Stress Analysis And Lightweight Design Of Large Hyperbaric Oxygen Chamber

Hyperbaric oxygen chamber is an important medical equipment and large hyperbaric oxygen chambers are more and more widely used.At present,methods for design of pressure vessels are applied for the structural design of the oxygen chambers and the lightweight design is the main consideration of the design of large hyperbaric oxygen chambers.In this thesis,different numerical stress analyses were performed on a large hyperbaric oxygen chamber.Load-carrying ability was studied and lightweight design was conducted.The main work and conclusions are as follows.(1)Stress analysis of the hyperbaric oxygen chamber was carried out using finite element method.Strength assessment was conducted based on stress classification theory.Results show that the strength at the large opening area of the structure cannot meet the strength requirements while that at the shell structure has a big strength margin.(2)Finite element limit analysis was performed on the hyperbaric oxygen chamber and the limit load was calculated.It is found that if local plastic flow and stress redistribution is allowed,the load-carrying ability of the structure will increase.In addition,it turns out that under the action of the limit load,the shell is only in the initial yield state,meaning that thickness of the shell can be decreased and the whole structure can be lightweight designed.By performing numerous limit analyses,the thinnest shell thickness was found to 5.7 mm under the strength requirements.(3)Using real stress-strain relationship,Elastio-Plastic analysis was applied to calculate the load-carrying capacity of a flat plate with a large rectangular opening at the center.It is found that the high stress occurs at the round corner of the opening connecting area.But unlike the results by stress classification analysis,the strength at the rectangular opening area meets the requirements when assessing the results obtained by Elastio-Plastic analysis.(4)Finite element method is applied to simulate the stress distribution at the structure of a plate with a large rectangular opening under the transverse pressure with the concentration on the reinforcement methods and effects.It is found that the stress is mainly the bending one.Unlike on a cylinder,a reinforcement ring is not effective to reinforce the plate with rectangular opening.By increasing the bending stiffness,adding the nozzle thickness or applying reinforcement ribs can effectively reinforce the strength of the plate with opening.Specifically,when the reinforcement ribs are parallel to the short edge of the nozzle at the opening and close to the round corner,the reinforcing effect is the most significant.