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Technical Paper

Robust Analysis of Clamp Load Loss in Aluminum Threads due to Thermal Cycling

2009-04-20
2009-01-0989
A DFSS study identified a new mechanism for clamp load loss in aluminum threads due to thermal cycling. In bolted joints tightened to yield, the difference in thermal expansion between the aluminum and steel threads can result in a loss of clamp load with each thermal cycle. This clamp load loss is significantly greater than the loss that can be explained by creep alone. A math model was created and used to conduct a robust analysis. This analysis led to an understanding of the design factors necessary to reduce the cyclic clamp load loss in the aluminum threads. This understanding was then used to create optimized design solutions that satisfy constraints common to powertrain applications. Estimations of clamp load loss due to thermal cycling from the math model will be presented. The estimates of the model will be compared to observed physical test data. A robust analysis, including S/N and mean effect summary will be presented.
Technical Paper

Shudder Durability of a Wet Launch Clutch Part I – Thermal Study and Development of Durability Test Profile

2009-04-20
2009-01-0329
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.
Journal Article

Chevrolet Sequel: Reinventing the Automobile

2008-04-14
2008-01-0421
Sequel is the third vehicle in GM's Reinvention of the Automobile and is the first zero emissions passenger vehicle to drive more than 300 miles on public roads without refueling or recharging. It is purpose-built around the hydrogen storage and fuel cell systems and uses the skateboard principle introduced in the Autonomy vision concept and the Hy-wire proof-of-concept vehicles. Sequel's aluminum structure, Flexray controlled chassis-by-wire systems and AWD system comprising a single front electric motor and two rear wheel motors make it, perhaps, the most technically advanced automobile ever built. The paper describes the vehicle's design and performance characteristics.
Journal Article

A Springback Compensation Study on Chrysler 300C Stamping Panels Using LS-DYNA®

2008-04-14
2008-01-1443
Springback compensation studies on a few selected auto panels from the hot selling Chrysler 300C are presented with details. LS-DYNA® is used to predict the springback behavior and to perform the iterative compensation optimization. Details of simulation parameters using LS-DYNA® to improve the prediction accuracy are discussed. An iterative compensation algorithm is also discussed with details. Four compensation examples with simulation predictions and actual panel measurement results are included to demonstrate the effectiveness of LS-DYNA® predictions. An aluminum hood inner and a high strength steel roof bow are compensated, constructed and machined based on simulation predictions. The measurements on actual tryout panels are then compared with simulation predictions and good correlations were achieved. Iterative compensation studies are also done on the aluminum hood inner and the aluminum deck lid inner to demonstrate the effectiveness of LS-DYNA® compensation algorithm.
Technical Paper

Friction Stir Welding of Aluminum for Automotive Closure Panel Applications

2008-04-14
2008-01-0145
Friction stir welding (FSW) shows advantages for joining lightweight alloys for automotive applications. In this research, the feasibility of friction stir welding aluminum for an automotive component application was studied. The objective of this research was to improve the Friction Stir Spot Welding (FSSW) technique used to weld an aluminum closure panel (CP). The spot welds were made using the newly designed swing-FSSW technique. In a previous study (unpublished), the panel was welded from the thin to thick side using both an 8 mm and a 10 mm diameter tool. The 10 mm tool passed various fatigue tests; however, the target was to improve performance of the 8 mm tool, especially to increase the number of cycle before the first crack appearance during fatigue testing. In this study fatigue tests and static strength was recorded for weld specimens that were welded from thick-to-thin with an 8 mm diameter tool.
Technical Paper

Transient One-Dimensional Thermal Analysis of Automotive Components for Determination of Thermal Protection Requirements

2008-04-14
2008-01-0733
During initial phases of vehicle development process, it is usually required to understand the temperature profile for all components. It is usually more effective and less costly if the thermal issues are determined and addressed before actual vehicles are built. Computational Fluid Dynamics (CFD) analysis tools are typically used for thermal management of the vehicle environment. However, for transient thermal analysis problems, running a full CFD requires solving the mass, momentum, and energy equations. This typically requires a lengthy computation time and extensive computer resources. The problem becomes more challenging when trying to conduct CFD analysis for several design iterations and for different duty cycles that may be of a transient nature. Therefore, the application of one-dimensional analysis early in the development phase can help point out the areas of prime concern.
Technical Paper

