Abstract: Air suspension stiffness directly affects performances of vehicle. Suspension stiffness mainly depends on the stiffness of air spring. Traditional methods can hardly predict the stiffness because the rubber air bag generates multiple nonlinear problems during working process. For this, based on the structure analysis and nonlinear finite element theory, a prediction method for the dynamic characteristic of air spring is proposed, in which Yeoh model is used to simulate the rubber layer, rebar model represents cord layer, listrium and piston are used as rigid body, airflow is coupled with air bag deformation..To prove its validity and feasibility, diaphragm air springs for bus suspension are taken as examples. 3-D solid model is built by using CAD software UG on the basis of the structure size. Mesh is also generated by using hypermesh softeware. The relationship between stress and strain of rubber materials is tested. Numerical calculation of the finite element model is carried out by using nonlinear finite element software abaqus. The calculation results show that the finite element method is feasible. It provides an economical and practical prediction method for the development of air springs for vehicle suspension.

Key words: Air spring, Finite element analysis, Hypermesh software