Dynamical Calculation And Experimental Research On Engine Mounting System

Automotive power trains mounting system is an important component of vehicle vibration control and play an important role in improving NVH characteristics and meeting a good plays in comfort.In this paper,we take the rubber mount as a subject studied and we study the power train mounting system from both theory analysis and experimental investigation.In general modeling method of mounting system,people use the static stiffness of rubber mount to build the stiffness matrix of calculation model.However,in actual condition,the rubber mount works at a certain frequency and amplitude of driving forces.Furthermore,the dynamic stiffness of rubber mount has a relationship with the frequency and amplitude of driving forces.So,in this paper,we take the engine idling condition as an example and stimulate the actual conditions of rubber mount,and test its dynamic stiffness in order to build the stiffness matrix of mechanical model to calculate the dynamic characteristics of mounting system in actual condition.Secondly,this article uses the traditional method based on mechanical hammer for the experimental modal analysis of mounting system.During the test,the natural parameters are different when we use different mass hammers because of the non-linear of rubber mount dynamic stiffness.Due to the deficiencies of traditional modal analysis, we use operational modal analysis to identify the modal parameters of mounting system in actual condition.Taking into account the modes of mounting system is intensive this paper use PolyMAX which is produced in recent years and has a better accuracy when identify modal parameters from system with intensive modes.The modal parameters identified are verified by MAC.In operational modal analysis,the modal parameters are more close to the dynamic characteristic of system in real working condition,because the date is directly come from the real working condition of engine mounting system.The errors between modal parameters calculated by stiffness matrix constructed with dynamic stiffness values and operational modal parameters are reduced significantly compared to modal parameters calculated by static stiffness values.Therefore,the mechanical model established by dynamic stiffness of rubber mount in actual condition can simulate the dynamic characteristics better.And this method has some sense for dynamic characteristics analysis of engine mounting system, optimum design and reduction of vibration and noise in specific working condition.