The cargo containment system of a liquid hydrogen carrier operates at extremely low temperatures, and the hull structures are also exposed to such low temperatures, resulting in a significant temperature gradient. This temperature gradient poses a threat to the safety of both the cargo containment system and the hull structure. This study conducts a temperature field analysis of the hull structure and cargo containment system of a 40 000 m³ liquid hydrogen carrier. The computational fluid dynamics (CFD) method is adopted, considering thermal conduction, thermal convection, and thermal radiation, as well as the thermal coupling effect of the hull structure. A partial cargo hold model is adopted for analysis, which properly reflects the structural arrangement of the cargo hold area and the cargo containment system. The temperature distribution in the cargo holds is analyzed based on the IGC (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk) and USCG (United States Coast Guard) load cases. The results provide a reference for the design of similar vessels.

The longitudinal coaming of the liquefied natural gas (LNG) carrier’s cargo tank dome is typically subjected to significant longitudinal loads during operation, leading to stress concentration and potential failure at the toe of the end bracket. To address this issue, a shape optimization study was conducted on the end bracket structure. The optimization process sequentially employed orthogonal experimental design, intuitive analysis, comprehensive experimental design, and a GA-BP-GA (Genetic Algorithm-Back Propagation-Genetic Algorithm) hybrid method for stepwise refinement. The results demonstrate that through shape optimization, the maximum stress of the bracket was reduced by 22.9% compared to the original design. The influence of various design variables on the maximum stress decreases in the order of horizontal arm length ( L), toe height ( h), and arc radius ( r). The introduction of dimensionless parameters C_L and C _r reveals that C_L exerts a greater influence on the maximum stress than C_r. A lower maximum stress is observed when the stress concentration is located at the arc edge. Furthermore, the optimal structural dimensions, which yield a lower maximum stress located at the arc edge, correspond to C_L values ranging from 1.15 to 1.25 and C_r values ranging from 1.1 to 1.3. The optimization design process, methodology, and related conclusions presented in this study can provide valuable references for the design of ship bracket structures.