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SAE 8620 and other steels are typically used in the carburized condition for powertrain applications in the automotive industry, i.e., differential ring gears, camshafts, and transmission gears. Although current recommended carburizing practice involves normalizing the steel prior to carburizing, elimination of this normalizing treatment could lead to significant cost reductions. This research examines whether the normalizing process prior to carburizing could be eliminated without negatively affecting part performance. This study focused on the effects of the initial microstructure on the residual stress, retained austenite, and effective case depths of carburized SAE 8620 and PS-18 steels.

The focus of this study was to determine the residual stress and retained austenite profiles for carbonitrided and nitrocarburized SAE 1010 plain carbon steel and to relate these profiles to one another and to the distortion resulting from heat treatment. Navy C-ring specimens were used for the purpose of this study and X-ray diffraction techniques were used to measure both residual stress and retained austenite. The findings from this research are then applied to a manufacturing application involving the surface hardening of a thin shelled, plain carbon steel automotive component.

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.

A D.C. permanent magnet motor powered fan can serve as a cooling package air flow meter. This allows for continuous air flow monitoring during vehicle operation with applications to more precise air flow control schemes. In the freewheel mode, the air flow is a linear function of the open circuit voltage of the motor. In the powered mode, the motor voltage and current can be used with a motor and fan model to predict fan air flow. The model is explained and verifying test results are presented. Comparison of the accuracy and complexity vs. that of arrays of precision anemometers is provided.

Spot Welding is an important welding technique which is widely used in automotive and aerospace industry. One of the keys of checking the quality of the welds is measuring the size of the nugget. In this paper, the Shearographic technique is utilized to test weld joint samples under the thermal loading condition. The goal is to identify the different group of the nuggets (i.e. small, middle, and large sizes, which indicate the quality of spot welds). In the experiments, the sample under test is fixed by a magnet method from behind at the four edges. Thermal loading was applied in the back side and the sample is inspected using the digital Shearographic system in the front side. Results show the great possibility of classifying the nugget size into three groups and the measurement is well repeatable.

This paper proposes the adaptation of a modulation technique called Modified Frequency Modulation (MFM) to vehicle multiplexing. MFM was developed during the latter 1960's for use in magnetic disk drives. Disk drives use MFM encoding to achieve a maximum density of recorded data on a disk. The advantage in vehicle multiplexing is that the technique is synchronous with an average of 0.75 transitions per bit. Another advantage is that it can tolerate a large amount of rise and fall time wave shaping, which can significantly reduce radiated EMI. The paper will compare the EMI characteristics generated by NRZ, PWM, VPWM, Manchester, and MFM encoding. Included are typical encoding requirements such as symbol generation, arbitration capabilities, latency, invalid bit testing as well as encoding techniques effect on the host microcomputer.

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.

A fundamental problem in the development of automotive thermal protection strategies is the understanding of the effect of time and temperature on vehicle components life and their performance throughout the life of the vehicle. Due to restrictions on emissions and the stringent requirements for improved fuel economy, the use of polymers and synthetic materials has been widely adopted in automotive applications. It is therefore critical to develop a process to estimate life of engineering materials based on thermal testing and material physical properties. While a series of carefully selected vehicle tests can determine components temperatures during different testing conditions, a need still exists to determine the expected component life and performance throughout the life of the vehicle. Kinetic models have been widely used, in literature, to determine the aging of polymeric and composite materials over time.

Finite element analysis (FEA) predictions of magnesium beams are compared to load versus displacement test measurements. The beams are made from AM60B die castings, AM30 extrusions and AZ31 sheet. The sheet and die cast beams are built up from two top hat sections joined with toughened epoxy adhesive and structural rivets. LS-DYNA material model MAT_124 predicts the magnesium behavior over a range of strain rates and accommodates different responses in tension and compression. Material test results and FEA experience set the strain to failure limits in the FEA predictions. The boundary conditions in the FEA models closely mimic the loading and constraint conditions in the component testing. Results from quasi-static four-point bend, quasi-static axial compression and high-speed axial compression tests of magnesium beams show the beam's behavior over a range of loadings and test rates. The magnesium beams exhibit significant material cracking and splitting in all the tests.

Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.

A method is proposed to qualify automotive component designs in the laboratory using multiaxial real time load/strain input data acquired in the field. Fatigue damage analysis methods are used to edit the field data to produce an accelerated test cycle that retains all of the damaging real time load histories present in the original test cycle. Use of this procedure can contribute to a significant reduction in product design/development time.

