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Microstructures and rolling contact fatigue properties of high carbon chromium bearing steels were investigated by means of electron microscopy, hardness and rolling contact fatigue tests. In order to examine the influence of heat treatment process and alloy composition on microstructure and rolling contact fatigue, two kinds of heat treatment processes, i.e., quenching/tempering (QT) and nitrocarburizing were performed on conventional AISI52100 and ASTM A485 Grade-1. Rolling contact fatigue life of the nitrocarburized alloys was longer than that of QT treated alloys by 3.7 times under a clean lubrication condition and was longer by 1.5 times under a contaminated lubrication condition. The amount of retained austenite in the nitrocarburized samples was found to be larger than that in the QT treated samples. As for alloy effects, rolling contact fatigue life of nitrocarburized ASTM A485 Grade-1 steel was superior to that of nitrocarburized AISI52100 steel.

In this work a numerical method for the design of components submitted to severe cyclic thermomechanical loading is developed. This tool is based on a Finite Element (FE) analysis. In a first part the temperature distribution is obtained and used in the second part for the mechanical computation. The analyses use the description of the geometry of the part, a precise information of the thermal properties, an appropriate behavior of the material at low and high temperature and a good assessment of the boundary conditions (heat transfer coefficients, contact, …). This method is applied to asses the low cycle fatigue design of a diesel turbo-charged exhaust manifold in cast iron. These calculations, failure location and lifetime estimation, obtained on two versions of this component, are compared to experimental data. The results show a good agreement in terms of critical zones location and of lifetime comparison in both versions and permit thus to classify the versions.

Component bench fatigue testing is a cost-effective way to evaluate the durability of exhaust catalytic converters. A successful bench fatigue test depends on the development of a test specification. The test specification should represent the actual customer duty cycle that the component is exposed to. Based on the concept of equivalent fatigue damage, a systematic approach is presented to obtain the test specification from the acquired road load data. A method based on damage analysis is proposed to determine the effective notch factor, and an empirical relationship is presented to account for the thermal effect on the test specification. The principles and procedures of multiple block testing and constant amplitude testing are also presented.

The automotive foundry industry is still facing greater challenge to make casting component lighter, stronger, tougher and cheaper. As computer process simulation technology has become a very helpful tool, more and more companies are popularly applying this tool in their optimizing casting structure and casting process designs. Fighting against casting defects is usually one of the major subjects in optimizing both casting structure design and casting process design. Computer simulation can reasonably predict “casting results” based on the structure/process data designed for a casting component previously or even conceptually. This prediction can provide us with some information about castability of a casting structure and then allow us to recommend for further improvement in its “original structure design” or to make a better casting process design to minimize the risk, i.e., those potential casting defects.

Data on the low and high cycle fatigue response as well as monotonic (non-cyclic) and cyclic flow properties are required by design engineers for the proper design of many components. Currently, there are no readily available sources for such information on ductile/nodular cast iron. The purpose of this study was to determine property design data similar to those in SAE standard J1099 for SAE Grade D5506 ductile iron. In this study, the monotonic and cyclic strin hardening properties, and the variation of elastic modulus after repetitive cyclic testing were determined for eight ductile iron castings selected to represent the range of properties possible in Grade D5506 ductile iron. Strain-life testing was conducted on four of the eight materials to calculate the strain and stress versus fatigue life (reversal) constants.

Intended for the designer of automotive components, this paper emphasizes the importance, and feasibility today, of using casting modeling early in the design process. Usage of computer modeling for metal casting has expanded greatly in just the past few years. This is due to both advances in computer power, and to the economical benefits from modeling. Benefits include optimization of the process parameters to ensure sound parts, reduction of scrap, and minimization of defects. Given the complexity of automotive castings and the expanded range of materials being cast, computer simulation has gained an important role with designers as well as foundrymen. However, most computer simulations to date have focused on solidification and shrinkage modeling. Only recently has modeling begun to include the metal flow behavior with its inherent complexity.

Automotive air conditioning compressors utilizing aluminum scrolls offer improvements in engine performance and fuel economy by lowering energy consumption, reducing weight, and allowing smaller packaging. This alternative compressor design was first commercially produced in 1981. Since this time, scroll compressors have continually increased their share of the original equipment compressor market for Japanese, European, and US automotive manufacturers. Two essential components in the compressor assembly are the aluminum scroll castings (fixed and orbiting). The first production aluminum scrolls were machined from sand castings. This process was then replaced by squeeze casting, which has now been in use for over 12 years. Forging has recently emerged as an alternative process. The design and structural requirements of the aluminum scroll component challenge both squeeze casting and forging processes.

