On crack-growth resistance curve fitting for ceramics

Abstract K R -curves of crack growth resistance were studied for a particulate ceramic-metal composite in the system lanthanium chromite–chromium in the temperature range 20 to 1100°C. It is shown that the K R -curves can be described satisfactory by an exponential function. With the use of this function, the similarity of the crack-growth resistance curves for the specimens tested at different temperatures can be demonstrated. The notch-size effect can also be minimized if the K R -curves are normalized with respect to crack length, the normalizing factor being the parameter l of the exponential function. A possible background in the framework of the model of the crack-face bridging by frictional ligaments in a wake zone is proposed.