Development of an Improved Cosmetic Corrosion Test for Finished Aluminum Autobody Panels

2007-04-16
2007-01-0417
Since 2000, an Aluminum Cosmetic Corrosion task group within the SAE Automotive Corrosion and Protection (ACAP) Committee has existed. The task group has pursued the goal of establishing a standard test method for in-laboratory cosmetic corrosion evaluations of finished aluminum auto body panels. A cooperative program uniting OEM, supplier, and consultants has been created and has been supported in part by USAMP (AMD 309) and the U.S. Department of Energy. Prior to this committee's formation, numerous laboratory corrosion test environments have been used to evaluate the performance of painted aluminum closure panels. However, correlations between these laboratory test results and in-service performance have not been established. Thus, the primary objective of this task group's project was to identify an accelerated laboratory test method that correlates well with in-service performance.
Technical Paper

High Performance Vehicle Chassis Structure for NVH Reduction

2006-04-03
2006-01-0708
The main objective of this paper was to determine if the vehicle performance can be maintained with a reduced mass cradle structure. Aluminum and magnesium cradles were compared with the baseline steel cradle. First, the steel chassis alone is analyzed with the refined finite element model and validated with experimental test data for the frequencies, normal modes, stiffnesses and the drive-point mobilities at various attachment mount/bushing locations. The superelement method in conjunction with the component mode synthesis (CMS) technique was used for each component of the vehicle such as Body-In-White, Instrument Panel, Steering Column Housing & Wheel, Seats, Cradles, CRFM, etc. After assemblage of all the superelements, analysis was carried out by changing the front and rear cradle gauges and the material properties. The drive-point mobility response was computed at various locations and the noise (sound pressure) level was calculated at the driver and passenger ears.
Technical Paper

Fatigue Strength Effect of Thread Forming Process in Cast Aluminum

2006-04-03
2006-01-0780
Two thread forming processes, rolling and cutting, were studied for their effects on fatigue in cast aluminum 319-T7. Material was excised from cylinder blocks and tested in rotating-bending fatigue in the form of unnotched and notched specimens. The notched specimens were prepared by either rolling or cutting to replicate threads in production-intent parts. Cut threads exhibited conventional notch behavior for notch sensitive materials. In contrast, plastic deformation induced by rolling created residual compressive stresses in the notch root and significantly improved fatigue strength to the point that most of the rolled specimens broke outside the notch. Fractographic and metallographic investigation showed that cracks at the root of rolled notches were deflected upon initiation. This lengthened their incubation period, which effectively increased fatigue resistance.
Technical Paper

On the Potential of Low Heat Rejection DI Diesel Engines to Reduce Tail-Pipe Emissions

2005-04-11
2005-01-0920
Heat transfer to the combustion chamber walls constitutes a significant portion of the overall energy losses over the working cycle of a direct injection (DI) diesel engine. In the last few decades, numerous research efforts have been devoted to investigating the prospects of boosting efficiency by insulating the combustion chamber. Relatively few studies have focused on the prospects of reducing emissions by applying combustion chamber insulation. A main purpose of this study is to assess the potential of reducing in-cylinder soot as well as boosting aftertreatment performance by means of partially insulating the combustion chamber. Based on the findings from a conceptual study, a Low Heat Rejection (LHR) design, featuring a Nimonic 80A insert into an Aluminum piston, was developed and tested experimentally at various loads in a single-cylinder Hatz-engine.
Technical Paper

