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A multi vector design tool to accurately predict instrument panel obscuration was developed to insure that critical legal displays in vehicles are not obscured. The concept provides for a computer generated light source shaped to replicate the human eyes. The light source is then projected onto a 3D math based arrangement and the resultant shadows are visible on the instrument panel surface and its displays. Design studios require criteria for the placement of the instrument cluster gages and displays, various controls, switches, and steering column stalks before an interior theme can be completed. Therefore, instrument panel obscuration and visibility must be determined early in the design process. The obscured areas are a function of the instrument panel surface, steering wheel rim, hub, spokes, and the location of the driver's eyes. This light source method allows engineers and designers the ability to quickly determine obscured areas.

e-Thermal is a vehicle level thermal analysis tool developed by General Motors to simulate the transient performance of the entire vehicle HVAC and Powertrain cooling system. It is currently in widespread (global) use across GM. This paper discusses the details of the air-conditioning module of e-Thermal. Most of the literature available on transient modeling of the air conditioning systems is based on finite difference approach that require large simulation times. This has been overcome by appropriately modeling the components using Sinda/Fluint. The basic components of automotive air conditioning system, evaporator, condenser, compressor and expansion valve, are parametrically modeled in Sinda/Fluint. For each component, physical characteristics and performance data is collected in form of component data standards. This performance data is used to curve fit parameters that then reproduce the component performance.

This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called “e-Thermal” was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling …) is introduced. Model data requirements and GM's strategy for acquiring component data are also described.

The wear test introduced in this paper can be used to determine and rank PV (pressure time velocity) capability of plastic materials for applications where a plastic part is rotating or reciprocating against a metal surface. It provides an accelerated test method to evaluate the wear performance of plastic materials. A single test can provide tribological information at multiple PV conditions. The tribological information obtained from this method includes coefficient of friction, PV (pressure times velocity) limits, and interface temperature profile. This test is currently used by General Motors Corporation to develop plastic materials for transmission thrust washer and dynamic seal applications. The test is running in two sequences (A & B), capable of a PV range from 50,000 psi-ft/min 500,000 psi-ft/min, under dry conditions. The PV steps in sequence A are combinations of high pressure and low velocity - for applications where high loads are expected, such as thrust washers.

The strong focus on reducing brake drag, driven by a historic ramp-up in global fuel economy and carbon emissions standards, has led to renewed research on brake caliper drag behaviors and how to measure them. However, with the increased knowledge of the range of drag behaviors that a caliper can exhibit comes a particularly vexing problem - how should this complex range of behaviors be represented in the overall road load of the vehicle? What conditions are encountered during coastdown and fuel economy testing, and how should brake drag be measured and represented in these conditions? With the Environmental Protection Agency (amongst other regulating agencies around the world) conducting audit testing, and the requirement that published road load values be repeatable within a specified range during these audits, the importance of answering these questions accurately is elevated. This paper studies these questions, and even offers methodology for addressing them.

Consumer expectations for automated vehicle operations such as automatic locking, remote ignition control, navigation, and entertainment are primary drivers for the increasing complexity of embedded automotive electronics modules. The prevalent practice for procuring these modules is to develop a written behavioral specification that is then used by an outside supplier to build and test the module. Validation test plans are written separately based on an understanding of the requirements. The challenges posed by the current practice include the inability to completely specify the expected behavior in a timely manner, the need to balance the design between low cost and new features demanded by the customer, and ensuring that the product exactly implements the specified behavior. Moreover, vehicle manufacturers desire the ability to explore sensitivity of specifications by identifying constraints on the system and assessing the product for ease of implementation.

Crash-test-data on local longitudinal and shear stiffness of the vehicle front is needed to estimate impact severity from car deformation in offset or pole impacts, and to predict vehicle acceleration and compartment intrusion in car-to-car crashes. Repeated full frontal crash-tests were carried out with a load-cell barrier to determine the local longitudinal stiffness with increasing crush. Repeated off-set tests were run to determine shear stiffness. Two single high-speed tests (full frontal and offset) were carried out and compared to the repeated tests to determine the rate sensitivity of the front structure. Four repetitions at 33.4 km/h provided equivalent energy absorption to a single 66.7 km/h test, when rebound was considered. Power-train inertial effects were estimated from highspeed tests with and without power-train. Speed effects averaged 2% per [m/s] for crush up to power-train impact, and post-crash measurements were a reasonable estimate of front-structure stiffness.

