Estimation of Weibull parameters from loose-bundle tests

The statistical variation in mechanical properties of carbon fibres has been studied by using monofilaments and loose bundles of 6000 filaments. Particular care has been taken in the preparation of these bundle samples so as to be able to measure the applied strain directly with a mechanical extensometer. Measurements were made of the number of initially loaded fibres in the bundle, the Weibull shape parameter, the bundle mean strength and the average strength of the fibres. Comparison with the results from classical single-filament tests shows that this technique allows us to obtain a valuable characterization of the reinforcement. (C) 1996 Elsevier Science Limited.