Tensile strength distribution for ceramic fiber having several kinds of defects.

Abstract

Ceramic fibers, e. g., boron fibers and carbon fibers etc., are known to contain several kinds of strength-limiting defects, and in this case the statistical analysis of their strength is mainly evaluated by the theory decided due to the weakest defect among all defects, the so-called "Weibull's weakest link theory". In this paper, from the tensile-test data of two types of boron fibers, we try to analyze from the view point that tensile strength is governed by the weakest defect, which is decided by competition among the several kinds of defect groups. The resukt is that the strength distribution curves predicted by multi-modal Weibull's distribution fitted to experimental plots better than those predicted by single Weibull's distribution for every gage length tested. The application of the multi-model Weibull's distribution also showed that the analysis gives the exact expected value of the bundle strength at a certain gage length. The multi-modal Weibull's distribution function may be applied to the statistical strength anblysis for ceramic fibers accompanied by several kinds of defects.