Abstract: 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.

Key words: shape optimization, orthogonal experimental design, intuitive analysis, comprehensive experimental design, GA-BP-GA method

摘要： LNG船液穹纵向围板在营运过程中通常承受较大的纵向载荷，导致其端肘板趾端因应力集中而损伤。针对此问题，该文对端肘板结构进行形状优化研究，分别采用正交试验设计、直观分析、全面试验设计及GA-BP-GA方法逐步寻优，结果表明：通过形状优化，肘板最大应力较原设计降低22.9%，各设计变量对肘板最大应力的影响程度由大到小依次为水平臂长L、趾端高度h、圆弧半径r;引入无因次量C_L和C_r，C_L对肘板最大应力的影响大于C_r;当肘板应力集中位于圆弧边缘时，最大应力较低，且当C_L取值为1.15 ~ 1.25、 C_r取值为1.1 ~ 1.3时，相应的结构尺寸设计较优。文中的优化设计流程、方法及相关结论可为船舶肘板的结构设计提供参考。

关键词: 形状优化方法, 正交试验设计, 直观分析, 全面试验设计, GA-BP-GA方法