In this study, sloshing model tests were conducted in terms of selected environmental conditions, vessel configurations, and loading conditions. Following ABS assessment procedures, dynamic structural analysis considering fluid-structure interaction has been conducted to determine design strength capacity for the NO 96 containment system. Spatial, temporal and statistical characteristics of the measured sloshing loads were investigated based on sloshing model test data. Linear transient FE analysis of the NO 96 containment system including both structure and LNG was performed to obtain structural responses at predefined critical locations under short duration triangular pulse, which is referred to as triangular impulse response function (TIRF). In the FE model, orthotropic material properties for plywood and acoustic medium for LNG were considered to develop the coupled fluidstructure FE model. The TIRFs were synthesized with the time history of measured sloshing loads to obtain dynamic structural response at critical locations in the box system. Statistical analysis results of peak stress values in each component of the containment system were used as the basis for determining design sloshing loads or strength assessment of the NO 96 containment system. Finally, the application of an ABS procedure in a practical LNG containment system has been implemented under sloshing impact loads.
In membrane-type LNG carriers, the impact pressure due to sloshing motion in liquid cargo hold is one of the most important load factors to be considered when designing a new liquid cargo hold and containment system. The sloshing model test has been performed to estimate the sloshing load due to random ship motion in the design sea states, and to provide the design load for the strength assessment of the LNG containment system. Pressures measured from sloshing model tests show a variety of temporal and spatial patterns (Lee et al, 2004). The magnitude, effective area and duration of the impact load are all important parameters when considering structural response of the containment system (Kim et al, 2003).
