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Creep-resistant magnesium alloys for automotive powertrain applications offer significant potential for vehicle weight reduction. In this study permanent mold casting, microstructure and creep behavior have been investigated for a series of ternary magnesium alloys (Mg-4Al-4X (X: Ca, Ce, La, Sr) wt%) and AXJ530 (Mg-5Al-3Ca-0.15Sr, wt%). A permanent mold was instrumented with twelve thermocouples and mold temperature was monitored during the casting process. Average mold temperature increased from 200°C to 400°C during a typical alloy casting series (fifteen to twenty castings). The cast microstructure for all alloys consists of primary α-Mg globular phase surrounded by eutectic structure which is composed of intermetallic(s) and α-Mg magnesium phases. The primary cell size of the AXJ530 increased from 18 to 24 μm with increasing mold temperature and a similar trend is expected for all alloys.

Two rigid rollover test devices were constructed to have the approximate dimensions, mass and inertial properties of a mid-sized Car and Sport Utility Vehicle (SUV). The rigid devices were used to generate vehicle and occupant responses from a series of laboratory rollover tests. For each rigid rollover test, a deceleration sled was used to subject each rigid vehicle to nearly identical lateral speeds and decelerations. The rigid vehicles were limited to a single roll by tethering the vehicles to the deceleration cart. The vehicle's roll rate, roll angle, lateral acceleration and Anthropomorphic Test Devices (ATD) neck responses generated from the rigid SUV were compared to the responses of a full vehicle production SUV under similar test conditions. The rigid SUV and Car devices were then used to examine the effects of activating safety belt pre-tensioning systems and roof mounted side curtain airbags at various times on ATD neck forces and moments.

Design optimization techniques are widely used to drive designs toward a global or a near global optimal solution. However, the achieved optimal solution often appears to be the only choice that an engineer/designer can select as the final design. This is caused by either problem topology or by the nature of optimization algorithms to converge quickly in local/global optimal or both. Problem topology can be unimodal or multimodal with many local and/or global optimal solutions. For multimodal problems, most global algorithms tend to exploit the global optimal solution quickly but at the same time leaving the engineer with only one choice of design. The paper explores the application of genetic algorithms (GA), simulated annealing (SA), and mixed integer problem sequential quadratic programming (MIPSQP) to find multiple local and global solutions using single objective optimization formulation.

NODULAR cast iron, so called because the graphite is present as finely dispersed, well-rounded particles, is made in two stages: The first stage consists of the addition of magnesium or other carbide formers, which promote the formation of white iron in one normally solidifying gray. In the second stage a ferrosilicon type of inoculant overcomes the tendency toward white iron and causes the graphite to precipitate out in the form of small spherulites. The methods of making nodular iron, the effect of composition on physical properties, economic factors involved, and potential applications are discussed in this paper.

Magnesium alloys are the lightest structural metal and recently attention has been focused on using them for structural automotive components. Fatigue and durability studies are essential in the design of these load-bearing components. In 2006, a large multinational research effort, Magnesium Front End Research & Development (MFERD), was launched involving researchers from Canada, China and the US. The MFERD project is intended to investigate the applicability of Mg alloys as lightweight materials for automotive body structures. The participating institutions in fatigue and durability studies were the University of Waterloo and Ryerson University from Canada, Institute of Metal Research (IMR) from China, and Mississippi State University, Westmorland, General Motors Corporation, Ford Motor Company and Chrysler Group LLC from the United States.

Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.

Impulsive sound events (i.e. door closing) are often characterized as being undesirably sharp sounding. A high degree of perceived sharpness is normally related to large amounts of high frequency energy relative to the low frequency energy. In this project third octave data generated from a filterbank was used to calculate the center of gravity (cg) of the third octave bands. The result is the frequency corresponding to the centroid of the third octave data. Sounds with substantial high frequency energy have a centroid location that occurs at a higher frequency. The mean of the third octave cg over the duration of the transient event was investigated, in addition to sharpness as defined by Aures [1] and calculated on a commercially available analyzer. Correlation analyses to subjective data indicate that the mean third octave cg and the commercially available method produce comparable results for the vehicle closure sounds studied here.

