Torsional Fatigue Test Method Research Of Automobile Half Shaft Based On The Actual Load Spectrum

Automobile half shaft torsion fatigue performance has an important influence on the fatigue reliability and safety of automobile.To this end,automobile half shaft torsion fatigue test has become an essential part during the process of design and development.At present,the domestic shaft torsion fatigue test method is basically from abroad or directly loaded with a standard load spectrum.There is a big difference with the domestic automobile axle actual driving conditions,which likely to cause over-testing or under-testing.Therefore,based on actual running condition of the automotive half shaft,the paper established an automobile half shaft torsion fatigue test method.Through the study of driving load spectrum sampling method,the load spectrum analysis method,the load spectrum compiling and loading method,the accuracy and efficiency of the half shaft torsion fatigue test was improved.There is an important theoretical significance and application value.Firstly,half shaft torque measurement system was established by the use of wireless telemetry and full bridge strain gauge.Torque calibration test was conducted in the high precision calibration test rig,and the sensitivity of the torque measuring system was confirmed using the least square method.The actual spectrum was collected using different drivers and Pascal cycle in the proving groundSecond,the actual spectrum was pretreated by removing the small signal and filtering.The repeatability of the spectrum was verified through the statistical analysis and power spectral density analysis.The damage of each cycle of load spectrum was calculated according to the Palmgren-Miner rule and the modified axle S-N curve.Sample spectrum was extracted based on the amount of damage.Uusing double parameter four-point rain flow method performed statistics count of actual spectrum.Overall cycles of vehicle half shaft were obtained accurately according to the method of rain-flow matrix extrapolation.Then,based on the overall cycles and the variable average method,two-dimensional spectrum of mean-amplitude was converted into one-dimensional amplitude cumulative cycle spectrum.Eight program spectrum was compiled using equal-area method.Damage was validated at the same time.On this basis,combined with loading cycle and loading sequence,half shaft torsion fatigue load spectrum was obtained using symmetrical cycle.Finally,torsion fatigue test rig was designed and built by the use of hydraulic servoPID control system.According to PID parameter adjustment,the torque signal was controlled precisely.Load spectrum was performed and validated with loading test.Finally,a torsion fatigue test method was established based on the actual spectrum of automobile half shaft.