Eshelby-Mori-Tanaka approach for post-buckling analysis of axially compressed functionally graded CNT/polymer composite cylindrical panels

Carbon nanotubes have drawn enormous attention in recent years due to their outstanding mechanical and multifunctional properties. In addition, the growing tendency of aeronautical engineering to incorporate advanced composite materials in aircraft structures suggests carbon nanotube reinforced composites as ideal materials for high-performance fuselage panels. Nevertheless, due to the theoretical difficulties in the underlying differential problem induced by curvature, along with the technology of carbon nanotube based composites that is still under development, the number of research works on the post-buckling behavior of carbon nanotube reinforced composite curved panels is still scant. Furthermore, numerous experimental results in the literature report about the wavy state of nanotubes in polymer matrices, as well as their tendency to gather in bundles due to their high van der Waals force attraction. Therefore, advanced homogenization approaches are needed to account for these phenomena and assist the structural design. In this context, this paper presents detailed parametric analyses of the post-buckling behavior of functionally graded carbon nanotube reinforced curved panels under uniaxial compression. In particular, the effects of filler content, fiber orientation, distribution along the thickness, and misalignment of fibers are investigated. To this aim, the overall elastic moduli of carbon nanotube reinforced composites are computed by the Eshelby-Mori-Tanaka method with consideration of waviness and agglomeration effects. The presented results prove the essential role of the micromechanical variables in the design of high-strength composite curved panels. Notably, the theoretical simulations highlight the detrimental effect of waviness and agglomeration on the mechanical response of these composites. In light of this study, it is concluded that the incorporation of the considered micromechanical variables is essential for the study of the post-buckling response of functionally graded carbon nanotube reinforced curved panels under axial compression.