Efficient Design of a Smooth Bending Cylinder via Parametric Studies and Optimization
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© 2019 by Timothy K. Minton. Published by the American Institute of Aeronautics and Astronautics, Inc. Various engineering industries, from aerospace to biomedical, require articulated cylindrical geometries to improve aerodynamic efficiency, provide a control surface, or protect from environmental degradation. Traditionally, such structures accomplish articulation by moving multiple discrete cylinders with respect to each other using mechanical linkages. However, hinged, nested or sliding linkages between the individual largely rigid bodies can impair the structural performance, can interfere with other bodies, and may not seal sensitive equipment inside the cylinder from the environment. Continuous bending cylindrical bodies that integrate flexible and compliant skins can maintain smooth surfaces during articulation. This work investigates the structural design of flexible cylindrical bodies subject to bending and radial pressure loads. Two primary design archetypes (machined and wave springs) are studied based on currently available commercial-off-the-shelf solutions. The performance of each design is quantified by analyzing metrics for the bending and radial stiffnesses of the structure as determined by detailed finite element modeling, and the design space of each concept is explored parametrically via design of experiments and heuristic optimization. For this study, an ideal bending cylinder exhibits a bending stiffness profile that matches a prescribed moment-rotation curve while maintaining sufficient prescribed radial stiffness to resist external pressure loads. The design space of possible concepts is presented, and the performance of each design is quantified by analyzing the trade off between radial and bending stiffnesses.
author list (cited authors)
Walgren, P., Seifert, R., Chapkin, W., Frank, G., Baur, J., & Hartl, D. J.