Thickness Optimization of Axisymmetric Tube by Three-Dimensional Finite-Element Analysis for High-Flexural Rigidity

Abstract

A numerical method is proposed for optimizing the wall thickness distribution of axisymmetric tube using three-dimensional finite-element method. It is essential to put intermediate nodes between adjustable nodes in the method. Using the proposed method, the wall thickness distributions are optimized to realize high-flexural rigidity under the condition that volume is constant. It is revealed that the constraint condition has significant effect on the optimized geometry. When the end of the tube is constrained completely, it is not necessary to increase the thickness at the end. In contrast, when the end is not constrained, the thickness must be increased substantially. Therefore, it is important to take the constraint condition of the tube into consideration for tube geometry optimization. It is also demonstrated quantitatively that the geometry optimization realizes the volume reduction of the tube from the point of flexural rigidity per volume. Moreover, the feasibility to produce the optimized tube is studied using a unique extrusion method with tapered mandrel, which has been proposed by the authors. In this unique method, the wall thickness is controlled arbitrarily by positioning the tapered mandrel during extrusion.