Mechanism of localized severe plastic deformation and damage fracture in fine-blanking using mixed displacement and pressure FEM
(1. National Die and Mold CAD Engineering Research Center,
Shanghai Jiao Tong University, Shanghai 200030, China;
2. Suzhou Dongfeng Fine-blanking Engineering Co Ltd, Suzhou 215004, China)
Shanghai Jiao Tong University, Shanghai 200030, China;
2. Suzhou Dongfeng Fine-blanking Engineering Co Ltd, Suzhou 215004, China)
Abstract: A mixed displacement-pressure updated Lagrange FEM was used to simulate the severe plastic deformation, which can overcome shear locking and volume locking. Together with adaptive remeshing technique based on strain gradient and surface curvature, the strain localization in severe plastic deformation can be captured. Schiffmann damage density was used to predict the developments of damage and fracture in sheet metal. The intensive dislocation and slip appear under the action of severe shear deformation, and metallic grains are flattened and elongated in shear band. Because of the existence of large radius of die edge, the flow direction of grains changes, and the grains are elongated and simultaneous. As a result, it is not easy to cut the grains off, and outer surfaces with clean cut are formed.
Key words: fine-blanking; damage; ductile fracture; mixed displacement-pressure FEM; adaptive remeshing