Tensile Mechanical Behaviors of High Loading of Carbon Nanotube/Epoxy Composites via Experimental and Finite Element Analysis

This article aims to explore the tensile behaviors of a randomly distributed carbon nanotube (CNT) reinforced epoxy (EP) composite with high CNT loading by experimental and finite element analysis (FEA). The CNT/EP with CNT loading of 22-25 wt% is prepared by resin-film infusion process. The obtained tensile strength and modulus of the as-prepared CNT/EP are increased by 141.7% and 175.3%, respectively, compared with the blank EP. When the CNT/EP prepreg (uncured) is prestretched with a tensile deformation of 2.5% to improve the alignment of CNTs, the yielded tensile strength and modulus of the cured composite are further improved by 6.3% and 10.8%. FEA result reveals that CNTs are the main stress carriers, and the maximum stress level undertaken by CNTs is 23-fold that of EP matrix. Also, the carrying capacity of CNTs is closely correlative to their alignments, when the orientation angle between CNTs' axes and loading direction is changed from 0 degrees to 61 degrees, CNTs bear continuously decreasing tensile stress; otherwise (61 degrees to 90 degrees), CNTs undertake increasing compressive stress. Moreover, CNTs affect their nearby stress fields within EP in a distance of 50-60 nm, which proves that stress can be effectively transferred from EP matrix to CNTs.