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General Motors Powertrain Division has developed the next generation big block V8 engine for introduction in the 1996 model year. In addition to meeting tighter emission and on-board diagnostic legislation, this engine evolved to meet both customer requirements and competitive challenges. Starting with the proven dependability of the time tested big block V8, goals were set to substantially increase the power, torque, fuel economy and overall pleaseability of GM's large load capacity gasoline engine. The need for this new engine to meet packaging requirements in many vehicle platforms, both truck and OEM, as well as a requirement for minimal additional heat rejection over the engine being replaced, placed additional constraints on the design.

General Motors Powertrain Group (GMPTG) has developed an all new small block V8 engine, designated LS1, for introduction into the 1997 Corvette. This engine was designed to meet both customer requirements and competitive challenges while also meeting the ever increasing legislated requirements of emissions and fuel economy. This 5.7L V8 provides increased power and torque while delivering higher fuel economy. In addition, improvements in both QRD and NVH characteristics were made while meeting packaging constraints and achieving significant mass reductions.

Over the past 20 years, polyvinyl chloride (PVC) has almost replaced metal in stationary glass reveal moldings with dramatic part cost savings on cars and trucks world-wide. The process of assembly is generally simple and convenient but to replace a reveal molding can be difficult. Many times, in order to replace the molding, it may also be necessary to replace or reseal the glass. In short, PVC reveal moldings, relatively inexpensive parts, are very expensive to service. Outside of general assembly and processing issues, there are 5 variables that may cause a failure in the performance of a stationary glass reveal molding. They are as follows: material degradation, crystallization, plasticizer loss, material properties, and molded-in stress. Because of modern standard PVC formulations and the material requirements of most automotive companies, material degradation, crystallization and plasticizer loss do not commonly cause failure. Material properties and molded-in stress do.

The super-ultra-low-emission-vehicle (SULEV) non-methane organic gas (NMOG) hydrocarbon exhaust standard as legislated by the state of California LEV II regulations is 10 milligrams per mile. This requires that the associative instrumentation must be capable of accurately and precisely determining total hydrocarbons (THC) concentrations on the order of 10 parts per billion-carbon (ppbC) for vehicle tests run under optimum conditions on a bag mini-diluter (BMD) test site. The flame ionization detector (FID) is the standard instrument used in the measurement of THC. Currently, there are many instrument manufacturers that produce these types of analyzers. This paper studies the limit of detection and accuracy capabilities of one of these instruments, the Beckman 400A FID. In addition, the paper shows evidence that supports that this “state of technology” as described by this instrument, is sufficient to meet the demands of the today's most stringent, vehicle emission standards.

To cope with the conflict requirements between the stability and handling performance, and the high-order and complex vehicle-trailer plant, a model tracking method is proposed. With this approach, a feedback control is designed to “decouple” the vehicle and the trailer plant, such that each tracks a well-defined second-order reference model independently yet coordinately. A feedforward control is designed to maintain its system steady-state performance. As a result, the proposed approach not only improves the system transient responses, but also its steady-state performance. This approach further yields a simple yet analytical control derivation that provides more insight to the system dynamics.

With the revolutionary advances in computing power and software technology, the future trend of integrating design and CFD analysis software package to realize an automated design optimization has been explored in this study. The integrated process of UG, ICEMCFD, and FLUENT was accomplished using iSIGHT for vehicle Aero/Thermal applications. Process integration, CFD solution strategy, optimization algorithm and the practicality for real world problem of this process have been studied, and will be discussed in this paper. As an example of this application, the results of an underhood thermal design will be presented. The advantage of systematical and rapid design exploration is demonstrated by using this integrated process. It also shows the great potential of computer based design automation in vehicle Aero/Thermal development.

Elastomeric isolators are used in a variety of different applications to reduce noise and vibration. To use isolators effectively requires the product design and development engineer to satisfy multiple objectives, which typically include packaging restrictions, environmental criteria, limitations on motion control, load requirements, and minimum fatigue life, in addition to vibration isolation performance. An understanding of elastomeric material properties and the methods used to characterize elastomeric component behavior is necessary to achieve desired performance. Typical design criteria and functional objectives for various isolator applications, including powertrain mounts, suspension control arm bushings, shock absorber bushings, exhaust hangers, flexible couplings, cradle mounts, body mounts and vibration dampers are also discussed.

