Diesel Sedan Interior Low Frequency Noise Characteristics Of Study

With the rapid development of the automobile industry as well as people's energy-saving and environmental protection requirements, high-speed moving vehicles, light direction, making vehicle noise, vibration and comfort (NVH) problems emerged, the quality of light is increased Motor vehicle body structure of the low-frequency vibration and noise within the vehicle, in particular the resonance of low-frequency noise. Diesel cars which NVH issues become more prominent is an important development trend of the car. This paper made a diesel car for the study and application of numerical simulation and experimental combination of methods to study the low-frequency noise inside the car's characteristics, In the process of numerical simulation takes full account of the interaction of the air inside the vehicle and body structure so that the results closer to reality.In the first, on the basis of the experimental modal analysis of the body in white, a car body structure of the finite element model, the cavity of cabin acoustic sound field of the finite element model and the structure-acoustic coupled model of the car structure and the cavity of cabin were established. And modal analysis was performed respectively for the models that were established above all. The correctness of the model was verified by the results of the comparison of the modal analysis by finite element model of the body in white and experimental modal analysis. Then the use of multi-body dynamics software ADAMS to build multi-body dynamic model of the car, the driving forces which derived from the engine and road were extracted respectively and the dynamic analysis techniques of the structure and sound field were applied. A detailed study of the dynamic characteristics of the coupled acoustic-structure system of the car was performed. The acoustic response of the coupled system by the driving forces which derived from the engine and road was analyzed and the road test results as well as calculated values were compared. The results show that: the magnitude of the car's interior noise increased as engine speed increase. The noise peak inside the vehicle was more at low-speed, but smaller changes in the amplitude. The level of the noise inside the car increased obviously and the noise peak was concentrated mainly in a few frequency points. Through the contrast of the measured value and calculated value of the cabin noise can be seen that the tendency was good to correspond with them in lower frequency bands and the gap was large in the higher frequency bands. The results of the further studies for acoustic contribution analysis of the vibration of the body panels showed that clothes tree panel, squab panel and the middle part of the floor panel which were the main noise source inside the car of contributions to the acoustics were the main panel for contribution; finally to direct at clothes tree panel, squab panel and the middle part of the floor panel which had larger contributions cabin noise in the analysis of panel contribution. And local stiffness was increased through the optimization of rebar of the more violent parts of vibration. The results for optimization analysis showed that there were good effects for clothes tree panel, squab panel and the middle part of the floor panel and the arrange of the strengthening rib were reasonable, which can reduce the amplitude of vibration apparently. The goal to reduce car noise had been to achieve.