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Automakers in the United States have started using bag mini-diluters (BMD) for developing, testing and certifying vehicles, to meet PZEV and SULEV regulation requirements. The BMD system which is a new technology developed by AIGER, is being used as an alternative to the traditional CFV/CVS system for accurate ultra low-level emission measurement. BMD system has shown to have considerable advantage over CFV/CVS system, especially at ULEV/SULEV emission levels. This paper details modifications and diagnostic checks conducted with the existing BMD system at the DaimlerChrysler Tech Center emissions facility, Auburn Hills, Michigan. This paper also discusses possible scenarios where the BMD system at DaimlerChrysler could give erroneous results due to system setup, optimization issues and equipment limitations.

At one time it was considered imperative to collect high frequency accelerometer data for accurate analysis. As a result current FMVSS regulations and SAE J2570 require the use of accelerometers with damping ratio of 0.05 or less (designated as undamped). This prevents the use of damped accelerometers for regulated channels. Damped accelerometers can provide comparable data and in some cases better data than undamped accelerometers, as long as they meet specific minimum requirements. To collect the most useful data, damped accelerometers should be added to the tool box of transducers used by crash test facilities.

In an effort to ensure that the characteristics of prototype friction materials do not differ from those of the “same” material when introduced into volume production and that, in production, these characteristics do not vary over time, DaimlerChrysler has instigated the processes of Shoe and Lining Fingerprinting and Production Variation Reduction. For the launch of the 1999 Jeep Grand Cherokee the concept of Production Variation Reduction was extended by the Jeep Platform and BBA Friction, Inc., to 25 pre-production batches of material to eliminate prototype to production variability.

Modern vehicles contain a multitude of networked electronics. This feature causes distributed functions in distributed electronics. Malfunctions occurring during EMC testing cannot be allocated precisely without detailed knowledge of the data streams. The electromagnetic environment during EMC-testing limits the possibilities of using standard solutions to detect these malfunctions. The paper will present a new tool, which is able to track the data streams in a CAN-Bus system during EMC-testing. By integrating EMC related parameters in the existing data stream of the vehicle's data bus, it is possible to keep a record of malfunctions as they occur.

This paper presents the results of optimization study for sunroof buffeting reduction using CFD technology. For an early prototype vehicle as a baseline model in this study a high level of sunroof buffeting 133dB has been found. The CFD simulation shows that the buffeting noise can be reduced by installing a wind deflector at its optimal angle 40 degrees from the upward vertical line. Further optimization study demonstrates that the buffeting peak SPL can be reduced to 97dB if the sunroof glass moves to its optimal position, 50% of the total length of the sunroof from the front edge. For any other vehicles, the optimization procedure is the same to get the optimal parameters. On the other hand, however, this optimization study is only based on fluid dynamics principle without considering manufacturability, styling, cost, etc. Further work is needed to utilize the results in the production design.

Traditional methods used to produce a die set (from developing initial machining cutter paths through finalized die tryout to produce a part that meets design intent) begin with draw simulation and development. It is here, traditionally, that scientific evaluation of actual metal stretch and theoretical ideals end. In past programs, a designed part would be simulated for stretch and a development model created to include various die compensations (i.e. springback, overcrown, etc.) based on past experience for area and amount. At this point, the die is cut and undergoes a metamorphosis through die tryout to finally produce a quality part. This is currently an open loop system. This paper will focus on the differences in the predicted way the die should look and the actual outcome (after part buyoff).

This paper presents the results of CFD study on sunroof buffeting suppression using a dividing bar. The role of a dividing bar in side window buffeting case was illustrated in a previous study [8]. For the baseline model of the selected vehicle in this study, a very high level of sunroof buffeting, 133dB, has been found. The CFD simulation shows that the buffeting noise can be significantly reduced if a dividing bar is installed at the sunroof. A further optimization study on the dividing bar demonstrates that the peak buffeting level can be reduced to 123dB for the selected vehicle if the dividing bar is installed at its optimal location, 65% of the total length from the front edge of the sunroof. The peak buffeting level can be further reduced to 100dB if the dividing bar takes its optimal width 80mm, 15% of the total length of the sunroof for this vehicle, while staying at its optimal location.