A marine umbilical is usually bundled by different functional components, the mechanical properties of which are very different. Under the action of external load, unreasonable cross-sectional layouts may lead to large cross-sectional deformation and contact pressure between components, thus affecting the umbilical service life. Firstly, a method to realize the compactness of cross-section layout was given by minimizing the cross-section radius. The symmetry of cross-sectional layout was described by introducing virtual gravity index based on the tensile stiffness of components while a quantifiable index was proposed to describe the fatigue wear problem between vulnerable components like steel pipes. Then, the multi-objective optimization model of cross-section layout was established considering the above three objectives. The genetic algorithm was introduced to solve the optimization model and three representative cross-section layouts were automatically obtained. Finally, the numerical simulation was used to verify and evaluate the different cross-sectional layouts, and then the optimal cross-section layout design was obtained. The results show that the optimization method proposed in this paper can improve the ability of global optimization, which has certain guiding significance for the cross-sectional layout design of umbilicals.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |