Research on the modeling and influence of flexible sub-frame on vehicle performance: Considering the high frequency excitation of the engine

The sub-frame which insulates the vehicle chassis from the high frequency excitation of the engine has a great influence on vehicle performance. Currently, the research on the influence of sub-frame on vehicle performance mainly aims at the vehicle vibration attenuation and noise reduction performance, and there is a lack of research on vehicle handling stability and the accurate description of the high frequency excitation force of the engine. This paper is characterized by a more accurate description of the role of the engine in the sub-frame excitation force, as well as a more comprehensive study of the impact of the sub-frame on vehicle performance. Firstly, the dynamic engine model with high frequency excitation changing with cylinder pressure is built, and the flexible sub-frame model is built by modal method. Then they are integrated into the vehicle simulation model. The simulation is conducted in the conditions of acceleration resonance, ride comfort and handling stability. Through the simulation this paper analyses the influence of the different key design parameters (mass, structure stiffness, mounting stiffness and damping coefficient) of sub-frame on the vibration isolation performance of sub-frame to vehicle, vehicle ride comfort and handling stability. This research may improve our understanding of the impact of the sub-frame and its mount system on the vehicle performance under the high frequency excitation of the engine, so as to provide an effective reference for their design.