A phenomenological study of bending
Résumé
In order to choose which model and parameters are necessary to evaluate springback of sheet metal submitted to bending, bending mechanics is deeply studied. This study is done with an analytical model based on the ones found in literature. It has been developed following the case of pure bending moment on assumptions of plane strain and plane stress in two orthogonal planes. Main assumptions are that the sheet is wide and thin, sheet thickness remains constant, neutral layer coincides with the mid-plane one and deformations keep small. Good results are found when material behaviour is accurately defined, but the model shows its limits when radius of curvature over thickness ratio is low. In this case, neutral layer shifts from the mid-plane one and the sheet thinners. Furthermore, when sheet width is low, anticlastic curvature appears and makes bending moment increase, so springback decreases.