Shape optimization of filament wound articulated pressure vessels based on non-geodesic trajectories

The most important issue for the design of articulated pressure structures reflects on the determination of the optimal meridian profile. In this paper, the optimal design for determining non-geodesics-based meridian profiles is outlined, subjected to geometrical limitations, stability-ensuring winding conditions and the Tsai-Wu failure criterion. The stress field is modeled using classical lamination theory, and the non-geodesic trajectories are employed to enlarge the design space and improve the structural performance. The searched optimal meridian profile is here approximated by cubic splines, which are based on equidistant knots. The objective is to maximize the performance factor using nonlinear optimization techniques. Two design problems are solved: firstly the optimal meridian profile determined using the present method is compared with the geodesic-isotensoid under the given opening radius. Secondly, the different optimal profiles with various slippage coefficients are obtained to demonstrate the effect non-geodesic trajectories have on the geometry and performance of articulated vessels. Results indicate that the articulated structure designed using the present method shows better performance, mainly triggered by increased internal volume as compared to that of the geodesic-isotensoid. Results also show that the structural performance of the articulated pressure vessel can further be improved with increasing slippage coefficients. (c) 2009 Elsevier Ltd. All rights reserved.