Wha-Soo Kim

Wet Drop Impact Response Analysis of CCS in Membrane Type LNG Carriers -I : Development of Numerical Simulation Analysis Technique through Validation-

While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.

Investigation of fatigue performance of low temperature alloys for liquefied natural gas storage tanks

One of the most important issues associated with liquefied natural gas (LNG) storage tanks, such as LNG carrier cargo tanks and land LNG tanks, is their structural integrity. In order to ensure the operating life and safety of LNG storage tanks used under operating conditions such as thermal and cyclic loadings, the securing of safety evaluations for fatigue performance is considered to be of particular importance. There have been various efforts to reduce the production costs of LNG storage tanks, such as the optimum selection of materials and the development of new low temperature materials. This, the motivation of this study is to evaluate new material candidates for LNG storage tanks. This study begins with a comprehensive review of the characteristics of low temperature alloys such as SUS 304L, Invar, A5083 and 9% Ni steel that are widely used for LNG storage tanks. Then, the fatigue characteristics of a newly developed low temperature material, 7% nickel steel are investigated. Finally, the fatigue performance of 7% nickel steel is compared with that of 9% nickel steel.