Crack Tip Constraint for Anisotropic Sheet Metal Plate Subjected to Mode-I Fracture

On the ground of manufacturing, sheet metal parts play a key role as they cover about half of the production processes. Sheet metals are commonly obtained from rolling and forming processes which causes misalignment of micro structure resulting obvious anisotropic characteristics and micro cracks. Presence of micro cracks poses serious attention, when stresses at the tip reach to the critical value. Present research deals with a thin anisotropic plate, containing an edge crack subjected to mode-I condition. To predict the nature of crack propagation, anisotropic triaxiality is formulated with special reference to Lankford’s coefficient and degree of anisotropy. The distribution of magnitude of anisotropic triaxiality is shown with respect to polar angle at crack tip supplemented by plastic zone shapes. Numerical evaluation has been carried out by considering five different cases of plane stress condition using Hill-von Mises yield criteria. Critical values so obtained apropos respective cases, as traced on the yield locus had been used to predict the location of crack propagation in sheet metal. It is revealed that the angle through which the crack propagate do not remain invariable for all combinations of Lankford’s coefficient and degree of anisotropy but it shifts for two of the five cases taken into consideration.

Keywords:

Triaxiality , Lankford’s coefficient , Mode I Fracture , Degree of anisotropy , Hill von mises criteria