The demands of modern society continue to drive automotive design to greater efficiency and cleaner operation at lower cost. Higher operating temperatures are now typically required to meet these demands, making the use of more robust materials and joining techniques a necessity. This paper describes how the benefits of reduced emissions and greater fuel economy along with quieter operation are achieved by using silicon-molybdenum modified ductile iron exhaust manifolds welded to close-coupled 400 series stainless steel catalyst cans. This weldment is made possible by using a newly-developed stabilized Ni-Fe-Mn-Cr-Cb welding wire called NI-ROD® Filler Metal 44HT. Durability testing of fabricated exhaust components under extreme dynamometer testing has shown that this welding material provides successful higher temperature performance by the ductile iron than that provided by previous weldments of the same iron.

Today's leading casting manufacturers employ many new technologies to produce high quality engineered castings. Foremost among these technologies is casting process simulation. With casting process simulation, casting designers and process engineers use sophisticated physical models to optimize casting filling and solidification patterns, microstructure and mechanical properties distributions, and residual stresses and distortion. Using casting process simulation early in the development cycle leads not only to higher quality castings, but also to shorter product development times, more castable designs, higher productivity, and castings that go well beyond what were once considered to be the limits of the casting process. This paper illustrates through case studies how both designers and producers of castings are using simulation to meet the increasing demands being placed on castings by the automotive and transportation industries.

Compositional and microstructural variations in a casting can often result in rather significant variations in the response to a given aging treatment, leading to location dependent mechanical properties. The objective of this study is to determine the effect of copper content and solidification rate on the aging behavior of a type 319 cast aluminum alloy. The nominal composition of the alloy is Al-7% Si-3.5% Cu-0.25% Mg, however, typical secondary 319 aluminum specifications allow copper levels to vary from 3-4%. Solidification rates throughout a casting can vary greatly due to, among other factors, differences in section size. To determine the effect of copper level and solidification rate on the aging response, aging curves were experimentally developed for this alloy. Three different copper levels (3, 3.5, 4%) and two solidification rates were used for this study. Aging temperatures ranged from 150-290°C with nine aging times at each temperature.

Proper alloy and process selection is critical to the commercial production and application of any high-integrity casting. These activities must be focused directly on critical part performance criteria. This paper presents examples of how a casting supplier, with a sound foundation in a broad range of the high-integrity casting techniques, can select and optimize critical criteria in the areas of product design, alloy design, casting process design and heat treatment to achieve a commercial manufacturing success which satisfies the casting customers' functional needs. Three case studies are described which show how proper process selection aided the casting customer in choosing the correct casting process. Case Study 1 Optimization of a 357 semi-solid metal casting (SSMC) alloy with T-5 heat treatment for a swaging application. Case Study 2 Optimization of a 365 alloy and T-5 heat treatment for Johnson Apparent Elastic Limit (JAEL).

Applying an equilibrium approach to bifurcation the buckling of elastoplastic plates is investigated. The conditions for the onset of buckling are established for simply supported plates under biaxial loading conditions. The theory is also applied to study the elastoplastic buckling phenomena of the Yoshida Buckling Test (YBT). It demonstrated that sheet dimensions used in the original YBT specimen design does not take full advantage of the maximum value of the induced compressive stress. The peak value of the induced compressive stress, which is - 14% of the tension stress, occurs at a width to length ratio of the sheet of b/a = 0.914. While the same theoretical dimension ratio of a standard YBT specimen at b/a = 0.4 results in an average induced compressive stress to be about -6% of the tension stress. The sensitivity of the buckling load predictions to mechanical properties of material is examined for all possible combinations of ratios of applied stress resultants.

Austempered Ductile Iron was first commercially applied in 1972. By the mid 1970's it had found its way into Chinese Military trucks and into commercial truck applications in Europe. By 1978, austempered ductile iron had been applied to light cars and trucks in the US. Today, it is estimated that over 50,000 tons per year of austempered ductile iron components are installed in cars and trucks world-wide. That production appears to be growing at a rate of exceeding 10% per year. As a family of materials, austempered ductile iron capably addresses the issues of weight, strength, stiffness, noise, cost and recyclability. From the first differential gear sets installed by General Motors in 1978, to light-weight truck-trailer wheel hubs, to high performance automobile suspensions, austempered ductile iron has found itself in many unique applications. This paper will review those applications, the reason(s) for the conversions, and the performance of those components.