Systems of alloys for liquid phase alloying during sintering were investigated. The solidification range of alloys of Mn-Ni-Cr-Mo-Fe and Mn-Cu-Ni was determined. Alloys with the lowest and narrowest melting range were prepared and atomized in nitrogen. Admixtures of master alloys to water-atomized, forging grade, pure iron powder were sintered at 1232°C (2250°F). After hot forging, these P/M steels exhibited hardenabilities which were 75%-90% of theoretical hardenability, as calculated from the factors for conventional steels. Alloying efficiency was further improved to 85%-100% of theoretical hardenability when additions of approximately 2% silicon and 1% rare earth misch-metal were made to the master alloys. The silicon and rare earth misch-metal additions were used to enhance diffusion and sintering.

The Multi Material Lightweight Vehicle (MMLV) developed by Magna International and Ford Motor Company is a result of a US Department of Energy project DE-EE0005574. The project demonstrates the lightweighting potential of a five passenger sedan, while maintaining vehicle performance and occupant safety. Prototype vehicles were manufactured and limited full vehicle testing was conducted. The Mach-I vehicle design, comprised of commercially available materials and production processes, achieved a 364kg (23.5%) full vehicle mass reduction, enabling the application of a 1.0-liter three-cylinder engine resulting in a significant environmental benefit and fuel reduction. This paper reviews the mass reduction and structural performance of aluminum, magnesium, and steel components for a lightweight multi material door design for a C/D segment passenger vehicle. Stiffness, durability, and crash requirements are assessed.

Engine dynamometer and laboratory flow reactor studies of automotive catalyst deactivation caused by the use of leaded fuel indicate that there are two different deactivation mechanisms: one, which dominates between 700 and 800 C, is the poisoning of the active platinum sites by lead oxide, or perhaps lead, and the other, which occurs below 550 C, is a build up of a gas diffusion barrier of lead sulfate. Both deactivation mechanisms can be temporarily reversed. Poisoning is reversed when the platinum is freed of lead oxide by lead sulfate formation below 650 C; and the barrier formed below 550 C can be made more permeable by thermal sintering of the lead sulfate at 600 to 700 C or its decomposition to lead oxide at 700 to 800 C. However, further exposure of the catalyst will again render it inactive via the mechanism predominating in that temperature region.

Computer simulation technology coupled with indoor laboratory facilities is being used in the automotive industry to provide up-front assessment of vehicle performance. This paper presents a technique to evaluate passenger vehicle tire wear performance as related to suspension and tire design early in the design process. Motivation for developing this tool is to optimize suspension and tire design to tire wear early in the design process. This approach has resulted in reductions in vehicle development time, dependency on outdoor testing and the need for expensive prototype vehicles. A full vehicle ADAMS model of a production vehicle is used to animate vehicle suspension kinematic motions, and dynamic tire forces of vehicle maneuvers for a preselected outdoor tire wear route. Time histories of five vehicle parameters are generated: radial force, slip angle or lateral force, camber, velocity and driving and braking torques.

Computer simulations of vehicle dynamics can be a useful investigative tool in drive-ability and NVH studies. As the present work demonstrates, oscillations of the drive-train under steady-state and transient conditions are amenable to mathematical analysis, especially in the torsional mode. Simulations of such a system with a lock-up torque converter are shown with emphasis on tip-in response, transmissibility of engine firing pulsations and self-excited oscillations. In particular, the method of interactive simulation is shown to be an effective design-aid tool in the investigation of drivetrain vibrations.

A demonstration structure was cast in AM60. The structure, known as the Generic Frame Casting or GFC, was designed specifically to mimic features seen in castings for closure applications. Excised samples were subsequently removed from different areas of the casting and tested under axial loading conditions. Component level tests were also conducted. Comparison of the excised sample results and the component level testing indicated the influence of local properties on the component level deformation. It was shown that varying the casting processing conditions could change the local ductility and yield strength in different areas of casting with the same geometry. Lowering the local ductility decreased the total displacement in a component level test and lowered the amount of energy absorption. Therefore, understanding the processing conditions and their influence on the local properties is important for predicting behavior in a component level test.

