Two fundamental questions in the mechanics and physics of fracture are: (i) What is the relation between observable features of a material’s microstructure and its resistance to crack growth? (ii) What is the relation between observable features of a material’s microstructure and the roughness of the fracture surface? An obvious corollary question is: What is the relation, if any, between a material’s crack growth resistance and the roughness of the corresponding fracture surface? 3D finite element calculations of mode I ductile crack growth aimed at addressing these questions will be discussed. In the calculations, ductile fracture of structural metals by void nucleation, growth and coalescence is modeled using an elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid. A material length scale is introduced via a discretely modeled microstructural feature, such as the spacing of inclusions that nucleate voids or the mean grain size. A particular focus will be on the use of such analyses to suggest the design of material microstructures for improved fracture resistance.

Abstract

Two fundamental questions in the mechanics and physics of fracture are: (i) What is the relation between observable features of a material’s microstructure and its resistance to crack growth? (ii) What is the relation between observable features of a material’s microstructure [...]