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A new aluminum alloy bearing material containing lead-base babbitt is described. This material provides the performance advantages of an overplated babbitt construction without requiring the plating procedure. Performance characteristics including fatigue, wear, score, and corrosion resistances and embedability are compared to standard SAE bearing materials on the basis of laboratory tests. Extensive engine dynamometer and vehicle field tests are described to show the excellent durability of this new material.

Dual-phase steels have been used primarily for reducing weight of complex shaped automotive parts which could not be made with less formable, conventional high strength steels. Recently, a microalloyed dual-phase steel was found also to possess superior machining characteristics. This paper describes laboratory data which compare machinability of dual-phase steel with that of conventional steels. The effects of material strength, tensile prestrain, and cutting depth on machined surface quality are elucidated. The improved machinability of dual-phase steel was explained on the basis of its unique micro-structure. In addition, two applications of dual-phase steel are discussed. In one application, broaching is the critical machining step, and dual-phase steel is currently used in production. In the other, turning is the critical step, and further studies are under way.

In order to understand better the head injury mechanism and to clarify the unsettled question as to whether the shear strain or the reduced pressure is the primary injury etiology during a given impact, a realistic model capable of predicting both the shear strain and the reduced pressure effects should be devised. The approach to such a realistic but complicated boundary value problem in biomechanics is achieved through the application of the finite element method. By use of the finite element displacement formulation, the human head is modeled as a viscoelastic core bonded to a thin viscoelastic shell, which simulates the brain and the skull, respectively. For purpose of comparison, two configurations-a spherical shape and a prolate ellipsoid-have been used to describe the geometry of the human head.

The flow of oil into a rotating crankshaft has been investigated. Analysis of the physics of the problem together with dimensional analysis indicates, for a given journal geometry, that a relationship exists between Reynolds number, non-dimensionalized pressure drop, and oil flow. Data obtained from an oil flow test rig are used to determine explicit correlations for two oil feed configurations; one journal with and one journal without a lead-in groove.

To verify the relationship between bearing oil film thickness and high-temperature, high-shear (HTHS) engine oil viscosity, accurate values for bearing oil temperature and shear rate are needed. Techniques for making these determinations are presented using data collected from engine tests with both single- and multigrade oils. A regression model is developed for estimating bearing oil film temperature as a function of engine operating variables. Bearing oil temperatures can be more than 20°C greater than sump temperatures. The relationships between film thickness and viscosity evaluated at several bearing shear rates are described. If oil viscosity is evaluated at the maximum bearing shear rate, previously published findings which conclude that multigrade oils provide a thicker oil film than single-grade oils are verified.

SAE 1046 steel axle I-beam forgings produced by the direct quench method and the conventional reheat and quench method were examined. Impact and tensile specimens obtained from sections of two direct quench and one conventional reheat and quench axle I-beams were tested. These data were correlated with hardness and microstructure to determine the relationship between microstructure and properties. The microstructure of direct quenched beams is coarse grained with a martensite case and bainite core. In contrast, the microstructure of conventionally heat treated beams is fine grained with a martensite and/or bainite case and pearlite core. Tensile and impact properties indicate that direct quenching is an acceptable alternative to the conventional reheat and quench process. Fatigue testing of direct quenched beams is currently being performed.

Oil film thickness measurements made in the front main bearing of an operating 3.8 L, V-6 engine were compared with rheological measurements made on a series of commercial and experimental oil blends. High-temperature, high-shear-rate viscosity measurements correlated with the film thicknesses of all single-grade and many multigrade oils. However, the film thicknesses provided by some multigrade oils were larger than could be accounted for by their high-temperature, high-shear-rate viscosities alone. Although the pressure-viscosity coefficients of some of the oils were significantly different from those of the majority of oils tested, they were not oils which produced unusual film thicknesses. As a consequence, correcting oil viscosities for the estimated pressures acting within the bearing was unsuccessful in improving the correlations. The correlations were improved, however, by accounting for the elastic properties of the multigrade oils.