采用有限元法对7B04-T651铝合金带筋试件进行了特征值屈曲分析,得到室温加载时的屈曲临界载荷;在临界载荷范围内进行了不同弯曲半径下160℃/20 h的蠕变时效成形试验,分析了预塑性变形对成形试件的外形轮廓和室温力学性能的影响。结果表明:预塑性变形虽能显著降低试件的回弹率,但较大的应变量会引起蠕变时效成形过程中筋条的失稳;成形试件的强度接近160℃/20 h人工时效状态,且随着预塑性变形量的增加有下降趋势,而同一试件筋条处的强度略高于蒙皮;伸长率和弹性模量整体上变化不大。
To obtain the buckling critical load at room temperature,eigenvalue buckling analysis for aluminum alloy 7B04-T651 stiffened structure part was performed by finite element method( FEM). Creep age forming( CAF) experiments within the critical load range were carried out at 160 ℃ /20 h under different bending radii,and the influences of pre-plastic deformation on component configuration and mechanical performance at room temperature were analyzed. The results show that pre-plastic deformation can significantly reduce the springback rate,but large plastic strain causes the stiffener buckling during CAF. The strength of formed components is close to that of the artificial aging condition at 160 ℃ /20 h,and it has a downward tendency with the increase of pre-plastic deformation. The strength of stiffener is slightly higher than that of skin on the same specimen. The elongation and elastic modulus show little change as a whole.