Study On Semi-active Suspension For Commercial Vehicles Using Magnetorheological Fluid Dampers

The advantages of magnetorheological fluid dampers as semi-active devices,compared to other semi-active and active techniques,have resulted in its increasing applications in the passenger car suspensions,train suspensions,seat suspensions,engine mountings and seismic structures.The literature,however,reveals that the applications of these dampers in primary suspension of commercial vehicles have not been investigated properly.This study has been designed to investigate the pros and cons of using magnetorheological fluid dampers in primary suspension of the heavy duty commercial vehicles.At first,a brief study of a heavy duty commercial vehicle dynamics,focusing on the suspension design requirements,is carried out.It is then followed by design study of magnetorheological fluid dampers for a vehicle suspension.The simulation studies are then carried out to investigate the ride comfort,vehicle stability and road damage reduction characteristics of a semi-trailer tuck using MRF dampers.A 7-DOF pitch-plane model of a semi-trailer truck is modeled and simulated in Matlab/Simulink.The passive dampers are replaced by the controllable magnetorheological fluid dampers,modeled using the modified Bouc-Wen model.Three ride comfort oriented system controller algorithms are analyzed,and their performance is compared to that of the passive suspension.Vehicle is simulated over two different road input profiles;road bump profile at low vehicle speed,and Class-A road profile at high speed.Simulation studies reveal that linear skyhook and 1 sensor mixed controllers show significant improvement in ride comfort under all input conditions,while on-off skyhook controller shows improvements only at low vehicle speeds.These comfort oriented system controllers have no clear significant effect on the vehicle stability or the road damage characteristics of the vehicle at high speeds but they showed improvement at low speeds.It can be concluded from this study that the semi-active suspensions with magnetorheological fluid dampers can be a good solution of the heavy duty commercial vehicle suspension issues.