Optimization And Application Of Internal Vibration Performance Of Bus Based On Transfer Path Analysis

With the improvement of people's living standard and their awareness of environmental protection,noise,vibration and harshness(NVH)has become an important indicators to evaluate the performance of engineering machinery.The transfer path analysis(TPA)is one of the main methods of NVH analysis of bus.Although there are many research achievements on the TPA at home and abroad,it is mainly focused on how to improve the efficiency and principle of TPA and there are few literature on the improvement of its precision and the complete application process.Therefore,to improve the accuracy of transfer path analysis,the method of improving the transfer path analysis based on mount stiffness method was put forward,and the method applied in the vibration problem of the medium bus was verificated so that optimization and application was carried out in this paper.The main work are listed as follows.Firstly,vibration signals of the key positions of the medium bus in idle were collected.By numerical and spectral analysis,the vibration levels of key testing points were evaluated.Then,a preliminary improvement plan in the internal vibration of the bus was put forward by transfer path analysis based on the inverse matrix method.Finally,the fitting signal of inverse matrix method was compared with the measured signal,and the results show the shortcomings of the method.Secondly,an improved mount stiffness method is put forward based on theoretical basis of conventional transfer path analysis and the method applied in the vibration problem of the medium bus was verificated.Meanwhile,contribution analysis based on TPA of results indicate the improvement direction for vehicle vibration problems in the two working conditions.Thirdly,combined with finite element simulation,modal synthesis and multi-body dynamics analysis method,the transfer path with larger contribution was improved.Firstly,the exhaust system support was redesigned,and the cantilever beam structure was changed to the integral structure,which improved the natural frequency and the modal shape.Secondly,combined with the mounting attaching point dynamic stiffness analysis,modal contribution analysis and modal strain energy calculation,the specific method of improving the frame structure was presented.Finally,Isight software and Matlab software are used to optimize the stiffness of the front suspension based on the DOE method.The results showed that the frequency distribution range and the modal decoupling rates both meet the engineering requirements.Finally,combined with the actual situation,test data and simulation results,the company improved the exhaust system support,frame structure and suspension system of the prototype bus,and relevant measures for the medium bus was put into practice.The vibration test results of the prototype bus before and after the rectification show that the vibration level of the steering wheel and the rear seat guide was obviously reduced,and the vibration level had already met the requirements of the company.