Numerical analysis of brittle materials fractured by sharp indenters

Indentation can be used to determine the fracture properties of materials. A detailed investigation is here presented on the reliability of finite element simulations of sharp indentations on cracked specimens. Elastic analyses of the stress and deformation fields arising from Vickers, Berkovich and cube-corner indenters generated the stress intensity factor along the edge of penny-shaped or elliptical cracks. Various materials with a range of properties were analysed and the results compared with published experimental data. Additional measurements from tests on soda-lime glass provided further opportunities for experimental validation of numerical predictions. The variation of the stress intensity factor indicated trends for crack growth patterns, which were consistent with experimental observations. Particular attention was given to the evaluation of the geometry-dependent parameter appearing in the relation yielding the fracture toughness of cracked indented materials. The numerical predictions of this parameter were remarkably consistent with experimental data and results from other approximate methods.