Recession of Elastic Modulus and Prediction of Springback for 7075 Aluminum Alloy Sheets.

The recession of elastic modulus happening in the plastic deformation of sheet metals had a big influence on the springback prediction in sheet metal forming processes. To study the recession law of elastic modulus for 7075 aluminum alloy sheets, the conventional cyclic loading experiments were used and a new bending-unloading experiment with the assistance of DIC strain measuring system was designed to test the elastic modulus. The testing results show that the elastic modulus has a significant decline with the growth of plastic deformations and the recession law of elastic modulus is influenced by the stress states during deformation. The recession laws obtained by two experiments were applied to the springback simulation of forming processes for a beam with shape C. The comparison between the results of simulations and experiments shows that the analysis results of springback from the recession law of cyclic loading experiments are better than that from the bending-unloading experiments. The prediction accuracy of the four springback angles is increased by 42%, 7%, 40% and 200% separately. [ABSTRACT FROM AUTHOR]