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研究了激光冲击强化对7050-T7451铝合金小孔件疲劳寿命和断口形貌的影响。采用ABAQUS对峰值压力2.7GPa下小孔构件孔壁与表面上的应力分布进行了研究,并基于仿真结果对试样进行激光冲击强化试验和疲劳拉伸试验。结果显示,激光双面冲击强化在板料两侧形成一定深度的残余压应力影响层,而在中心形成一定范围的残余拉应力层,这也是导致疲劳源由孔角向孔壁中心转移的主要原因;在应力水平165.8MPa、195.0MPa和275.4MPa下,试样的疲劳寿命分别平均可增大451%、216%、116%;经激光冲击强化后,试样的疲劳源位置由孔角转移至孔壁内部,且疲劳裂纹扩展区面积明显增大。研究表明,激光冲击强化能明显改善铝合金小孔构件的疲劳性能,但强化效果随外加载荷的增加逐渐减小。
The impact of laser shock on fatigue life and fracture morphology of 7050-T7451 aluminum alloy small-hole parts was studied. ABAQUS was used to study the stress distribution on the pore wall and the surface of the orifice member with a peak pressure of 2.7 GPa. The laser shock and fatigue tests were carried out on the specimens based on the simulation results. The results show that the laser double-sided impact strengthening forms a certain depth of residual compressive stress layer on both sides of the sheet, while a certain range of residual tensile stress layer is formed in the center, which is also the main cause of fatigue source transfer from hole angle to hole wall center. The fatigue life of specimens increases by 451%, 216% and 116% respectively at the stress levels of 165.8MPa, 195.0MPa and 275.4MPa. After laser shock, the fatigue source position of the specimen is shifted from the hole angle To the inner wall of the hole, and the fatigue crack growth area increased significantly. The results show that laser shock strengthening can obviously improve the fatigue behavior of the aluminum alloy small-aperture components, but the strengthening effect decreases with the increase of the applied load.