Finite Element Analysis On Creep Age Forming Of 7075 Aluminum Alloy

As a kind of new forming technology, creep age forming combines age-hardening and creep forming into one process and has exhibited unique advantages in manufacturing large complex integral panels of aerospace components. With the rapid development of modern industry, this technique has been widely used in abroad aerospace industry. Currently, this technology is considered as one of the important forming techniques for integral panels of future aircrafts, and has significance in improving the forming quality of aircraft.In the domestic, for lack of enough basic research and technological achievements supports, especially in accuracy control of springback, creep age forming technology has not been industrialized implemented. For its high strength and good corrosion resistance, 7075 aluminum alloy is especially applicable in manufacturing aircraft fuselage structures. In this work, based on the finite element(FE) software ABAQUS, the FE scheme of creep age forming of 7075 aluminum alloy sheets were conducted, and the related creep ageing behaviors and springback were investigated and also verified by experiments. The major work and conclusions are reported as follows:First of all, the creep age forming experiments were conducted in the drying box by using the mechanical loading setup, to determine the best creep aging temperature of 7075 aluminum alloy of 180℃,and the best creep aging time of 12 h. Based on uniaxial creep tensile experiments with such optimal parameters, the material parameters of creep constitutive model of 7075 aluminum alloy were obtained according to the experimental data derivation, through fitting and verifying of the experimental and simulation results of the constitutive equations. The constitutive model achieved can well describe the creep age forming behaviors of the alloy.Secondly, based on the above experimental parameters and constitutive model, the numerical model for creep age forming of 7075 aluminum alloy sheet was established by using ABAQUS platform. By comparing simulation and experimental results, the accuracy of the FE model was verified, and the springback regulations of creep age forming analysis of 7075 aluminum alloy sheet were reported by FE model, and the effects of creep age forming time, die radius, sheet thickness and temperature on springback were investigated. The springback and curvature radius changes according to such parameters, namely, directly affecting sheet springback.Finally, springback compensation principles were performed for mold surface optimization. The amount of compensation for mold surface was obtained by FE simulations, and a precise mold surface was final achieved by several compensation and optimization. This work has provided a new method for mold design of creep age forming technology.This paper is mainly concerned with FE investigations on creep age forming, the results of which will provide a reference value in engineering practice on creep age forming of 7075 aluminum alloy.