Viewing 1 to 19 of 19
Technical Paper
Andrea Ferrero, Marcello Badiali, Richard Schreck, June-sang Siak, William Whited
A new core binder system (1) was used to produce foundry cores for casting hollow aluminum suspension parts by the low pressure, gravity flow, semi-permanent mold method. These and other prototype aluminum parts made using the system demonstrate that easy core removal from complex castings, core and sand recycling, and an improved environment in the core making facilities will increase productivity, improve product quality and reduce manufacturing costs.
Technical Paper
G. Dale Cheever, Robert A. Ottaviani, Vardarajan R. Iyengar
The presence of marred and scratched areas detract from the appearance of current automotive topcoat systems. Although the final determination of the extent of the damage to the paint surfaces must be made by human visual evaluation, machine estimation of this damage has value in being a tool for screening large numbers of different paint technologies. Scattered light from marred regions (both single and multiple scratches) in an automotive basecoat/clearcoat system was generated and collected in a goniophotometer. The areas under the intensity/angle curves were obtained using an extended trapezoidal rule for numerical integration. This technique shows promise in correlating goniophotometric data with human evaluation of marred areas. This technique may be of value in screening different paint technologies and chemistries.
Technical Paper
Alan L. Browne
A test program was conducted to characterize the impact response of an experimental 2-ply windshield construction with a polyurethane (PUR) plastic inner layer. Windshield impact tests were conducted using a linear impactor test facility. Principle among the findings was that the impact response of prototype PUR 2-ply windshields does not differ that significantly from that of baseline 3-ply HPR (High Penetration Resistance) windshields for the subcompact vehicle geometry tested. However, the impact responses of both PUR 2-ply and 3-ply HPR subcompact vehicle windshields were found to be highly variable. Average performance of either construction could thus be enhanced if ways could be found (and then implemented) to reduce this variability.
Technical Paper
Spyros I. Tseregounis, Michael L. McMillan
Nine engine oils were evaluated in two GM vehicles: a 1993 Pontiac Grand Am with a 2.3L Quad4 engine and a 1993 Buick LeSabre with a 3.8L (3800) V-6 engine. Standard EPA (Environmental Protection Agency) fuel economy (FE), vehicle-dynamometer tests were conducted. The results were compared with the fuel economy obtained with a standard ASTM reference oil (BC). The vehicle data from this program were used in evaluating the new engine-dynamometer ASTM Sequence VI-A test designed to predict “real world” fuel economy in vehicles. EPA 55/45 combined fuel economy performance in the GM vehicles ranged from almost 2 percent improvement (over the BC oil) for an SAE 5W-20 oil, to over 2 percent poorer fuel economy than the reference oil for an SAE 20W-50 oil. The two different engines responded similarly to the different oils and showed similar trends.
Technical Paper
Gerard Malaczynski, Xiaohong Qiu, Aboud Hamdi, Alaa Elmoursi
This paper describes a bench method to evaluate the frictional behavior, under scuffing conditions, of some test coupons of standard materials currently used in making cylinder bores and pistons. The usefulness of this method is in evaluating new materials and coatings that may enable the elimination of iron liners from engine blocks. While investigating the potential application of Plasma Source Ion Implantation (PSII) on engine piston/bore materials, we have systematically studied the scuffing related friction behavior of aluminum 390 alloy and cast iron. A pin-on-disk tribometer is used under dry sliding conditions. Testing parameters for simulating cold scuff in bench tests have been specified. This proposed test method offers a screening tool desirable for the development of PSII technology and may also be useful for the design of other new surface modification techniques.
Technical Paper
Xiaohong Qiu, Alaa Elmoursi, Gerard Malaczynski, Aboud Hamdi, Paul Wilbur, Brett Buchholtz
This paper examines the potential use of diamond-like carbon (DLC) on aluminum alloy pistons of internal combustion engines. Our approach is to apply a DLC coating on the piston running against an aluminum-390 bore thus eliminating the iron liners in a standard piston/bore system. Experimental data, using a pin-on-disk tribometer under unlubricated test conditions, indicate that the performance of the DLC coating against aluminum 390 exhibits superior friction resistance compared to aluminum-390 against cast iron; the latter material couple representing the materials currently being used in production for the piston/bore application. Moreover, by thermally cycling the DLC coatings we show that improved friction and wear properties can he maintained to temperatures as high as 400°C.
