F2008-04-013
New NVH Experimental Evaluation of Vehicle Cavity Fillers
A new test methodology has been developed to quantify the performance of BETAFOAMTM vehicle cavities fillers. This test methodology focuses on the vehicle BIW (Body in White) and provides a proper test environment for individual cavity fillers. Historically, to measure the performance of various cavity fillers, cavity channels were tested with and without cavity fillers. This technique has a serious limitation in that it doesn't provide the proper upstream and downstream boundary condition to the cavity fillers. This technique also does not provide a link between the component and overall vehicle performance.
The new test methodology developed at Dow Automotive overcomes these shortcomings. Since the focus of the methodology is BIW, the proper boundary condition is automatically resolved and the results obtained from this test methodology can be related to vehicle NVH (Noise, Vibration and harshness) performance.
In this study a noise source generator was placed at different locations within the vehicle body to generate the desired noise level. The goal was to realistically simulate wind, tire and the powertrain noise sources at the vehicle level and evaluate the performance of the vehicle cavity fillers. By placing several microphones in the vicinity of the A, B, C and D pillars, the noise reduction performances of the individual baffles were obtained. This new test methodology was implemented and validated for a typical sport utility vehicle BIW. Noise reductions (NR) of all pillars were evaluated with and without baffles. The results obtained from the NR data provide the NVH performance of the baffles and also shows the effectiveness of this test methodology.
Finally, this test methodology can be utilized in conjunction with the OEM vehicle development process. It replaces the "cut and try" effort with a systematic engineering methodology. This methodology could also help to develop the vehicle cavity filler's location, size and performance.
Poster presentation: Body design for passenger cars, trucks and buses