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Fundamental differences exist between sheet metal forming and hydroforming processes. Sheet metal forming is basically a one step metal fabrication process. Almost all plastic deformation of an originally flat blank is introduced when the punch is moved normal to a clamped sheet metal. Hydroforming, however, consists of multiple steps of tube making, pre-bending, crushing, pressurization, etc. Each of the above mentioned steps can introduce permanent plastic deformations. The forming limit diagram obtained for sheet metal forming may or may not be used in hydroforming evaluations. A failure criterion is proposed for predicting bursting failures in tube hydroforming. The tube material's stress-strain curve, obtainable from uniaxial tensile test and subjected to some postulations under large stress/strain states, is used in judging the failure.

This paper discusses an analytical technique for computing the failure rate of steel springs used in automotive part applications. Preliminary computations may be performed and used to predict spring failure rates quickly at a very early stage of a product development cycle and to establish program reliability impact before commitment. The analytical method is essentially a combination of various existing procedures that are logically sequenced to compute a spring probability of failure under various operational conditions. Fatigue life of a mechanical component can be computed from its S-N curve. For steels, the S-N curve can be approximated by formulae which describe the fatigue life as a function of its endurance limit and its alternating stress. Most springs in service are preloaded and the actual stress fluctuates about a mean level. In order to compute an equivalent alternating stress with zero mean, an analytical method based on the Goodman Diagram is used.

The Cadillac Electronic Climate Control heating and air conditioning system provides automatic control of the passenger compartment temperature. It utilizes a microcomputer to control the operation of electrical, mechanical and vacuum components that regulate the amount and temperature of air delivered into the car to maintain the “customer set” comfort level. The first step in the evolution of this new system was to define the performance requirements. With this established, the system was then designed, tested and developed in the laboratory and on the road until this desired performance was achieved.

This study examined whether the effect of subsidiary tasks on driving performance can be predicted from stationary (static) testing. Alternative methods for assessing the performance of drivers during their use of in-vehicle information systems were examined. These methods included static testing in stationary vehicles, as well as dynamic, on-road testing. The measures that were obtained from static tests were evaluated in terms of how well they could predict measures obtained from driving performance during on-road testing (which included concurrent use of secondary information systems). The results indicated that measures obtained in static test settings were highly correlated with corresponding measures obtained from on-road performance testing.

Contamination protection of brake rotors has been a challenge for the auto industry for a long time. As contamination of a rotor causes corrosion, and that in turn causes many issues like pulsation and excessive wear of rotors and linings, a rotor splash protection shield became a common part for most vehicles. While the rotor splash shield provides contamination protection for the brake rotor, it makes brake cooling performance worse because it blocks air reaching the brake rotor. Therefore, balancing between contamination protection and enabling brake cooling has become a key critical factor when the splash shield is designed. Although the analysis capability of brake cooling performance has become quite reliable, due to lack of technology to predict contamination patterns, the design of the splash protection shield has relied on engineering judgment and/or vehicle tests. Optimization opportunities were restricted by cost and time associated with vehicle tests.

This paper describes a test of 2500 General Motors passenger cars equipped with anti-lacerative windshields and driven in rental fleets. It also de840391 scribes the laboratory tests conducted prior to the fleet installation of the test windshields. Evaluation of haze development caused by abrasion of the anti-lacerative surface will take several more years of exposure. Other test results have been encouraging, except for the difficulties encountered in the removal of stickers and decals from the inner surface.

As component and systems sophistication in both cars and trucks increase, improved diagnostic capabilities are required to assure proper and expedient serviceability. Replacement of electrical modules, starter motors, carburetors, fuel injectors and even whole engines or transmissions is encouraged by high labor costs and continued vehicle mobility mandates. The remanufacturing business has grown and components previously discarded now provide valuable core elements to feed the industry. To achieve efficient utilization of capital, equipment and labor, remanufacturers must estimate when this supply of core elements will be available and plan their production schedules accordingly. In order to properly service private individuals and commercial fleets, minimize vehicle downtime and reduce life cycle costs, adaptation of available analytical tools must be made.

As a result of raised awareness regarding the proliferation of individual OEM recommended ATFs, and discussion in various forums regarding the possibility of ‘universal’ service fill fluids, it was decided to study how divergent individual OEM requirements actually are by comparing the fluids performance in industry standard tests. A bench-mark study was carried out to compare the performance of various OEM automatic transmission fluids in selected industry standard tests. All of the fluids evaluated in the study are used by certain OEMs for both factory and service fill. The areas evaluated included friction durability, oxidation resistance, viscosity stability, aeration and foam control. The results of this study are discussed in this paper. Based on the results, one can conclude that each ATF is uniquely formulated to specific OEM requirements.

The level of filtration in an engine can have a significant impact on wear rates due to abrasive particles. Tests were conducted to establish a relationship between the level of filtration and abrasive engine wear. Although the tests were run in a laboratory environment, wear was reduced by as much as 70% by going from a 40 micron filter to a 15 micron filter. Testing was performed on a heavy duty diesel engine and later with an automotive gasoline engine. The results from both engines were consistent and showed that the relationship developed can be applied to nearly any internal combustion recipricating engine.

