THEORETIC ANALYSIS ON SPRINGBACK IN BENDING CONSIDERING THE INITIAL RESIDUAL STRESS

In the process of actual bending,if it has initial residual stress inside the sheet metal,the initial residual stress will superimpose the bending stress and then impact the sheet metal’s springback. The traditional theory of bending springback does not consider the influence of initial residual stress,hence based on the plane strain assumption,this paper proposes an approximate calculation formula of springback angle using the material model complying with Mises yield criterion and linear hardening,and conducts comparative simulation analyses of bending springback using the finite element software ABAQUS. The theoretical calculations and the simulation results have a good agreement which verifies the correctness of the theoretical model. The results show that both residual stress and thickness have significant influence on sheet metal’s springback: along the width direction,springback at different position of sheet metal with different initial residual stress are not uniform; both increasing the initial residual stress peak value and reducing the thickness will increase the springback difference at different position of the sheet metal with different initial residual stress.