Development of the 2006 Corvette Z06 Structural Cast Magnesium Crossmember

2005-04-11
2005-01-0340
Since its very beginning in 1953, Corvette has been a pioneer in light weight material applications. The new 6th generation corvette high performance Z06 model required aggressive weight savings to achieve its performance and fuel economy targets. In addition to aluminum body structure and some carbon fiber components, the decision to use a magnesium front crossmember was identified to help achieve the targets. An overview of the Structural Cast Magnesium Development (SCMD) project will be presented which will provide information on key project tasks. Project focus was to develop the science and technical expertise to manufacture and validate large structural magnesium castings, which provide a weight reduction potential of 35 percent with respect to aluminum. The die cast magnesium cradle is being produced from a Mg-Al-RE alloy, designated AE44, for high temperature creep and strength performance as well as casting ductility requirements.
Technical Paper

Development of an Improved Cosmetic Corrosion Test for Finished Aluminum Autobody Panels

2005-04-11
2005-01-0542
A co-operative program initiated by the Automotive Aluminum Alliance and supported by USAMP continues to pursue the goal of establishing an in-laboratory cosmetic corrosion test for finished aluminum auto body panels that provides a good correlation with in-service performance. The program is organized as a task group within the SAE Automotive Corrosion and Protection (ACAP) Committee. Initially a large reservoir of test materials was established to provide a well-defined and consistent specimen supply for comparing test results. A series of laboratory procedures have been conducted on triplicate samples at separate labs in order to evaluate the reproducibility of the various lab tests. Exposures at OEM test tracks have also been conducted and results of the proving ground tests have been compared to the results in the laboratory tests. Outdoor tests and on-vehicle tests are also in progress. An optical imaging technique is being utilized for evaluation of the corrosion.
Technical Paper

CFD for Flow Rate and Air Re-Circulation at Vehicle Idle Conditions

2004-03-08
2004-01-0053
CFD method for the calculation of flow rate and air re-circulation at vehicle idle conditions is described. A small velocity is added to the ambient airflow in order to improve the numerical stability. The flow rate passing through the heat exchangers is insensitive to the ambient velocity, since the flow rate is largely determined by the fan operation. The air re-circulation, however, is quite sensitive to the ambient air velocity. The ambient velocity of U=-1m/s was found to be the more critical case, and is recommended for the air re-circulation analysis. The CFD analysis can also lead to design modifications improving the air re-circulation.
Technical Paper

A Novel Design Concept of a Lateral Sliding Bucket Seat on Roller Mechanisms

2003-10-27
2003-01-2753
A novel lateral sliding vehicle bucket seat was developed to address consumer needs for improved facile access to third row seats in minivans and sport utility vehicles. The concept provides for a second row bucket seat to slide laterally across a vehicle floor by roller mechanisms that roll across steel rails that transverse the vehicle floor. The system consists of two T-section type steel rails mounted parallel to each other at a distance equal to the seat riser support attachment features. The seat risers contain a roller mechanism that enables contact with the cylindrical portion of the steel rails. Each steel rail contains rectangular openings spaced appropriately to allow the seat latching mechanisms to engage securely. The seat riser supports at the rear include a releasable clamping mechanism hook that engages and disengages into the rectangular openings of the steel rails.
Technical Paper

Vehicle Panel Vibro-Acoustic Behavior and Damping

2003-05-05
2003-01-1406
Damping treatments are widely used in passenger vehicles, but the knowledge of damping treatments is often fragmentary in the industry. In this study, vibro-acoustics behavior of a set of vehicle floor and dash panels with various types of damping treatments was investigated. Sound transmission loss, sound radiation efficiency as well as damping loss factor were measured. The damping treatments ranged from laminated steel construction (thin viscoelastic layer) and doubler plate construction (thick viscoelastic layer) to less structural “bake-on” damping and self-adhesive aluminum foil-backed damping treatments. In addition, the bare vehicle panels were tested as a baseline and the fully carpeted floor panel was tested as a reference. The test data were then examined together with analytical modeling of some of the test configurations. As expected, the study found that damping treatments add more than damping. They also add mass and change body panel stiffness.
Technical Paper

Development of an Improved Cosmetic Corrosion Test By the Automotive and Aluminum Industries for Finished Aluminum Autobody Panels

