文摘
In order to be able to assess the acoustic characteristics of new rear axles respectively rear final drives at an early stage of development, a hybrid evaluation procedure was developed: this makes it possible to compare various construction stages on the basis of vehicle and test bench measurements. Transfer path analyses are used to calculate what contribution of the sound pressure on the driver鈥檚 ear is made up of structure-borne sound from the rear final drive (based on operational acceleration measured on the test bench and the bodywork鈥檚 transmission characteristics measured on the vehicle), which is used to classify the various construction stages. To use the test bench measurements for forecasting, the test object must have vibration characteristics that are as close as possible to those of the vehicle. In view of the above, comprehensive comparative measurements were taken with the help of artificial excitation and operational excitation. The measurement positions identified in the process were used to validate the calculation method by operating the very same rear final drive on the test bench and in a vehicle. In both cases, the rear final drive鈥檚 contribution of the total vehicle interior noise level was calculated, in one case on the basis of excitation from the vehicle measurement and in the other case on the basis of excitation from the test bench measurement. The good correlation between the vehicle-based and test bench-based calculations confirmed the applicability of the method. The 鈥渧irtual鈥?installation of the rear final drive enables faster construction stage comparisons because there is no need for alteration work on the vehicle and the rear final drive that is to be compared can simply be integrated into the existing test bench environment.
