Modelling methods for complex interconnection of very large floating structures based on discrete-module-beam hydroelasticity theory
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摘要:
目的 在离散模块−梁单元（DMB）水弹性理论框架下，提出针对连接形式复杂的超大型浮体结构（VLFS）的新的建模方法，并与已有方法进行对比分析。 方法 首先，概述基于DMB的水弹性分析方法，给出求解连续VLFS结构在波浪作用下的动力响应步骤；然后，针对VLFS复杂连接处进行建模，通过定义连接处的刚度矩阵，对与连接处相邻的两个集中质量间的力与位移关系进行修正，获得新的结构刚度矩阵和受力矩阵，并求解水弹性方程；最后，探究在弯曲刚度变化时采用4种方法求得的VLFS结构动力响应的变化趋势，分析各方法存在差异的原因。 结果 结果表明，4种建模方法都可以准确地计算出连接形式复杂的VLFS结构水弹性响应。 结论 所述建模方法可以用于计算多铰接或具有断裂位置的非连续VLFS结构的动力响应，并可拓展DMB方法的应用范围。 Abstract:Objective The aim of this paper is to proposes new methods for modelling a very large floating structure (VLFS) with complex connections in the framework of the discrete-module-beam (DMB) hydroelasticity theory, and makes a comparison with the existing methods. Method First, a brief introduction of the DMB-based hydroelasticity analysis method is given, followed by procedures for calculating the dynamic response of VLFS under regular waves. A structural stiffness matrix is then defined to model connections with complex forms in VLFS. Corrections are made to the relationship between the forces of two lumped masses and their displacements, obtaining a revised structural stiffness matrix and excitation force matrix, and solving the new hydroelastic equations. Finally, the varying trends of the structural dynamic response of VLFS against different bending stiffness by four methods are explored, and the corresponding reasons for their response differences are analyzed. Results The results show that all four methods are capable of precisely predicting the hydroelastic response of VLFS with complex forms of interconnection. Conclusion The methods in this paper extend the application of the DMB-based method in predicting the dynamic response of non-continuous VLFS, such as multi-hinged VLFS or VLFS with fracture places. -
图 1 在DMB理论框架下的连续型弹性浮体建模原理图
Figure 1. Modelling of a continuous elastic floating structure in the framework of DMB hydroelasticity theory
图 3 在DMB理论框架下的两模块超大型浮体连接处建模原理图
Figure 3. Schematic of modelling interface of a two-modules-interconnected VLFS in the framework of DMB hydroelasticity theory
图 5 在DMB理论框架下多模块铰接处建模的子结构法原理图
Figure 5. Schematic of modelling the hinged interconnection by substructure approach in the framework of DMB hydroelasticity theory
图 8 不同弯曲刚度下超大型浮体垂向位移和弯矩分布
Figure 8. Distribution of vertical displacement and bending moment along the hinged VLFS under different bending stiffnesses
图 9 铰接处相邻子模块重心处的垂向位移、剪力和弯矩之间的差值随弯曲刚度的变化曲线
Figure 9. Variation of the D-values between two adjacent sub-modules gravity center's vertical displacement, shear force and bending moment
图 10 铰接连接处的结构受力示意图
Figure 10. Schematic of the loads near the structure at the hinged position
图 11 子模块端面处的剪力
Figure 11. The vertical shear force at the interface of each discretized submodules
表 1 4种不同的连接处建模方法比较
Table 1. Comparison of modelling the interconnections by different approaches
建模方法 运动方程
系数矩阵维度连接处及其附近集中质量间
的结构变形假设虚拟刚度法 $ {\text{6}}N \times 6N $ 刚性假设 限制矩阵法 $ \left( {6N + 5h} \right) \times \left( {6N + 5h} \right) $ 刚性假设 子结构法 $ {\text{6}}N \times 6N $ 弹性假设 全节点法 $ \left( {6N + 12h} \right) \times \left( {6N + 12h} \right) $ 弹性假设 注：$ N $为DMB水弹性分析方法中的离散子模块（或集中质量）数目，
h 为多模块弹性浮体的连接处数目。
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