Analysis Of Door Jittering Based On Transmission Path Method And Vibration Isolation Rate

With the improvement of automobile design level and production technology,more and more attention is paid to the comfort performance of automobile,the problem of vehicle noise and vibration control is becoming more and more important.Noise,vibration and comfort are referred to as the NVH problem for vehicles in the automotive world.Automobile manufacturers also take the improvement of noise and vibration performance as the highlight of new cars,and put a lot of effort into solving the problem of vibration and noise of vehicles.The jitter problem of automobile closures seriously affects the quality of cars.Therefore,it is of great significance to explore the causes of automobile closure jitter and to form a feasible method of evasion analysis.In this thesis,the phenomenon of abnormal jitter of the left rear door is studied when a certain SUV travels on the washboard pavement with a speed of 15 km / h.Firstly,the finite element model of the whole vehicle is established,and the precision of the finite element model of the whole vehicle is verified by comparing the constrained mode of the vehicle door.The acceleration response of C column side-circumference and left rear door are outputted by the test acceleration excitation in the wheel center of the finite element model of the whole vehicle,and compared with the measured acceleration response,the feasibility of the loading method is verified.In the finite element model,the road test condition of the washboard is simulated effectively,which provides an effective analysis model for the subsequent analysis.Based on the virtual prototyping model and the transfer path analysis,the important transfer paths,such as the connecting point between the lateral stabilizer rod and the body,the installation point of the door lock,are found.The results show that the analysis method used in this paper has certain reference and feasibility.Based on the principle of isolation rate,a theoretical model of isolation rate of single rubber bushing in MATLAB is established.The effect of stiffness change on isolation rate of the system is explored.It is found that proper reduction of stiffness value of rubber bushing is beneficial to the improvement of vibration isolation.In the finite element mounting system,the weak plates are found by modal contribution analysis,and the dynamic stiffness of the mounting attachment point is improved by optimization.The analysis shows that the vibration isolation effect can also be improved by increasing the dynamic stiffness of the connection point.Based on the analysis of the cause of door jitter and the study of the factors affecting the vibration isolation rate,the stiffness of the transverse stabilizer bushing is reduced by 30% in the finite element model of the vehicle.The peak acceleration of the left rear door is reduced by 22.9%,and the dynamic stiffness of the attaching point of the lateral stabilizer rod is increased,while the peak value of the acceleration of the left rear door decreases by 32.8%.In addition,we also increased the stiffness of the door sealing tape by two times,increasing the door sealing reaction force.The peak acceleration of the left rear door decreases by 26.3%.The reliability of the jitter optimization scheme is verified by the actual vehicle test.The jitter analysis and optimization method established in this thesis can provide theoretical guidance for the jitter problem of the closing parts of other vehicle models.