Author(s)

K. Suzuki & K. Tanaka

Abstract

Stable crack growth from an indentation crack was observed under increas- ing bending loads in the newly developed system for A-curve experiments. A crack shows a stepwise growth and the mean length of growth steps was 22/im for the increasing part of the A-curve. The resistance for crack growth is a unique function of the amount of crack extention from the indentation crack, irrespective of the indentation load. 1 Introduction The fracture strength of smooth specimens of ceramics is controlled by the R-curve behavior of crack growth from small material defects [1]. Vickers indentation cracks have been used as a starter defect to obtain the 72-curve characteristics for small cracks. Lawn et al. [2, 3] estimated the R-curve from the bending strength of specimens with indentation cracks. Several investigators [4-6] observed the behavior of crack growth from indentation cracks wi

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