Nonlocal effects in ductile fracture predictions

A nonlocal constitutive formulation for a porous ductile material is discussed, in which delocalization relates to the damage mechanism. In the context of an elastic-viscoplastic material model delocalization is incorporated in terms of an integral condition on the rate of increase of the void volume fraction. The effect of the material length is illustrated by computations for plastic flow localization in a shear band and for matrix failure in a metal matrix composite. Also, the identification of the proper material length is discussed, based on comparison with predictions of a cell model analysis.