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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.

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.

The 2007 Diesel particulate matter (DPM) standard of 0.01 g/bhp-hr represents a 90% reduction of the previous standard and corresponds to roughly 100 micrograms (μg) gained on the filter sample used to determine compliance. The factors that influence the accuracy and precision by which this filter can be weighed are analyzed and quantified. The total uncertainty, representing best and typical cases, is between 1 and 5 μg. These uncertainties are used to compute the total uncertainty of the brake specific emission calculation. This uncertainty also depends on flowrate uncertainty, face velocity, and secondary dilution ratio. For a typical case, the total fractional uncertainty is in the range of ∼5 – 70% at 10% of the standard and ∼1 – 10% at 90% of the standard.

Particulate emissions from heavy-duty buses were measured in real time under conditions encountered during the standard Central Business District (CBD) driving cycle. The buses tested were equipped with 1994 Detroit Diesel Engine Corporation 6V92-TA engines, and some included after treatment devices on the exhaust. Instantaneous, time-resolved measurements of CO2 and amorphous carbon concentrations were obtained using an optical extinction technique and compared to simultaneous results obtained using conventional dilution tunnel sampling methods. Good agreement was obtained between the real-time extinction measurements and the diluted CO2 and cycle-integrated filter measurements. The instantaneous measurements revealed that acceleration transients accounted for roughly 80% of the particulate mass emitted during the cycle but only about 45% of the fuel consumption.

Results of comparisons of computed and measured soot and NO in a direct-injection Diesel engine are presented. The computations are carried out using a three-dimensional model for flows, sprays and combustion in Diesel engines. Autoignition of the Diesel spray is modeled using an equation for a progress variable which measures the local and instantaneous tendency of the fuel to autoignite. High temperature chemistry is modeled using a local chemical equilibrium model coupled to a combination of laminar kinetic and turbulent characteristic times. Soot formation is kinetically controlled and soot oxidation is represented by a model which has a combination of laminar kinetic and turbulent mixing times. Soot oxidation appears to be controlled near top-dead-center by mixing and by kinetics as the exhaust is approached. NO is modeled using the Zeldovich mechanism.

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.

Over the past five years, the US Automotive Materials Partnership (USAMP) has brought together representatives from DaimlerChrysler, General Motors, Ford Motor Company and over 40 other participant companies from the Mg casting industry to create and test a low-cost, Mg-alloy engine that would achieve a 15 - 20 % Mg component weight savings with no compromise in performance or durability. The block, oil pan, and front cover were redesigned to take advantage of the properties of both high-pressure die cast (HPDC) and sand cast Mg creep- resistant alloys. This paper describes the alloy selection process and the casting and testing of these new Mg-variant components. This paper will also examine the lessons learned and implications of this pre-competitive technology for future applications.

Earlier work [1] shows that kinetics of Diesel soot oxidation is different from that of ethylene diffusion flame soot oxidation [2], possibly due to metals from lube oil. This study investigates the influence of metals on soot oxidation and the exhaust particle emissions using lube oil dosed fuel (2 % by volume). This method does not simulate normal lube oil consumption, but is used as a means of adding metals to particles for oxidation studies. This study also provides insight into the effect of systems that mix lube oil with fuel to minimize oil change service. The HTO-TDMA (High Temperature Oxidation-Tandem Differential Mobility Analyzer) technique [1] was used to measure the surface specific oxidation rate of Diesel particles over the temperature range 500-750 °C. Diesel particles sampled from the exhaust stream of a Diesel engine were size segregated by differential mobility and oxidized in situ in air in a heated flow tube of known residence time and temperature profile.

Particle size distribution and number concentration measurements have been made in the diluted exhaust of a medium-duty, turbocharged, aftercooled, direct-injection Diesel engine using a unique variable residence time micro-dilution system that allows systematic variation of dilution and sampling conditions, and a scanning mobility particle sizer (SMPS). The measurements show that the number concentrations in the nanoparticle (Dp < 50 nm) and the ultrafine (Dp < 100 nm) ranges are very sensitive to dilution conditions and fuel sulfur content. Changes in concentration of up to two orders of magnitude have been observed when conditions are varied over the range that might be encountered in typical laboratory dilution systems. For example, at a dilution ratio of 12, dilution temperature of 32 °C, and a residence time of 1000 ms, the number concentrations reach 6 × 108 part.

