A TENSION ZONE MODEL OF BLANKING AND TEARING OF DUCTILE METAL PLATES

The objective of this paper is to theoretically predict the plastic re sistance and the plastic work in blanking and tearing of ductile metal plates. It is found that shear resistance in blanking of metal plates is attributed to two factors. First, there are large rotations of mat erial elements in the shear zone. These rotations give rise to large t ensile deformation in a direction oblique to the shear surface. The Te nsion Model is developed to determine the role of this factor in blank ing tests and the shear load instability is revealed. The other factor is due to the reduction of shear area caused by the crack propagation through the thickness. With the Tension Model as a representative ele ment, the Blanking Model with a moving fracture front is proposed to p redict the shear force, the plastic work, and the shape and size of th e plastic shear zone. Good agreement is found with the published exper imental results for a variety of materials by other investigators. Fin ally, the three-dimensional tearing process is modeled as a two-dimens ional blanking problem. Then the Blanking Model is applied to the plat e tearing to determine the specific work of fracture.