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1. chinaXiv:201804.00310 [pdf]

Analysis of the Hydroelastic Performance of Very Large Floating Structures Based on Multi-Modules Beam Theory

Xu, Jin; Sun, Yonggang; Li, Zhifu; Zhang, Xiantao; Lu, Da
Comment:本文发表在《Mathematical Problems in Engineering》
分类: 交通运输工程 >> 船舶、舰船工程

The hydroelastic behavior of very large floating structures (VLFSs) is investigated based on the proposed multi-modules beam theory (MBT). To carry out the analysis, the VLFS is first divided into multiple sub-modules that are connected through their gravity center by a spatial beam with specific stiffness. The external force exerted on the sub-modules includes the wave hydrodynamic force as well as the beam bending force due to the relative displacements of different sub-modules. The wave hydrodynamic force is computed based on three-dimensional incompressible velocity potential theory, and the boundary element method with the free surface Green function as the integral kernel is adopted to numerically find the solution. The beam bending force is expressed in the form of a stiffness matrix. The coupled motion equation is established according to the continuous conditions of the displacement and force. The motion response defined at the gravity center of the sub-modules is solved by the multi-body hydrodynamic control equations, then both the displacement and the structure bending moment of the VLFS are determined from the stiffness matrix equations. To account for the moving point mass effects, the proposed method is extended to the time domain based on impulse response function (IRF) theory. The accuracy of the proposed method is verified by comparison with existing results. Detailed results through the displacement and bending moment of the VLFS are provided to show the influence of the number of the sub-modules, and the influence of the moving point mass.

提交时间: 2018-03-30 点击量40下载量19 评论 0

2. chinaXiv:201706.00364 [pdf]

Hydrodynamic analysis of multi-body floating system in waves: from rigid to flexible structures

Zhang Xiantao; Lu Da; Sun Yonggang; Gao Yun
分类: 交通运输工程 >> 船舶、舰船工程

The hydrodynamic problem for multi-body systems in waves has complexity in both wave structure interaction and coupled dynamics with interconnection. A consistent approach is developed for calculating the dynamic response of multi-body floating systems. This method is based on multi-rigid-body hydrodynamics and Euler-beam bending theory and can be used to deal with rigid or flexible multi-body floating systems in both frequency and time domain. Within the framework of this consistent approach, a stiffness approximation method is proposed to calculate the natural frequency and corresponding oscillation mode of a hinged multi-module structure. This is significant for both traditional multi-body floating system (for the purpose of structural safety) and wave energy converters (for the purpose of power efficiency). The hydroelasticity theory proposed by Lu et al. (2016), which is used to deal with continuous flexible structures with cross section of simple shapes, is extended to be applicable for multi-module flexible structures with cross section of arbitrary shapes and varied geometric features in longitudinal direction. Finally, an effective strategy is established to analyse in time domain the dynamic response of a hinged multi-module flexible structure with moving point loads on the upper surface in waves, representative of vehicles moving on a floating bridge or airport.

提交时间: 2017-06-09 点击量2356下载量843 评论 0

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