Experimental Tests to Characterize the Behavior and Properties of HexPly Continuous Fiber Unidirectional Composite and TuFF Discontinuous Fiber Composite

This report summarizes test procedures for characterizing the quasistatic, room-temperature behavior of two IM7/PEKK (intermediate modulus 7/polyetherketoneketone) composite material systems: a continuous fiber (CF) carbon fiber polymer composite system from Hexcel® (Hexcel Corp.), referred to as “HUDC” (HexPly® unidirectional composite), and a discontinuous short fiber composite system provided by the University of Delaware, referred to as “TSFC” (Tailorable Universal Feedstock for Forming (TuFF) short fiber composite) or simply “TuFF.” The report also presents data obtained from analysis of the laboratory tests for the two unidirectional composites. Comparison of the mechanical properties of the TuFF fiber composite with those of the CF composite indicated that the TuFF material system has nearly equivalent (less than 15% difference) elastic moduli in all three principal material directions. Similarly, the TuFF fiber composite’s strengths under both tension and compression in the fiber direction, as well as the in-plane shear moduli, showed nearly equivalent values as compared to the CF composite. Improved transverse strength, in-plane shear strength, and both out-of-plane shear moduli were seen in the TuFF material. The TuFF material system, however, showed a significant reduction (~40%) in through-thickness tensile strength as compared to the CF material system.