Injury risk curves for SID-IIs thorax and abdomen rib deflections proposed for future NCAP side impact evaluations were developed from tests conducted with the SID-IIs FRG. Since the floating rib guide is known to reduce the magnitude of the peak rib deflections, injury risk curves developed from SID-IIs FRG data are not appropriate for use with SID-IIs build level D. PMHS injury data from three series of sled tests and one series of whole-body drop tests are paired with thoracic rib deflections from equivalent tests with SID-IIs build level D. Where possible, the rib deflections of SID-IIs build level D were scaled to adjust for differences in impact velocity between the PMHS and SID-IIs tests. Injury risk curves developed by the Mertz-Weber modified median rank method are presented and compared to risk curves developed by other parametric and non-parametric methods.

The US Environmental Protection Agency (EPA)’s heavy duty diesel emission standard was tightened beginning from 2007 with the introduction of ultra-low-sulfur diesel fuel. Most heavy duty diesel applications were required to equip Particulate Matter (PM) after-treatment systems to meet the new tighter, emission standard. Systems utilizing Diesel Oxidation Catalyst (DOC) and Catalyzed-Diesel Particulate Filter (DPF) are a mainstream of modern diesel PM after-treatment systems. To ensure appropriate performance of the system, periodic cleaning of the PM trapped in DPF by its oxidation (a process called “regeneration”) is necessary. As a result, of this regeneration, DOC’s and DPF’s can be exposed to hundreds of thermal cycles during their lifetime. Therefore, to understand the thermo-mechanical performance of the DOC and DPF is an essential issue to evaluate the durability of the system.

A new generation Northstar DOHC V8 engine has been developed for a new family of rear-wheel-drive (RWD) Cadillac vehicles. The new longitudinal engine architecture includes strategically selected technologies to enable a higher level of performance and refinement. These technologies include four-cam continuously variable valve timing, low restriction intake and exhaust manifolds and cylinder head ports, a steel crankshaft, electronic throttle control, and close-coupled catalysts. Additional design features beyond those required for RWD include optimized block ribbing, improved coolant flow, and a newly developed lubrication and ventilation system for high-speed operation and high lateral acceleration. This new design results in improved performance over the entire operating range, lower emissions, improved fuel economy, improved operating refinement, and reduced noise/vibration/harshness (NVH).

A key element of General Motors' Advanced Propulsion Technology Strategy is the electrification of the automobile. The objectives of this strategy are reduced fuel consumption, reduced emissions and increased energy security/diversification. The introduction of hybrid vehicles was one of the first steps as a result of this strategy. To determine future opportunities and direction, an extensive study was completed to better understand the ability of Plug-in Hybrid Electric Vehicles (PHEV) and Extended-Range Electric Vehicles (E-REV) to address societal challenges. The study evaluated real world representative driving datasets to understand actual vehicle usage. Vehicle simulations were conducted to evaluate the merits of PHEV and E-REV configurations. As derivatives of conventional full hybrids, PHEVs have the potential to deliver a significant reduction in petroleum usage.

Reducing Carbon Dioxide (CO2) emissions is one of the major challenges for automobile manufacturers. This is driven by environmental, consumer, and regulatory demands in all major regions worldwide. For conventional vehicles, a host of technologies have been applied that improve the overall efficiency of the vehicle. This reduces CO2 contributions by directly reducing the amount of energy consumed to power a vehicle. The hybrid electric vehicle (HEV) continues this trend. However, there are limits to CO2 reduction due to improvements in efficiency alone. Other major improvements are realized when the CO2 content of the energy used to motivate vehicles is reduced. With the introduction of Extended Range Electric Vehicles (E-REVs) and Plug-in HEVs (PHEVs), electric grid energy displaces petroleum. This enables the potential for significant CO2 reductions as the CO2 per unit of electrical energy is reduced over time with the improving mix of energy sources for the electrical grid.

Tensile measurements and fracture surface analysis of low carbon heat-treated boron steel are reported. Tensile coupons were quasi-statically deformed to fracture in a miniature tensile testing stage with custom data acquisition software. Strain contours were computed via a digital image correlation method that allowed placement of a digital strain gage in the necking region. True stress-true strain data corresponding to the standard tensile testing method are presented for comparison with previous measurements. Fracture surfaces were examined using scanning electron microscopy and the deformation mechanisms were identified.

