Research On Vibration Characteristics Of A Commercial Vehicle Drive Shaft

Commercial vehicles include: tractors,trucks,engineering dump trucks,special vehicles,with large load capacity and long wheelbase.The commercial vehicle drive shaft has a low working speed and a high torque.The influence of transmission shaft vibration on the NVH of the whole vehicle cannot be ignored.This paper takes the heavy-duty commercial vehicle drive shaft as the research object.the vibration characteristics of the transmission shaft are studied,from the theoretical analysis,model establishment,prototype simulation,experiment and comparison,optimization and improvement.The main contents are:(1)Transmission shaft vibration characteristics.The excitation factors of the vibration of the transmission shaft are studied.Based on the kinematics and dynamics of the single universal joint,the force and vibration of the single universal joint are analyzed.Further,the vibration mechanism of the intermediate support of the three universal joint drive shafts is studied.And put forward the vibration isolation theory of the intermediate support.Provide theoretical support for the study of the vibration characteristics of the subsequent drive shaft.(2)Vibration model establishment and simulation of drive shaft.The vibration of the drive shaft assembly under simulated environment is studied.Build and simplify the 3D solid model of the drive shaft through CATIA,import ADAMS,set the constraints and drive,generate the flexible body shaft tube,solve the various modes of the shaft tube,design the dynamic unbalanced piece,describe the contact force with the intermediate support,and determine the engine 3 The parameters of the speed fluctuation caused by the order of the main harmonics,running simulation,draw the vibration speed with the trend of the gear position,and find that the resonance occurs at the engine speed of 1500r/min,and the vibration frequency frequency domain shows the vibration under the condition of the eleventh gear.The frequency is consistent with 1 frequency of the shaft speed.It is found that the amplitude of the vibration velocity is positively correlated with the angle between the axes,and the angle between the axes needs to be controlled below 5°.(3)The drive shaft vibration test bench was designed and developed.The test bench adopts the electric closed control mode,which can provide different speed and torque matching,which can meet the measurement of the angle between different axes,different lengths and different number of drive shafts.The vibration test results show that the vibration of the intermediate support of the drive shaft reaches the extreme value when the rotation speed is around 1600r/min.The vibration frequency is consistent with the frequency of the shaft rotation speed.The vibration change trend is consistent with the simulation trend,which verifies the correctness of the model.(4)The optimization scheme of the transmission shaft vibration appearing in the common speed section is studied.Based on the ADAMS model,the axial trajectory method,the deceleration map method and the critical speed calculation method are applied to check the internal and external excitation sources of the vibration of the transmission shaft.The main influencing factors of the vibration anomaly are structural resonance rather than engine excitation.It is proposed to replace the shaft tube material with carbon fiber and increase the intermediate support stiffness from 1350N/mm to 2850N/mm.After optimization,the vibration of the drive shaft reaches the ideal range,and the vertical support is minimal.