Research on Nonlinear Stiffness Characteristics of Hydro-Pneumatic Spring

A kind of hydro-pneumatic spring with adjustable stiffness was designed. The two-level stiffness converse each other when oil pressure reach a certain value. A complex nonlinear mathematic model of hydro-pneumatic spring was set up on the basis of comprehensive analysis of it s working principle and structure. Simulation results comparison and theoretical analysis with the test data of bench test showed that the mathematic model is authentic.