Matrix crack initiation in ceramic matrix composites Part I: Experiments and test results

Abstract

A systematic study has been undertaken to examine the relationships between the matrix cracking initiation stress and the influencing factors in the microstructure for a class of fiber-reinforced ceramic matrix composites. Experimental and analysis results thus obtained are presented in a two-part sequence of papers. Part 1 describes the experimental details pertaining to composite fabrication, mechanical characterization, matrix cracking test, in situ observations, test results and discussions. The main objective of the experiment is to study the mechanical roles played by some of the microstructural factors during the process of matrix cracking so as to obtain a deeper understanding of the matrix cracking mechanisms at the microstructural level. The experiment also provides a valuable addition to the matrix cracking database. In Part II, a critical review is given of the currently available matrix cracking models. The purpose of the review is to delineate the salient features in each model in terms of the assumed matrix cracking mechanisms and the abstracted microstructure. The models are then applied to predict the matrix cracking initiation stresses for the composite systems tested in the experiment. Comparisons are made between the experimental results and the results predicted by the various theoretical models. Part I is presented in this paper; Part II is contained in Ref. 1.