Shape optimisation of axisymmetric cylindrical nozzles in spherical pressure vessels subject to stress constraints

In this study, optimal shapes of intersecting pressure vessels are sought u sing a novel topology/shape optimisation method, called Metamorphic Develop ment (MD). An industrial benchmark design problem of finding the optimal pr ofile of variable thickness that connects a spherical shell pressure vessel to a cylindrical nozzle is considered. Two types of intersecting structure s, distinguished by Rush and protruding nozzles, are investigated. The opti mum profiles of minimum mass intersecting structures are found by growing a nd degenerating simple initial structures subject to stress constraints. Th e optimisation seeks to eliminate the stress peaks caused by the opening. T he optimised structures are developed metamorphically in specified infinite design domains using both rectangular and triangular axisymmetric finite e lements that are ideally suited for modelling continua with curved boundari es. It is shown that the design with a protruding nozzle would produce a be tter stress distribution than the design with a Rush nozzle. The results de monstrate the success of the method in generating suitable, practical solut ions to the design problem. (C) 2001 Elsevier Science Ltd. All rights reser ved.