The Nonlinear Mathematical Model and Characteristics of Hydro-Pneumatic Spring

Taking a hydro-pneumatic spring in off-road vehicle as study object, this paper built the nonlinear mathematical model of hydro-pneumatic spring. The compression of oil, the nonlinear stiffness of air spring and dynamic friction between the piston and wall of cylinder are taken into account. The model is simulated by different frequencies and amplitudes of sine wave. The comparison between the simulative (results) and experimental data proves the validity of the nonlinear model. Based on the correct mathematical (model,) the characteristics of stiffness and frequencies, the characteristics of damping with different velocity and pressure drop of damping valve with different flowrate were analyzed.