In this paper, the Sloshel experimental database is first used to validate some of the key points of the Bureau Veritas' guidelines for strength assessment of LNG membrane tanks under sloshing loads (Bureau Veritas, 2011). A finite element model of the NO96 containment system used during the Sloshel experiments is first built, and validated against Sloshel experimental database. This model is then used to compute structural capacities, which are finally compared to the impact pressures measured during Sloshel experiments. In a second part, some leads are given on how to improve the current methodology, by numerically analyzing the influence of the hydroelasticity onto the structural response of an impacted structure. To achieve this, the numerical tools for hydro-structure interactions, developed and validated during the Sloshel project (Malenica, 2009), are used: a set of simplified impacting waves is defined, with different values of impact angles and velocities. To investigate hydro-elastic effects, their impacts on a simplified MarkIII panel are simulated:

  • first in a non-coupled way: the deformations of the structure do not influence the hydrodynamic loading;

  • then in a fully hydro-elastic coupled way: the hydrodynamic loading does depend on the deformations of the structure.

The comparison of the two sets of calculation can then quantify the hydro-elastic effects as a function of the non-coupled structural response.

Strength Assessment of LNG Membrane Tanks Under Sloshing Loads

Sloshing became a very important practical problem in the last decade due to the increased activities in the liquefied natural gas (LNG) transport. The most common LNG carriers belong to the so-called membrane type. Within this membrane type concept, which is of main concern here, the LNG is kept at very low temperature (−163°C) by means of a complex insulation system, also called cargo containment system (CCS), attached to the ship structure.

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