Finite Element Analysis And Optimal Design Of Non-radial Opening Of Pressure Vessel

Opening design nozzles for pressure components such as shells are the key structure of pressure vessels.After opening the shells,the overall strength and metal bearing area are weakened,while the non-radial opening structure destroys the symmetry of orthogonal nozzles on this basis,making the opening structure a weak part of pressure vessels.Therefore,it is the key to ensure the safe operation of pressure vessels to analyze the strength of non-radial nozzle structure and explore the factors affecting its stress distribution.Taking the nozzle structure with openings in the shell as the research object,the strength structure is studied by using the three-dimensional finite element method and theoretical calculation,and the influence law of three parameters,including the angle between the center line of the nozzle shell,the opening ratio and the thickness ratio of the nozzle to the shell,on the maximum stress of the structure is explored.With the increase of the angle between the nozzle and the center line of the shell,the stress decreases and the bearing capacity of the structure increases,among which the radial opening structure has the best strength With the increase of the ratio of nozzle thickness to shell thickness,the maximum stress decreases sharply at first and then slowly.The reinforcement of nozzle wall thickness improves the structural strength significantly,but excessive increase of nozzle thickness will lead to the decrease of reinforcement effect and increase of manufacturing cost.With the increase of opening ratio,the ratio of long axis to short axis of elliptical opening increases,and the maximum stress of structure increases continuously,so the opening ratio should not exceed 0.60 in design.In order to reduce the risk of equipment failure,it is necessary to ensure the quality of welds in intersecting areas and select reasonable reinforcement structures.The positions of the maximum stress points of the above three models are basically the same,and they are all located in the center of the inner wall of the nozzle at the acute angle side of the intersection area between the nozzle and the shell.The structure was analyzed the intensity by Equal Area Reinforcement Method in GB/T150-2011 and Ultimate Load Analysis in ?????52857-2007,and the result of theoretical calculation was verified by Elastic Stress Finite Element Method and Ultimate Load Finite Element Method.The consequence shows that the Ultimate Load Method is more convenient and more conform to real material.It also can make the best use of the material and increase the economic performance.In practical engineering,the vessel not only bears internal pressure,but also bears axial force and bending moment load under the influence of external factors.Based on the national standard of Russian Federation,the strength of structure under single load and combined load is checked and verified by finite element method.The results show that the stress of nonradial perforated nozzle under combined load is more complicated than that under single load,so it is necessary to consider combined load when checking strength,which is more in line with engineering practice.The response surface method was used to optimize the structural parameters,and the response diagram of the relationship between nozzle wall thickness,shell wall thickness,nozzle shell centerline angle,opening diameter and equivalent stress was obtained.The optimal parameters of container lightweight were solved,which saved the cost and shortened the design cycle.