| The ride comfort is required more and more strictly with the improvement of standard of life. It has become an important performance index by which the vehicle succeed more easily in the competition.Both dynamic and mathematic models of planar five-freedom and special eight-freedom are developed respectively by Lagrange-equation and Newton, and the corresponding math model is concluded, the response analysis of eight-freedom model is conducted in the frequency region and influence of the ride comfort which come from some parameters is observed. Because the different stiffness match of front and rear suspension is very influencing to the ride comfort, optimal model of ride comfort is developed, regarding the rms of driver's acceleration as the objection, regarding the stiffness of front and back suspension as optimal variable, regarding quiet flexibility,dynamic flexibility,frequency and dynamic load as nonlinear constraints. By Matlab program and using SQP, the optimal match of front and back suspension's stiffness is achieved, this optimal model consider not only request of quiet,dynamic flexibility,frequency and damp, but also security of run and peace of road, it is closer to the fact than other models which only consider partial restriction . Then the torsion bar spring according to the optimal match is design.At the same time, in order to forecast and check the ride comfort of new match suspension, a eight-freedom ride comfort emulational model in temporal region is erected basing on Simulink and the curves of some important indexes are observed in the temporal region, and we know the new suspension is satisfied to the design from the emulation. We can reduce some actual experiment through the emulational experiment, it not only quickens the design but also slows the costing of the design, So more and more emulational experiment are applied to the engineering design.Finally, I summarize the paper and bring forward the way of research in the future.
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