Casting technology developmentshave led to a manufacturing process that allows the casting of thin wall (2-3mm) heat resistant ferritic stainless steel exhaust manifolds which can replace stamped and tubular weldments as well as iron castings where temperature requirements are increased. This casting process combines the thin wall and clean metal benefits of the counter gravity, vacuum-assist casting process using thin, light-weight bonded sand molds supported by vacuum-ridgidized sand. This combination is called the LSVAC (Loose Sand Vacuum Assisted Casting) process, a patented process. This process will significantly contribute to the growth of near-net shape steellstainless steel castings for automotive and allied industries. For exhaust manifolds, a modified grade of ferritic stainless steel with good oxidation resistance to 950°C in high dew point synthetic exhaust gas atmospheres was developed.

Truck driver eye and head position tools have been developed to describe where certain percentages of truck drivers position there eyes and heads in various workspace arrangements. Separate equations describe the accommodation level for driver populations with male to female ratios of 50/50, 75/25, and a range from 90/10 to 95/5. These equations can be used as a design tool to locate the curves in vehicle space to describe the region behind which the given populations eyes and heads would be located. Equations and curves are provided for both the drivers eye and head in the side view. It has become increasingly apparent that there is a need for improved methods of accommodating truck drivers in heavy truck cab design. Currently, practices used in the automobile industry for passenger car design are utilized for the design of heavy trucks. These practices.

Truck driver shin-knee and stomach postion tools have been developed to describe where certain percentages of truck drivers position there knees and stomachs in various workspace arrangements. Separate equations describe the accommodation level for driver populations with male to female ratios of 50/50, 75/25, and a range from 90/10 to 95/5. These equations can be used as a design tool to locate the curves in vehicle space to describe the region behind which the given populations shin-knees, and stomachs would be located. Equations and curves are provided for both the left leg, which operates the clutch, and the right leg, which operates the accelerator.

Electro-Motive Division of GM jointly with HRL Laboratories have developed a software tool, called TechPro, which assists in troubleshooting of diesel locomotives. The tool has been tested extensively in the field for the last two years. It has improved significantly the quality of diagnosis of locomotives. The tool is based on Graphical Probabilistic Models and Case Data Bases. We will discuss the design of the tool, its performance and will show its relevance to diagnosis of automobiles.

Casting, machining and structural simulations were completed on a V8 engine block made in Compacted Graphite Iron (CGI) for use in a racing application. The casting and machining simulations generated maps of predicted tensile strength and residual stress in the block. These strength and stress maps were exported to a finite element structural model of the machined part. Assembly and operating loads were applied, and stresses due to these loads were determined. High cycle fatigue analysis was completed, and three sets of safety factors were calculated using the following conditions: uniform properties and no residual stress, predicted properties and no residual stress, and predicted properties plus residual stress.

Fully Flexible Valve Actuation (FFVA) systems provide maximum flexibility to adjust lift profiles of engine intake and exhaust valves. A research grade electro-hydraulic servo valve based FFVA system was designed to be used with an engine in a test cell to precisely follow desired lift profiles. Repetitive control was chosen as the control strategy. Crank angle instead of time is used to trigger execution to ensure repeatability. A single control is used for different engine speeds even though the period for one revolution changes with engine speeds. The paper also discusses lift profile extension, instantaneous lift profile switching capability and built-in safety features.

Free form fabrication, or rapid prototyping as it is commonly known, is the creation of a physical entity, directly from numerical description, using an additive process. The mathematical data used is typically in the form of a 3D CAD file, but it may also be obtained from a reverse engineering process. This paper presents a review of three of the leading FFF (free form fabrication) systems which are commercially available. Time constraints will allow us to describe only three of these products. Although this does not do justice to a technology where there are more than 30 different systems in various stages of development, these examples represent the vast majority of machines which are in the marketplace today.

A front suspension laboratory test procedure was developed to reproduce time-correlated fatigue damaging events from a light truck road durability test. Subsequently, the performance of front suspension systems for the GMT 400 light truck program were evaluated in terms of customer reliability. Both prototype and pilot testing, as well as computer modeling, were used in the evaluation.

During early 2005 General Motors released a newly developed ATF for the factory fill of all GM Powertrain stepped gear automatic transmissions. The new fluid provided significantly improved performance in terms of friction durability, viscosity stability, aeration and foam control and oxidation resistance. In addition, the fluid has the potential to enable improved fuel economy and extended drain intervals. Since the performance of the new fluid far exceeded that of the DEXRON®-III service fill fluids available at the time it became necessary to upgrade the DEXRON® service fill specification in order to ensure that similar fluids were available in the market for service and repair situations. This latest upgrade to the service fill specification is designated DEXRON®-VI [1].

The purpose of this paper is to provide an overview of the process of selection, development and approval of General Motors original equipment TPC passenger car tires. We have attempted to minimize detail in each specific area, but intend to provide a general comprehension of the thought processes involved and the procedures used to select the proper tire size and type for a vehicle. We will then describe the tire performance criteria involved in the overall development and approval process and will subsequently consider tire noise requirements in somewhat greater detail. The paper will conclude by describing the General Motors Tire Performance Criteria (TPC) System, which is a documentation of the General Motors Tire Performance requirements and test procedures.