High Frequency Vibration And Acoustic Characteristics Of Powertrain Using Statistical Energy Analysis

The problem of vibration and noise of the powertrain is the industry's long-standing concern, the present research work is mainly focusing on low frequency region. Although the energy level of high frequency is low, it has great impact on sound quality. As the engine developed toward to be lighter may makes the modal density higher, the problem of vibration and acoustic in high frequency is more significant than ever in the past. The present research work mainly uses finite element method (FEM), boundary element method (BEM) or experimental modal analysis methods, and all of them have limitation in high frequency research. Statistical energy analysis (SEA) method is taken to investigate the characteristics vibration and acoustic of powertrain in high frequency in this paper. Most attention has been paid on measurement and validation of SEA parameters, analysis of high frequency vibration response of powertrain and ways of the SEA parameters impact the vibration and acoustic response. The results show that SEA can analysis the vibration and acoustic response of complex structure availably.Methods of getting internal loss factors (the ratio of dissipated energy and stored energy) and coupling loss factors (the ratio of energy transferred to other subsystem and stored energy) by measurement were investigated. The internal loss factor and coupling loss factor of two coupled plates was tested by the modified power injection method. And the vibration response of the coupled plates was measured. Then the SEA model was established in VAONE using the measurement results of internal loss factor and coupling loss factor, and in the same time ,vibration response of random force excitation was calculated. Since the results of formulation and actual measurement agree preferably, the validity of the measurement method and the effectiveness of analyzing vibration response using SEA were proved.Vibration response in high frequency of powertrain was analyzed using SEA. In the sum of the above results, concerning using equivalent mass instead of actual mass, the high frequency vibration response of powertrain was analyzed and was validated by measurement. It is proved that SEA is an effective and accurate way of analyzing the vibration response of powertrain.Based on the above research, the way of internal loss factor, coupling loss factor, equivalent mass and energy ratio influence the vibration and acoustic response were investigated by the method of varying parameters, which were the foundation of further work.