Model-based design is a collection of practices in which a system model is at the center of the development process, from requirements definition and system design to implementation and testing. This approach provides a number of benefits such as reducing development time and cost, improving product quality, and generating a more reliable final product through the use of computer models for system verification and testing. Model-based design is particularly useful in automotive control applications where ease of calibration and reliability are critical parameters. A novel application of the model-based design approach is demonstrated by The Ohio State University (OSU) student team as part of the Challenge X advanced vehicle development competition. In 2008, the team participated in the final year of the competition with a highly refined hybrid-electric vehicle (HEV) that uses a through-the-road parallel architecture.

It is well known that lining reduction through wear affects contact pressure profile and noise generation. Due to high complexity in brake noise analysis, many factors were not included in previous analyses. In this paper, a new analysis process is performed by running brake “burnishing” cycles first, followed by noise analysis. In the paper, brake lining reduction due to wear is assumed to be proportional to the applied brake pressure with ABAQUS analysis. Brake pads go through four brake application-releasing cycles until the linings settle to a more stable pressure distribution. The resulting pressure profiles show lining cupping and high pressure spots shifting. The pressure distributions are compared to TekScan measurements. Brake noise analysis is then conducted with complex eigenvalue analysis steps; the resulting stability chart is better correlated to testing when the wear is comprehended.

Brake squeal has been a persistent quality issue for automobile OEMs and brake system suppliers. The ability to model and measure brake squeal dynamics is of utmost importance in brake squeal reduction efforts. However, due to the complex nature of brake squeal and the wide frequency range in which it occurs, it is difficult to accurately correlate and update analytical models to experimental results. This paper introduces a systematic and rigorous correlation and updating process that yields FE models, which can accurately reproduce high-frequency brake squeal dynamics.

This paper presents a project that was done to solve an integration problem between a brake system and a cruise control system on a GM vehicle program, each of which was supplied by a different supplier. This paper presents how the problem was resolved using a CAE tool which was a combination of formulated MS/Excel spreadsheet, Overdrive (GM internal code), and iSIGHT of Engineous Software Inc, which is a process integrator and process automator. A sensitivity study of system reliability was conducted using iSIGHT. The most sensitive factor was found through the sensitivity study. Thereafter, a Robust design was obtained. The recommended Robust Design was implemented in the vehicle program, which led to a substantial cost saving. The CAE software tool (the combination) developed through the problem solving process will be used to ensure quality of brake and cruise system performance for future vehicle programs.

Achieving optimum results and developing systems that are towards production intent is a challenge that the General Motors Sequel platform not only overcame, but also enhanced by providing an opportunity to achieve maximum integration of new technologies. Implementation of these new technologies during this project enabled us to understand the impact and rollout for future production programs to enhance performance and add features that will enable General Motors to make quantum leaps in the automotive industry. Presented are aspects, objectives and features of the Sequel's advanced Brake-By-Wire system as it migrates from concept towards production readiness. Also included in the paper are the objectives for system design; functional/performance requirements and the desired fault tolerance. The system design, component layout, control and electrical system architecture overviews are provided.

Appropriate road noise levels are critical to perceived quality in today's highly competitive automotive industry. Tire noise is often one of the dominant sources. In order to provide effective noise control schemes it is imperative to fully define the noise paths. In this paper, a case study of an experimental lab method is presented that allows definitive understanding of the structure-borne and airborne spectral contributions of tire noise. For this study, interior noise data were collected using a 10 ft road wheel. Data were collected for the front and rear tires. These measurements contained both the structure-borne and airborne contributions. The same test was performed with the tire physically disconnected from the vehicle structure. This measurement contained only the airborne contribution. The structure-borne contribution was then calculated as the difference in noise levels between the two cases.

Mechanical Efficiency of toroidal traction drives is the key parameter for transmission engineers worldwide to accept their use in continuously variable transmissions. In this work, the traction drive efficiencies are investigated analytically as well as experimentally as a function of speed, torque, speed ratio and temperature for two different CVU's. In addition, creep at the traction contact is measured and compared with the prediction of the simulation model. In a stand-alone test rig, the drag torque associated with the power-roller thrust bearing is also measured.

