Studying buckling of composite rods made of hybrid carbon fiber/carbon nanotube-reinforced polyimide using multi-scale FEM

In this paper, the buckling behavior of rods made of carbon fiber/carbon nanotube-reinforced polyimide (CF/CNT-RP) under the action of axial load is investigated based on a multi-scale finite element method. A dual-step procedure is first adopted to couple the micro- and nano-scale effects in order to obtain the equivalent elastic properties of CF/CNT-RP for various volume fractions of CF and CNT. The interphase effect between CNTs and the polymer matrix is taken into consideration. Further, the dispersion of CF/CNT into the polymer matrix is assumed to be random. Then, rods with square and circular cross-sections are considered whose stability characteristics are analyzed. The finite element modeling is performed using two models including a 3D brick model and a 2D beam model. Selected numerical results are given to study the effects of volume fraction of CNT/CF, interphase, and geometrical properties on the axial buckling response of the multiscale composite rods. (C) 2020 Sharif University of Technology. All rights reserved.