Effect of Imperfections on the Buckling Behaviour of a Pressurized Circular-Elliptical Toroid

Abstract

It has been reported that the presence of imperfections in a nonconventional toroidal vessel can affect the buckling response of
the structure, depending mainly on the cross-sectional parameters
of the shell. This paper attempts to provide information regarding
the buckling sensitivity of externally pressurized circularelliptical toroidal shells containing initial geometric
imperfections in the form of eigenmodes. The toroidal vessel itself
is made up of a top semi-circular toroidal segment that is joined
tangentially to a bottom semi-elliptical segment at their equatorial
circles of latitude. A numerical approach using the commercially
available ABAQUS tool was employed for the investigation in
which suitable mesh densities and boundary conditions leading to
the lowest failure values were adopted throughout. Various
degrees of imperfections were separately superimposed in both
the tall (b/a=3.0) and short (b/a=0.5) toroids, keeping a/t=200
constant for all cases considered. While the buckling of short
toroidal vessels was insensitive to initial geometric imperfections,
the tall ones were found to be generally sensitive to the
imperfections, with up to 70% reduction in failure loads recorded
in some cases