Interference and Residual Stress of Al-Li Alloy After Automatic Riveting

Al-Li alloy is a new alloy material used in aviation manufacturing. The riveting technology of Al-Li alloy is an important research direction of modern aircraft manufacturing. The distribution of residual stress after riveting is affected by the amount of interference in the hole of Al-Li alloy sheets. The automatic drilling and riveting equipment was used to rivet Al-Li alloy sheets with different thicknesses for researching the relationship between riveting process and residual stress distribution. The automatic riveting process of Al-Li alloy was simulated by ABAQUS/Explicit, and the interference amount generated in Al-Li alloy wall under different riveting force, rivet length, the thickness of sheets and rivet material were analyzed by experiment and simulation. Then the residual stress distribution characteristics along the thickness direction of Al-Li alloy sheet under various conditions were deduced. The results indicate that the interference produced in the hole wall of Al-Li alloy sheets and the residual stress have a highly consistent tendency under various technological conditions, i.e. interference and residual stress increase with the argument of the riveting force. However, they will decrease with the increase in the rivet length. As the total thickness of the sheet increases, the average interference amount and the average residual stress increase at the beginning and then decrease. When the total thickness of the sheet is 4.2 mm, the interference and residual stress reach peak value. In addition, the average interference amount produced by 7050-T73 aluminum alloy rivets is reduced by 6%-12% compared to that produced by 2117-T4 aluminum alloy rivets. And the residual stress is reduced by 8%- 12%.