Double Tube Shock Absorber Model for Noise and Vibration Analysis 2013-01-1912
The “structure-borne” noise of the shock absorber is often responsible for undesirable noise in the car interior cabin. These vibrations are attributed to friction, opening/closing of the valves, fluid cavitation or other complex phenomena.
Early numerical prediction of the level of these vibrations in the car development process saves time and money. Most of the shock absorber models existing in the literature are limited to analysis of vehicle ride and handling. For noise and vibration analysis, the published works do not explicitly describe any model with its associated assumptions and a clear correlation with the experiments for high frequencies. Moreover there is no interpretation of the physical meaning of the high-frequency content of the response.
The objective of the present work is to build a double tube shock absorber model correlated up to 700 Hz. Experimental testing results are presented in this paper in order to put in evidence the non-linear phenomena localized on the piston shock absorber. The model includes the fluid compressible behavior, non-linear flow-rate pressure relationship and spring valve dynamics. Unknown parameters like bulk modulus are identified with experimental data.
The numerical results are compared to the experiments, showing that the shock absorber model is able to reproduce very well the local non-linear phenomena. This confirms our hypothesis and improves our knowledge of the potential noise sources in the shock absorber.