Second- and Third-Order Elastic Constants of Filaments of HexTow((R)) IM7 Carbon Fiber

作者：Oliveira L; Hitchcock D; Behlow H; Podila R; Skove M J^*; Serkiz S M; Rao A M

来源：Journal of Materials Engineering and Performance, 2014, 23(3): 685-692.

DOI：10.1007/s11665-013-0826-2

• carbon fibers
• high-order elastic constant
• nonlinear mechanical behavior

Single filaments of HexTow(A (R)) IM7-12K carbon fiber were subjected to tensile measurements on a device which applies a known stress sigma, and measures the resulting strain epsilon, and the change in resistivity Delta rho. Young%26apos;s modulus E, the resistivity rho, the piezoresistivity Delta rho/rho epsilon, and the nonlinearity in the stress-strain relation delta, were determined to be 264.1 +/- A 16.0 GPa, 1.5 +/- A 0.1 x 10(-3) Omega cm, 1.3 +/- A 0.1, and -4.96 +/- A 0.23, respectively. The values obtained for Young%26apos;s modulus and the resistivity of the fiber are in reasonable agreement with the values reported by the manufacturer. To the best of our knowledge, this is the first report of a measurement of a third-order elastic constant of a single filament of HexTow(A (R)) IM7-12K. Given the high elastic strains attainable in these fibers and the negative value of delta, the usual calculation of E from a linear fit to the stress-strain data leads to an incorrect higher value of E. According to the accepted thermodynamic definition of the elastic constants, one must use the initial slope of the stress-strain curve to evaluate E. We also observed that the glue used to secure the fiber has an influence on the apparent modulus of the fiber.

• 出版日期2014-3