Shear band post-bifurcation analysis of FCC single crystals - ductile fracture of FCC crystals by shear band formation Ⅱ

摘要

A numerical analysis, based on crystal plasticity, of the formation and the propagation of localized shear bands in ductile single crystals is carried out in order to establish a fundamental basis for predicting the forming limit of sheet metals. The critical state of shear band formation and the direction of the shear band of each element are predicted by the bifurcation theory. For the post-bifurcation analysis, a hypothetical 13th slip system is introduced into the elements that satisfy the bifurcation conditions. Results of numerical analysis of plane strain compression reveal that an envelope line connecting the shear band directions of elements penetrates the metal layer. We define the moment of shear band penetration as the stage of metal fracture. The experimental results of single crystals under the plane strain compression also suggest that shear bands are closely related to metal ductile fracture.