A pseudo-coupled analytic fluid-structure interaction method for underwater implosion of cylindrical shells. (June 2017)

• Record Type: Journal Article
• Authors: Gish, L.A.
• Is Part Of: Applied ocean research. Volume 66(2017)
• Page Start: 156
• Page End: 163
• Publication Date: 2017-06
• Subjects: Implosion -- Fluid-structure interaction -- Pressure pulse -- Cylindrical shell -- Large deformations; Ocean engineering -- Periodicals; 620.416205
• DOI: 10.1016/j.apor.2017.05.013
• Languages: English
• ISSNs: 0141-1187

Abstract

Highlights: Underwater implosion pulse energy was estimated using an energy balance approach. The pulse energy is equal to the maximum system kinetic energy during collapse. The time-variant fluid pressure was found using an explicit time-stepping methodology and potential flow theory. Analytic solution of pulse energy matched numerical simulation results within 5%. Abstract: Underwater implosion, the rapid collapse of a structure caused by hydrostatic pressure, is a fully coupled, highly dynamic and nonlinear fluid-structure interaction (FSI) problem. The primary motivation behind studying implosion is the short-duration, high-pressure pulse generated in the surrounding water. This paper presents a simplified analytic method to estimate the energy in the pressure pulse, based on potential flow theory. The method accounts for the varying fluid pressure and accompanying FSI. The focus is on long, thin, unstiffened metallic cylindrical shells that collapse in mode 2. The implosion pulse energy is shown to be equal to the maximum system kinetic energy developed during collapse. The kinetic energy is calculated using an energy balance approach and analytic solutions for plastic energy dissipation and energy required to compress the internal air. The time-varying fluid pressure, and subsequently the work done by the fluid on the cylinder, is found using a novel explicit time-stepping methodology. The result is a pseudo-coupled analytic solution for the fluid pressure time history and implosion pulse energy. Solutions for pulse energy agree with RANS numerical simulations within 5%.