Strength Assessment of LNG CCS Plate Using Progressive Damage Modeling

Mark III cargo containment system (CCS) is considered in this study to investigate its structural strength under applied loads. This membrane type Liquefied Natural Gas (LNG) CCS is exemplified as plated structure, and it is constructed by stacking various engineering materials including plywood, triplex, reinforced PU foam and supporting series of mastic upon inner steel hull structure. The plated Mark III structure is considered as a laminated composite structure, and therefore, the strength analysis procedure of laminated composite materials is employed to perform its strength assessment. In developing the finite element models of Mark III CCS plate, commercially available general purpose finite element analysis package like MSC PATRAN and MARC are used. In the operation of LNG carrier Mark III CCS is subjected to a wide range of temperature variation, i.e. about −170°C to 20°C. Thus different material properties of Mark III CCS plate at these temperature levels are considered in the FE models. Based on the developed FE models, the strength assessment procedure of Mark III CCS plate is developed incorporating various strength based failure criteria for composite materials such as maximum stress, Hill, Tsai-Wu, Hoffman, Hashin and failure states such as initial and post-initial failures. As a result, failure details like failure locations and load values are obtained.