Strength and Stability Analysis of Cassini Ovaloidal Heads of the Cylindrical Pressure Vessel with Geometrical Imperfections

Abstract

Considering the wide application of cylindrical geometry in the construction of the body of aerial, marine and ground structures, the design of the heads connected to the body according to the placement conditions while maintaining the stress continuity at the connection point is of great importance. In this article, using the existing geometric relationships for special space shells, including Cassini oval shells of revolution, they are used as dished-end connected to the cylindrical pressure vessel and to investigate their strength and stability against external pressure as well as their buckling analysis. After extracting the relations related to the geometry of Cassini shells and establishing the boundary conditions for the connection of the shell to the cylinder, the stress analysis is performed based on the theory of membrane stress. Conversely, by creating the geometry of Cassini shells in Abaqus software and using scripting with Python, dimensionless stresses are extracted for shells with different shape parameters. Comparing the results of analytical and numerical solutions in this case shows the correctness of the analysis process. In the following, while extracting the critical load related to linear buckling, the effect of defects of different shapes (resulting from the superposition of the shapes of linear buckling modes) on the post-buckling behavior of Cassini heads has been investigated.