A Review of External Pressure Testing Techniques for Shells including a Novel Volume-Control Method

A review of conventional testing methods for applying external hydrostatic pressure to buckling-critical shells is presented. A new "volume-control" pressure testing method, aimed at preventing catastrophic specimen failures and improving control of specimen deformation near the critical load, is also introduced. The implementation of conventional and volume-control systems in an experimental program involving the destructive pressure testing of ring-stiffened cylinders is described. The volume control method was found to improve control fo the specimen deformations, especially near the critical load, and catastrophic failures observed while using a conventional setup were avoided. The quasi-static tracking of post-collapse load-deformation relationships for snap-through buckling behaviour was possible while using a volume-control system, but precise control of dynamic shell deformations during buckling was not achieved for specimens failing with large buckling lobes. Expressions for estimating the available control over specimen deformations for pressure testing systems are presented. Keywords: external pressure, hydrostatic pressure, shell, buckling, collapse, experiment