Effect of virtual kinetic energy on springback simulation accuracy

For the simulation accuracy of springback problem in sheet metal forming,the effect of punch virtual velocity and sheet virtual density on the sheet strain energy was studied in this paper.Taking a benchmark of unconstrained cylinder bending in Numisheet'2002 as a example,the bending processes were simulated under conditions of different virtual velocities and different virtual densities by explicit/implicit FEM code.The comparisons with experiment data show that with the increase of virtual velocity and virtual density,the virtual kinetic energy increases while the sheet strain energy decreases and the precision of springback simulation gets worse.In order to keep a satisfactory precision for springback simulation,the virtual velocity and virtual density should be rationally controlled to ensure that the virtual kinetic energy should be less than 7% of the total strain energy.