Preliminary data for testing fibers at high strain rates using the Kolsky bar test by Ming Cheng et al. 1 indicated minimal effect of strain rate on the tensile stress-strain behavior of PPTA, poly (p-phenylene terephathalamide) fibers. In a different study, Lim et al.2 reported that the tensile strengths of the copolymer aramid fibers are strain rate dependent. Usually with single fiber tests, a large sample population is needed to get statistically significant results. To date with high strain rate tests, technical issues associated with specimen preparation appear to limit the number of samples that can be tested within a reasonable time. In this study, the authors investigate the feasibility of a new gripping design in order to ultimately establish a reliable, reproducible, and accurate Kolsky bar test methodology for single fiber tensile testing with high throughput. Preliminary results performed under a quasi-static strain rate with 5 mm and 60 mm gauge lengths showed that the PPTA fibers are gauge length dependent. This gripping and size effect must be considered in determining the true strain rate effect on fiber strength.
Proceedings Title: Experimental Mechanics in the Age of Modeling and Simulation
Conference Dates: June 13-15, 2011
Conference Location: Uncasville, CT
Conference Title: 2011 SEM Annual Conference and Exposition on Experimental and Applied Mechanics
Pub Type: Conferences
soft body armor, single fiber, Kolsky bar, statistics