Research And Numerical Simulation Of Fatigue Performance Of 2024 Aluminum Alloy Shot Peening Forming Panel

Shot peening,as the preferred processing method for wing panels,has many advantages such as no mold forming,high forming accuracy,and improved fatigue performance.However,if the crater generated on the surface is too large,it will easily cause stress concentration and increase in roughness and deteriorate surface performance.Ultrasonic strengthening can accurately align the shot peening formed wall panels.Ultrasonic strengthening after shot peening can further improve the fatigue performance and has a relatively small effect on the roughness.How to quantify the impact of these shot peening processes on fatigue performance and obtain the optimal parameters in the composite process has become an urgent problem in the shot peening processing of aircraft wall panels.In this paper,the composite process of shot peening forming,shot peening,and ultrasonic strengthening is used to strengthen the surface of the detail fatigue rate(DFR)specimens of the wall panel,and the effect of different shot peening parameters on the surface properties is studied.The ABAQUS random shot peening finite element model was established to study the impact of shot peening parameters on the surface properties of the specimen,and the fatigue life prediction model of DFR specimens was established using ABAQUS and FE-SAFE software to optimize subsequent shot peening parameters and fatigue life prediction provide guidance.The main research contents are as follows:The 2024 aluminum alloy DFR benchmark and cut-off samples are shot peened,shot peening formed,ultrasonically strengthened,and fatigue tested.The residual stress,microhardness,and roughness changes of different samples are measured,and different pit diameters,ultrasonic strengthening,and The influence of secondary strengthening and other factors on the fatigue life of the specimen and the DFR performance.The study found that the fatigue performance of the pit diameter is the best at 1.4 mm,and both ultrasonic strengthening and secondary strengthening can improve the fatigue performance of the specimen,and the effect of ultrasonic strengthening is more significant.The random shot peening finite element model established by the ABAQUS discrete particle element method is used to simulate the shot peening with different shot peening parameters.The simulation results show that the depth of the residual stress field and the maximum residual stress depth increase with the increase of the shot peening speed.The increase in shot peening coverage results in an increase in the value of residual stress on the surface,and the depth of the residual stress affected layer remains unchanged.With the increase in the diameter of the shot peening forming pit,the depth of the residual stress field increases,and the maximum residual stress does not change.Comparing the simulation results with the experimental research results,it is found that the two are basically the same.The finite element method combined with ABAQUS and FE-SAFE is used to predict the life of the benchmark and cut-off specimens,and the simulated life is compared with the test life.It is found that the simulation and test results are basically consistent,which proves the effectiveness of the method.This model was used to compare the fatigue performance of different shot peening speeds and coverage rates.It was found that the fatigue performance was better when the shot peening speed was 60 m/s and the coverage rate was 300%.