A Research On Accelerated Fatigue Test Method For Commercial Vehicle Transmissions

As an important part of power system of commercial vehicle,commercial vehicle transmission plays the role of regulating power and torque,speed and so on,itadapts to the car starting,acceleration,deceleration,parking and other driving state is by changing the transmission ratio,these have a great impact on the performance of the whole vehicle’s power,economy,comfort and lifetime.Therefore,in order to further accelerate the development of new products,in the premise of ensuring the reliability of commercial vehicle transmission,it is necessary to improve the transmission fatigue life test technology to shorten the development cycle.This paper based on the theory of fatigue life prediction,in the base of a large number of transmission fatigue life test,was improved the test method of fatigue life of transmission,and puts forward the method of technology accelerated life test method according to the theory of accelerated fatigue test,and using finite element simulation to forecast the fatigue life of the transmission,which has theoretical and practical meaning to master the state properties of commercial vehicle transmissions fatigue life.First of all,this paper makes a study and summary of the factors affecting the fatigue life,studies the fatigue damage theory of commercial vehicle transmission.This paper explores the characteristics of different fatigue damage theory,through the research methods of accelerated fatigue test theory and fatigue life calculation,the method of accelerated test study of fatigue life are summarized.Secondly,a finite element model of transmission gear is established,by applying different input torque to the gear,the stress process of transmission gear under constant amplitude fatigue test and accelerated fatigue test conditions have been simulated,and the gear dynamic contact stress and dynamic bending stress under different conditions have been simulated separately,which create conditions for the analysis of fatigue life the following.Again,the S-N curve of gear material is established in FE-SAFE software,select the fatigue criterion suitable for the simulation of gear meshing characteristics,combined with the results of stress and strain whichobtained by the dynamic analysis of the gear,forecast and analysis on the fatigue life of different test conditions on the gear respectively,then use the acceleration coefficient which hae been verified by fatigue life simulation to enhance loading torque of the subjects of the gearbox gear referencing constant amplitude fatigue test method,and derive a accelerated fatigue life test plan which suitable for the transmission of commercial vehicle.Finally,introduces the test system of transmission fatigue life test,and then set up a set of test overall operation process,on the basis of the operation process,running the experiment according to the established transmissionaccelerated fatigue life test scheme.The failure of the transmission is analyzed and summarized in the process of the experiment,and the experimental results are compared with the finite element simulation results.