Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Structural performance analysis of multi-module floating body with connector based onhydroelasticity
Xinyun Ni, Jun Ding, Ye Lu, Yuchao Chen, Qibin Wang, Ziyang Wei, Ying Chen, Xiaoming Cheng
China Ship Scientific Research Center
Wuxi, Jiangsu, China

ABSTRACT
Very large floating structures (VLFS) play an important role in theexploitation and utilization of marine resources. When the floating
body reaches a certain scale, we often use the connecter to assemble
multiple modules as a super large-scale floating platform. The fluidstructure coupling effect between multi-module VLFS and thesurrounded waves will become very prominent. The traditional
analysis method of taking the floating body as a rigid body is no longer
suitable for the analysis of the performance of the floating body. The
hydroelastic analysis method can fully consider the coupling effect offluid and structure and acquire the coupling solution of fluid andstructure, which can present the performance of multi-module VLFS
more accurately.
The development of hydroelasticity theory can be traced back to the1970s. In 1977, Betts et al. proposed the hydroelasticity theory ofsymmetric response analysis considering only two-dimensional effects
of a ship hull. In 1979, Bishop et al. Conducted extensive and in-depth
research on two-dimensional hydroelasticity and established thefoundation of hydroelasticity. In the early 1980s, Wu (1984) and Priceet al. (1985) combined the three-dimensional seakeeping theory andstructural dynamics to develop an analytical theory and method foranalyzing the hydroelastic response of the three-dimensional floating
structure with complex shape and proposed a fluid-structure couplingboundary condition with a wider application range, namely Price-Wuboundary condition. Through continuous accumulation, Du (1996)
improved the hydroelasticity analysis method based on the developed
three-dimensional hydroelasticity theory in the frequency domain. The
established method could take into account the influence of nonuniform steady flow and ship speed, further expanding the application
scope of the hydroelasticity theory. In the 1990s, Wu et al. (1997)
established a three-dimensional nonlinear hydroelastic theoreticalanalysis method to calculate the nonlinear hydroelastic response offloating structures. Through the establishment of this theory, the effectof second-order wave force can be added to the three-dimensional
linear hydroelastic generalized motion equation. The dynamic responseof the floating body under the combined action of first-order wave
forces and second-order forces is analyzed. In recent years, a great deal

Multi-module floating body is an important structural type of offshore
engineering equipment, which has attracted more and more attention
from researchers in recent years. The evaluation of motion response,
connector load, and overall structural strength is a key step in thedesign process of the multi-module floating structure. The traditional
theory of rigid body motion cannot meet the requirements ofperformance evaluation of floating body with multiple modules, while
the hydroelastic method can fully consider the effect of fluid-structure
coupling and large deformation, and predict the performance of thestructure more accurately. Therefore, in this paper, the hydroelastic
theory will be adopted to analyze the performance of a multi-module
floating body. In the process of finite element model analysis of thestructure, the modal shape of the platform assumed as a flexible bodywas calculated, and the modal load of the connector and typical sectionof each module are acquired. Based on the modal shape obtained by
the finite element method and the generalized fluid-structure couplingboundary conditions, the source strength is distributed on the wet
surface element of the floating body, and the complicated Green
Function is used to calculate the source strength and then the velocity
potential and the hydroelastic response of the multi-module floatingbody. After obtaining the hydroelastic response of the floating body,the RAOs of the overall strength and the connector load of the structure
are calculated by the mode superposition method. In this paper, thehydroelastic responses of the multi-module floating body under theworking condition are illustrated, and also compared with the model
test results. The short- and long-termed prediction of hydroelastic
responses of the floating body under irregular waves is displayed,which plays important technical support for the design of the multimodule floating body.

KEY WORDS: multi-module floating body; hydroelastic response;model test; short- and long-termed prediction.

INTRODUCTION

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