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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.

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.

Brake caliper and corner behavior in the off-brake condition can lead, at times, to brake system performance issues such as residual drag (and related issues such as pulsation, judder, and loss of fuel economy), and caliper pryback during aggressive driving maneuvers. The dynamics in the brake corner can be strikingly complex, with numerous friction interfaces, rubber component and grease dynamics, deflections of multiple components, and significant dependence on usage conditions. Displacements of moving parts are usually small, and the residual forces in the caliper interfaces involved are also small in comparison with other forces acting on the same components, making direct observation very difficult. The present work attempts to illuminate off-brake behavior in two different conditions - residual drag and pryback - through the use of low-range pressure distribution sensors placed in between the caliper (pistons and fingers) and the brake pad pressure plates.

In response to the TREAD act of 2002, ASTM F09.30 Aged Tire Durability Task Group was formed with the objective of developing a scientifically valid, short duration aged durability test which correlates to field behavior. The target end-of-test condition was belt edge separation (or related damage). One strategy, driven by that objective, has been a steady state design of experiment investigating aging temperature and duration as well as roadwheel speed, pressure and deflection. The rationale behind investigating a steady state test and selecting these parameters and methodology for setting their initial values is reviewed.

In the work leading to the TREAD Act, some members of Congress expressed the need for some type of aging test on light vehicle tires. Since no industry-wide recommended practice existed, the ASTM F09.30 Aged Tire Durability task group was established in 2002 to develop a scientifically valid, short duration, laboratory aged tire durability test which correlates to in-service aging. The target end-of-test condition was belt edge separation (or related tire conditions). One strategy, driven by that objective, has been a Steady State DOE investigating aging temperature and duration, as well as, roadwheel speed, pressure and deflection. Testing was performed on three tire types, including two where relevant field aging data was publicly available from NHTSA studies. A region of interest, within the design space, was identified where target end-of-test conditions were possible and undesirable (non-target or non-representative of those seen in consumer use) were avoided.

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.

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.

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].

A numerical simulation of the flow structure around an idealized automotive A-pillar rain-gutter and the sound radiated from it is reported. The idealized rain-gutter is an infinitesimally thin backward facing elbow mounted on a flat plate. It is kept in a virtual wind-tunnel with rectangular cross-section. The transient flow structure around the rain-gutter is described and time-averaged pressure distribution along the base plate is provided. Time-varying static pressure was recorded on every grid point on the base-plate as well as the rain-gutter surfaces and used to calculate sound pressure signal at a microphone held above the rain-gutter using the Ffowcs-Williams-Hawkings (FWH) integral method was used for calculating sound propagation. Both the transient flow simulation as well as the FWH sound calculation were performed using the commercial CFD code FLUENT6.1.22.

The goal of this study is to assess the total Life Cycle Global Warming Impact of the current HFC-134a (R134a) refrigeration system and compare it with the effect of proposed alternatives, HFC-134a Enhanced, HFC-152 (R152a), R744, R744 Enhanced and R290, based on life cycle analysis (LCA). The enhanced systems include control strategies to elevate the compressor suction pressure as the evaporator load is reduced. The hydrofluorocarbons HFC-134a and HFC-152a are greenhouse gases (GHGs) and are subject to the Kyoto Protocol timetables, which when the treaty takes effect will require participating developed countries to reduce their overall CO2 equivalent emissions of six GHGs by at least 5% by 2012 from 1990 levels.

This pager documents a one shift (10 hour) wind tunnel test program conducted on a Corvette C5 prepared for Sports Car Club of America (S.C.C.A.) World Challenge racing. The testing was conducted at the Canadian National Research Center in Ottawa, Canada. Specific areas of test included front fascia and under tray, rear air discharge, rear wing configuration and angle, B-pillar configuration, and ride height. Standard wind tunnel test procedures were followed. In total twenty-six separate configurations were evaluated. Data for front and rear lift, total drag, and lift/drag (L/D) ratio are provided for each test configuration. The cumulative effects of the aerodynamic changes evaluated in this program, calculated at 192 KPH (120 MPH), increased front down force by 318 N (72 Lb.), and rear down force by 770 N (173 Lb.). Lift/drag ratio was improved from -0.597 to -1.016. These changes increased total drag by 381 N (86 Lb.).

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.

