Analysis of bridging stress effect of polycrystalline alumina using double cantilever beam method

Abstract

The in situ crack opening displacement (GOD) with respect to the distance behind the stationary crack tip was measured in three alumina ceramics with different grain size. An analytical model which can describe the relationship between the bridging stress and the microstructure and a double cantilever beam (DCB) analysis which includes the bridging stress effect are developed in order to analyze the experimental results. The present model shows that the distribution of grain size as well as the average grain size are key microstructural Factors that determine the bridging stress Function. The results indicate that the shape of the bridging stress distribution is closely related to the grain size distribution. The effect of the bridging stress on the COD is taken into consideration in the DCB analysis. The crack closure due to bridging stress is calculated using the conventional power law relation and the new distributive bridging stress function developed in the present study. (C) 1997 Acta Metallurgica Inc.