Search Results

We propose a composite thermal model of the vehicle passenger compartment that can be used to predict and analyze thermal comfort of the occupants of a vehicle. Physical model is developed using heat flow in and out of the passenger compartment space, comprised of glasses, roof, seats, dashboard, etc. Use of a model under a wide variety of test conditions have shown high sensitivity of compartment air temperature to changes in the outside air temperature, solar heat load, temperature and mass flow of duct outlet air from the climate control system of a vehicle. Use of this model has subsequently reduced empiricism and extensive experimental tests for design and tuning of the automatic climate control system. Simulation of the model allowed several changes to the designs well before the prototype hardware is available.

A relationship between the risk of significant thoracic injury (AIS ≥ 3) and Hybrid III dummy sternal deflection for shoulder belt loading is developed. This relationship is based on an analysis of the Association Peugeot-Renault accident data of 386 occupants who were restrained by three-point belt systems that used a shoulder belt with a force-limiting element. For 342 of these occupants, the magnitude of the shoulder belt force could be estimated with various degrees of certainty from the amount of force-limiting band ripping. Hyge sled tests were conducted with a Hybrid III dummy to reproduce the various degrees of band tearing. The resulting Hybrid III sternal deflections were correlated to the frequencies of AIS ≥ 3 thoracic injury observed for similar band tearing in the field accident data. This analysis indicates that for shoulder belt loading a Hybrid III sternal deflection of 50 mm corresponds to a 40 to 50% risk of an AIS ≥ 3 thoracic injury.

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.

Although rollover crashes represent a small fraction (approximately 3%) of all motor vehicle crashes, they account for roughly one quarter of crash fatalities to occupants of cars, light trucks, and vans (NHTSA Traffic Safety Facts, 2004). Therefore, the National Highway Traffic Safety Administration (NHTSA) has identified rollover injuries as one of its safety priorities. Motor vehicle manufacturers are developing technologies to reduce the risk of injury associated with rollover collisions. This paper describes the development by General Motors Corporation (GM) of a suite of laboratory tests that can be used to develop sensors that can deploy occupant protection devices like roof rail side air bags and pretensioners in a rollover as well as a discussion of the challenges of conducting this suite of tests.

The Auto/Steel Partnership established the Light Truck Frame Project Group in 1996 with two objectives: (a) to develop materials, design and fabrication knowledge that would enable the frames on North American OEM (original equipment manufacturer) light trucks to be reduced in weight, and (b) to improve corrosion resistance of frames on these vehicles, thereby allowing a reduction in the thickness of the components and a reduction in frame weight. To address the issues relating to corrosion, a subgroup of the Light Truck Frame Project Group was formed. The group comprised representatives from the North American automotive companies, test laboratories, frame manufacturers, and steel producers. As part of a comprehensive test program, the Corrosion Subgroup has completed tests on frame coatings. Using coated panels of a low carbon hot rolled and pickled steel sheet and two types of accelerated cyclic corrosion tests, seven frame coatings were tested for corrosion performance.

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.

By design, frontal New Car Assessment Program (NCAP) tests focus on a narrow portion of the spectrum of field crash events. A simple, high level parsing of towaway crashes from NHTSA's National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) files shows that only a small fraction of occupants (but a somewhat larger portion of their harm as measured by ISS) find themselves in crash circumstances remotely similar to NCAP crash conditions. Looking only at seat location, area of damage, direction of force, distribution of damage, and estimated delta-V filters significantly restricts the relevance of NCAP even before critical factors like belt use and vehicle crash partner are considered. Given the limited scope of frontal NCAP it should not be surprising that it has limited usefulness in discriminating among various vehicles' overall performance in the field.

Many traffic collisions are the result of the driver's failure to notice the other vehicle. It is often cited in police reports that the driver "looked but did not see.'' The purpose of Daytime Running Lights (DRLs) is to increase the visual contrast of DRL-equipped vehicles. Visual contrast, which is the difference in brightness between two areas, is an important characteristic enabling a driver to detect objects. This paper begins with a brief regulatory history of DRLs in the U.S. and how General Motors Corporation (GM) introduced DRL-equipped vehicles. It also describes a DRL effectiveness study conducted by Exponent Failure Analysis Associates of San Francisco for General Motors Corporation. The study compared the collision rates of specific General Motors Corporation, Saab, Volvo and Volkswagen vehicles before and immediately after the introduction of DRLs. Since DRLs are not visible from behind a vehicle, rear-end collisions were not included in the study.

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.

For model year 2003, the General Motors Corporation is introducing new medium duty trucks - the Chevrolet Kodiak and GMC TopKick. These new trucks replace the previous versions of the Kodiak and TopKick medium duty trucks that were introduced in 1989 and the Chevrolet and GMC 3500HD that debuted in the 1991 model year. This new series of trucks marks a clear change in General Motors' strategy in the medium duty marketplace. It emphasizes General Motors' strong commitment to the medium duty market, as well as a strong focus on customer needs, vehicle quality and reliability. This paper describes the General Motors strategy in the medium duty market, along with the history of the design and development of these new products. Finally, this paper will discuss performance to program objectives.

Airbag systems have been part of passenger car and truck programs since the mid-1980's. However, systems designed for medium and heavy duty truck applications are relatively new. The release of airbag systems for medium duty truck has provided some unique challenges, especially for the airbag sensing systems. Because of the many commercial applications within the medium duty market, the diversity of the sensing environments must be considered when designing and calibrating the airbag sensing system. The 2003 Chevrolet Kodiak and GMC TopKick airbag sensing development included significant work, not only on the development of airbag deployment events but also non-deployment events – events which do not require the airbag to deploy. This paper describes the process used to develop the airbag sensing system deployment events and non-deployment event used in the airbag sensing system calibration.

