Vibration Isolation Performance Analysis of a Nonlinear Fluid Inerter-Based Hydro-Pneumatic Suspension

To further enhance the ride comfort of vehicles, a new type of fluid inerter-based hydro-pneumatic suspension (FI-HPS) is proposed. First, this paper combines the fluid type inerter with the dual-chamber hydro-pneumatic suspension (DHPS) and fully considers the nonlinear factors. The nonlinear dynamic model of the fluid inerter is derived, and three structural models, namely the traditional DHPS S0, the ideal FI-HPS S1, and the nonlinear FI-HPS S2, are established. Then, the non-dominated sorting genetic algorithm II (NSGA-II) is employed to optimize the key parameters of the S1 and S2 suspensions. With the S0 suspension as a comparison subject, the simulation results show that the S2 suspension can significantly improve the vehicle’s ride comfort performance. In terms of the time-domain analysis, the root-mean-square (RMS) value of the vehicle body acceleration is reduced by 20.5%, the RMS value of the suspension working space is reduced by 12.7%, and the RMS value of the dynamic tire load is reduced by 8.0%. The frequency domain results indicate that the S2 suspension can effectively reduce the suspension offset frequency vibration, with a more significant effect at low frequencies. Upon analysis of impulsive road conditions, the peak-to-peak (PTP) value of the vehicle body acceleration is reduced by 14.2%, and the PTP value of the suspension working space is reduced by 6.3%. It is revealed that the inclusion of the nonlinear parasitic damping force in the fluid inerter can effectively enhance the overall performance of the hydro-pneumatic suspension system.