Noise and vibration are critical to a customer’s overall positive or negative perception of passenger cars. Increasing market demands regarding comfort mean that a vehicle’s acoustic features must demonstrate continuous improvement to remain competitive.
In the new model car, the influence of vibration excitation (caused by force) and noise transfer (transfer functions) of suspension should be investigated by considering the three dimensions of noise behavior of the vehicle.
Measurement under real operating conditions using a servo-hydraulic multi-channel test rig was chosen. The level of the excitation was chosen in such a way that the coherence on the response signals was mostly above 90%.
It was found that noise sensitivity of the upper transfer path (piston rod - upper mount - body – interior) is distinctly higher than the lower transfer path (shock absorber tube - lower mount - wheel carrier - chassis - body – interior). At a frequency range of 300–1000 Hz, level differences up to 20 dB were obtained. The three-directional comparison of noise sensitivity of damper upper attachment shows, that X-/Y- directions are most sensitive transfer paths for suspension noise.
The improvement of acoustics properties was concentrated on optimization of the upper transfer path.