IAM - Ceramic Materials and Technologies

Crack-Tip Toughness from Vickers Crack-Tip Opening Displacements for Materials with Strongly Rising R-Curves

  • Author:

    S. Fünfschilling, S; Fett, T;Oberacker, R; Hoffmann, MJ; Schneider, GA; Becher, P; Krusic, JJ

  • Source:

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 2011, Band 94, Heft 6, S. 1884-1892

Abstract

Accurate measurements of the intrinsic crack-tip toughness, KI0,
are essential to understanding the strength and toughness of
bridging ceramics. Furthermore, even the most carefully made
R-curve measurements cannot accurately assess this initial
toughness point. In this manuscript, both rigorous and approximate
methods are proposed for determining KI0 from crack-tip
opening displacement (COD) measurements on Vickers indent
cracks for materials with steeply rising R-curves. Such approaches
are attractive because of the relative ease of producing
indentation cracks and analyzing the CODs; further, the
latter method is of particular interest because it saves considerable
computational effort. Both the advantages and limitations
of the proposed methods are discussed. Finally, based on
applying the above methods to three Si3N4 ceramics, it was
concluded that there is a common crack-tip toughness of
KI0=2.2+/-0.3 MPa m-1/2.