Fatigue Reliability Analysis And Evaluation Of The Drive Axle

The drive axle is located at the end of the automobile's powertrain,including the transmission system and the load-bearing system.The transmission system realizes the speed reduction and the torque increase,and ensures that the wheels on both sides can turn at different speeds.The load-bearing system is the basis for the installation of the transmission system and brakes,and is subject to excitation from the suspension and wheels.It can be seen that the drive axle is a key component of the whole vehicle.Whether the transmission system or the bearing system fails,it will threaten the safety of the driver and passenger,and bring hazards to the road traffic.In fact,the working environment of the drive axle is complicated and it is prone to fatigue failure.Therefore,the reasonable and effective fatigue reliability assessment of the drive axle is an important guarantee for the safe and reliable operation of the whole vehicle,and is also of great significance for improving economic efficiency.Due to the complexity of the fatigue problem of the drive axle,there are still some problems that need to be studied in the existing fatigue reliability analysis methods.Aiming at the fatigue reliability analysis under random variable amplitude load,based on Miner's damage accumulation theory and "stress-strength" interference model,this paper studies the fatigue life calculation method and reliability analysis method,which can be verified by the fatigue test data of the drive axle and the simulation analysis results,so that the existing engineering problems can be solved and the application range of reliability methods can be expanded.The main research contents of the thesis are as follows:(1)The thesis proposes the probability damage rule when the fatigue life obeys the lognormal distribution and Weibull distribution,and establishes the reliability interference model of "deterministic cumulative damage-probability damage threshold".The validity of the model is verified by the tests with variable amplitude load.(2)The thesis conducts stress analysis and damage calculation on the drive axle transmission components under bench test and test field test conditions respectively,and applies the proposed reliability model for fatigue reliability assessment.By compare with test results and simulation analysis methods,the effectiveness of the analytical methods used is verified.(3)The finite element analysis of the welded axle housing under the load conditions of the bench test and the test field is carried out,and the equivalent structural stress of the weld is calculated by the main S-N curve method.The proposed model is used for reliability evaluation,and the results are compared with the experimental results and simulation results.Finally,the weakest part of the weld is optimized to improve the fatigue reliability of the axle housing.