The Experimental Safety Vehicle program in General Motors was a study in meeting the Department of Transportation performance requirements, with the sole objective being to meet or exceed all of the contract specifications. This vehicle was not intended for production; it was a safety idea car with many unique features including a four-wheel, anti-lock disc brake system using a hydraulic power brake system with an electro-hydraulic back-up system. In addition, the design of the dual piston caliper for the disc brakes provides a redundant system thereby minimizing the effect of a single line or hose failure. This feature coupled with the redundant back-up power brake system provided performance under various failed conditions approximately equal to the original effectiveness with only a slight increase in pedal effort. This brake system, developed for the ESV, satisfied the General Motors performance objectives, and equaled or surpassed the contract requirements of the ESV program.

By adapting vehicle control systems to the skill level of the driver, the overall vehicle active safety provided to the driver can be further enhanced for the existing active vehicle controls, such as ABS, Traction Control, Vehicle Stability Enhancement Systems. As a follow-up to the feasibility study in [1], this paper provides some recent results on data-driven driving skill characterization. In particular, the paper presents an enhancement of discriminant features, the comparison of three different learning algorithms for recognizer design, and the performance enhancement with decision fusion. The paper concludes with the discussions of the experimental results and some of the future work.

Impact Harshness and Impact Shake are two related aspects of ride performance. Vehicle designs often need to meet the conflicting requirements between these two performance areas. The fundamental dynamics and general effect of vehicle and suspension design parameters need to be understood to reduce the cost and time associated with early vehicle development and ensure built-in quality. This study investigates the influence of the parameters in suspension and tire wheel systems on each of the performance metrics. Attempts are made to rank-order the relative sensitivity of each parameter on each of the metrics and propose approaches to improve ride quality.

Full-load operation of a small-displacement spark-ignition direct-injection (SIDI) engine was thoroughly investigated by means of computational analysis and engine measurements. The performance is affected by many different factors, which can be grouped as those pertaining to volumetric efficiency, to mixing and stratification, and to system issues, respectively. Volumetric efficiency is affected by flow losses, tuning and charge cooling. Charge cooling due to spray vaporization is often touted as the most significant benefit of direct-injection on full-load performance. However, if wall wetting occurs, this benefit may be completely negated or even reversed. The fuel-air mixing is strongly affected by the injection timing and characteristics at lower engine speeds, while at higher engine speeds the intake flow dominates the transport of fuel particles and resultant vapor distribution. A higher injector flow rate enhances mixing especially at higher engine speeds.

Sport Utility Vehicles (SUV) and light duty trucks have gained in popularity for the last several years and the demand for more car-like behavior has increased, accordingly. Two areas for potential improvement are vehicle stability and maneuverability while parking. 4WS (4 wheel steering system) is known as an effective solution to stability and low speed maneuverability. In this paper, we identify a new systematic design method of two degree of freedom vehicle state feedback control algorithm that can improve vehicle stability, and show its control effects for a SUV with trailer towing. Low speed maneuvering is improved when the rear tires are steered in negative phase relative to the front tires. However with a large rear steer angle at low speed, the vehicle's rear overhang tracks a wider swing-out path than a 2WS vehicle. For this concern, we propose a new swing-out reduction control algorithm.

Steer-by-wire systems (SBW) offer the potential to enhance steering functionality by enabling features such as automatic lane keeping, park assist, variable steer ratio, and advanced vehicle dynamics control. The lack of a steering intermediate shaft significantly enhances vehicle architectural flexibility. These potential benefits led GM to include steer-by-wire technology in its next generation fuel cell demonstration vehicle, called “Sequel.” The Sequel's steer-by-wire system consists of front and rear electromechanical actuators, a torque feedback emulator for the steering wheel, and a distributed electronic control system. Redundancy of sensors, actuators, controllers, and power allows the system to be fault-tolerant. Control is provided by multiple ECU's that are linked by a fault-tolerant communication system called FlexRay. In this paper, we describe the objectives for fault tolerance and performance that were established for the Sequel.