| As a surface strengthening process,shot peening can improve the fatigue strength of material effectively.It is generally believed that the residual stress introduced by the shot peening can improve the fatigue resistance of the material,but the shot-peening increases the roughness of the material surface while introducing the residual stress,which has a negative effect on the fatigue properties of the material.In addition,there is a certain correlation between roughness and residual stress.Therefore,it should be paid enough attention of the residual stress introduced by shot peening,the increased roughness,the correlation between the two,and the effect on fatigue life.In this paper,the respective advantages of experimental research and numerical simulation were combined.Based on the 2024 aluminum alloy,shot peening and related experimental research were conducted,while the corresponding ABAQUS finite element numerical model were established to simulate the experiment process.The correctness and validity of the model were tested through comparing the results between experiment and simulation.Then,the influence of parameters was study by numerical simulation.The main research was as follows.(1)2024 aluminum alloy specimens were treated by shot peening,and their roughness Ra were measured by experimental measurement.The numerical model of multiple shots was simulated by ABAQUS/Explicit.The Ra were obtained from the statistics of nodal displacements along some sample paths based on the proposed discretized formula.The correctness and validity of the simulation method are verified by the comparison between the experiment and the simulation results.Finally,the effect of the shot peening parameters on the roughness was studied by using the numerical model.(2)The residual stress of the specimen after treating by shot peening was measured,and the residual stress curve of the shot peening stress distributing along the depth was obtained.At the same time,the corresponding residual stress curve was obtained by the multiple shots numerical model.Through comparing the results to verify the simulation method.The influence of shot peening parameters on residual stress is studied by numerical simulation.Finally,the linear fitting and correlation analysis of the roughness and residual stress under different parameters are carried out,and the correlation between the characteristic value of the residual stress and the corresponding roughness was established.(3)Three-point bending fatigue test on 2024 aluminum alloy specimens with shot peening and not shot peening were treated by fatigue testing machine,and the experimental results of fatigue life were obtained.A two dimensional plane stress model of the specimen was established by ABAQUS.The extended finite element method was used to simulate the initiation and propagation of the crack under cyclic loading.The correctness of the extended finite element numerical model was verified by comparing the experimental results.Finally,the model was used to study the effect of residual stress on fatigue life under different load conditions. |
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