Sound Sources Identification And Frequency Response Analysis For Interior Noise Of Heavy Duty Commercial Vehicle Cab

The physical and mental health of the ride personnel and driving safety are harmed by interior noise, so it is important to predict interior noise in the early of the new model development, finding out the main causes of vehicle noise and putting forward the corresponding improvement measures to reduce the driving indoor noise have the extremely vital significance. The research method of interior noise basically has three kinds, namely the finite element method the boundary element method and statistical energy method. Because, this study researched driving indoor low-frequency structure noise, so the finite element method was chose for research method of this paper.This paper is based on the research of cab noise analysis and control, a subproject of National"863"Program. Cab and cavity finite element models were established, based on the finite element method, they were analyzed by natural modal and validated through the experimental modal. In addition, according to the principle of similar model, the simplified cab and cavity models were established. And there made a comparative study between simple model modal, detailed models modal and experimental modal. In order to analyze interaction between the structure and the cavity, this paper established the simplified acoustic-structure coupled model and the coupled modal was studied. The conclusion that the sound pressure of cab is decided by the dynamic characteristic of structure and the acoustic characteristics of cavity was verified through this study. Imposed the incentive acceleration which was obtained by the vehicle road test to the simplified acoustic-structure coupled model to make a frequency response , and frequency response results and experimental results were compared, and the relevant analysis was done too. On the basis of this, the overall driving indoor noise level were studied, and the simulation results were compared with the results of test.The data obtained by the vehicle road test were classified, and a sound source recognition model was established, in this model, floor vibration ceiling vibration and backwall vibration were considered as vibration source, the engine compartment noise and tire noise were considered as noise source. The four conditions data were processed using the software PULSE.Labshop, and the main reason that driving indoor caused noise was discovered, through the spectrum analysis and coherent analysis and put forward the corresponding measures to reduce noise.