Abstract: As a new type of fishery cultivation equipment, the deep - sea aquaculture cage can cultivate fish with high economic value in the sea areas far away from the land. In order to explore the possible damage that the instability of the net - hanging poles may cause to the main structure of the platform, this paper takes a certain aquaculture platform in Guangdong as an example. Using finite - element software, displacements in different directions sufficient to cause fracture in the poles are applied to the free ends of the net - hanging poles. These displacements are designed to study the cracking process and ultimate bearing capacity of the typical nodes when they are subjected to forces in different directions. Different - thickness outer plates of the floating boxes are also set up to study the influence of the relative stiffness between the outer plates and the net - hanging poles on the fracture behavior and ultimate bearing capacity of the typical nodes. Through numerical calculations, it is found that when the same load is applied to the typical nodes with different plate thicknesses, the main structures of the 6 - mm and 8 - mm outer plates crack first, while for the 10 mm and 12 mm outer plates, the net - hanging poles fracture before the main structures. The results show that when the relative stiffness increases from 0.5 to 0.67, the weight increases by 8.8%, and the deformation - resistance capacity increases by 44%; when the relative stiffness increases from 0.67 to 0.83, the weight increases by 8.1%, and the deformation - resistance capacity increases by 33%; when the relative stiffness increases from 0.67 to 1, the weight increases by 7.5%, and the deformation - resistance capacity increases by 25%. It can be considered that the increase in the steel material of the typical nodes has little effect on the improvement of the ultimate bearing capacity, and an appropriate reduction in the plate thickness can be considered in the platform design stage. The analysis results show that if the stiffness of the main structure of the aquaculture cage is much greater than that of the poles, the fracture phenomenon is usually limited to the welds and the roots of the net - hanging poles and cannot extend to the main body of the aquaculture cage, resulting in only local plastic deformation of the main structure. On the contrary, when the stiffness of the main body of the aquaculture cage is lower than or close to that of the poles, the main structure of the node fractures first, and the fracture area gradually expands to the pole part. The results also show that the ultimate bearing capacity of the typical nodes of the net - hanging poles increases significantly with the increase in the thickness of the outer plates of the floating boxes. Based on this discovery, this paper proposes the calculation equations for the ultimate bearing capacity of the typical nodes in various directions, providing a theoretical basis for relevant engineering designs. 

Key words: deep-sea aquaculture net cage, ductile damage failure model, fracture simulation, bearing capacity

摘要： 深远海养殖网箱作为一种新型的渔业养殖装备，能够在远离陆地的海域养殖经济价值较高的鱼类。为了探究挂网撑杆失稳可能对平台主体结构造成的损伤，以广东某养殖平台为例，利用有限元软件对挂网撑杆的自由端加载不同方向的足够使其发生断裂的位移，以研究典型节点承受不同方向作用力时的开裂过程及极限承载力；又设置不同厚度的浮箱外板，以研究外板与挂网撑杆相对刚度对典型节点断裂行为以及极限承载力的影响。通过数值计算发现，对不同板厚的典型节点加载相同载荷时，6 mm、8 mm 外板主体结构先开裂，10 mm、12 mm 外板则是挂网撑杆先于主体结构断裂。通过统计后发现，当相对刚度从0.5增加至0.67时，质量增加了8.8%，抵抗变形的能力增加了44%；当相对刚度从0.67增加至0.83时，质量增加了8.1%，抵抗变形的能力增加了33%；当相对刚度从0.67增加至1时，质量增加了7.5%，抵抗变形的能力增加了25%。可认为该典型节点钢料的增加对极限承载力的提高作用并不明显，在平台设计阶段可以考虑适当减少板厚。分析结果表明，若网箱主体结构的刚度远大于撑杆刚度，断裂现象通常仅局限于焊缝及挂网撑杆根部，且无法延伸至网箱主体，致使主体结构仅出现局部塑性变形。相反，当网箱主体刚度低于或接近撑杆刚度时，节点主体结构首先发生断裂，且断裂区域逐渐扩展至撑杆部分。研究表明，挂网撑杆典型节点的极限承载力随着浮箱外板厚度的增加而显著增大。提出了各方向典型节点极限承载力的计算方程，为相关工程设计提供了理论依据。

关键词: 深远海养殖网箱, Ductile damage延性金属损伤模型, 断裂模拟, 承载性能