Reducing the high cost of hardware testing with analytical methods has been highly accelerated in the automotive industry. This paper discusses an analytical model to simulate the driveline bending integrity test for the longitudinal 4WD-driveline configuration. The dynamic stresses produced in the adapter/transfer case and propeller shaft can be predicted analytically using this model. Particularly, when the 4WD powertrain experiences its structural bending during the operation speed and the propeller shaft experiences the critical whirl motion and its structural bending due to the inherent imbalance. For a 4WD-Powertrain application, the dynamic coupling effect of a flexible powertrain with a flexible propeller shaft is significant and demonstrated in this paper. Three major subsystems are modeled in this analytical model, namely the powertrain, the final rear drive, and the propeller shafts.

In order to engineer Squeak & Rattle (S&R) free vehicles it is essential to develop an objective measurement method to compare and correlate with customer satisfaction and subjective S&R assessments. Three methods for exciting S&Rs -type surfaces. Excitation methods evaluated were road tests over S&R surfaces, road simulators, and direct body excitation (DBE). The principle of DBE involves using electromagnetic shakers to induce controlled, road-measured vibration into the body, bypassing the tire patch and suspension. DBE is a promising technology for making objective measurements because it is extremely quiet (test equipment noise does not mask S&Rs), while meeting other project goals. While DBE is limited in exposing S&Rs caused by body twist and suspension noises, advantages include higher frequency energy owing to electro-dynamic shakers, continuous random excitation, lower capital cost, mobility, and safety.

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.

The bulge test in hydroforming is a simple fundamental experiment used to obtain basic knowledge in tube expansion. The results can be used to assist design and manufacturing of hydroformed automotive parts. It also can be used to develop a failure criterion for tubes in hydroforming. For these purposes, a section of a long unsupported tube with fixed ends was simulated numerically to obtain the mechanical states of the tube subjected to internal pressure. Steel and aluminum tubes are used. For the bulge tests, the internal pressure reaches a maximum and then decreases in value without failure while the stress, strain and volume of the tube keep increasing. A failure criterion for the bursting of a tube is proposed based on the stress-strain curve of the material.

The work presented here builds on the practical and effective spot weld fatigue life prediction method, the structural stress method (SSM), that was developed at Stanford University. Constant amplitude loading tests for various spot weld joint configurations have been conducted and the SSM has been shown to accurately predict fatigue life. In this paper refinements to the structural stress approach are first presented, including a variable amplitude fatigue life prediction method based on the SSM and Palmgren-Miner's rule. A test matrix was designed to study the fatigue behavior of spot welds under tensile shear loading conditions. Constant amplitude tests under different R-ratios were performed first to obtain the necessary material properties. Variable amplitude tests were then performed for specimens containing single and multiple welds.

The development of systems and components for control of exterior noise has traditionally been done through an iterative process of on road testing. Frequently, road testing of vehicle modifications are delayed due to ambient environmental changes that prevent testing. Vehicle dynamometers used for powertrain development often had limited space preventing far field measurements. Recently, several European vehicle manufacturers constructed facilities that provided adequate space for simulation of the road test. This paper describes the first implementation of that technology in the U.S.. The facility is typical of those used world wide, but it is important to recognize some of the challenges to effective utilization of the technique to correlate this measurement to on road certification.

This paper describes the methodology used to achieve optimum aerodynamic performance of the 1992 through 1995 Oldsmobile Cutlass Supreme IMSA GT race car and will demonstrate the continuous improvements successfully used to respond to rule changes and competition. The concerted effort by the sanctioning body to limit the aerodynamic performance of IMSA GT race cars for the 1995 season required a rigorous wind tunnel test program backed by track validation to maintain the necessary aerodynamic balance, cooling flows, engine induction flow, and overall competitive parity. The specific modifications that were evaluated to accommodate these rules changes will be detailed in this paper. Special test methodologies developed to better understand specific aerodynamics questions such as the effects of vehicle attitude, internal cooling flows, underbody treatments, and engine air inlet performance will also be discussed.

The function of the inlet header of a catalytic converter is to diffuse the inlet exhaust flow, decreasing its velocity and increasing its static pressure with as little loss in total pressure as possible. In practice, very little diffusion takes place in most catalytic converter inlet headers because the flow separates at the interface of the pipe and the tapered section leading to the substrate. This leads to increased converter pressure loss and flow maldistribution. An improved inlet-header design called the Enhanced Diffusion Header (EDH) was developed which combines a short, shallow-angle diffuser with a more abrupt expansion to the substrate cross section. Tests conducted in room air (cold flow) and engine exhaust showed that improved inlet-jet diffusion leads to substantial reductions in converter restriction. EDH performance was not compromised by the presence of a right-angle bend upstream of the converter.