Higher horsepower per liter engines have put more demand on the crankshaft, often requiring the use of forged steel. This paper examines cost reduction opportunities to offset the penalties associated with forged steel, with raw material and machinability being the primary factors evaluated. A cost model for crankshaft processing is utilized in this paper as a design tool to select the lowest cost material grade. This model is supported by fatigue and machinability data for various steel grades. Materials considered are medium carbon, low alloy, and microalloy steels; the effects of sulfur as a machining enhancer is also studied.

A unique opportunity arose to make a direct comparison of aluminum, sheet molding compound (SMC) and steel using a common hood design. In considering all possible material combinations of inner and outer panels, it was discovered that some of the combinations were incompatible due to material properties. Only the compatible material combinations were considered. Three different joining techniques - welding, bonding and bonded hem flanging - were evaluated. The cost, weight and structural performance of the chosen hood material combinations were established. Areas of further development were identified, including design optimization for specific material combinations.

A computer-controlled body panel testing machine has been used to quantify stiffness and dent resistance of body panels at Chrysler. The influence of yield strength and local reinforcement on the mechanical behavior of automotive door panels has been investigated. Medium strength steels in the range of 210 -240 MPa yield strength have produced significant improvements in dent resistance over a 160 MPa yield strength steel. Considerable improvements in dent resistance can also be attributed to the use of local, adhesively attached, glass fiber reinforcement patches. The effects of boundary conditions and panel shape on stiffness and dent resistance are illustrated in this application.

A running loss test procedure has been developed which integrates a point-source collection method to measure fuel evaporative running loss from vehicles during their operation on the chassis dynamometer. The point-source method is part of a complete running loss test procedure which employs the combination of site-specific collection devices on the vehicle, and a sampling pump with sampling lines. Fugitive fuel vapor is drawn into these collectors which have been matched to characteristics of the vehicle and the test cell. The composite vapor sample is routed to a collection bag through an adaptation of the ordinary constant volume dilution system typically used for vehicle exhaust gas sampling. Analysis of the contents of such bags provides an accurate measure of the mass and species of running loss collected during each of three LA-4* driving cycles. Other running loss sampling methods were considered by the Auto-Oil Air Quality Improvement Research Program (AQIRP or Program).

Seats play an important role in determining customer satisfaction and safety. They also represent three to five percent of the overall vehicle cost and weight. Therefore, automotive manufacturers are continuously seeking ways to improve the areas of comfort, safety, reliability, cost and weight within the seat system. The purpose of this paper is to review the development of an automotive front seat constructed of injection molded nylon frames and metal mechanisms. This development program was initiated for the purpose of reducing vehicle weight while increasing the reliability and safety of the front seats. This paper will review the material and process selection decision, a design overview, the performance criteria and the results of tests performed on the injection molded front seats.

A selection of commercially available chromium and chromium-free post phosphate rinses along with a deionized water rinse were evaluated over several zinc and zinc-alloy coated sheet steels. The test specimens were pretreated and electrocoated on-line in an automotive assembly plant. The effect of the rinse treatments on the cosmetic corrosion performance of the substrates, after 5 years of exposure in an outdoor scab corrosion test was determined. After this exposure none of the rinse treatments had performed better than deionized water rinse on zinc and zinc-iron coated sheet. The zinc-nickel coating showed improved scribe creepage when treated with the Cr+6/Cr+3 rinse. Data is provided comparing the concentration of the treatments used vs scribe creepage and chipping corrosion paint loss.

A comprehensive selection of automotive sheet steels were exposed in an outdoor scab corrosion test to provide a base-line of cosmetic corrosion performance. Eighteen different coated sheet steels along with CRS as a control were processed using two commercially available zinc phosphate chemistries. The phosphating was done using both immersion and spray phosphate processes in a laboratory and an automotive assembly plant. Scribe creepage results are reported for 5 years outdoor scab exposure. Comparisons of the scribe creepage behavior of CRS, zinc, and zinc alloy coatings and the effect of the phosphate treatment are provided. An estimate of 10 years field performance is made.

Typical sand-casting techniques have been shown to be inappropriate in pouring particulate reinforced aluminum metal matrix composite (Al-MMC) castings. New gating/risering configurations were necessary to produce castings of acceptable soundness. Several automotive components, including brake rotors, cylinder liners and camshaft thrust plates, were prepared using special techniques. Initial durability test results of several Al-MMC prototype components are presented.

Resin transfer molding (RTM) is the process of choice for the Body Panels of the Viper Sports car. The objective of this paper is to outline the reasons for the choice of RTM, and discuss development of technology for Class A surfaces and the paint system. Accomplishments to date and finally the work yet to be completed will also be defined. Conclusions from the work to date indicate that the RTM process enables a reduction in vehicle development time through faster prototypes and tool build times and that high quality, Class A surfaces can be successfully achieved even with epoxy tools. Additional work is ongoing to reduce cycle times and finishing costs, and to improve the in-process dimensional stability.