A method of extracting Weibull survival model parameters from filament bundle load/strain data

Abstract

Failure probability data for structural fibers are needed to quantify the spread in strength of the filaments. Such data are typically obtained by testing large numbers of individual filaments. A method is given for extracting Weibull failure parameters from a single fiber-bundle tensile test by Fourier deconvolution. The fiber-bundle test is performed by using gripping techniques that result in distributed filament lengths. The generalized convolution equation eliminates the need for an assumed survival model. Examples of the analysis use experimental data for Thornel T-300 and Kevlar 49 fibers. The widened length distribution shifts the response from catastrophic failure to a more even sequence of filament failures. This effect improves the data quality compared to the traditional test that uses a single filament length. If deconvolution replaces the tedious testing of individual filaments, it would allow rapid analysis of fiber quality and improve prediction of properties in the composite.