Analysis of isogrid reinforced cylindrical vessels in the case of axially symmetric buckling

Abstract

Isogrid structures are a configuration of stiffeners of different sections, which make up a lattice placed on thin plates, with the aim of increasing the buckling factor of the overall structure. Because of the major benefits of isogrid structures when applied to increase the buckling factor and to decrease the mass of the structures the isogrid is placed on, its use has intensified until it has become a complete design technique for building cylindrical vessels under high compressive forces. Unfortunately, the detailed geometry of isogrid structures cannot be easily modelled or computed using FEM software, due to the high number of elements required to reliably mesh such a structure and the large amount of time taken to compute the results. This paper attempts to mitigate this problem by considering an analytical approach of sectioning the cylindrical vessel into component modules. These modules, consisting of a thin plate with isogrid stiffeners attached to it, are approximated as an overall thin plate with modified properties. The analytical algorithm is then implemented in a computed algebra system, which will quickly compute approximate values for the buckling factor and mass of the structure.

Keywords

• isogrid
• numerical applications
• stiffener
• buckling
• total mass
• cylindrical vessels