Estimation of Nonlinear Roll Damping by Analytical Approximation of Experimental Free-Decay Amplitudes

Abstract

Damping is critical for the roll motion response of a ship in waves. A common method for the assessment of damping in a ship’s rolling motion is to perform a free-decay experiment in calm water. In this paper, we propose an approach for estimating nonlinear damping that involves a linear exponential analytical approximation of the experimental roll free-decay amplitudes, followed by parametric identification based on the asymptotic method. The restoring moment can be strongly nonlinear. To validate this method, we first analyzed numerically simulated roll free-decay data using rolling equations with two alternative parametric forms: linear-plus-quadratic and linear-plus-cubic damping. By doing so, we obtained accurate estimates of nonlinear damping coefficients, even for large initial roll amplitudes. Then, we applied the proposed method to real free-decay data obtained from a scale model of a bulk barrier, and found the simulated results to be in good agreement with the experimental data. Using only free-decay peak data, the proposed method can be used to estimate nonlinear roll-damping coefficients for conditions with a strongly nonlinear restoring moment and large initial roll amplitudes.

Journal

Journal ID (publisher-id): JOUC

Title: Journal of Ocean University of China

Publisher: Science Press and Springer (China )

ISSN (Electronic): 1672-5182

Publication date (Electronic): 06 July 2019

Publication date (Print): 01 October 2019

Volume: 18

Issue: 4

Pages: 812-822

Affiliations

¹College of Engineering, Ocean University of China, Qingdao 266100, China

²Key Laboratory of Ocean Engineering of Shandong Province, Ocean University of China, Qingdao 266100, China

³Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao 266001, China

⁴Shandong Provincial Key Laboratory of Ocean Environmental Monitoring Technology, Qingdao 266001, China

⁵National Engineering and Technological Research Center of Marine Monitoring Equipment, Qingdao 266001, China

Author notes

*Corresponding author: SHAO Meng

Article

Publisher ID: s11802-019-3912-8

DOI: 10.1007/s11802-019-3912-8

Copyright statement: Copyright © Ocean University of China, Science Press and Springer-Verlag GmbH Germany 2019.

License:

The copyright to this article, including any graphic elements therein (e.g. illustrations, charts, moving images), is hereby assigned for good and valuable consideration to the editorial office of Journal of Ocean University of China, Science Press and Springer effective if and when the article is accepted for publication and to the extent assignable if assignability is restricted for by applicable law or regulations (e.g. for U.S. government or crown employees).

Product

Self URI (journal-page): https://www.springer.com/journal/11802