Based On Operational Transfer Path Analysis Method Research On Identification Of Vehicle Interior Noise

In the working state of an automobile,vibration or noise generated by engine body structure,intake,exhaust system and other components is transferred to the vehicle through the body or air,after the superposition of the sound cavity in the car,vehicle interior noise is formed,which reduces the driving and riding comfort.This paper aims to identify the input excitation and transfer path that affect the interior noise,to provide a comprehensive and reliable "test-calculate-analysis" comprehensive research method for reducing interior noise.Based on the application theory of OTPA method,crosstalk cancellation between input signals is realized by singular value decomposition and principal component reduction method,and least square method is used to fit the singular value of input signals to calculate the transfer function and improve the calculation accuracy.Comparison analysis between the test data and the OTPA calculation of interior noise response point,to prove that there was no path omission through the consistency of the sound pressure amplitude of the two with the change of speed,at the same time,the reliability of the system energy transfer network model built based on the calculation formula of OTPA contribution was also proved.Root mean square calculation.FFT transformation,order analysis and average auto power spectrum calculation are adopted to the contribution data post processing,under the condition of speed,order and frequency,to analysis the contribution of each path.For example,to analysis the contribution of interior noise of a measured vehicle,the vibration acceleration and sound pressure signals of the vehicle under stationary idling and acceleration conditions were obtained,after many tests,calculations and analyses,it is concluded that the large contribution to integrated interior noise is the structure path of engine left mounting passive side Z direction and the air path of engine compartment,the large contribution of peak interior noise is the structure path of engine right mounting passive side Z direction and the air path of engine compartment.Accurate judgment was made as to whether the large contribution was caused by one or two factors in the input excitation and transfer path.The response modification analysis method and the coherent analysis method were adopted to identify the interior noise,after comparative analysis,the path that had a great impact on the peak interior noise was consistent with the result of contribution analysis,which verified the reliability of the OTPA numerical calculation method and contribution analysis method.The general applicability of this method is demonstrated by many experiments.