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

Research on Design of Domestic Spherical Sector Window with Conical Edge
ChengJun Gao, WenXin Qu, Shuai Liu, XuYing Jiang
China ship scientific research center
Wuxi City, JiangSu Province, China

ABSTRACT

are basically imported from abroad. In order to solve the neck sticking
problem of manned submersible, it is necessary to study the structuralstrength of spherical sector observation windows made of domestic
materials. The structural stress and creep of small thin-walled conicalspherical sector acrylic
observation window were studied inliterature(Shi, Yang, and Yu, et al. 2014, 2015, 2019, 2020). Du etal.(2019) study the structural strength of Jiaolong conical frustum
acrylic observation window, and studies the effects of different friction
coefficient, cone angle and thickness diameter ratio on the structural
strength of conical frustum observation window. It is concluded that theaxial displacement and equivalent stress at the center of the inner side ofconical frustum observation window decrease with the increase offriction coefficient. When the friction coefficient between observation
window and window base is less than 0.3, The friction coefficient has
an obvious influence on the structural performance. Stachiw(1969) has
carried out a large number of short-term load failure tests and long-term
continuous load tests for spherical sector acrylic observation window.
According to the development requirements of spherical sector
observation window of large-depth manned submersible and referring toASME code(2016), a large-size spherical sector observation window isdesigned in this paper. The real-time strain is monitored through thepressure bucket strength test of the prototype of full-size sphericalsector observation window. The radial and circumferential strains ofspherical sector observation window under different pressures areanalyzed by finite element numerical method, and compared with theexperimental results. In addition, the effects of different friction
coefficients and conical edge chamfer on the displacement and stress ofspherical sector observation window are studied. Finally, the optimal
design results of spherical sector observation window are given.

Window is an important part of manned pressure spherical shell ofmanned submersible. The large-scale observation window is thedevelopment trend of large-depth manned submersible, and the designof large-size spherical sector observation window is the designdifficulty of large-depth manned submersible. In this paper, a prototype
of spherical setorobservation window with conical edge is designed tomonitor the real-time strain through the strength test of pressure barrel.
The radial and circumferential strains of spherical sector observation
window under different pressures are analyzed by finite element
numerical method, and compared with the experimental results. The
effects of different friction coefficients and the chamfer of the contact
surface of the observation window on the displacement and stress of thespherical sector observation window are studied. Finally, the optimal
design results of observation window are given.

KEY WORDS: spherical sector window with conical edge;design;
friction coefficient; chamfer.

INTRODUCTION
The observation window is an important part of the manned pressure
spherical shell of manned submersible(Lu, et al., 2008). The large-scaleobservation window is the development trend of large-depth manned
submersible. The large-size spherical sector acrylic observation window
is widely used in deep-sea manned submersible, and is often used in themanned cabin of manned diving equipment such as sightseeing
submersible and submarine rescue lifeboat. Compared with the conicalfrustum observation window, It can provide divers with a wide
underwater observation field of vision. The design difficulty of large
spherical sector observation window lies in strength and sealing. Due tothe viscoelastic characteristics of acrylic, the deformation varies greatly
with temperature and pressure. Liu et al.(2010) point out that the designof spherical sector observation window involves not only creep, sealing
and contact boundary, but also strength. Stachiw and Jerry et al.(1975,1976, 2004)conducted a number of studies on the installation ofspherical sector observation window and different cross-sectional formsof sealing ring. ASME code(2016) has clear requirements for thestructural thickness of spherical sector observation window and themechanical properties of acrylic raw materials.
At present, the acrylic materials meeting the requirements of ASME
code have not been disclosed in China. Therefore, the observation
windows or raw materials of China's large-depth manned submersible

DESIGN OF SPHERICAL SECTOR ACRYLIC WINDOWThe research object of this paper is the spherical sector observation
window made of domestic industrial flat acrylic. The mechanicalproperties of flat acrylic are shown in Table 1.
Table.1 Mechanical properties of domestic large thickness industrial
acrylic(38℃)
Density
Elastic Modulus
Poisson's
Compressive yield(MPa)
Ratio
strength (MPa)(kg / m³）3300
0.38103
1190
The observation window for submersible is generally designed
according to ASME code(2016). The maximum working depth of this1169