激光冲击强化铝合金小孔构件的疲劳寿命研究

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。

Research on Fatigue Life of Aluminum Alloy With Fastener Hole by Laser Shock Processing

The effect on fatigue life and fracture morphology of 7050-T7451 aluminum alloy hole by laser shock processing (LSP) was investigated.ABAQUS was used to study the stress distribution of hole wall path and surface path of the hole under different peak pressures.The LSP test and the fatigue tensile test were carried out based on the simulation results.The results show that laser double-sided shock processing on the sides of the sheet forms a depth of residual compressive stress layer,and in the center forms a range of residual tensile stress layer,which is also the main reason for the transfer of fatigue source froms the hole angle to center of the hole wall.Under the stress level of 165.8MPa,195.0MPa and 275.4MPa,the fatigue life of the samples increased by 451％,216％ and 116％ respectively.After LSP,the fatigue source position of the sample is transferred from the hole angle to the inside of the pore wall,and the area of fatigue crack area is obviously increased.The research show that LSP can obviously improve the fatigue properties of the aluminum alloy with fastener hole,but the strengthening effect decreases with the increase of the external load.