Evaluating the Isolation Performance of Three Seat Suspension Models of Off-Road Vehicles

Three suspension structures including the parallel vertical suspension (PVS), the horizontal parallel suspension (HPS), and the negative stiffness element added into suspension (NSES) of the driver's seat are proposed to improve the driver's ride comfort of off-road vehicles. Based on the dynamic models of the PVS, HPS, and NSES established and simulated under the same random excitations of the cab floor, the effect of the design parameters of the proposed models is analyzed, and the design parameters are then optimized to evaluate their isolation performance. The indexes of the root-mean-square (r.m.s) accelerations of the vertical seat direction, pitching seat angle, and rolling seat angle are used as the objective functions. The study results indicate that the dynamic param-eters of the PVS, HPS, and NSES greatly affect the driver's ride comfort while their geometrical dimensions insignificantly affect the driver's ride comfort. With the dynamic parameters of the PVS, HPS, and NSES optimized, the r.m.s seat acceleration in the vertical direction with the NSES is strongly reduced by 74.0% in comparison with the HPS; while the r.m.s accelerations of the pitching seat angle and rolling seat angle with the PVS are greatly decreased by 99.1% and 99.8% compared to the NSES. Therefore, the ride comfort of the driver's seat is remarkably improved by using the NSES while the driver's seat shaking is obviously ameliorated by using the PVS. To enhance the ride comfort and reduce the shaking of the driver's seat, a combination of the PVS and NSES should be applied to the seat suspension of off-road vehicles.