Comparison of the Fracture Toughness of High Temperature Ceramic measured by Digital Image Correlation and Indentation Method


There are many applications to create damage (i.e. short cracks) related to wear or erosion, polishing, machining and grinding (Srinivasan, 1991 and Smith, 1992). The fracture toughness values for short cracks are important in situations where small crack size scales limit performance. The extension of pre-existing cracks under cyclic loading or applied load in one direction these represent another method to extend the short crack (Fuller, 1983).A problem arises with many ceramic-based materials because the toughness is not constant, but instead increases with increasing crack-size scale. This behavior known as the R-curve effect and this effect occurred due to interaction of the crack with the microstructure (Cook, 1985 and Swanson 1987). The fracture toughness for these types of materials is measured for long cracks but it will not give suitable values for the short crack behavior.