Well-to-Wheels analyses are important tools that provide a rigorous examination and quantify the environmental burdens associated with fuel production and fuel consumption during the vehicle use phase. Such assessments integrate the results obtained from the Well-to-Tank (WtT) and the Tank-to-Wheels (TtW) analysis components. The purpose of this study is to provide a preliminary Tank-to-Wheels assessment of the benefits associated with the introduction of alternative powertrains and fuels in the Chinese market by the year 2015 as compared to the results obtained with conventional internal combustion engine vehicles (ICEVs). An emphasis is given on the vehicles powered by those fuels that have the potential to play a major role in the Chinese auto-sector, such as: M10, M85, E10, E85, Di-methyl Ether (DME) and Coal-to-Liquids (CTL). An important conclusion of this report is that hybridization reduces fuel consumption in all propulsion systems.

An advanced variable valve actuation (VVA) system is characterized following end-of-life testing to enable fuel economy solutions for passenger car applications. The system consists of a switching roller finger follower (SRFF) combined with a dual feed hydraulic lash adjuster and an oil control valve that are integrated into a four cylinder gasoline engine. The SRFF provides discrete valve lift capability on the intake valves. The motivation for designing this type of VVA system is targeted to improve fuel economy by reducing the air pumping losses during part load engine operation. This paper addresses the durability of a SRFF for meeting passenger car durability requirements. Extensive durability tests were conducted for high speed, low speed, switching, and cold start operation. High engine speed test results show stable valvetrain dynamics above 7000 engine rpm. System wear requirements met end-of-life criteria for the switching, sliding, rolling and torsion spring interfaces.

This paper presents the new techniques/methods being used for the rapid vehicle development and system level performance assessment. It consists of two parts: the first part presents the automated multilevel substructuring (AMLS) technique, which greatly reduces the computational demands of larger finite element models with millions of degrees of freedom(DOF) and extends the capabilities to higher frequencies and higher level of accuracy; the second part is on the superelement in conjunction with the Component Mode Synthesis (CMS) and also Automated Component Mode Synthesis (ACMS) techniques. In superelement, a full vehicle model is divided into components such as Body-in-white, Front cradle/chassis, Rear cradle/chassis, Exhaust, Engine, Transmission, Driveline, Front suspension, Rear suspension, Brake, Seats, Instrument panel, Steering system, tires, etc. with each piece represented by reduced stiffness, mass, and damping matrices.

Power-hop is a self-excited and potential locally unstable torsional vibration of a vehicle's driveline, caused by stick and slip of the tire. It is especially prevalent in high-powered cars and trucks, under heavy acceleration. Torque arms have been used to reduce power-hop for many solid axle suspension vehicles, mostly trucks and old rear wheel drive sports cars. It has long been known that the shortest torque arm easily reduces power-hop, but will increase hop under braking (braking-hop). The fundamental mechanism of torque arm effects on solid axle suspension vehicles, however, has not yet been fully explained. This study explains the stability of solid axle, torque arm suspension vehicles under heavy acceleration and braking. Analytical techniques utilize conventional linear analysis and a non-linear coupling force in a 4 degree of freedom dynamic model.

Model-based design and development is emerging in the automotive industry, largely revealing its popularity in chassis control systems [1]. Although it is an efficient and accepted design tool for chassis systems, proper processes and strategies need to be in place to ensure the integrity and correctness of the production software. This paper describes software testing strategies for complex chassis control systems in a model-based environment. In detail, it highlights various testing methods for different phases, such as unit testing and integration testing. It will also address issues and challenges that were faced with each method and propose possible solutions.

Under the initiative of the United States Council for Automotive Research LLC (USCAR§) Transmission Working Group, a collaborative effort was made with LuK USA LLC to study the influence of the friction interface parameters on the shudder durability of a wet launch clutch. A test bench was designed. Clutch configurations with different combinations of four friction materials (A, B, C and D), three groove patterns (waffle, radial and waffle–parallel) and two separator plate conditions (nitrided and non–nitrided) were considered. Considerable improvement in performance was seen by changing from CVT fluid* to DCT fluid*. A thermal analysis based on thermal model predictions and measurement correlations was conducted. Comparisons of clutch configurations with four and five friction plates were done. The waffle and radial groove pattern showed better heat transfer than the waffle–parallel groove pattern.

The staircase fatigue test method is a well-established, but poorly understood probe for determining fatigue strength mean and standard deviation. The sensitivity of results to underlying distributions was studied using Monte Carlo simulation by repeatedly sampling known distributions of hypothetical fatigue strength data with the staircase test method. In this paper, the effects of the underlying distribution on staircase test results are presented with emphasis on original normal, lognormal, Weibull and bimodal data. The results indicate that the mean fatigue strength determined by the staircase testing protocol is largely unaffected by the underlying distribution, but the standard deviation is not. Suggestions for conducting staircase tests are provided.