Experimental Verification of the End-Effect Weibull Model as a Predictor of the Tensile Strength of Kevlar-29 (Poly p-Phenyleneterephthalamide) Fibres at Different Gauge Lengths

This paper describes the first application of the four-parameter end-effect Weibull model as a predictor of tensile failure frequency at a gauge length different from that used to generate the model parameters. As-received Kevlar-29 fibres were tensile tested at gauge lengths of 10, 25 and 40 mm. The resulting failure data were used to determine four empirical constants using a maximum-likelihood regression. The model and parameters were used to predict failure frequency at a gauge length outside the initial range (5 mm). The results show that the end-effect Weibull model accurately represents the data from which its parameters are evaluated and that the model may be applied as an effective predictor for gauge lengths beyond the original testing range.