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Technical Paper

2-D Springback Analysis for Stretch-Bending Processes Based on Total Strain Theory

A theoretical model is presented for predicting springback of wide sheet metal subjected to 2D-stretch-bending operation. The material is assumed to be normal anisotropic with n-th power hardening law, σ = Fεn. Two types of stretch-bending experiment, bending with simultaneous stretching and stretch-bending followed by consecutive re-stretching, is conducted using AK sheet steel and sheet aluminum alloy A5182-O. The measured values of springback are in good agreement with analytical ones for a wide range of bending radii, stretching forces, and loading conditions. Furthermore, a calculation method for predicting springback configurations of 2D sheet metal parts with arbitrary cross-sections which include both stretch-bending and stretch-bending-unbending deformation is proposed.
Technical Paper

2-Stage Torque Converter and Double Clutch

THE development of the two-stage torque converter with automatic double clutch is presented here. The author covers particularly the substitution of casting for fabrication for several of the units in the transmission.
Technical Paper

2006 Chevrolet Corvette Z06 Aluminum Spaceframe

This paper describes the engineering, manufacturing and integration necessary to produce the Corvette's first ever all-aluminum spaceframe (see Figure 1). The engineering and manufacturing of the spaceframe was a joint venture between General Motors and suppliers ALCOA (Aluminum Company of America) and Dana Corporation. ALCOA led the initial design of the spaceframe; Dana Corp led the manufacturing; General Motors' Engineering and Manufacturing groups led the integration of the assembly. The aluminum spaceframe design is modeled after the baseline steel structure of the Corvette coupe. The aluminum spaceframe reduces 140 lbs from the steel baseline and enters the plant at 285 lbs. This frame allows the 2006 Corvette Z06 to enter the market at a 3100 lbs curb weight. Aluminum casting, extruding, stamping, hydroforming, laser welding, Metal Inert Gas (MIG) welding, Self Pierce Riveting (SPR), and full spaceframe machining make up the main technologies used to produce this spaceframe.
Technical Paper

2006 Chevrolet Corvette Z06 Aluminum Spaceframe Design and Engineering Technology

The General Motors (GM) Corvette design team was challenged with providing a C6 Z06 vehicle spaceframe that maintained the structural performance of its C5 predecessor while reducing mass by at least 56 kg. An additional requirement inherent to the project was that the design must be integrated into the C6 assembly processes with minimal disruption, i.e. seamless integration. In response to this challenge, a collaborative team was formed, consisting of design engineers from General Motors, Alcoa and Dana Corporation. The result of this collaborative effort is an aluminum Z06 spaceframe that satisfies the high performance expectations of the vehicle while reducing the mass by approximately 62 kg. The frame consists of aluminum extrusions, castings and sheets joined by MIG welding, laser welding and self-piercing rivets. The extrusions are 6XXX series alloys, the castings are permanent mold A356 while the sheet panels are formed from the 5XXX series of alloys.
Technical Paper

25 Development of Rapid Composite Plating System for Motorcycle Engine Cylinders

Weight reduction of automobiles is key technology in order to improve fuel economy and driving performance. Concerning of the motorcycle engine, weight reduction is also the fundamental and important technologies. Cylinder is one of the main parts of engine and the wear characteristics of the cylinder liner are largely related to the engine performance. Gray iron liners squeezed in aluminum cylinder block have been widely used. This is due to the excellent resistance to abrasion of gray iron. In order to realize light all aluminum cylinder, the good abrasion resistant method is necessary to develop to be applied with inner surface of liners. We have developed the new Rapid Composite Plating System for the motorcycle engine cylinders. This system made it possible to adopt all aluminum cylinders without cast iron liners to new type of engine.
Technical Paper

42 Volt Architecture on Powder Metallurgy - Opportunities

The 42-Volt electrical system is being introduced in automobiles to provide the extra power needed for various electromagnetic devices. These paper discuses the opportunity offered by the 42Volt for powder metal parts and the challenges. Major opportunities are in motors. A brief discussion of motors and the performance requirements for the magnetic core material used is included. Brushless motor design can benefit the most from insulated iron powder compacts because of the design simplicity of powder metal parts and three dimensional flux capability which is most beneficial in rotating devices.(P/M stands for powder metallurgy and not permanent magnets)
Technical Paper

4300 F Thermocouples for Re-Entry Vehicle Applications Part II

This paper presents a discussion of the component evaluation and design development work performed in developing a 4300 F reentry vehicle nose cap temperature sensor. Material compatabilities, insulation resistance, and atmospheric pressure effects on bare wire calibration data are discussed in some detail. The final design is outlined and the application problems discussed. The probe utilizes: a sintered iridium high temperature sheath (4300 F) and platinum 20% rhodium as the low temperature sheath (3000 F); beryllia as insulation -- hard fired at 4300 F and compacted powder at 3000 F; tungsten versus tungsten 26% rhenium as the thermocouple pair.
Technical Paper

