Havacılık ve Uzay Teknolojileri Dergisi (Jul 2017)
BUCKLING ANALYSIS OF CFRP COMPOSITE CYLINDRICAL SHELL WITH CUTOUTS IN BENDING
Abstract
Composite materials have many advantages when compared to metallic structures due to their better mechanical properties such as high specific stiffness and strength, high fatigue endurance and better impact properties. In addition, they offer higher corrosion and chemical resistance, better dimensional stability and design flexibility over metallic materials. Especially, in aerospace industry carbon fiber reinforced polymer (CFRP) composite is widely used because of its lightweight and high fatigue strength properties. The work presented in this study includes the effect of different size cutouts at both sides of the CFRP composite cylinder under pure bending. The results of a parametric study, concerning on the effects of a pair of cutouts symmetrically located at ±90° positions with respect to the vertical axis perpendicular to the bending axis, varying size of the cutouts and evaluating their effects on the buckling and maximum load levels of circular cylindrical shell were presented. The analysis methods that were used for the evaluation of the buckling and failure characteristics of shells include linear buckling analysis and nonlinear failure analysis using Riks method. During the nonlinear analysis, the imperfections coming from the buckling eigenvalue analysis were included at rates of 1%, 2.5%, 5% and 10% of the shell thickness to investigate the effect of imperfections. Analyses were performed using the commercial FEM solution ABAQUS. In that model, the stacking sequence was defined to be 24 layers of conventional fiber orientation angles.
