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

Study on bending mechanics of arch-shaped deformable structure
filled with hydrogel beads based on discrete element method
Peng Jin1 Gongxun Liu1* Xin Liang1 Liquan Xie2 Guojun Hong1
1 CCCC National Engineer Research Center of Dredging Technology and Equipment Co., Ltd, Shanghai, China
2 College of Civil Engineering, Tongji University, Shanghai, ChinaBernd, Doug and Hanspeter, 2012; Li, Guo, Gong, Qing and Li, 2016).
Additionally, deployable deformable structures offer advantages
including low stow volume, light weight, low cost, easy extensibility,and ability to mitigate other limitations of underwater unmanned robot
and underwater structure. Li et al. (2017, 2020) proposed to apply
deployable deformable structures whose main frame was an inflatabletubular structure made of synthetic fabrics in deep-sea exploration.
Comer and Levy (2012) have proven that the inflatable beam can beconsidered a standard Euler-Bernoulli Beam. Apedo et al. (2010, 2014)
proposed a 3D Timoshenko beam with a homogeneous orthotropic
woven fabric through three-dimensional nonlinear finite element
analysis of inflatable beams, which were made of modern textile
materials and could be used as a load-bearing beams or arches when
inflated. However, the inflatable deployable method has limitation to
the need of storing hydraulic pressure in advance to complete the gas
reserve, so as to provide inflation for the inflatable deployable structure,in the underwater environment. Some researchers and scholars haveproposed replacing gas with hydrogel beads to expand the deployable
deformable structure in underwater environment. The hydrogel beads
swell and retain a significant fraction of the water they absorb (Sachiko,Shuichi and John, 2008; Ahmed, 2015), which have already been
applied in many fields, like biomedical science (Stamatialis, Papenburg,Gironés, Saiful, Bettahalli, Schmitmeier and Wessling, 2008), coaldehydration (Sun, Zhang, Shi, Tang, and Wu, 2002), sensor (Liu, Tang,Tham, Yuk, Lin, Lu and Zhao, 2017) and concrete (Kong and Zhang,2014). The swollen hydrogel beads have toughness to obtain a certain
strength (Ahmed, 2015). Xie et al. (2019) conducted numericalsimulations about the bending tests of beam-shaped deformablestructures composed of various hydrogel beads and inflatable outer
frames through discrete element method, and the results showed thatthe filling degree and radii of the hydrogel beads had a direct effect on
the deformation resistance of the composite deformable structures. Li etal. (2019) proposed an underwater inflatable tubular structure of nylon
sleeves filled with hydrogel beads, and carried out bending tests of theinflatable tubular structures under different lengths, slenderness ratios
and bead densities; their results provided the experimental Young'smodulus and deformation of the inflatable tubular structures underdifferent conditions. In addition, researches on the application ofABSTRACT
Applying deformable structures in underwater environment is a hot
topic in ocean development. In this study, an underwater arch-shaped
deformable structure filling the swollen hydrogel beads in its flexible
outer frame was proposed. Based on discrete element method, after thecalibrations of the mesoscopic numerical parameters of the flexible
outer frame and hydrogel beads, numerical simulations of bending tests
on different arch-shaped deformable structures under a central load of
10N, were established to study deformations and force chains in thesestructures. The results showed the swollen beads filled in structure
could help to achieve the desired structural shape and strength, and thefilling degree of the beads offered more influence on the composite
structure's bending resistance than the bead's radius.

KEY WORDS: Hydrogel bead; bending test; discrete element method;arch-shaped deformable structure.

INTRODUCTION
With the rapid development of human social life, terrestrial resources
are over-exploited. Countries all over the world have paid theirattention to developing underwater resources in the ocean. In theprocess of deep-sea development in full swing, underwater unmanned
robots are widely used in the construction of deep-sea marine
development platforms and underwater structures due to theirflexibility, such as the Bluefin Spray Glider produced by General
Dynamics of USA.
However, the traditional underwater unmanned robot and underwater
structure are large and heavy before entering the water, and theirprocess of entering the water is time-consuming, labor-intensive andfinancial-intensive. To improve work efficiency, deployable
deformable structures can be applied in this field, which have alreadybeen conducted in many other fields like aerospace (Meguro, Haradaand Watanable, 2004; Perrygo, 1999; Guo, Shi, Li, Deng and Liu, 2018)
and civil engineering (Fish, 1974; Gong, Li and Song, 2010; Moritz,

First author: Peng Jin, Ph.D, jinpeng@cccc-drc.com*Corresponding author: Gongxun Liu, Ph.D, liugongxun972@126.com

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