Constitutive modeling and springback simulation for 2524 aluminum alloy in creep age forming

The constitutive modeling and springback simulation for AA2524 sheet in creep age forming (CAF) process were presented. A series of creep aging tests were performed on AA2524 at the temperature of 180-200 °C and under the stress of 140-210 MPa for 16 h. Based on these experimental data, material constitutive equations which can well characterize creep aging behaviors of the tested alloy were developed. The effect of interior stress distributed along the sheet thickness on springback was simulated using FE software MSC. MARC by compiling the established constitutive models into the user subroutine. The simulation results showed that the amount of sheet springback was 61.12% when merely considering tensile stress existing along the sheet thickness; while sheet springback was up to 65.93% when taking both tensile and compressive stresses into account. In addition, an AA2524 rectangular sheet was subjected to CAF experiment in resistance furnace. The springback value of the formed rectangular sheet was 68.2%, which was much closer to 65.93%. This confirms that both tensile and compressive stresses across the sheet thickness should be considered in accurately predicting springback of the sheet after forming, which can be more consistent with experimental results.