Effect of waviness on the mechanical properties of carbon nanotube based composites

Carbon nanotubes have been regarded as ideal reinforcements of high performance composites with enormous applications. In this paper, effects of wavy carbon nanotubes on mechanical properties such as elasticity and strength aspects are investigated for nanocomposites using a 3-D representative volume element with long and short wavy carbon nanotubes. The carbon nanotube is modeled as a continuum hollow cylindrical shape elastic material with some curvature in its shape. The effect of the waviness of the carbon nanotubes and its parameters are studied. Numerical equations are used to extort the effective material properties for the different geometries of representative volume elements, under axial loading for straight carbon nanotubes. It is observed that waviness significantly reduces the effective reinforcement of the nanocomposites. The effective moduli are very sensitive to the waviness and this sensitivity decreases with the increase of the waviness. In the case of short carbon nanotubes, increasing trend is observed up to a specific value of waviness index. Tensile strength analysis shows a decreasing trend of the strength against the increasing the values of waviness indices. Geometry of the RVE is also found to be affecting the strength of the carbon nanotube reinforced composites. Simulation is applied on the straight carbon nanotubes with the hexagonal representative volume element, and the results are found to be consistent with the rule of mixtures results, which validate the proposed model.