Research of Riding Stability of Passenger Cars Based on Operational Modal Parameter Identification

Low frequency vibration of vehicles installed with SW160 bogies causes passengers feel sick and uncomfortable.To solve this problem, accelerations of carbodies and bogies of the vehicles are measured,and vehicle modal parameters are identified with the stochastic subspace identification method.The results show that the damping ratios of the upper and lower center roll sway and tieting head vibration of carbodies are rather low.It is one of the main reasons to cause low frequency vibration to carbodies when the low center roll sway are excited and cannot be effectively suppressed.After installing new air springs and secondary lateral dampers each with the damping coefficient of 60 kN·s/m,the vehicles are tested again.The results of operational modal analysis show the damping ratios of the upper and lower center roll sway are increased evidently,and the frequencies are decreased accordingly.Analysis of the power spectra of accelerations of the carbody floor shows that the low frequency vibration is effectively attenuated.