Based on the macro-micro unified constitutive equation of stress relaxation of 2219 aluminium alloy

the user subroutine was redeveloped and compiled into nonlinear finite element analysis software MSC. Marc. The simulation model of the stress-relaxation aging forming process of the 2219 aluminum alloy tank cover was established and the stress-strain and mechanical property evolution of the stress-relaxation aging forming process of the cover were analyzed. The optimization design of the mold surface based on springback compensation analysis is performed

and the mold profile that meets the requirements of the forming target is determined. The stress relaxation aging forming experiment of 2219 aluminum alloy was carried out. The results of experiment and simulation were analyzed. The results show that the experiment results of stress relaxation aging forming agree well with the results of finite element simulation. The relative deviation of the forming surface radiuses between experiment and simulation is 0.22%

and the relative deviation in the yield strength is 3.13%. The relative deviation of the surface radiuses between the experiment and the target profile is 0.52%

and mechanical properties meet target design requirements. To sum up

the established finite element model can accurately predict the shape and property evolution of the stress relaxation aging process of the cover

and can be used to guide the stress relaxation aging forming of the 2219 aluminum alloy tank cover.