A continuously monitored single‐filament composite (CM‐SFC) test was conducted to measure the stress at which successive fiber breaks occur in the single fiber fragmentation process. This exercise was performed with a limited number of samples of various types. The purpose was to explore the possibility of using this test as a simple alternative means of (i) measuring the size effect in single fibers, (ii) calculating the Weibull shape and scale parameters for fiber strength, (iii) calculating the fiber/matrix interfacial shear strength from the extrapolated value of fiber strength using the loading history of a single fragmentation test, rather than from the value of fiber strength extrapolated from extensive testing of single fibers at various gage lengths, as is usually done. These are aspects of the SFC test that have largely been ignored so far. The results presented here confirm the possibility of using the CM‐SFC test for such purposes, with a certain degree of approximation, as discussed. Additional information supplied by this test as well as a possible effect of fiber pre‐tensioning on fragmentation results (including the value of the interfacial shear strength) are also briefly discussed.
The wetting of cylindrical monofilaments by liquid polymers is a problem of much scientific and technological importance.In particular, the characterization of the physicochemical nature of interfaces is a key problem in the field of advanced fibrous composites. The macroscopic regime contact angle, which reflects the energetics of wetting at the solid-liquid interface, is difficult to measure by usual methods in the case of very thin cylindrical fibers.In the present article a numerical method is proposed for the calculation of macroscopic regime contact angles from the shape of a liquid droplet spread onto a cylindrical monofilament.This method, which builds on earlier theoretical treatments by Yamaki and Katayama [1], and Carroll [2], very much improve the accuracy of the contact angle obtained. Experimental results with high-strength carbon, para-aramid, and glass fibers, are presented to demonstrate the high degree of accuracy of the method proposed.
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