Improving Ride Comfort in Vehicles with Seat Vibration Isolator Embedded with Different Negative Stiffness Models

The research proposes three types of structural models of the negative stiffness structure (NSS) using steel springs (SS), air springs (AS), and roller springs (RS) for the seat vibration isolator to improve the ride quality in vehicles. A three-dimensional (3D) dynamics model of the vehicle with the seat vibration isolator embedded with the SS, AS, and RS is established under various vehicle working conditions. Based on the genetic algorithm (GA), the dynamic parameters of the SS, AS, and RS are optimized to further improve ride quality. The isolation efficiency of the optimized SS, AS, and RS are then evaluated via the root-mean-square (RMS) accelerations of the driver’s seat (a_ws ), vehicle body pitching (a_wϕb ), and rolling angles (a_wθb ) and the Seat Effective Amplitude Transmissibility (SEAT) of the seat vibration isolator. The research shows that the seat vibration isolators embedded with the SS, AS, and RS remarkably improve the vehicle ride quality in comparison to that without the SS, AS, and RS under different operating conditions. In addition, the isolation efficiency of the SS, AS, and RS is also significantly influenced by their dynamic parameters. With the SS, AS, and RS optimized, the stable value of the dimensionless restoring force under the change of the dimensionless deformation of the seat vibration isolator with the optimized AS is lower than that of the optimized SS and RS; thus, the optimized AS improves the driver’s ride quality better than the optimized SS and RS. Especially, under the random road surface, the a_ws , a_wϕb , a_wθb , and SEAT with the optimized AS are greatly reduced by 73.1%, 9.2%, 8.4%, and 77.7% compared to the seat vibration isolator without the NSS, respectively. Consequently, the seat vibration isolator using the optimized AS should be used to enhance the ride quality of vehicles.