Effect of structural parameters on design of variable-stiffness composite cylinders made by fiber steering

Abstract

A variable stiffness composite cylinder made by fiber steering is optimized for maximum buckling load due to pure bending. A multistep design optimization procedure is developed to get the maximum potential improvement in structural performance. To improve the computational efficiency, low-cost and computationally inexpensive surrogate models based on radial basis functions (RBF) are used as approximate for the high fidelity finite element (FE) analyzes. Different RBF formulations are also studied and compared with each other in terms of their accuracy.The effects of radius (R) and aspect ratio (L/R), as two structural parameters, on the structural improvement of the variable stiffness cylinders are also investigated. Keeping the thickness (t) constant, radius (R) is shown to have no considerable effect on the buckling load improvement of the variable stiffness cylinders whereas the aspect ratio (L/R) has a substantial effect on the buckling load improvement. Improvements up to 38.5% are obtained for cylinders with low aspect ratio.