft and the nickel barrier layer underneath the overlay after the overlay is removed by wear. It is concluded that the seizure load of such a copper-lead bearing is greatly affected by the quality of the shaft surface. Different seizure propagation modes were observed on a bored and a broached bearing. Seizure is more likely to propagate on a broached bearing surface and therefore a broached bearing has a lower seizure load than a bored bearing.; Shaft materials and surface texture also have significant effects on the seizure load of the bearing-shaft system. Ferrite in shaft materials reduces the seizure load of the shaft. Burrs on a shaft surface are detrimental to its seizure resistance and therefore a better polished shaft has a higher seizure load. Seizure load decreases as the shaft speed increases. |
