Multi-Impact Durability and Processing of Thick-Section Carbon-Glass/Epoxy Hybrid Composites Toughened With Thermoplastic Polyurethane Inter-Layer Films

Report No. ARL-TN-0501
Authors: Steven E. Boyd and James P. Wolbert
Date/Pages: September 2012; 30 pages
Abstract: Research was conducted on 3-D (three-dimensional) carbon and glass hybrid epoxy composites toughened with thermoplastic polyurethane (TPU) film inter-layers. The study focused on the effect of sample processing methods on impact degradation rates. The newly developed low velocity impact, four quadrant multi-hit testing protocol described in other works by Emerson et. al (2010 and 2011) and Boyd et. al (2011), which are referenced in this report, and has been successfully used to rank thick-section (>13 mm) composite materials and is used here. Samples were successfully processed using room temperature, standard molding techniques, and post-cures for the toughened SC-15 epoxy with little to no warpage and defects. The use of thicker sub-layers and strengthening of the composite interfaces with TPU inter-layers arrested damage progression, reduced overall delamination, and lowered stiffness degradation per impact. However, a mismatch in carbon and glass fiber properties in the hybrid samples produced extensive localized damage per impact and had the net effect of reducing sample stiffness.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2012