Relationship between fiber flaw spectra and the fragmentation process: A computer simulation investigation

Abstract

The single-filament-composite (SFC) fragmentation test can be utilized to provide quantitative information on the fiber strength distribution and the fiber/matrix interface shear stress, which are important properties that control the performance of fiber composites. An accurate interpretation of the fragmentation data, however, is difficult owing to the stochastic nature of the fragmentation process, as well as the complex interplay between the fiber flaw strength variation and the stress transfer zones about every broken flaw. In this work we have developed a computer simulation approach that models the fragmentation process by explicitly incorporating considerations regarding the strength and spatial distributions of the flaws. The effect of stress variation along the fiber length is accounted for by incorporating specific fiber-loading models. From the simulation it is demonstrated that the fragmentation data may be used to produce a rough sketch of the underlying flaw strength spectrum. An examination of the fragment size statistics suggests that appropriate analysis of the SFC data may be utilized to detect the occurrence of matrix/fiber interface yielding or debonding. An alternative methodology for mapping out the flaw strength distribution by means of a multiple-long-fiber failure test is also presented for comparison purposes.