ON THE STRUCTURAL VALUATION IN OBLIQUE WAVES OF A LARGE LIQUEFIED NATURAL GAS CARRIER BY 3D-FEM MODEL APPROACH

Abstract

This structural valuation in oblique equivalent waves has as a study case a large LNG liquefied natural gas carrier, with an overall length of 289.3 m, structural gas membrane tanks, and a double hull. From the operation load cases, for the numerical study, a selection of the main cases is made, full cargo and ballast. The selected oblique design wave conditions are specific to unrestricted navigation areas, sagging and hogging wave-free surface, with the heading angle covering the oblique relevant cases. The computation of the LNG carrier equilibrium in oblique design waves is done by a three-parameter nonlinear approach, with the own P_QSW software. The 3D-FEM large LNG carrier model is developed by Femap/NX Nastran software. The structural valuation in oblique design waves, by strength and freeboard criteria, of the large LNG carrier involves 3D and 1D models. For practical purposes, the strength valuation results are synthesized as polar diagrams, for the relevant heading angles of the oblique design waves, representing the wave height safety limits for preserving the large LNG carrier structural integrity.