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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.

Microalloyed (MA) steels have been developed as one of the most significant metallurgical advances over the last thirty years, with their property improvement and cost effectiveness characteristics. Even though the underlying principles for microstructural property control of these steels have been well established, applications of these steels are still limited in scale mainly due to a lack of their understanding. This review paper focuses on mechanical property control of these steels. Since the properties depend mainly on the composition and microstructure which in turn are controlled by steel making and processing, metallurgical variables are reviewed in this first part of the review. These include their strengthening mechanisms, effects of composition and processing on their behavior, and the various MA steel microstructures.

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.

A few years ago hydraulic fluid power component manufacturers had the luxury of long lead times to develop new products. In today's competitive global market, pump and valve design engineers must be able to shorten development lead times and get new, less costly products to production in order to satisfy customer demands. This paper describes how one fluid power component manufacturer uses rapid prototyping technology to speed up the development cycle by making: fit and form models, design evaluation test samples, and tooling for prototype castings.

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.*

ON THE basis of laboratory and field tests of passenger-car and light-truck rear axles, the authors conclude: 1. The capacity of present axles can be increased, without increasing axle size, when greater load-carrying antiwear and antiscore lubricants are available. 2. Gear noise will always be a major problem because axle gears are operating at varying speeds and loads whenever a car is in motion. Many gear noise problems can be overcome by proper tooth development and by testing in the actual car model under which the axle will be used. 3. The only reliable basis for torque-capacity rating is the tractive effort (wheel-slip torque). 4. The limited-slip type of differential will eventually become standard equipment on all passenger cars, if only to improve car handling and stability during high-speed driving under varying traction conditions.