A Micro-Toughness Model for Ductile Fracture

Ductile fracture occurs through growth and coalescence of micro-voids that originate at the location of inclusions and precipitates. The plastic work dissipated in these micro-separation processes leading to the creation of a unit fracture surface area is a measure of the micro-toughness of the material. Furthermore, void growth and coalescence processes are accompanied by plastic deformation of the material surrounding the voids. The energy dissipated by the micro-separation processes of void growth and coalescence, and the plastic deformation in the bulk material surrounding the voids together contribute to the overall fracture toughness of the material. Conventional fracture toughness tests fail to individually measure these two very different contributions. As a result, there is limited transferability of fracture toughness test data from the laboratory to an actual structure.