A method to estimate the influence of the notch-root radius on the fracture toughness measurement of ceramics

The fracture toughness measurement of ceramics is based on notched specimens. If the notch-root radius is too large, it leads to overestimate the actual fracture toughness of the material. It is then necessary to control the notch shape and to machine it carefully in order to have a root-radius small enough (<10 μm) to be below the sensitivity threshold of the material. Then, the notch confounds with a sharp crack. Alternatively, it is proposed in this work to bring a correction to the measured fracture toughness depending on the notch-root radius. No restriction is brought to this radius except that it must be small compared to the notch length.