Validating a Facile Approach to Measuring Fracture Toughness by Instrumented Indentation Without Imaging Crack-Lengths

Probing the fracture toughness of brittle materials by measuring the crack-length generated from indentation experiments is often practiced in many areas of materials research. However, when the cracks are too small to be measured accurately, an energy-based approach has recently been proposed by several researchers. In the work presented here, this approach is compared with the well-known crack-length method on six different materials. We found that the energy-based method and crack-length method yield significantly different results for all materials but converge if the energy method is modified with a correction factor using a calibration sample.