Parametric FEA Study of Burst Pressure of Cylindrical Shell Intersections

In an earlier paper (2009, “Burst Pressure of Pressurized Cylinders With the Hillside Nozzle,” ASME J. Pressure Vessel Technol., 131(4), p. 041204), an elastic-plastic large deflection analysis method was used to determine the burst pressure and fracture location of hillside cylindrical shell intersections by use of nonlinear finite element analysis. To verify the accuracy of the finite element results, experimental burst tests were carried out by pressurizing test vessels with nozzles to burst. Based on the agreement between the numerical simulations and experimental results of Wang et al. (2009, “Burst Pressure of Pressurized Cylinders With the Hillside Nozzle,” ASME J. Pressure Vessel Technol., 131(4), p. 041204), a parametric study is now carried out. Its purpose is to develop a correlation equation by investigating the relationship between various geometric parameters (d/D, D/T, and t/T) and the burst pressure. Forty-seven configurations, which are deemed to cover most of the practical cases, are chosen to perform this study. In addition, four different materials are employed to verify that the proposed equation can be employed for different materials. The results show that the proposed equation resulting from the parametric analysis can be employed to predict the static burst pressure of cylindrical shell intersections for a wide range of geometric ratios.

Analysis and Comparison of Pad Reinforcement of Pressure Vessel by Elastic and Elastoplastic FEM

Considering reinforcement pad and the cylindrical shell as an integral model and a contact model, stress analysis for opening-reinforcement structures of a cylindrical shell is performed by elastic and elastoplastic FEM. By comparison of two sub-models and two material constitutive relations (elastic and elastoplastic), the stress distribution of cylindrical shell intersections by the contact model is similar to that by the integral model, but there are some differences of the stress at contact surfaces of the shell and the reinforcement pad between by the contact model and by the integral model. In general, the stress analysis of the integral model for pad reinforcement can approximately represent that of the contact model. Finite element analyses for different nozzle diameters and different oblique angles in nozzle and cylinder shell intersections are carried out. The stress distribution and the maximum stress are affected by oblique angle. But the difference of the maximum stress intensity among different diameters is small.

Influence of Pad Reinforcement on the Limit and Burst Pressures of Large Diameter Cylindrical Shell Intersections

The purpose of the paper is to provide some experimental results for the limit pressure of a vessel-nozzle intersection under internal pressure with a large pad-reinforced opening (d/D = 0.526). It is expected that the data obtained from the burst test will serve as the basis for the development of more accurate design guidelines for this type of reinforced intersection. A comparison of the limit and burst pressures with and without pad reinforcement is also carried out. The present test results indicate that pad reinforcement yields an effective improvement of the limit and burst pressures of a vessel.

Collapse Strength of Complex Metal Shell Intersections by the Effective Area Method

Cone-cone intersections and cone-cylinder intersections with or without ring stiffeners are common features in silos, tanks, pressure vessels, piping components, and other industrial shell structures. Under internal or external pressure, these intersections are subject to high circumferential membrane stresses as well as high bending stresses due to the presence of a slope discontinuity. As a result, they are susceptible to local plastic collapse. This paper first provides a summary of the effective area method initially proposed by Rotter for the plastic limit loads of cone-cylinder intersections in silos. The method is then generalized for complex intersections of cones and cylinders under uniform pressure and improved by including the local pressure effect. Results from the effective area method are compared with rigorous finite element results for a number of cases to demonstrate its accuracy. It is shown that the method is not only elegant and accurate, but also leads to a single simple formula for different types of intersections which is particularly suitable for codification purposes.

Stress Analysis of Shell Intersections With Torus Transition Under Internal Pressure Loading

Thin shell theory and finite element method were used to investigate shell intersections with torus transition. The developed special-purpose computer program SAIS is employed for elastic stress analysis of the shell intersections. Comparison of calculated results with experimental data are presented. The parametric study of models for the radial nozzle connections in shells under internal pressure loading was performed. The results are presented in graphical form. Nondimensional geometric parameters are considered to analyze the effects of changing these parameters on stress ratios in the shell intersections.