Research On Low Frequency Noise Reduction Of Heavy Truck Based On Wavelet Coherence

With the rapid development of automobile industry,when the power performance meets people’s needs,consumers pay more and more attention to ride comfort,which were evaluated by the interior noise.The interior low-frequency noise is mainly the structural noise,which caused by the vibration of vehicle panel,and it can be reduced effectively by optimizing.This paper takes a heavy truck as the research object,by processing the stationary signal and the non-stationary signal,a method for calculation the panel contribution is established,which based on wavelet coherence analysis,the influence of the panel on the interior noise in different frequency range is obtained,and the corresponding noise reduction method is proposed.Firstly,carry out road test to get the sound pressure signal of measuring points.wavelet packet analysis obtains that the energy of sound pressure signal is mainly concentrated in the low-frequency band,spectrum analysis shows that there are many peaks in the low-frequency range.Then,under the condition of constant and acceleration speed,collecting vibration signals of vehicle panel and noise signals of measuring points.For stationary signal,by using the partial coherence method,obtain the correlation relationship between them in a certain frequency band.For non-stationary signal,by using wavelet coherence analysis,which can describe the correlation between two non-stationary signals in time and frequency domain,and using the phase information to assist judgment.The significance test of the calculation results under a certain degree of confidence is carried out,which ensures the accuracy of the method.After the validity is verified by the simulation signal,calculate the correlation between the measured non-stationary signals,obtain the influence of vibration signal on noise signal in continuous frequency range.Finally,combine the results of partial coherence analysis and wavelet coherence analysis,find out the specific panel to be optimized,and implement damping treatment.Carry out the verification test under the test environment unchanged.The results show that the maximum peak value of the sound pressure in the optimized vehicle decreases by 7d B(A),and the OA value of the right ear of the driver is 68.95 d B(A),which is less than the 70 d B(A)required by the subject.This method effectively reduces the interior noise and improves the riding comfort of the heavy truck.In summary,this paper proposes a method for calculating the panel contribution,which based on wavelet coherence analysis,this method is different with simulation analysis,which using experiment test,by applying partial coherence in the concerned frequency band,combine with wavelet coherence analysis in the continuous frequency range,to find out the influence of vibration signals of different vehicle panels on the sound pressure signal.This method provides a reference for solving the problem of coherent analysis of non-stationary signals in engineering applications.