Through-Thickness Property Measurement of Three-Dimensional Textile Composites

Report No. ARL-TR-4765
Authors: Ryan L. Karkkainen; Paul Moy; Jerome T. Tzeng
Date/Pages: April 2009; 22 pages
Abstract: Three-dimensional (3-D) reinforcement of thick composite parts is utilized to increase delamination resistance and through-thickness properties, which often represent the weak link of such structures. Stitching, z-pinning, or a 3-D textile weave may be employed. In the current study of a 3-D, orthogonal-woven, glass-epoxy composite, a specimen is designed for cases in which a sufficiently thick specimen for standard test setups cannot be created due to manufacturing limitations. A minimum width is dictated by the need to capture a sufficient number of through-thickness stitches in the specimen cross section. Thickness is limited by manufacturing feasibility, as stitches can only penetrate through a certain thickness, and further limitation is imposed by the ability of resin to penetrate the fiber preform during cure. Thus, a specimen must accommodate this low aspect ratio geometry. To this end, several specimens have been designed using finite-element method analysis and validated experimentally. Multiple specimen types were investigated to determine an optimum specimen and to ensure geometry independence of the obtained properties. Optimized specimens have shown good agreement with stiffness predictions as well as promising, consistent results for strength determination.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2009