Component Contribution Analysis Of Vehicle Indoor Pass-by Noise Based On OPAX Method

Although the high speed development of the automotive industry has brought great convenience to our life,automobile noise pollution is becoming more and more serious at the same time.The vehicle pass-by noise is known as a typical indicator of the automobile noise level,so achieving better control of it has become a common goal for governments and automobile manufacturers all over the world.As one of the fundamental methods to study the noise,vibration and harshness(NVH)problem of automobiles,transfer path analysis(TPA)technology has stimulated a variety of methods in practical application,including traditional TPA method,operational transfer path analysis(OPA)method and operational-X transfer path analysis(OPAX)method.Each of these three methods has different applicable occasions with different advantages.The OPAX method,which combines high accuracy of traditional TPA method and high efficiency of OPA method,achieves a good compromise between accuracy and time consumption,and has broad potential to be applied in industry.However,few studies have been conducted on the application of OPAX method in the vehicle pass-by noise problem.Considering the fact that the noise level of a certain passenger car fails to meet the design requirement at its trial production stage,this paper proceeds from the goal of contribution analysis of the vehicle pass-by noise.Experimental research was carried out on low-noise four-wheel-drive revolving drum test table in the semi-anechoic chamber using OPAX method.First,the main noise sources of a vehicle under specific working condition were located by an acoustic camera quickly and accurately.A series of work aiming to identify the main noise sources were conducted including establishing the OPAX model,measuring the operational data,testing the frequency response functions,calculating the operational loads and computing the path contributions.Then the shielding method was used to conduct a comparison test to further verify the feasibility of applying OPAX method to the component contribution analysis of the vehicle indoor pass-by noise.Finally,according to the analysis results,feasible rectification measures were proposed to provide reference for the improvement of the NVH performance of the target vehicle.