Vibration Analysis Of Motorcycle Based On OPAX Transfer Path Method

With the improvement of people’s quality of life,the users’ pursuit of motorcycle vibration comfort is getting higher and higher.How to diagnose and improve motorcycle vibration is an urgent engineering problem for motorcycle enterprises.In this paper,a motorcycle has large vibration problem,using the transfer path analysis(TPA)method to analyze and diagnose its vibration transfer path,find out the main transfer path,and implement the corresponding improvement,finally achieve the purpose of improving the motorcycle vibration comfort.(1)Comparing the analysis accuracy,modeling time and application scope of traditional Transfer Path Analysis method,operational Transfer Path Analysis method and OPAX method,considering the analysis accuracy and modeling time,as well as the characteristics of rigid connection between motorcycle engine and frame,OPAX method is applied to carry out vibration transfer path of motorcycle.Multi-band model suitable for mounting rigid connection is used to identify the load of motorcycle structure.(2)Considering that the engine vibration is transmitted to the rider through the handlebar,foot and seat,and the convenience of vibration testing,vibration testing and vibration comfort evaluation were carried out on the left hand handle,left and right foot and seat.It is found that the vibration comfort of the left hand handle is poor at 6600r/min,7300r/min and 7700r/min,and the cushion is poor at 7700r/min.By comparing the weighted RMS of the acceleration in the xyz direction of the left hand handle and the seat,it is found that the main vibration direction of the left hand handle and the seat is z direction.Therefore,the vibration transfer path analysis of the left hand handle z direction and the seat z direction is determined.(3)The transfer path of OPAX vibration transfer path model was constructed by motorcycle finite element model.Combined with the evaluation results of motorcycle vibration comfort and the test path points and extra indicator points,a motorcycle OPAX vibration model was established with engine suspension as the path points,handlebar and seat cushion as the target points,and four points on the frame as the extra indicator points.Based on the path transfer function of the motorcycle finite element model and the vibration data of the extra indicator points,the working load of the path points is identified.(4)The simulation results of motorcycle OPAX vibration transfer path model are compared with the experimental results,the peak frequency is consistent,the amplitude is close,the comparison results verify the feasibility of motorcycle OPAX vibration transfer path model.The comprehensive contribution analysis method combining amplitude and phase was used to analyze the vibration transfer paths of handgrip and seat z-direction.The main transfer paths were identified as left front suspension z-direction and right front suspension z-direction when the xyz direction was not grouped,and the main transfer paths were left front suspension and right front suspension.The analysis of the vibration transfer characteristics of the main transfer path shows that the large vibration contribution of the main transfer path is caused by the transfer function.(5)According to the principle of multi degree of freedom system modal decoupling,in view of the multi degree of freedom system also can begin from a single degree of freedom system,analysis of the mass,stiffness and damping of the influence of the transfer function,and puts forward the reduce the left front suspension,right front suspension stiffness,and increase the handle tube,cushion the support stiffness of the improved scheme,and the simulation to predict the effect of the improved scheme,The total weighted root mean square acceleration of the seat at 7700r/min decreased by 15.35%,and the total weighted root mean square acceleration of the handle at 6600r/min,7300r/min and7700r/min decreased by more than 10%.The vibration comfort was significantly improved.The total weighted RMS of the cushion at 7700r/min decreases by 15.35%,which meets the requirements of vibration comfort.At the same time,the strength of the improved structure is checked,and the results show that the improved structure can not only effectively reduce the vibration transmission,but also meet the strength requirements.