Indentation testing of a brittle material using a notionally ‘sharp’ indenter may reveal several important physical properties, including fracture toughness, surface finish information and the residual stress state. In the case of shallow cone indenters, the contact and fracture mechanics is well defined and closed-form solutions exist in elasticity theory. However, no real indenter is atomically sharp, and the scope of the present article is to quantify how a finite apex radius may modify the stress state induced by a conical indenter. In particular, implications for the load-displacement relation, occurrence of yielding and maximum contact pressure induced are found. A brief discussion of the influence of edge radius on the flat-ended indenter, once used to induce Hertzian type ring cracks, is also included, as this may be treated by a similar procedure
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