Notch sensitivity of ductile metallic foams: A computational study

The role of notches in the fracture strength of metal foams has been studied using a multiscale model based on a two-dimensional Voronoi representation of the cellular architecture. The effect of the crack length to the specimen width ratio on the net section strength of double edge notch (DEN) specimens and central crack panels (CCP) has been investigated in two ways: (i) by fixing the number of cells in the width and (ii) by fixing the number of cells in the ligament. Notch strengthening has been observed in DEN specimens in excellent agreement with experiments. Analysis of the strain fields suggests that in the DEN configuration, the constraint imposed on the rotation fields in the notch tip zones of the ligament enhances the net section strength. In CCP specimens, stress concentration and free-edge effects produced a small level of notch weakening. Our results show that both the ligament length as well as the notch length (normalized by the cell size) influence the notch behaviour in two-dimensional metal foams. (C) 2011 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.