Vibration Analysis And Optimization Of Transmission Shaft For Heavy Truck

With the improvement of people's living standards,and the premise of ensuring safety,ride comfort is getting more and more attention.The drive shaft is one of the main transmission parts of a car,and its vibration characteristics seriously affect the comfort of the vehicle.The thesis takes the drive shaft of a heavy truck as the research object,establishes its dynamic equation and virtual prototype model,optimizes the parameters of the drive shaft vibration,reduces the vibration of the drive shaft,and improves the NVH performance of the vehicle.The main content of the thesis research is:Using space projection geometry and space geometry theory,the kinematics and dynamics equations of the cross-axis universal joint are established.The relationship between the output shaft speed,additional bending moment and input shaft rotation angle is analyzed.Based on the road excitation simulink model,a simulink model of the vehicle's two-degree-of-freedom vibration quarter system is established to analyze the up and down movement of the rear axle during the driving process of the vehicle.Based on the vector method,this thesis establishes the relationship between the drive shafts and the rear axle movement.Taking the drive shaft assembly system as the research object,considering engine output fluctuations and rear axle bounce,a mathematical model of coupled bending and torsion vibration of the drive shaft assembly system is established according to the concentrated mass method and the flexibility influence coefficient method,and the Runge Kutta method is adopted.The differential equations are solved,and the effects of different shaft tube outer diameters,wall thicknesses,rigidity and damping of the intermediate support on the vibration characteristics of the intermediate support are respectively studied.Then,using the above four parameters as optimization variables,the optimization objective(the amplitude of the lowest intermediate support)and constraint conditions are proposed,and the particle swarm optimization model is established to obtain the optimization results.This thesis uses CATIA and Adams software to establish a dynamic simulation model of the drive shaft assembly system and study the change law of the vibration characteristics of the intermediate support at different speeds and torques.The thesis uses the bench test platform to perform vibration tests on the drive shaft,and compare the test results.