2003-03-03
2003-01-1235
The Automotive Aluminum Alliance in conjunction with SAE ACAP founded a corrosion task group in 2000 with a goal to establish an in-laboratory cosmetic corrosion test for finished aluminum auto body panels, which provides a good correlation with in-service performance. Development of this test involves a number of key steps that include: (1) Establishing a reservoir of standard test materials to provide a well-defined and consistent frame of reference for comparing test results; (2) Defining a real-world performance for the reference materials through on-vehicle tests conducted in the U.S. and Canada; (3) Evaluating existing laboratory, proving ground, and outdoor tests; (4) Conducting statistically designed experiments to evaluate the effects of cyclic-test variables; (5) Comparing corrosion mechanisms of laboratory and on-vehicle tests; and (6) Conducting a round robin test program to determine the precision of the new test. Several of these key steps have been accomplished.
Technical Paper

CFRM Concept for Vehicle Thermal System

2002-03-04
2002-01-1207
Condenser, fan, radiator power train cooling module (CFRM) proposed by Delphi Automobile Systems was evaluated in the context of vehicle thermal system analysis. The results from the CFRM configuration were compared with those from the conventional condenser, radiator, and fan power train cooling module (CRFM). The analysis shows that for a typical passenger vehicle, the underhood temperature for the CFRM configuration is more than 10°C lower than its CRFM counterpart when the fan is operating at the same speed of 2500 rpm. This is due mainly to the higher mass flow rate impelled by the fan in the CFRM configuration. At the equal mass flow condition, both the CFRM and the CRFM configurations give similar underhood temperatures; but the fan in the CFRM configuration uses 19% less power, due mainly to the reduction in the fan speed needed to impel the same amount of mass flow rate.
Technical Paper

Oxidation Stability of Automatic Transmission Fluids -A Study by the International Lubricants Standardization and Approval Committee (ILSAC) ATF Subcommittee

2001-05-07
2001-01-1991
The International Lubricant Standardization and Approval Committee (ILSAC) ATF subcommittee members have compared the two oxidation bench test methods, Aluminum Beaker Oxidation Test (ABOT) and Indiana Stirring Oxidation Stability Test (ISOT), using a number of factory-fill and service-fill ATFs obtained in Japan and in the US. In many cases, the ATFs were more severely oxidized after the ABOT procedure than after the same duration of the ISOT procedure. The relative severity of these two tests was influenced by the composition of the ATFs. The bench test oxidation data were compared with the transmission and the vehicle oxidation test data.
Technical Paper

PEM Fuel Cell System Solutions for Transportation

2000-03-06
2000-01-0373
PEM Fuel Cell technology has been advancing rapidly during the last several years as evidenced by various vehicle demonstrations by the major automotive companies. As the development continues to bring hardware to automotive system level solutions, many engineering challenges arise. This paper will deal with two (2) of these areas from an automotive system level perspective: Thermal Management and the Fuel Cell Stack. Both of these sub-system areas are critical to the success of the technology in meeting the requirements of tomorrow's automotive customer.
Technical Paper

Experimental and Modeling Evaluations of a Vacuum-Insulated Catalytic Converter

1999-10-25
1999-01-3678
Vehicle evaluations and model calculations were conducted on a vacuum-insulated catalytic converter (VICC). This converter uses vacuum and a eutectic PCM (phase-change material) to prolong the temperature cool-down time and hence, may keep the converter above catalyst light-off between starts. Tailpipe emissions from a 1992 Tier 0 5.2L van were evaluated after 3hr, 12hr, and 24hr soak periods. After a 12hr soak the HC emissions were reduced by about 55% over the baseline HC emissions; after a 24hr soak the device did not exhibit any benefit in light-off compared to a conventional converter. Cool-down characteristics of this VICC indicated that the catalyst mid-bed temperature was about 180°C after 24hrs. Model calculations of the temperature warm-up were conducted on a VICC converter. Different warm-up profiles within the converter were predicted depending on the initial temperature of the device.
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