Published: Jan 1979
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In recent studies on indentation fracture in brittle materials, use of the cracks which form beneath a pointed indenter and grow stably with load has been suggested as a simple technique for the determination of fracture toughness (Kc). The applicability of this technique has been assessed by performing tests on a number of polycrystalline ceramics, glass-ceramics, and glasses which span a range of fracture toughness from 0.7 to 4.5 MN−3/2. Various sharp indenter geometries were tested and it was concluded that cracks produced with the Vickers indenter were the easiest to measure. The existing theories for calculating Kc from experimental measurements (crack length, load, etc.) have been evaluated and their applicability has been determined. The results demonstrate the usefulness of a Vickers pyramid in obtaining a qualitative ranking of Kc for a wide range of brittle materials. A number of practical problems associated with this technique are discussed.
fracture toughness, indentation fracture, brittle materials, brittle materials testing, sharp indenters, fracture (materials)
Member of technical staff, Sandia Laboratories, Albuquerque, N. Mex.