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 of the effect of motion modeling and damping on the prediction accuracy of excessive accelerationin waves
Fei Duana,b,c, Ning Ma*a,b,c, Xiechong Gua,b,c, Yaohua Zhoud
aState Key Laboratory of Ocean Engineering, Shanghai, China;
bSchool of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China;
cInstitute of Marine Equipment, Shanghai Jiao Tong University, Shanghai, China;dRules & Technology Center of China Classification Society, Shanghai, China;

framework of the second generation intact stability criteria (SGISc) after
the “ MV Pacific Adventurer”, “Chicago Express” and “Guayas”
serious accidents (SLF 54/INF.6, 2011; SLF 54/INF.7, 2011; SLF
54/INF.10, 2011). This problem usually involves vessels sailing inballast condition having high values of metacentric height (Bu, Gu, Luand Wei, 2019). In addition, the evaluation of excessive acceleration
adopted in the criterion is the roll of the ship in pure beam seas under thecondition of zero-speed. At present, the stability criteria of excessive
acceleration is mainly composed of the vulnerability criterion and thedirect stability assessment (DSA), among which the vulnerability
criterion is divided into two levels (SDC3/WP.5, 2016). The hierarchy
between levels was abolished since the 7-th session of Working Groupon Intact Stability of the SDC Sub-Committee, hence the assessment
could start at any level (SDC 7/WP.6, 2019; Rosano, Begovic,
Boccadamo and Rinauro, 2020).

ABSTRACTThe International Maritime Organization (IMO) has incorporated thefailure mode of excessive acceleration into the framework of the second
generation intact stability criteria (SGISc) at its 53rd meeting. According
to the existing accident conditions, the ship's forward speed is ignored
and beam long-crested wave conditions are adopted. In this paper, theinfluence of damping and degrees-of-freedom on ship motion andacceleration are analyzed by potential flow theory. The accuracy of shiplateral acceleration prediction under different numerical models arecompared. The simplified method recommended by IMO was used for
1-degrees-of-freedom (DOF) numerical model, Rankine Panel method
and CFD method were used for 6-DOF simulation. The catenary
mooring model is used to restrict the monotonously changing sway andyaw motions in CFD simulation. The nondimensional responseamplitude operators of lateral acceleration by different numerical models
are compared with model tests results. The results show that the critical
damping coefficient has the greatest influence on the calculation
accuracy of roll motion and lateral acceleration. The reduction of ship'sdegree-of-freedom will lead to the increase of roll motion and lateralacceleration. The numerical results of excessive acceleration obtained by
1-DOF model has the lowest accuracy while 6-DOF model has thehighest accuracy. The calculation accuracy of lateral acceleration can beimproved by using the modified roll damping coefficient in Rankine
Panel method method. The CFD results are in best agreement with theexperimental results. The Rankine Panel method is more efficientconsidering the calculation time.

In the current study, suggestions for modification of the coefficient C ofthe rolling period are proposed by Borisov, Luzyanin, Kuteynikov andSamoylov (2015). The correlation between load conditions, sea state andlong-term probability of excessive acceleration is discussed by Ogawa(2015). In order to find the allowable KG curves associated with Level 1and 2 of the excessive acceleration criterion, Boccadamo and Rosano(2019) evaluated the excessive acceleration of four naval vessels underfive different displacements. The three-dimensional time domain panel
method is used by Bu, Gu, Lu and Wei (2019) to evaluate the excessiveacceleration of a ship directly. The results show that the 4-DOF (swayheave-roll-pitch) mathematical model is more accurate than the 3-DOF(heave-roll-pitch) mathematical model. However, the calculation process
involves domain matching, which is also time-consuming. Kuroda, Hara,
Houtani and Ota (2019) only consider the weak nonlinearity of incident
wave force and static water restoring force on the hull surface calculationin DSA of excessive acceleration.

KEY WORDS:

Second generation intact stability; excessiveacceleration; degrees-of-freedom; ship motion.

INTRODUCTION

In the formulation of excessive acceleration criteria, the first and second
level of assessment adopt a simplified 1-degrees-of-freedom (1-DOF)

The excessive acceleratiton failure mode has been incorporated in the2117