Pressure Hull Optimization Using General Instability Equations Admitting More than One Longitudinal Buckling Half-Wave,

Abstract : An improved method for predicting general instability admitting more than one longitudinal half-wave is adapted to an automated optimal design precedure described in NCE Reports NV5 and NV6. The original procedure assumes that the critical buckling shape contains only one longitudinal half-wave. This assumption is incorrect when ultra-high strength steels are used if what appears to be a questionable independent frame buckling constraint, used in the original design procedure, is relaxed. Design studies demonstrate that substantial weight benefits are possible at conventional operating depths (around 1,000 feet) if ultra-high strength steels are utilized and the new design equations are employed. Little weight improvement results from the use of high strength steels using the original design procedure. (Author)