72 Curved Fins and Air Director Idea Increases Airflow through Brake Rotors

Hayes Lemmerz has pursued fin configurations in straight and curved fin rotors to achieve high airflow velocity. The largest increase in airflow velocity of 37.2% is achieved by curving fins to a specific entry and exit angle and increasing surface area by increasing fin number. There is a need for funneling air into the narrow entry in the hub area. The new “Hayes Air Director” successfully channels air into the curved fins. Hayes Lemmerz is in the process of casting rotors with curved fins and the air director idea. Dynamometer and vehicle tests will follow. The current renwood model of the rotor design shows 34.8 to 37.2% increase in airflow velocity when tested on the Hayes Airflow machine.
Technical Paper

A Beginning Toward Understanding the Corrosion Resistance of Ferritic Stainless Steels

To date the market for P/M stainless steel has not developed appreciably, and has centered largely on the development of austenitic 300 series stainless steels. Although these stainless steels are noted for their resistance to corrosion in many media, it has been difficult for P/M parts fabricators to produce parts that will sustain 1,000 hours of protection in a 5% salt solution. The problem starts with the water atomized powders and continues with the sintering practice exercised to produce the parts. Reasons for lack of corrosion resistance, based upon these considerations, will be discussed. In addition, the ferritic stainless steels are being considered seriously for fuel injectors. These emerging applications derive from the corrosive environment that may become a problem if and when alternative fuels are introduced. P/M ferritic stainless steels may also assume a position as a corrosion resistant magnetic material required in ABS systems which are currently emerging.
Technical Paper

A Bigger Payload from Steel Foundries

The existing market conditions place heavy demands on the steel foundries to increase their capacity and output. Expansion hinges on the ability of the foundry to “earn the dollar” to permit the modernization of existing facilities and construction of new plants. It also requires that the foundry industry modernize its production methods and techniques; update its equipment; and that the consumer engineer assist in developing casting design features that will be more readily adaptable to the capabilities of the foundry operation. “A Bigger Payload from Steel Foundries” requires more than physical expansion-it demands cooperative and intelligent endeavor on the part of foundry management and consumer engineering.
Technical Paper

A Case Study in Structural Optimization of an Automotive Body-In-White Design

A process for simultaneously optimizing the mechanical performance and minimizing the weight of an automotive body-in-white will be developed herein. The process begins with appropriate load path definition though calculation of an optimized topology. Load paths are then converted to sheet metal, and initial critical cross sections are sized and shaped based on packaging, engineering judgment, and stress and stiffness approximations. As a general direction of design, section requirements are based on an overall vehicle “design for stiffness first” philosophy. Design for impact and durability requirements, which generally call for strength rather than stiffness, are then addressed by judicious application of the most recently developed automotive grade advanced high strength steels. Sheet metal gages, including tailored blanks design, are selected via experience and topometry optimization studies.
Technical Paper

A Case Study of a Die-Cast Magnesium Structure Supporting Transmission Shifter Mechanisms and Interfaced with other Structural Systems

During the last several years the use of magnesium die-castings for automotive applications has been on the rise. Magnesium's use in die-cast form has been expanding at an average growth rate of more than 15% a year. Reasons for the increase are both practical and economic. Magnesium die-castings offer components having the lowest mass when compared to almost any other structural material. Magnesium die-alloys exhibit properties that bridge the gap between engineered plastics and metals. The mechanical performance ratios (strength-to-weight and stiffness-to-weight) of magnesium also compete favorably with metals and plastics. Economically, magnesium alloys prices have fallen during the last several years making them extremely competitive with other materials.
Technical Paper

A Comparative Design Study for Aluminium and Magnesium Automatic Transmission Converter Housings

The demand for vehicles with improved NVH characteristics, fuel economy and emissions control has increased dramatically in recent years. To meet these objectives stiffer and lighter housings are required so as to avoid troublesome driveline vibrations, while at the same time produce lighter structures to reduce the overall vehicle weight and improved fuel economy. A feasibility study was undertaken to examine the differences between the use of magnesium alloy and aluminium alloy for an automatic transmission converter housing. The design process, design constraints, design methodology, alloy selection and some unique magnesium design requirements are outlined. The differences between the two designs are investigated by simulating their static and dynamic performances using Finite Element Analysis (FEA). A sand cast prototype was produced for the first stage of the feasibility study, with the ultimate aim to produce die cast magnesium converter housings if feasible.
Technical Paper

A Comparative Evaluation of Mechanical Properties and Machinability of Austempered Ductile Iron (ADI) and Microalloyed Steel

