Published: Jan 1969
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Several test methods used for the evaluation of carbon filaments and composites are presented. Included are methods for determining tensile, compressive, interlaminar shear, and bearing strength properties of flat and tubular carbon composites. The tensile and compressive properties of composite materials having varying fiber volume functions are reported. The use of both tubular and flat specimens made it possible to determine the effect of narrow (flat) specimens versus wide (cylindrical) specimens on the strength properties of the composite. Interlaminar shear strength (ILS) studies of carbon composites, using flat short-beam specimens, indicated that the strength and the mode of failure obtained are very sensitive to the selected span-to-depth ratio (SDR). Results also show that the apparent ILS increases approximately 25 percent by changing the SDR from eight to four. The bearing strength of a multidirectional composite was found to be 38,000 psi, which is 90 percent of the tensile strength. In addition to methods for composite properties evaluation, material control test methods are described. These include a yarn tension test, resin content, and void content determination.
carbon composites, fiber composites, composite materials, carbon yarn, mechanical properties, evaluation, tests
Hoggatt, J. T.
Research specialist, The Boeing Company, Seattle, Wash.
Paper ID: STP49805S