Determination of single fibre strength distribution from fibre bundle testings

Abstract

The strength of fibres used as reinforcement materials for advanced composites is often assumed to follow the two-parameter Weibull distribution function. However, the experimental process widely used for obtaining the two parameters is tedious and prone to error. In this paper, two simple methods for determining the parameters of the Weibull distribution function are developed based upon the analysis of the tensile curves of fibre bundles. The first method focuses on the relation between the shape of a fibre bundle tensile curve and the survivability of fibres; the second method makes use of the relation between the maximum load point of a fibre bundle tensile curve and the shape parameter of the Weibull distribution of fibre strength. These two methods, in particular the second one, have greatly simplified the fibre testing process. Experimental results on Thornel-300 carbon fibres further demonstrate the validity of these techniques.