Austempered Ductile Iron (ADI) samples were heat treated to produce materials with tensile strengths in the range of 100 ksi to 170 ksi. Microalloyed steels were also produced with equivalent tensile and yield strength levels. These steels were evaluated for mechanical properties in terms of tensile and yield strength, ductility, impact toughness, fracture toughness and fatigue strength. Machinability was extensively evaluated through tests of drilling, turning and plunge machining. This paper reports on this comprehensive comparative evaluation of these two important classes of materials for use in the automotive industry.
Technical Paper

A Comparative Study of Four Alloys for Automotive Brake Drums

A drag dynamometer was used to evaluate the performance of automotive brake drums made from four kinds of materials with different thermal conductivities. In the order of decreasing thermal conductivity they are chromium copper, aluminum/cast iron composite, cast iron, and nickel-aluminum bronze. All of the drums were of the standard configuration used in SAE J 661a, or closely approximated it. The drums were run in conjunction with three types of lining materials: nonabrasive, moderately abrasive, and highly abrasive. Temperatures near the lining/drum interface, coefficients of friction, and lining wear were measured and compared. For a given amount of work done, the temperature near the drum surface was found to be lowest for the chromium copper drums, with progressively higher temperatures in the aluminum/cast iron composite, nickel-aluminum bronze, and cast iron drums. Relative lining wear and coefficient of friction varied with the type of lining tested.
Technical Paper

A Comparative Study on the Performance of Ventilated Brake Discs Manufactured in Different Advanced Materials

Two different aluminium alloy materials have been used to produce ventilated brake discs, on one hand, AS17G0.6 hypereutectic alloy and on the other hand, AS7G0.6 reinforced with 20% in wt. of SiC particles. The casting production technique used has been Low Pressure Casting (LPC) and some of the brake discs have been heat treated using a T6 treatment. Once the ventilated brake discs were produced and machined, they were tested in a dynamometer in order to compare the performance under service conditions of the aluminum alloy and grey cast iron (GCI) discs currently used in the market.
Technical Paper

A Comparison of Boundary Layer Treatments for Heat Transfer in IC Engines

Three different models, the law-of-the-wall, a modified law-of-the-wall, and an approximate one-dimensional solution to the energy equation are compared for the spatially-resolved prediction of engine heat tranfer. The multidimensional hydrodynamic code KIVA is used for the fluid mechanic simulation. Two different engine geometries are studied; one being a pancake-shaped chamber, and the other a bowl-in-piston geometry. The comparisons are done for a range of initial conditions of gas flow. Rates-of-pressure-rise were also varied to represent rates typical of those encountered in motored engines, and those found in fired engines. Comparisons with experimental results show that the heat transfer predictions using the law-of-the-wall may be in error when source terms such as the transient, work and chemical energy terms have a significant effect in determining the temperature profile in the boundary layer.
Technical Paper

A Comparison of Neural Networks and Wavelets Networks for Predicting Creep and Rupture Resistance of Ferritic Steels

This work is based in a model of neural and wavelets networks using published experimental data. The objective is to compare a neural and a wavelet network estimating the creep rupture strength based on chemical composition of Fe-2.25Cr-Mo and Fe-(9-12)Cr steels, and on its heat treatment temperature and life time. It will be determined the configuration that provides the best fit of the data.
Technical Paper

A Comparison of the Impact Characteristics of Several Magnesium Die Casting Alloys

Interest in ductile, tough magnesium alloys has been stimulated by designers seeking lightweight, efficient steering control structures. The simultaneous need for deformable, energy-absorbing components redirected metallurgists to consider the impact behavior of “high-ductility”, AM-series, magnesium alloys. This paper provides a comparison between the “workhorse” AZ91D magnesium alloy and the less-common, AM60B alloy. Specific application to a steering column bracket illustrates the development processes involved in selecting the appropriate alloy.
Technical Paper

A Comparison of the Magnetic Properties of Hot Repressed and 7.4 g/cm3 Iron and 0.45% Phosphorus Iron Cores

Atomized iron powder was screened to narrow fractions and annealed. Intermetallic Fe3P powder was blended with the fractions to provide an alloy containing 0.45% phosphorus after sintering. Cores were pressed to a density of 7.4 g/cm3 and sintered at temperatures ranging from 1600°F (870°C) to 2600°F (1430°C) in hydrogen. Magnetic properties were determined from the sintered cores and compared with previous properties measured for iron and hot repressed 0.45% phosphorus iron. It was found that the induction at any density level was approximately 500 gausses (0.05 teslas) lower than for iron. Remanent magnetization was influenced by the size of the pores. If pores were large, remanent magnetization was 8 K gausses (0.8 teslas) and increased to 12 K gausses (1.2 teslas) as the pores become finer. Both maximum permeability and the coercive force were improved when 0.45% phosphorus was added.