Application of Digital Image Correlation (DIC) in Dynamic Notched Semi-Circular Bend (NSCB) Tests

Notched semi-circular bend (NSCB) specimen has been successfully used in fracture tests of brittle materials. As a suggested method for measuring the dynamic fracture toughness of rocks by the International Society for Rock Mechanics (ISRM), this method only measures the fracture initiation toughness of the sample with given external load and geometrical parameters. Using the digital image correlation (DIC) method combined with ultra-high speed photography, the objective of this paper is to measure more fracture parameters of the NSCB specimen loaded by a split Hopkinson pressure bar (SHPB) system. The displacement and strain fields during the fracture propagation process were determined using DIC method. The location of the crack tip, the fracture initiation toughness and the fracture propagation toughness were subsequently calculated using the deformation fields. Compared with the traditional NSCB tests, the optical method of DIC provides much more information on the fracture propagation process.