Shot peening is a commonly used surface treatment process used to improve the fatigue life of aircraft, automotive and other highly stressed structural components. This improvement is attributed to the formation of compressive residual stress on the surface layer of the material by the impingement of spherical media (shot). The compressive residual stress usually decreases the tensile stress created in the component by “in service” external forces and therefore increases the fatigue strength of the part. To quantify the improvement resulting from shot peening, the fatigue behavior of powder-forged connecting rods and laboratory test bars from the base material (2% copper steel), both in the stress-free (unpeened) and surface treated (shot peened) condition were compared. The fatigue data were correlated with the residual stress generated at the surface. The stress magnitude and depth were determined using x-ray diffraction analysis.

Today nearly all automotive manufacturers are developing motor-generator systems for improved fuel economy by implementing idling-stop and other power train enhancements. It is said that powertrain technology has always pioneered the development of automotive electronic control throughout history. The integrated starter generator (ISG) promises to expand the scope of powertrain control further through fuel economy improvement, emissions reduction, longitudinal vehicle dynamics improvement and customer feature enhancements. At the present time the cost imposed by usage of an ISG system is very high due mainly to its need for a power optimized 42V battery and high power electronics. This paper takes a critical look at the vehicle benefits attributable to ISG and its implementation costs over various vehicle classes.

Gear whine can be reduced through a combination of gear parameter selection and manufacturing process design directed at reducing the effective transmission error. The process of gear selection and profile modification design is greatly facilitated through the use of simulation tools to evaluate the details of the tooth contact analysis through the roll angle, including the effect of gear tooth, gear blank and shaft deflections under load. The simulation of transmission error for a range of gear designs under consideration was shown to provide a 3-5 dB range in transmission error. Use of these tools enables the designer to achieve these lower noise limits. An equally important concern is the dynamic mesh stiffness and transmissibility of force from the mesh to the bearings. Design parameters which affect these issues will determine the sensitivity of a transmission to a given level of transmission error.

An extremely tough alumina based ceramic coating produced by a modified anodizing process developed at Moscow Aviation Institute has been evaluated for light weight, wear resistant component applications in automotive powertrain. The process details and test results from comparative evaluation of friction and wear properties for cylinder bore application, referenced to cast iron baseline, are presented and discussed.

High ductility cast aluminum alloys are seeing more use in vehicles as a greater effort is made to replace components made from heavier steel and iron alloys with lighter weight alloys such as aluminum. High ductility cast aluminum has significant advantages by allowing for complex shape and considerable consolidation of parts in body structures. However, joining can be a challenge because one popular method for aluminum joining, self-piercing riveting (SPR), requires a ductility of greater than 10%, forcing the common high ductility Al alloys to undergo a T6 heat treatment which adds cost and potential distortion issues to Al component. In this study, friction stir spot welding was investigated as a potential joining technique for this material in the as-cast condition. Samples of as-cast Aural-2™ alloy were joined to Aural-2™, 5754, and 6061 alloys, to determine the manufacturing feasibility, weld strength, and fatigue strength using this joining technique.

The use of die cast magnesium for automobile transmission cases offers promise for reducing weight and improving fuel economy. However, the inferior creep resistance of magnesium alloys at high temperature is of concern since transmission cases are typically assembled and joined by pre-loaded bolts. The stress relaxation of the material could thus adversely impact the sealing of the joint. One means of assessing the structural integrity of magnesium transmission cases is modeling the bolted joint, the topic of this paper. The commercial finite element code, ABAQUS, was used to simulate a well characterized bolt joint sample. The geometry was simulated with axi-symmetric elements with the exact geometry of a M10 screw. Frictional contact between the male and female parts is modeled by using interface elements. Material creep is described by a time hardening power law whose parameters are fit to experimental creep test data.