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Quality control and materials development of cellular polyurethane foam used in light-duty automotive air filter seals rely on measurement of mechanical and physical properties such as tensile strength, elongation, compression set, specific gravity, and durometer hardness. These properties are typically measured on specimens cut from slabs formed in preheated closed molds. However, these slabs are nonuniform in specific gravity, and property measurements vary with location within a slab. The effect of sampling location on mechanical and physical properties is discussed.

THE INCREASED use of midship-mounted transmissions in large equipment has emphasized the need for a torsionally resilient connection from the engine to reduce vibration transfer. To increase the torsional flexibility needed in these systems, the spring rate of the system must be reduced by such constructions as a flexible coupling, a spring-loaded damper, or a rubber torsional spring. This paper discusses these systems, emphasizing rubber springs. Some advantages of such a drive are: it provides an amplitude limitation with impact loads and a cushion to reduce noise and prevent clattering and contacts noises on parts with backlash, it smooths out transition periods to reduce loads on bearings and gears, its clamping characteristics can be adjusted by various rubbers, and its rubber cushion provides a degree axial flexibility.*

Who will repair the cars of the future? By the year 2001 there will be over 200 million vehicles registered in the United States. The closing of many new car dealerships and the reduction of service bays at oil companies are contributing to the decline of traditional service outlets to repair vehicles. Certain trends, however, are emerging that indicate that a shortage of auto repair technicians will not exist. Vehicles have been improved and maintenance schedules and warranties have been extended. The quality of the modern vehicle has impacted some traditional types of auto repair that used to be done. Rustproofing and engine tune-ups are just two such businesses. Factory rustproofing and the use of rust resistant materials have forced muffler shops and rustproofing businesses to change their repair focus. Tune-up services have changed to engine performance services because of the change in vehicle technology.

In spite of being a popular topic in technical publications, scuffing between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. This paper will discuss results of metallurgical and metrological (post-mortem) examinations of the scuffing between hard and soft cylinder liners and different piston ring coatings after field, engine and bench testing. Detailed metallurgical analysis describes the lubricity mechanism between various piston ring coatings and iron cylinder liner at different temperatures with and without oil. The paper will explain the origin of the scuffing through lack of or inadequate lubrication at top dead center, particularly for hardened iron heavy-duty diesel cylinder liners.

Thermoplastics have been used increasingly for automobile components for both interior and under-the-hood applications. The plastic parts are made through various molding process such as compression molding, injection molding and blow molding. For parts with large or complicated geometry, small portions of the part may have to be molded first, then joined together using a welding process. The welded regions usually exhibit inhomogeneous and inferior mechanical performance compared to the bulk regions due to the differences in thermal history. The microstructures and mechanical properties of welded thermoplastics have been examined using hot-plate welded polyethylene. The specimens are prepared at various thermal conditions to simulate the real welding process. The thermal properties in welds are monitored using DSC (Differential Scanning Calorimetry) and the crystallinities are calculated.

The wear patterns of the rings and grooves of a diesel engine were analyzed by using a ring dynamics/gas flow model and a ring-pack oil film thickness model. The analysis focused primarily on the contact pressure distribution on the ring sides and grooves as well as on the contact location on the ring running surfaces. Analysis was performed for both new and worn ring/groove profiles. Calculated results are consistent with the measured wear patterns. The effects of groove tilt and static twist on the development of wear patterns on the ring sides, grooves, and ring running surfaces were studied. Ring flutter was observed from the calculation and its effect on oil transport was discussed. Up-scraping of the top ring was studied by considering ring dynamic twist and piston tilt. This work shows that the models used have potential for providing practical guidance to optimizing the ring pack and ring grooves to control wear and reduce oil consumption.

This paper discusses corrosion fatigue and the corrosive environment as they relate to an industrial engine head gasket joint. The paper will identify possible corrosive elements which initiate corrosion fatigue failures. The sources of the corrosive elements will be cited with the associated concentration levels. The paper will formulate a hypothesis as to how the corrosive elements are transferred through the engine coolant system. Utilizing a Scanning Electron Microscope (SEM) and an Energy Dispersive X-ray Spectroscope (EDX), an analysis of coolant residue at the fracture will show evidence of the corrosive elements to verify the proposed hypothesis. Information from engines in the field will be compared to laboratory engine tests to show how laboratory and field results are significantly different. The main corrosive failure of the engine head gasket is flange cracking.

A detailed methodology is presented in this paper for a complete assessment of various forces, torques, and kinematic effects due to universal joint angularities and shaft yoke phasing. A modular approach has been adopted wherein constitutive equations represent each of the key elements of a driveline namely the driveshaft, coupling shaft, universal joint, and the transmission/axle shafts. Concentrated loads are used wherever loads are being transferred between the elements of a driveline. Local matrices are developed for the equilibrium of the respective driveline members. The local matrices are then assembled into a global matrix and solved for the kinematic state of the complete driveline. A 6x15 matrix has been developed to represent a general shaft in the system and a 6x10 matrix has been developed for a universal joint cross. This gives us a complete picture of all the loads on all driveline members.

Microalloyed (MA) steels have been developed as economical alternatives to the traditional quenched and tempered (QT) steels. The physical metallurgy principles underlying their basic composition-processing-microstructure-property interrelationships have been reviewed in the first part of the review. In this second part of the review, mechanical properties as well as fabrication properties, such as mahinability, weldability, and formability, are discussed. Flat products (such as strips, sheets, and plates), long products (including bars, rods, sections/profiles), and forging articles made of MA steels are investigated. Since most engineering components made of these steels are subjected to cyclic loading, fatigue and fracture performance of MA steels and their comparison with the QT steels are also evaluated in this review.