Browse Publications Technical Papers 2007-01-2300
2007-05-15

A Fully Absorptive Vehicle Underbody - A New Noise Abatement Strategy 2007-01-2300

Worldwide OEM's are seeking for potential to further reduce noise & CO2 pollution. Especially the European premium class vehicles are basically all equipped with aerodynamic under-shields in order to reduce the air drag coefficient, and hence to lower fuel consumption and CO2 emission. The complete absorptive vehicle underbody approach has proved to be a promising noise abatement strategy. First, it leads to substantial exterior and interior noise improvements and also to a reduction of the disturbing cold start Diesel engine noise in the neighborhood. Second, it bears significant potential for further weight reduction.
The absorptive underbody treatments were first developed in the virtual environment of Statistical Energy Analysis (SEA), where each component is specified according to its acoustic characteristics, namely its airflow Resistivity.
A complete underbody absorption package consists of; Absorptive engine shield, Absorptive aerodynamic body shield, Absorptive textile wheel arch liners (front & rear), and Absorptive heat shields.
During a second optimization loop a full vehicle SEA model was used to fine-tune the entire acoustic package in respect of best acoustic performance with minimum weight. This new strategy of a complete absorbing vehicle underbody has been positively tested on several vehicles in the lab and on the road. Exterior & interior noise reductions up to 1.5 dB(A) and 3.0 dB(A) respectively, were achieved.

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