Vibration Transfer Path Analysis Based On A SUV Left Rear Door Shaking Problem

With the rapid development of domestic automobile industry,the competition among national brands and joint venture brands is becoming increasingly fierce.NVH technology which represents the technical level of a car and affects the customers’feelings of driving experience,is the focus of carmakers’ research and development.When a SUV drove straightly on the washboard road at the speed of about 30km/h,its left rear door shook abnormally.To solve this problem,vibration transfer paths and their contributions were studied in this paper.First,the finite element model of the SUV interior trim body was established to figure out the trim body mode.By comparision with the test result,the maximum error of the frequency of the four modes including the first-order torsion mode and the first-order bending mode is within 11%,and the reliability of the finite element model of the interior body wad verified.Second,the SUV rigid flexible coupling model and the washboard road model were established.The accelerations of each point between the chassis and body were calculated when the car was driving at the speed of 30 km/h on the washboard road.The vibration accelerations of rear doors were calculated based on the accelerations of each point and the finite element model.It showed that the maximum vibration acceleration of the right rear door is 3146 mm/s2 and the maximum vibration acceleration of the left rear door is 8513.6 mm/s2.Then the simulation results and the experimental test results were compared,and the result showed that the maximum error of the peak vibration accelerations is 16.2%,and the amplitude frequency error is 8.3%.So the abnormal shake of the left rear door and the accuracy of the vibration acceleration calculation were verified.Finally,regarding to the problem that vibration accelerations of the two main measurement points on the left rear door were larger,the contribution of each path was calculated and the main transfer paths were found out.It showed that the rear anti-sway bar bush and the left diagonal control arm bush are the main transfer paths,and their contributions are 62.48%and 11.72%respectively.The radial stiffness of the two bushes were optimized based on the response surface methodology.Based on the optimization scheme,the vibration accelerations of the same location were simulated and tested at the same time.The resulted vibration accelerations were reduced by about 29%and 24%respectively,so the effectiveness of the optimization scheme and the transfer path analysis method was verified.