偏相干分析在客车降噪中的应用

车内低频噪声一直是汽车NVH研究关注的重点问题,常需要找到对噪声影响较大的振动结构进行改进,但是振动对场点的贡献并不能代表对整个声场噪声的贡献量。针对多峰值多场点的车内声场问题,引入"总相干系数"和"相干系数和"的概念对现有的偏相干分析方法进行改进。对某型客车的车内噪声进行小波包分解,得到车内声场的声学特性,确定研究的频率范围。通过对各板件振动与车内测点噪声信号进行偏相干分析,确定对车内声场影响较大的结构,并在实车上实施了改进措施。结果表明,车内噪声测点声压级降低0.5 d B~2 d B,为有效降低客车车内噪声提供了指导方向。

Application of Partial Coherence Analysis in Interior Noise Reduction of Passenger Cars

The interior low-frequency noise has been attracted the focuses of automotive NVH research. It always needs to identify the vibrating structures that have greater impact on interior noise. Contribution of vibration to the noise of field points fails to completely represent the contribution to the whole interior acoustic field. For the interior acoustic field with multiple frequency peaks and multiple field points, the "total coherence coefficient "and "coherence coefficient sum", as two new parameters were introduced to improve the existing partial coherence analysis method. Then the interior noise of the passenger car was analyzed by wavelet packet and the acoustic characteristics of the interior acoustic field and the concerned frequency range were obtained. The structures having greater impact on interior noise were identified by the coherence analysis of panel vibration and noise signal and the improvement measures were carried out on the actural car. The results of test showed that the noise of field points reduces 0.5-2dB. This method provides a reference for reducing the interior noise of passenger car with multiple field points.