Abstract:Hydropneumatic suspensions properties are determined by its internal state, and the internal state of the inside substance largely determines the suspension response to external input. Based on the structural characteristics of the hydropneumatic suspension, considering the gas dissolved in the oil and the gas generated by orifice and seal friction, the output force was established by nonlinear mathematical model. The analysis model was built based on Simulink, and the working process of hydropneumatic suspension was analyzed. Response under different frequency excitation and gas pressure changes were contrastively analyzed, the influences of oneway valve damping hole parameters change and the characteristics of gases dissolved in oil on hydropneumatic suspension external characteristics were analyzed. The results show that: oneway valve size change has little effect on hydropneumatic suspension external characteristics under continued sinusoidal excitation, but the size of damping hole has greater impact; the characteristics of gases dissolved in oil will affect the hydropneumatic suspension external characteristic; oil and gas not separation type oilgas suspension solution characteristics can reduce the vibration amplitude of the output force of suspension. The suspension internal state is more stable, effectively improving the reliability of the whole system.