In recent years, many companies have put forward some problems about the preset manufacture of large marine valves (such as the diameter of Φ 5350mm) according to the demand. However, according to the existing marine valve design manual the corresponding standards, there is still a lack of statistical data about the design of large-diameter marine valves, there is also a lack of experience in the design of large-scale marine valves. Because of this, it is necessary to carry out careful correct calculation analysis, to carry out deformation stress analysis calculation. then according to the final results of the implementation of the default. Therefore, it is guaranteed to have satisfactory tightness sufficient strength. However, because of the particularity of marine valve structure, it is difficult to analyze calculate with classical mechanical method, only the finite element method is used to analyze calculate. The finite element method is used to analyze calculate the valve body butterfly plate of Φ 5350mm marine butterfly valve, so as to provide theoretical basis for reasonable structure preset optimization prevent unnecessary material consumption.

　　The essence of the finite element analysis method is to idealize the elastic cicada body with infinite degrees of freedom into an element body with only finite degrees of freedom through two approximations, so as to simplify the problem into a structural problem suitable for numerical solution. The first approximation is element partition, the very accurate boundary is separated into simple boundary, the connected objects are separated into a series of elements only connected by nodes, the structural separation is also known as the clear division of the grid, the scattered elements will replace the original elastic cicada body; The second approximation is the real complex displacement dispersion, which is approximately expressed in the final result form of the analysis, the final result of the analysis can be seen directly.

　　This requirement explains clearly that up to now, the development practical application of finite element analysis method rely on a critical tool: computer is used in practical calculation. By using the systematic software of computer to carry out analysis calculation, the speed of analysis is greatly increased, it plays a very important role in practical application.

　　1 Structure of marine valve

　　The valve body is double flange stiffened type; the butterfly plate is special-shaped plate, on which different stiffened plates are reasonably arranged. The structure is relatively complex. Manual calculation is considered appropriate, the office load is large. Because it is considered appropriate, 3D finite element analysis software is used for calculation.

　　Finite element analysis of 2 valve body

　　Structural dispersion is the basis of finite element method. The so-called structural decentralization is that the elastic cicada body to be analyzed is divided into finite element bodies according to certain rules, so that the adjacent elements are connected at the nodes, the load between the elements is only transmitted by the nodes. Structural dispersion is also known as clear grid division. The scattered element aggregates will replace the original elastic cicada. All calculation analysis will be carried out on this calculation plate.

　　Firstly, the finite element plate type of valve body with simple concise structure is established.

　　2.1 confirmation of boundary conditions

　　The variation of the valve body is mainly affected by the self weight of the valve body itself the weight of other marine valve components (such as valve plate power plant), because the weight of other components should be fully considered in the calculation. We the variation calculation of the valve body when the marine valve is vertically placed, load 3G gravity acceleration in Y direction, load y X constraints at the bottom of the valve body When the diameter of the valve is larger, the pipe end effect will be exposed, because the z-direction constraint of the marine valve is loaded on the two flanges.

　　2.2 stress analysis

　　Because the front diameter of marine valve is large, it is generally considered that it is suitable to use steel plate welding structure, because the main consideration is the influence of the weight of the whole body of marine valve on the valve body, so as to prevent the valve body large self weight deformation, which affects the normal operation of marine valve. The acceleration of gravity is g, but in fact, the perspective of safety, we calculate it by 3G. Loading y = 3G, through the finite element analysis calculation, we can get the self weight deformation of the valve body under 3 times of the gravity acceleration. It is known that the larger variation is 0.6 mm.

　　Finite element analysis of 3-valve plate

　　According to the previous experience of marine valve design, the main board its rib plate on the valve plate are given a size first, because it belongs to the special-shaped plate, because it needs to accurately establish its group stiffness matrix, do group finite element analysis, because it needs group modeling, so it can ensure the continuity stress relevance of the whole butterfly plate, ensure the correct calculation results.

　　3.1 confirmation of boundary conditions

　　When working, the motor rotates with the valve shaft valve plate by reducing the speed. The torque of the valve shaft is transmitted to the valve plate through the connecting parts on the valve plate. When the valve plate is subjected to the force of the fluid medium, the force is also transmitted to the valve body through the connecting parts, because the constraint conditions of the connecting parts on the valve plate should be: the three moving coordinates of X, y, Z should be limited, their three rotating coordinates should also be limited. Therefore, the node of the inner wall photo of the joint is regarded as a fixed point, its displacement rotation angle are zero.

　　3.2 stress analysis

　　First of all, consider the utility of fluid medium. In this design, the office pressure is 0.1MPa (1.0kg / cm2), but in fact, the perspective of safety, we calculate it as pressure = 0.3MPa (3kg / cm2).

　　Before after the valve plate transformation, there is a transformation. The larger position of the transformation is at the outermost point on the core surface of the valve plate rotation axis. In this case, the larger transformation is Zmax = 0.21mm.

　　4. Analysis of the final results

　　The variant analysis of marine valve is that the main components of marine valve will change after being stressed. After the final result, it is very convenient to carefully check analyze the situation after the variant, analyze compare the state before after the variant, also get the variant volume of the previous official's point. After calculation analysis, if the deformation of the member after being stressed exceeds the allowable range the deformation is very small, the structure (such as thickness) shall be corrected, so as to obtain a reasonable structure.

　　The stress analysis of marine valve is that the stress will be generated after the stress analysis of marine valve, the larger stress on the component can be found directly through the analysis of the final results. The rationality of the component structure is analyzed optimized the perspective of stress, the reinforcement bar is reasonably placed in the position with large stress to strengthen the marine valve.

　　It can be seen the above analysis that through the stress calculation stress analysis of the main components of marine valves, we can find out the position the structural stress is greater the deformation is greater. The two are combined to correct the structure of marine valves, obtain a reasonable structure to ensure that it has enough strength rigidity, prevent the bulky structure causing material, data energy loss The cost of quality, reduce the cost of guidance.

　　5. Conclusion

　　Through the simulation analysis calculation of marine valves, the following conclusions can be drawn

　　(1) It can calculate the stress everywhere on the marine valve components reveal the stress value, so it can find out the position with larger stress optimize it. It can find the latent problems in the preset stage of the product, so it can reduce the number of attempts the cost of attempts.

　　(2) It can show the deformation of the valve plate under the force, also can get the deformation value of the valve plate. In this example, the position of the valve plate with larger deformation is the outermost point on the core surface of the valve plate rotating shaft, which can be targeted to enhance prevent the consumption of raw materials.

　　(3) After calculation analysis, the structure design is rationalized optimized to ensure that the design object has enough strength stiffness, save resources reduce costs.

　　(4) The reliability of products engineering is guaranteed, the time for products to be put into the market is reduced.

　　(5) Analyze the accident of the marine valve with problems find out the cause of the problem.

　　The application of finite element analysis technology in the design of marine valves has made a qualitative leap in the design level of marine valves. After the stress calculation analysis of the key structure of marine valves, the guiding opinions on the design of marine valves are given.