Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering ConferenceShanghai, 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

Ultimate Strength of Laser-Welded Web-Core Sandwich Plates Under Combined Compression And
Lateral Pressure
Qiang Zhonga,b, Zhengjun Hanc, Deyu Wanga,baState Key Laboratory of Ocean Engineering, Shanghai Jiao Tong UniversityShanghai, Chinab
Institute of Marine Equipment, Shanghai Jiao Tong UniversityShanghai, ChinacChina Ship Development and Design Center
Shanghai, China

buckling and even collapse may occur in the service period of ships
when overloaded in an extreme situation. In this regard, it is necessary
to study the ultimate strength and collapse mode of the plate undercompression.

ABSTRACTIn this paper, the ultimate strength and collapse behavior of laserwelded web-core sandwich plates under combined compression andlateral pressure are investigated based on a 3-D nonlinear finite element
method (FEM). Both geometric nonlinearity and material nonlinearity
are taken into consideration. The ultimate strength characteristics oflaser-welded web-core sandwich plates, especially under transverse
compression, are investigated in this study, and the influence of lateralpressure is taken into account. Besides, the effect of laser weld rotation
stiffness on the ultimate strength and collapse behavior of laser-welded
web-core sandwich plates under compression and lateral pressure isstudied. Some important conclusions can be obtained from this paper,
which are useful insights for the development of the ultimate strength
theory of ship structures and lay a good foundation for the study of theultimate strength of laser-welded web-core sandwich plates in thefuture.

The deformation modes of the sandwich plates in the buckling andpost-buckling have been studied by many scholars. The deformation
modes include the local buckling and global buckling. Kolsters andZenkert (2006a, 2006b) studied the local buckling of the face plates
between the webs in both the web direction and the direction
orthogonal to it. In their study, there was foam filled with the core of
the sandwich plate. However, Kolsters and Wennhage (2009) proposedthat the global buckling of the sandwich plates should be the most
likely failure mode for the large span of strong supporters such as
longitudinal girders and transverse frames. Jelovica and Romanoff(2013) theoretically investigated the load-carrying behaviour ofgeometrically imperfect web-core sandwich plates in the post-buckling
regime. The global buckling mode dominated in the buckling and postbuckling regime. Nevertheless, the first eigenmode which was used as
the initial deflection did not include the local initial deformation. Zhongand Wang (2021) numerically investigated the ultimate strength
behavior of the laser-welded web-core sandwich plates under in-planecompression. The global deflection of the sandwich plate and the local
deflections of the face plates were both introduced in the ultimate
strength analyses. Both the local buckling and global bucking occurredin the ultimate limit state which shows that such method of introducing
the initial deflection is reasonable. However, they did not study theinfluence of the rotational stiffness of T-joint on the failure mode.
Moreover, the ultimate strength and the failure modes of the laserwelded web-core sandwich plate under the transverse compression inwhich the stiffness is relatively weak has not been studied yet.

KEY WORDS: Laser-welded web-core sandwich plate; ultimate
strength; collapse behavior; compression; lateral pressure; rotational
stiffness.

INTRODUCTION
Humankind is becoming increasingly aware that energy has to be used
more efficiently to preserve the environment. One possible way toincrease the energy efficiency of a ship lies in reducing its structuralweight, allowing a higher amount of cargo to be transported. Advancesin laser-welding technology have allowed the use of new structuralconcepts that allow higher weight savings in the shipbuilding industry.
A sandwich plate has a lower weight for the same flexural stiffness ofthe traditional structure as a result of the material being positioned
away from the neutral axis. This study concentrates on the lase-welded
web-core sandwich plates, which have two face plates separated by theweb plates.

A web-core sandwich plate is special as its transverse shear stiffnesses
in both directions have a huge difference. To be specific, the shear
stiffness in the core direction, DQx is is larger by few orders than that in
the direction perpendicular to the webs, DQy. When laser welding isadopted to connect the face and web plates, the weld thickness is muchless than that of the web plates, which makes such difference even

When applied on a ship deck, the web-core sandwich plates are
subjected to the compression loads. In this regard, buckling, post-3088