Structural Opotimization And Fatigue Analysis Of Large-calibred Gate Valve Body

Large-calibred gate valve DN is 350mm-1200mm. They are widely used in the process industry. As the result of large-calibred valve body restricted by installation size, the cavity is designed to round or oval in shape which contains flashboard.So it is hard for us to analyze it using the theoretical formula, further the structural optimization. We has no option but to rely on engineering experience. The valve body is one of the most important components of large-calibred valve. Because of its structure, there can be complex stress concentration and deformation. Then it cause body life is reduced and the leakage.Therefore, through the advanced CAE (Computer Aided Engineering) technique, we can do structure stiffness and strength analyses for the large-calibred valve body. Then we can do structural optimization design and the fatigue analysis. In short, it will provide us guidance and shorten the product development process.The main subject of this thesis is about large-calibred valve. By using the finite element software ANSYS, we can do some work such as static analysis, structural optimization and fatigue analysis.In ANSYS Workbench platform, the geometrical model of large-calibred valve body can be built. According to the actual situation, we set boundary conditions. According to the actual conditions and experiment conditions, we respectively apply loads. Then we make static analysis and study intensity and distribution of equivalent stress. We conclude that large-calibred valve body can not meet the requirement under the experiment pressure and there is a phenomenon of stress concentration. So we make some ribs at the outside of the cavity in order to reduce the maximum equivalent stress and make the stress well-distributed.As the engineering requirement being met, we optimize the struct of ribs and find a most effective solution. Based on two kinds of methods, we optimize the structure of ribs. Only the latter method uses the center method as an optimization algorithm. Both the two optimization method results consistent, but the latter iterative procedure is less and simple in calculation. Optimization results show that the maximum equivalent stress of the body decreases 35.82%. The stress concentration decreases and the stress distributes more evenly so that it improves the strength and rigidity of the gate valve.Using ANSYS Workbench Fatigue software, combining Fatigue damage theory and the III volume of ASME regulations, we make fatigue analysis of large-calibred valve body and find out the weak body parts. Then we design the body by structural optimization and increase the strength and improve the using life of the valve body.