| Conventional indentation fracture test determines fracture toughness only for the centre-loaded half-penny crack of brittle materials; this method, however, has an ambiguous constant related to the indentation residual stress. Thus, in this study, we intend to evaluate the fracture toughness more exactly by quantifying the indentation residual stress and analyzing the real shape of indentation crack. For this purpose, indentation energy is separated into the strain energies in both elastic zone and plastic zone, when stress continuity at the elastic/plastic boundary is assumed. Then, the indentation residual stresses in both zones can be obtained from the separated strain energies, respectively. The critical crack size and the crack shape are determined from the observation of fracture surface and the extraction of post-indentation crack growth. For soda-lime glass and WC-Co, considering the crack shapes as halfpenny and Palmqvist types, respectively, we could evaluate more repeatable and consistent indentation fracture toughnesses of both materials. |
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