Length effects in elastic imperfect cylindrical shells under uniform bending

• Main Author: Fajuyitan, Oluwole Kunle
• Other Authors: Sadowski, Adam ; Wadee, Ahmer
• Published: Imperial College London 2018
• Subjects: 624
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.762183

Recent computational investigations into the buckling behaviour of perfect elastic thin-walled cylindrical shells under uniform bending, a ubiquitous reference structural system that enjoys wide practical applications, have demonstrated that the stability behaviour of this shell system depends largely on the length. Consequently, four distinct length domains – short, medium, transitional and long – were introduced to categorise the response of the system based on the relative influence of end boundary restraint and cross-sectional ovalisation. However, most investigations on this particular shell system have only focussed on near-perfect geometric cases despite the vast research efforts that were made on the subject of imperfection sensitivity in a related reference system of cylindrical shells under uniform axial compression. Furthermore, the potential coupling between length and imperfection sensitivity has never been studied for any shell system. This research thus seeks to understand and characterise the effect of length on the elastic stability of imperfect cylindrical shells under uniform bending, considering diverse forms of geometric imperfections. The stability investigations were performed over a wide parametric variation of length, radius-to-thickness ratio, end boundary condition, form and amplitude of geometric imperfection, using a combination of modern finite element analysis software and programming languages. It was confirmed that there exists a relationship between the length of the shell system and imperfection sensitivity and this relationship was characterised into realistic, but conservative closed-form, algebraic expressions as a proxy to undertaking further computational investigations by analysts. The study also offers an efficient computational strategy that may be adopted in managing large computational analyses through most modern finite element suites and it is envisaged that this strategy will appeal to computational analysts who are encouraged to adopt the automation methodology described herein to explore other structural systems.