Previously-reported draw-bend tests showed large discrepancies in springback angles from those predicted by two-dimensional finite element modeling (FEM). In some cases, the predicted angle was several times the measured angle. With more careful 3-D simulation taking into account anticlastic curvature, a significant discrepancy persisted. In order to evaluate the role of the Bauschinger Effect in springback, a transient hardening model was constructed based on novel tension-compression tests for for three sheet materials: drawing-quality steel (baseline material), high-strength low-alloy steel, and 6022-T4 aluminum alloy. This model reproduces the main features of hardening following a strain reversal: low yield stress, rapid strain hardening, and, optionally, permanent softening or hardening relative to the monotonic hardening law. The hardening law was implemented and 3-D FEM was carried out for comparison with the draw-bend springback results.

A failure prediction methodology that can predict sheet metal failure under arbitrary deformation histories including rotating principal stretch directions and bending/unbending with consideration of damage evolution is reviewed in this paper. An anisotropic Gurson yield criterion is adopted to characterize the effects of microvoids on the load carrying capacity of sheet metals where Hill’s quadratic anisotropic yield criterion is used to describe the matrix normal anisotropy and planar isotropy. The evolution of the void damage is based on the growth, nucleation and coalescence of microvoids. Mroz’s anisotropic hardening rule, which was proposed based on the cyclic plastic behavior of metals observed in experiments, is generalized to characterize the anisotropic hardening behavior due to loading/unloading with consideration of the evolution of void volume fraction. The effects of yield surface curvature are also included in the plasticity model.

This paper reviews the relationship of the anisotropy of plastic behavior of sheet metal to crystallographic textures and the effect of anisotropic plastic behavior on sheet forming processes Although the basis is crystallographic, the anisotropy of cubic metals can be approximated by a continuum yield criterion. Use of this criterion in analyses of sheet forming gives better results than the usual quadratic criterion.

The use of tailor welded blanks (TWBs) in automotive applications is increasing due to the potential of weight and cost savings. These blanks are manufactured by joining two or more sheets of dissimilar gauge, properties, or both, to form a lighter blank of desired strength and stiffness. This allows an engineer to “tailor” the properties of the blank to meet the design requirements of a particular panel. TWBs are used in such places as door inner panels, lift gates, and floor pans. Earlier investigations of the use of TWBs targeted steel alloys, but the potential of further weight savings with aluminum TWBs is gaining interest in the automotive industry. Unlike steel TWBs, the welds in aluminum TWBs are not significantly stronger than the base material and are occasionally the fracture site. Additionally, the reduced formability of aluminum, as compared with drawing-quality steels, makes the application of aluminum TWBs more difficult than steel TWBs.

A simple problem of tube expansion to fill the die corners in the hydroforming process is studied. Based on a two-dimensional plane stress model the tube is simulated numerically using a static implicit finite element analysis, particularly, the commercial finite element code ABAQUS. Similar to the development and application of two-dimensional finite element codes for sheet metal forming, this two-dimensional model provides insight of the detailed deformation and stress/strain development otherwise lost in a more complex three-dimensional model. To facilitate discussions, high friction is assumed such that the tube does not slide on the die surface after contact. The calculated results predict the requirement to form sharp corners and demonstrate the development of the deformation, strain and stress states in the tube.

Tubular hydroforming provides a number of advantages over conventional stamping processes, including reduction in part counts and weight reduction, improved strength and stiffness of structural components, lower tooling costs, and higher dimensional accuracy. In order to provide hydroforming guidelines for product designers and process engineers, and to obtain fundamental understandings of such forming process, we begin a series of study on failure analysis of tubular hydroforming under internal pressure and end feeding. The focus of this paper is placed on the condition of the onset of bursting. Bursting is an instability phenomenon where the tube can't sustain any more internal pressure. Splitting usually follows due to extreme deformations in the bursting area. Onset of bursting depends on process parameters such as pressure and end feeding, as well as on material properties. A mathematical analysis is conducted in this paper for the conditions of onset of bursting.

This paper describes a robust, secure Java-based Telematics platform that enables the rapid development and deployment of distributed infotainment and safety service applications. Such a distributed architecture allows the Telematics client in the vehicle to offload data and compute-intensive operations to the server, while executing location-sensitive and vehicle-centric services onboard. Further, by careful segmentation of the client and server modules, multiple tiers of the client product can be designed and rapidly assembled, ranging from inexpensive, thin clients to costlier, self-contained ones. By basing it on Java, we harness and empower a large development community, while reaping all the benefits of Java.