optimal geometry design and finite element analysis of welded internal stiffener ring in cylindrical vessel made of high strength aluminum

Design of structures in aerospace needs minimum weight. Cylindrical thin-walled pressure vessels are one of the most functional among these structures and one of the main ways to reduce weight of these structures is using stiffener rings. In this research in order to find optimum structure weight، internal stiffener ring dimensions were optimized with genetic algorithm coupled with a neural network. In other hand، for joining the stiffener rings to vessel، welding is a conventional way. However، this process can produce welding residual stresses and distortions، which add to external loads and cause structure failure. So in order to predict and control these effects، a comprehensive simulation tool was developed to predict distortions and residual stresses generated in double sided fillet-welded internal stiffener ring on a cylindrical pressure vessel. Results showed that the T-stiffener ring have the best results and the optimum ring dimensions were determined and reported. In addition، magnitude of residual stresses was near to half of base metal yield strength and in weld region، hoop residual stress was tensile and axial residual stress was tensile on inner surface and compressive on the outer surface of vessel. Moreover Effect of tack welds were appeared on residual stress distribution like tiny peaks and have more effect on hoop residual stress distribution on stiffener ring position.