Use of Indentation Fracture to Determine Fracture Toughness

摘要

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 (K/sub c/). 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 MNm/sup -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 K/sub c/ 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 K/sub c/ for a wide range of brittle materials. A number of practical problems associated with this technique are discussed. (ERA citation 03:048385)