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    高干涉量压合衬套强化铝合金孔结构的疲劳性能

    Fatigue Properties of Aluminum Alloy Hole Structure Strengthened byHigh Interference Fit Bushing Technique

    • 摘要: 分别采用高干涉量压合衬套单侧挤压强化和两侧挤压强化两种工艺对7050铝合金孔结构进行强化,研究孔结构的残余应力和疲劳性能,并采用梯形累积法由疲劳断口定量反推出疲劳裂纹萌生寿命和扩展寿命。结果表明:孔结构中形成深度达12 mm的残余压应力场,单侧挤压强化试样挤入端的残余应力显著低于挤出端的,两侧挤压强化试样挤入端和挤出端的残余应力相当;单侧挤压强化试样和两侧挤压强化试样的平均疲劳寿命比未挤压强化试样的分别提高了770%和1 500%,高干涉量压合衬套强化技术具有显著的疲劳强化效果,且双侧挤压强化的效果更好;高干涉量压合衬套强化技术可同时提高孔结构的疲劳裂纹扩展寿命和萌生寿命,且萌生寿命提高的幅度更大。

       

      Abstract: 7050 aluminum alloy hole structure was strengthened by high interference fit bushing technique with single-side expansion and both-side expansion processes. The residual stress and fatigue properties of the hole structure were studied. The fatigue crack initiation life and growth life were derived quantitatively from fatigue fracture by the trapezoidal accumulation method. The results show that the residual compressive stress field with the depth of 12 mm was formed in the hole structure. The residual stress on the in-side of the single-side expansion strengthening sample was higher than that on the out-side, while the residual stresses on the in-side and out-side of the both-side expansion strengthening sample were almost the same. Compared with non-expansion strengthening sample, the average fatigue lives of single-side expansion strengthening and both-side expansion strengthening samples increased by 770% and 1 500%, respectively; the high interference fit bushing technique had obvious fatigue strengthening effects, and that of the both-side expansion strengthening process was better. The high interference fit bushing technique could both increase the fatigue growth life and initiation life of the hole structure, and the increase of initiation life was greater.

       

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