Keywords: submarines, glass composites, buckling, non-linear analysis, ANSYS, finite element..

The investigations, which were carried out for the first time, involved the analyses of 38 composite circular cylinders, using different theoretical methods, and comparing the theoretical results, with the experimental results, to discover which one was the most reliable. The fibre layout of 22 of the glass/carbon circular cylinders was three layers of carbon fibres at 0 degrees (lengthwise) and two layers of E-glass fibres at 90 degrees (circumferentially), and the fibre layout of the glass circular cylinders were in the form of twelve layers of E-glass 0/90...0/90 degrees. Previous experimental work done at the University of Portsmouth showed that failure occurred due to the common modes, namely shell instability and axisymmetric deformation, which related to this study. The analyses presented in this paper showed that most of the specimens failed as a result of shell instability. The methods that were used to create a design chart method were obtained from the results of an in-house computer program RCONERTV, and the commercial finite element package ANSYS. Both eigen buckling analysis and nonlinear analyses were carried out. Analyses made by RCONERTV were carried out only for orthotropic properties. The theoretical results taken using ANSYS and RCONERTV were used, together with the experimental results, to produce the design charts. Overall this paper proves that for predicting the critical buckling pressure, for composite material vessels, the von Mises formula results were better and safer. This work is of importance in the design of deep-diving submarine pressure hulls, required for both military and commercial purposes.

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