Technical Paper
M. D. Hanna, J. N. Johnson, M. S. Rashid, Tom Blake
ACuZinc™ 5, a GM-patented, high-performance ternary zinc-copper-aluminum alloy which is suitable for manufacturing net shape die castings, plays a vital role in the success of new automotive parts and systems. The new parts were designed to meet the auto industry's higher load and safety specifications. The superior mechanical properties of ACuZinc™ make it suitable for structural applications where commercial zinc die casting alloys have been found to be inadequate. From a business viewpoint, ACuZinc™ can help in penetrating new markets by competing for cast iron, powder metal and brass applications. ACuZinc is a registered GM trademark.
Technical Paper
Kenneth B. Gross, Nelson A. Kelly, Sridhar Reddy, Nipurn J. Shah, Theresa A. K. Grain
All air bag systems use a pyrotechnic combustion process for the generation of gases. In some systems, it is also used for the heating of stored gases to quickly inflate the air bag. As a by-product of the process, gases and particles are produced that enter the passenger compartment resulting in inhalation of these substances. We have previously shown that systems using sodium azide as the gas generant can initiate asthmatic attacks in susceptible individuals. To evaluate whether the effluents from new-generation, non-azide air bag systems also have the potential to produce adverse responses, we performed controlled exposures of mild to moderate asthmatics to the effluents from six of these air bag systems. Each volunteer asthmatic subject was pulmonary function tested (baseline), and then seated in the back seat of the test vehicle. The air bag system was deployed and the subjects remained in the vehicle for twenty minutes.
Technical Paper
Robert D. Stephens, Ronald L. Williams, Gregory A. Keoleian, Sabrina Spatari, Robb Beal
Federal standards that mandate improved fuel economy have resulted in the increased use of lightweight materials in automotive applications. However, the environmental burdens associated with a product extend well beyond the use phase. Life cycle assessment is the science of determining the environmental burdens associated with the entire life cycle of a given product from cradle-to-grave. This report documents the environmental burdens associated with every phase of the life cycle of two fuel tanks utilized in full-sized 1996 GM vans. These vans are manufactured in two configurations, one which utilizes a steel fuel tank, and the other a multi-layered plastic fuel tank consisting primarily of high density polyethylene (HDPE). This study was a collaborative effort between GM and the University of Michigan's National Pollution Prevention Center, which received funding from EPA's National Risk Management Research Laboratory.
Technical Paper
Kuo-Kuang Chen, Joe Jiyu Chen, Xiao Ming Chen
Corner fill is a simple benchmark conceived to gain knowledge of tube hydroforming. In corner fill of tube hydroforming, an originally long round tube is positioned in a cylindrical die with square cross-section and expands under applied internal pressure to fill the corners of the die. In order to ensure burst of the tubes, the cross-sectional dimension of the square die is chosen to be greater than the outer diameter of the tube. A two-dimensional plane strain finite element model has been developed to study the tube behaviors under applied internal pressure. This model treats the corner fill process more realistically than shell elements models because thickness stress and distortions of a normal segment through the thickness of the tube can be simulated [Chen, 2004]. The calculated results of stress and strain and the change of tube geometry as functions of pressure are presented.
Technical Paper
Xiaohua Hu, Jidong Kang, David S. Wilkinson, Mukesh Jain, Peidong Wu, Raja K. Mishra, Anil K. Sachdev, Sooho Kim
We have studied the formability of continuous strip cast (CC) AA5754 aluminum alloy for automotive applications. Strip casting technology can considerably reduce material cost compared with conventional direct chill (DC) cast aluminum sheets. However, the CC material tends to exhibit much less post-localization deformation and lower fracture strains compared with DC sheets with similar Fe content, although both alloys show similar strains for the onset of localization. Bendability of the CC alloy is also found to be inferior. The inferior behavior (post-necking and bendability) of the CC alloy can be attributed to the higher incidence of stringer-type particle distributions in the alloy. The formability of the AA5754 alloy has also been studied using two dimensional microstructure-based finite element modeling. The microstructures are represented by grains and experimentally measured particle distributions.
Technical Paper
Kushal Narayanaswamy, Yongsheng He
Selective Catalytic Reduction (SCR) is effective over a wide temperature window to reduce NOx emissions from engine exhaust during lean operations. In this study, different supplier SCR catalysts are investigated and modeled. A global Ammonia SCR reaction mechanism has been used, and kinetic parameters for selective catalytic reduction of NOx by Ammonia were developed for both Copper (Cu)-zeolite and Iron (Fe)-zeolite SCR catalysts. The kinetic analysis was performed using a commercial one dimensional (1-D) aftertreatment code, coupled with an optimizer. The optimized kinetics have been validated extensively with laboratory reactor data for various operating conditions on three supplier catalysts - two Copper and one Iron based formulations. Both steady state and transient tests are performed and the developed SCR models are shown to agree with the experimental measurements reasonably well.
