Keywords: shock absorbers, hydraulic simulation, NVH, knocking noise, vehicle noise, vehicle vibration, harshness, noise prediction, piston rod acceleration
Simulation tool for shock absorber noise prediction in time and frequency domains
This paper investigates the validity of a hydraulic simulation model to calculate the piston rod acceleration for further frequency domain analysis. At the present time, simulation results analyses of shock absorber characteristics are mostly restricted to the low frequency range for the hydraulic behaviour and the high frequency range for Noise, Vibration and Harshness (NVH) studies. However increasing demand on vehicle noise reduction is focusing more attention on high frequency matters caused by shock absorbers hydraulic effects. The most important noise concern related to shock absorbers is knocking noise. This is a structural noise caused by the vibration of chassis components excited by the shock absorber's piston rod vibrations. These vibrations are caused mainly by valves opening-closing and friction during stroke changes. The validation process is based on quantitative and qualitative comparison results between test and simulation both in time and frequency domain.