A concise review of small-scale specimen fracture toughness testing

The fracture toughness of materials is a fundamental parameter in assessing the structural integrity of crack-containing structures. Issues relating to economic demands in the availability of materials for testing and imposing strict rules to structures that exhibit enhanced toughness due to geometries and loading conditions caused the need to consider the application of fracture toughness measurement with small-scale specimens. The current small-scale testing and fracture toughness characterization still need to fully fulfil the fracture toughness data transferability from the laboratory test specimens to real structures influenced by unavoidable defects. This paper outlines the conventional elastoplastic fracture toughness approaches and how they apply to small-scale specimen fracture toughness testing. Recent techniques to characterize three-dimensional elastoplastic stress-strain fields around the crack tip were highlighted, as an extension to the current two-parameter fracture toughness assessment was proposed. Explicit expressions were given to develop an analytical formulation for small-scale fracture toughness measurement and characterization.