Technical Paper
Jidong Kang, David S. Wilkinson, Mukesh Jain, Raja K. Mishra
Strip cast AA5754 sheets are of interest for automotive interior panel applications. However, Portevin-Le Chatelier (PLC) bands are seen in this material and cause surface quality concerns. Moreover, shear banding is the main failure mechanism of this material. However, the relationship between PLC bands and shear bands is still controversial in the literature. In order to delineate this problem, the digital image correlation (DIC) strain mapping technique is used to explore the three-dimensional structures of PLC bands and shear bands in AA5754 sheets. Two-dimensional DIC measurements were carried out simultaneously on both of the sheet sample surfaces (front and back side) of an AA5754 tensile sample using a commercially available optical strain mapping DIC-based system (Aramis). DIC measurements were also conducted on the thickness direction. Based on the strain mapping results, the three dimensional structures of both PLC bands and shear bands are constructed.
Technical Paper
Kuo-Kuang Chen
The accurate prediction of burst of hydroformed tubes is a research area of considerable importance in order to evaluate a design before prototyping. This report applies the presently available criteria (forming limit diagram, stress-based forming limit diagram, extended stress based forming limit curve and the plastic strain criterion) to some of the benchmark examples carried out by the Auto/Steel partnership. It was found that the formability predictions are lowest if the plastic strain criterion is used and highest if either the stress-based criteria are used. Predicted and measured results were also compared.
Technical Paper
S. G. Liter, C.-W. Park, M. Kaviany, J. T. Wang, J. Kang, Y. G. Lee
A numerical model is presented that is capable of isolating and quantifying the heat flux from the gas within the bag to the air bag fabric due to internal surface convection during the inflator discharge period of an air bag deployment. The model is also capable of predicting the volume averaged fabric temperatures during the air bag deployment period. Implementation of the model into an air bag deployment code, namely Inflator Simulation Program (ISP), is presented along with the simulation results for typical inflators. The predicted effect of the heat loss from the bag gas to the fabric on the internal bag gas temperature and pressure and the resulting bulk fabric temperature as a function of fabric parameters and the inflator exit gas properties are presented for both permeable and impermeable air bag fabrics.
Technical Paper
G. Paul Montgomery, Lynn T. Truss
The design of pockets on automotive sheet metal parts can significantly affect part formability. We have developed regression formulas for predicting the failure depth of a symmetric rectangular pocket as a function of the geometric parameters that define the pocket. The formulas were developed by statistically selecting combinations of geometric pocket parameters for formability analysis and using formability simulations to determine the pocket failure depth for each selected parameter combination. The regression formulas were tested by comparing their predictions with simulations for combinations of part parameters not used to develop the formulas.
Technical Paper
Bob R. Powell, Alan A. Luo, Vadim Rezhets, John J. Bommarito, Basant L. Tiwari
A family of low-cost, creep-resistant magnesium alloys has been developed. These alloys, containing aluminum, calcium, and strontium are designated as “ACX” alloys. Developed for engine blocks and transmissions, the “ACX” alloys have at least 40% greater tensile and 25% greater compressive creep resistance than AE42, and corrosion resistance as good as AZ91D (GMPG 9540P/B corrosion test). These alloys are estimated to cost only slightly more than AZ91D and have as good castability. Creep data up to 200°C, tensile properties at room temperature and 175°C, corrosion results and microstructure analysis are presented and discussed. These alloys have the potential to enable the extension of the substantial weight reduction benefits of magnesium to powertrain components.
Technical Paper
Thomas B. Stoughton
The stress-based forming limit criterion has recently been shown to exhibit no significant dependence on strain path for a wide range of materials. This paper describes the effect of material models on the definition of the stress-based forming limit criterion. It is shown that although the shape of the forming limit curve in stress space is sensitive to the type of material model used, the degeneracy of the path dependent strain-based curves to a single curve in stress space shows little sensitivity to the material model. Consequently, the stress based forming limit criterion is shown to provide a more practical and robust measure of forming severity than is possible using the conventional forming limit diagram.
Technical Paper
Paul E. Krajewski
The use of sheet magnesium for automobile body applications is limited, in part, due to its low room temperature formability. Elevated temperature forming of magnesium sheet could enable the manufacture of automobile body closure and structural panels to meet vehicle mass targets. The effect of temperature in improving the formability of sheet magnesium has been known since the 1940's; however, automobile applications for sheet magnesium still have been very limited. The present work characterizes the elevated temperature mechanical behavior of commercially available magnesium sheet alloys at temperatures between 300°C and 500°C. The materials are then evaluated using both warm forming and superplastic forming technologies.
Viewing 1 to 19 of 19


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