Investigation On Dynamical Ride Comfortbility Of Vehical Seat And Narrow-band Random Dynamics Systems

The paper includes mainly two parts. The first one is dynamical ride comfortbility investigation of vehical seat, and the second one is investigation of narrow-band random dynamics systems.Investigate vehicle seat-person vibration discipline is important for improving ride comfortability of vehicle occupants. Magnetorheological fluid (MRF) damper is used in seat suspension system. The modified Bingham model is adopted for MRF damper. The nonlinar vibratation theory and numerical simulation method are applied to the two freedom seat-person model. The analytical solutions are basically conformed to the numerical solutions. The physical parameters of the MRF damper's effection on the system is also obtained. It can provide theory basic for control system.The methods of deterministic dynamics systems applied to non-linear stochastic dynamics systems can exploit new ways for stochastic dynamics systems. Now many achievements of stochastic dynamics systems belong to systems of broad-band random excitations, but in realism many systems are narrow-band random parameter excited dynamics systems. For these systerms, only few theoretic methods are applided. The complex normal form method is a effective method and has been widely used in the analysis of deterministic systems. So it is important to apply complex normal form method to investigation of narrow-band random parameter excited dynamics systems.The paper applies complex normal form method to narrow-band random parameter excited dynamics systems. The principal resonance and stability of the Duffing Rayleigh and Van der pol oscillator under combined harmonic and narrow-band random parameteric excited are obtained. The theoretical analyses are verified by numerical results. The theoretic results and numerical results are all show that when the intensity of the random excitation increases, the nontrivial steady state solution may change from a limit cycle to a diffused limit cycle. The largest Liapunov exponent three-dimensional surface is also abtained by numerical method. The complex normal form method is also verified by multiple scales in the systerm.