Indentation Of Ceramics With Spheres: A Century After Hertz

This article reviews the nature and mechanics of damage induced in ceramics by spherical indenters, from the classical studies of Hertz over a century ago to the present day. Basic descriptions of continuum elastic and elastic-plastic contact stress fields are first given. Two distinct modes of damage are then identified: Hertzian cone cracks, in relatively hard, homogeneous materials, such as glasses, single crystals, fine-grain ceramics, and diffuse subsurface damage zones in relatively tough ceramics with heterogneous microstructures (shear, "quasi-plastic" mode).