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Nanowire Stiffening of Woven Composites Towards Enhancing Interlaminar Fracture Toughness
Abstract
The objective of this paper is to explore the feasibility of using Zinc Oxide nanowires as potential interlaminar stiffeners textile polymer based composites. A comparison between the fracture toughness of a regular carbon fiber composite and a nanowire stiffened composite is performed to evaluate whether the ZnO nanowires enhance or decrease the fracture toughness. In this paper, both mode I and mode II fracture toughness of the interfaces within carbon fiber woven polymer matrix composites are investigated. Different methods have been proposed to calculate the fracture toughness experimentally and computationally. The interlaminar mode I (GIC) and mode II (GIIC) fracture toughness of a woven carbon/epoxy composite was measured using double cantilever beam (DCB) and end notched flexure (ENF) test, respectively. Eight woven carbon laminate specimens were tested for each method, where in mode I each specimen had 8 layers and in mode II each specimen had 20 layers of dry fabric of carbon fiber. A 0.002 in thick Teflon sheets were inserted in the mid-plane of the composite to simulate a crack. Reinforcement of ZnO nanowires were added to four specimens of mode I and mode II each. The fracture toughness of all the specimens were calculated. The values of GIC and GIIC were compared between the specimens with and without ZnO nanowires. The initiation and propagation of the crack was recorded, and every specimen showed a stable crack growth during the tests. The results showed the fracture toughness of the specimens with ZnO nanowires increased 43% in comparison to the specimens without ZnO nanowires in mode I. Also, the fracture toughness of the specimens with ZnO nanowires increased 28% in comparison to the specimens without ZnO nanowires in mode II.