孔挤压强化对7050铝合金孔结构疲劳性能的影响

Effects of Hole Expansion Strengthening on Fatigue Properties of 7050 Aluminum Alloy Hole Structure

为了探究不同相对挤压量的开缝芯棒孔挤压强化对7050铝合金疲劳性能的影响,建立了开缝芯棒孔挤压强化有限元模型,开展了开缝芯棒孔挤压强化试验,分析了孔挤压强化试样孔壁残余应力和受载试样孔壁应力分布规律,探究了相对挤压量、残余应力和疲劳寿命之间的关系,揭示了开缝芯棒孔挤压强化工艺的抗疲劳增益效果。结果表明:试样孔壁挤入端,相对挤压量为2%、3%和4%,孔壁的最大残余压应力为246.8、338.6和367.7MPa,相对挤压量与孔壁最大残余压应力呈正相关;受载试样孔壁挤入端,相对挤压量为2%、3%和4%,孔壁最大应力为451.2、368.7和321.6MPa,相对挤压量与孔壁最大应力呈负相关;相对挤压量为2%、3%和4%的试样中值疲劳寿命是相对挤压量为0%的1.17、1.52和1.71倍。

In order to investigate the effect of hole expansion strengthening of split mandrel with different relative expansion amount s on the fatigue properties of 7050 aluminum alloy,a finite element model of hole expansion strengthening of split mandrel was established,and hole expansion strengthening of split mandrel experimental was carried out.The residual stress on the hole wall of the hole expansion strengthening specimen and the distribution law of the stress on the hole wall of the loaded specimen were analyzed.In addit ion,the relationship among relative expansion amount,residual stress and fatigue life were explored.Finally,the fatigue resistance effect of hole expansion strengthening of split mandrel was revealed.The results show that when the relative expansion amount is 2%,3%,and 4%,the maximum residual compressive stress of the hole wall is 246.8,338.6,and 367.7 MPa at the inlet area of the hole wall of the specimen,respectively.The relative expansion amount is positively correlated with the maximum residual compressive stress of the hole wall.In inlet area of the hole wall of the loaded specimen,when the relative expansion amount is 2%,3%,and 4%,the maximum stress of the hole wall is 451.2,368.7,and 321.6 MPa,respectively;the relative expansion amount is negatively correlated with the maximum stress of the hole wall.The median fatigue life of specimens with relative expansion amount of 2%,3%,and 4%is 1.17,1.52,and 1.71 times of that of the specimens with relative expansion amount of 0,respectively.