The Body Division of the Automotive Corrosion and Prevention Committee of SAE (ACAP) has conducted biannual surveys of automotive body corrosion in the Detroit area since 1985. The purpose of these surveys is to track industry-wide corrosion protection improvements and to make this information available for public consumption. The survey consists of a closed car parking lot survey checking for perforations, blisters, and surface rust. This paper reports the results of the seven surveys conducted since 1985.

Allison Gas Turbine Division of General Motors is performing the first phase of a multiphase development project aimed at demonstrating an electric vehicle based on a proton exchange membrane (PEM) fuel cell. This work is sponsored by the Office of Transportation Technologies of the U.S. Department of Energy (DoE) through the DoE's Chicago Field Office (Contract No. DE-AC02-90CH10435). This work complements major efforts under way to produce electric vehicles for reducing pollution in key urban areas. Battery powered vehicles will initially satisfy niche markets where limited range vehicles can meet commuter needs. The PEM fuel cell/battery hybrid using methanol as fuel potentially offers an extremely attractive option to increasing the range, payload, and/or performance of battery powered vehicles.

A detailed description of the oxidative stability of GM's DEXRON®-VI Factory Fill Automatic Transmission Fluid (ATF) is provided, which can be integrated into a working algorithm to estimate the end of useful oxidative life of the fluid. As described previously, an algorithm to determine the end of useful life of an automatic transmission fluid exists and is composed of two simultaneous counters, one monitoring bulk oxidation and the other monitoring friction degradation [1]. When either the bulk oxidation model or the friction model reach the specified limit, a signal can be triggered to alert the driver that an ATF change is required. The data presented in this report can be used to develop the bulk oxidation model. The bulk oxidation model is built from a large series of bench oxidation tests. These data can also be used independent of a vehicle to show the relative oxidation resistance of this fluid, at various temperatures, compared to other common lubricants.

In this paper, the concept of ridedown analysis is extended to provide the total occupant energy and ridedown energy as functions of time. The difference between the total occupant energy and the energy absorbed by the front structure represents the energy which is dissipated by deforming the components of the restraint system. This analysis allows an improved understanding of the restraint system as a whole, and how its components interact with each other and with the front structure of the car to dissipate the occupant's energy throughout the crash event.

A driving simulator development project at the Systems Engineering and Technical Process Center (SE/TP) is exploring the role of driving simulation in the vehicle design process. The simulator provides two vehicle mockup testing arenas that support a wide field of view, computer-generated image of the road scene which dynamically responds to driver commands as a function of programmable vehicle model parameters. Two unique aspects of the simulator are the fast 65 ms response time and low incidence rate of simulator induced syndrome (about 5%). Preliminary model validation results and data comparing driver performance in a vehicle vs. the simulator indicate accurate handling response dynamics within the on-center handling region (<0.3g lateral acceleration). Applications have included supporting the development of new steering system concepts, as well as evaluating the usability of vehicle controls and displays.

An objective, biomechanically based assessment is made of the risks of life-threatening brain injury of frontal crash test results. Published 15 ms HIC values for driver and right front passenger dummies of frontal barrier crash tests conducted by Transport Canada and NHTSA are analyzed using the brain injury risk curve of Prasad and Mertz. Ninety-four percent of the occupants involved in the 30 mph, frontal barrier compliance tests had risks of life-threatening brain injury less than 5 percent. Only 3 percent had risks greater than 16 percent which corresponds to 15 ms HIC > 1000. For belt restrained occupants without head contact with the interior, the risks of life-threatening brain injury were less than 2 percent. In contrast, for the more severe NCAP test condition, 27 percent of the drivers and 21 percent of the passengers had life-threatening brain injury risks greater than 16 percent.

Since 1985, the Body Division of the Automotive Corrosion and Prevention Committee of SAE (ACAP) has conducted biannual surveys of automotive body corrosion in the Detroit area. The purpose of these surveys is to track industry wide corrosion protection improvements and to make this information available for public consumption. The survey consists of a closed car parking lot survey checking for perforations, blisters, and surface rust. This paper reports the results of the five surveys conducted to date.

The dilemma of using a shoulder belt force limiter with a 3-point belt system is selecting a limit load that will balance the reduced risk of significant thoracic injury due to the shoulder belt loading of the chest against the increased risk of significant head injury due to the greater upper torso motion allowed by the shoulder belt load limiter. However, with the use of air bags, this dilemma is more manageable since it only occurs for non-deploy accidents where the risk of significant head injury is low even for the unbelted occupant. A study was done using a validated occupant dynamics model of the Hybrid III dummy to investigate the effects that a prescribed set of shoulder belt force limits had on head and thoracic responses for 48 and 56 km/h barrier simulations with driver air bag deployment and for threshold crash severity simulations with no air bag deployment.

This study assembled a database of anatomic dimensions of Indy Car drivers and developed procedures that can be used as models for future compilations of anatomic data from specialized populations. The database defines the body configuration for the Indy Car driver population and indicates that the current HYBRID III, midsize male crash dummy will provide a reasonable approximation of that population if used in investigations involving issues of crash protection. This study took advantage of a unique opportunity to assemble an anthropometric database from a specialized population which was compared to an existing database collected from a comparable sub-set of the United States population.