The Vibration Analysis For A Bus Chassis

The chassis system, whose vibration characteristics has a direct impact on vehicle NVH, is the core module of the vehicle. Chassis vibration sources include road incentives, the powertrain incentives, the drive shaft incentive and so on, and they are connected with frame, rear axle, exhaust system, steering system and other subsystems by suspension, powertrain mounting system, the intermediate support system of drive shaft and other vibration isolation devices directly or indirectly. The ultimate purpose of vibration analysis is rational planning each subsystem natural frequency, avoiding resonance and maximize reducing the transmission of vibration by the vibration isolation devices.Different anslysis methods were chosed to resolve the different subsystems. Mode analysis of frame was used to get the natural frequencies and mode shapes, which is based on finite element method, and modal test was carried out to verify. A6DOFs dynamics model for powertrain mounting system was built based on vibration theory, and the Lagrange vibration equation was solved to get the rigid body modes and mode shapes, which is Implemented energy decoupling. The drive shaft rigid-flexible coupling model was built based on virtual prototyping technology to obtain the natural frequency of drive shaft, which was used to study the impact of speed, torque, and intermediate support stiffness to the drive shaft’s vibration. Establishment of rigid-flexible coupling model of the vehicle, vibration transmission of Suspension was studied through the ride simulation and the ride experimental.The quency distribution of the various subsystems and vibration isolation performance of the vibration isolation system was analyzed and evaluated based on previous modal analysis and dynamic simulation. Robust optimization of powertrain’s mounting system natural frequency and energy decoupling was carried out with the genetic algorithm of multi-island and Taugchi method. Vibration isolation performance of the drive shaft’s intermediate support and suspension was improved by changing the stiffness of the drive shaft’s intermediate support and the damping of suspension. Contrasted with the previous model, the natural frequency of the optimized chassis model had a reasonable distribution, and the vibration isolation performance of powertrain mounting system, intermediate support of drive shaft and suspension had been significantly improved.