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.

A two-dimensional optimization process which simultaneously adjusts the spark timing and air-fuel ratio of a lean-burn natural gas fueled engine has been demonstrated. This has been done by first mapping the thermal efficiency against spark timing and equivalence ratio at a single speed and load combination to obtain the 3-D surface of efficiency versus the other two variables. Then the ability of the control system to find and hold the combination of timing and air-fuel ratio which gives the highest thermal efficiency was explored. The control system described in SAE Paper No. 940546 was used to map the thermal efficiency versus equivalence ratio and ignition timing. NOx, CO, and HC maps were also obtained to determine the tradeoffs between efficiency and emissions. A load corresponding to a brake mean effective pressure of 0.467 MPa was maintained by a water brake dynamometer. A speed of 2000 rpm was maintained by a fuel-controlled governor.

In this work, engine-out particle mass (PM) and particle number (PN) emissions were experimentally examined from a gasoline direct injection (GDI) engine operating in two lean combustion modes and one stoichiometric mode with a fuel of known properties. Ten steady state operating points, two constant speed load steps, and an engine cold start were examined. Results showed that solid particles emitted from the engine under steady state stoichiometric conditions had a uniquely broad size distribution that was relatively flat between the diameters of 10 and 100 nm. In most operating conditions, lean homogenous modes can achieve lower particle emissions than stoichiometric modes while improving engine thermal efficiency. Alternatively, lean stratified operating modes resulted in significantly higher PN and PM emissions than both lean homogeneous and stoichiometric modes with increased efficiency only at low engine load.

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.

A one-stage dilution tunnel has been developed to sample and dilute diesel exhaust. The tunnel has the capability of simulating many aspects of the atmospheric dilution process. The dilution rate and overall dilution ratio, temperature, relative humidity, and residence time in the tunnel, as well as residence time and temperature in the transfer line between the tunnel and exhaust sampling point may be varied. In this work we studied the influence of the exhaust transfer line, tunnel residence time, and dilution air temperature on the exhaust particle size distribution. The influences of fuel sulfur content on the size distribution and on the sensitivity of the size distribution to dilution and sampling conditions were also examined. We do not suggest an optimum dilution scheme, but do identify critical variables.

The effects of fuel sulfur content and dilution conditions on diesel engine PM number emissions have been researched extensively through steady state testing. Most results show that the concentration of nuclei-mode particles emitted increases with fuel sulfur content. A few studies further observed that fuel sulfur content has little effect on the emissions of heavily-used engines. It has also been found that primary dilution conditions can have a large impact on the size and number distribution of the nuclei-mode particles. These effects, however, have not yet been fully understood through transient testing, the method used by governments worldwide to certify engines and regulate emissions, and a means of experimentation which generates realistic conditions of on-road vehicles by varying the load and speed of the engine.

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.

This work discusses the development of SAE procedure J2747, “Hydraulic Pump Airborne Noise Bench Test”. This is a test procedure describing a standard method for measuring radiated sound power levels from hydraulic pumps of the type typically used in automotive power steering systems, though it can be extended for use with other types of pumps. This standard was developed by a committee of industry representatives from OEM's, suppliers and NVH testing firms familiar with NVH measurement requirements for automotive hydraulic pumps. Details of the test standard are discussed. The hardware configuration of the test bench and the configuration of the test article are described. Test conditions, data acquisition and post-processing specifics are also included. Contextual information regarding the reasoning and priorities applied by the development committee is provided to further explain the strengths, limitations and intended usage of the test procedure.

Forming of sheet metal structures induces pre-strains, thickness variations, and residual stresses. Pre-strains in the formed structures introduce work hardening effects and change material fatigue properties such as stress-life or strain-life. In the past, crashworthiness and durability analyses have been carried out using uniform sheet thickness and stress- and strain-free initial conditions. In this paper, crashworthiness and durability analyses of hydroformed front rails, stamped engine rails and shock towers on a full vehicle and a Body-In-White structure are performed considering the residual forming effects. The forming effects on the crash performance and fatigue life are evaluated.