Pubblicazione scientifica

Guidance Notes on Whipping Assessment of Large Container Ships

FILONE TECNOLOGICO	TEMA
economia circolare e sostenibilità

RIASSUNTO

Abstract

One of the critical issues for large container ships is the vibration of the hull girder due to wave impact which leads to excitation of whipping responses. This study presents analysis guidance to determine values of dynamic bending moments considering the effects due to whipping which are suitable for design application. The analysis for predicting structural capacities has been carried out by computing ultimate longitudinal strength. In addition the assessment of the safety against failure due to excessive maximum loads is accomplished in Ultimate Limit States. Eventually the whipping effects and design assessment are summarised and discussed.

INTRODUCTION

The demand for larger container ships has increased dramatically in the last decade as world trade continues to grow and with the marine industry requirements for more energy efficient ships. Currently the largest of these ships have a capacity of 18,000 TEU and designs of 20,000 TEU or more are on order. Springing and whipping phenomena can be critical for the design and operation of these large container ships due to their large deck openings and the slender hull form combined with high speed of these ships.

Wave impact loads are important in the structural design and wave impact causes both local and global effects. One of the critical issues on global effects for large container ships is the vibration of the hull girder due to wave impact which leads to excitation of whipping responses of the ship's hull girder. High whipping responses are usually driven by large bow flare angles, high ship speed, and a low draught in association with flat bottom. Occasionally stern counter slamming can lead to high whipping responses.

Ship whipping is the rapid flexing of the hull girder as a consequence of a wave impact on the hull. This usually results in high frequency cyclic oscillations of the hull girder which may result in increased wave induced vertical bending moments and shear forces compared to linear theory. The oscillations of the whipping responses usually decay rapidly after several wave periods due to damping effects. The total number of whipping cycles in the ship's life is small. Therefore the increase in vertical bending due to whipping is primarily a global strength issue (Lloyd's Register, 2014).

DATA

Data di pubblicazione: 26/06/2016

AUTORI

LEE YONGWON
WHITE NIGEL
WANG ZHENHONG
KIM YOUNG-HWAN
YANAI YOSHINARI
WANG ZHI-JUN

ENTE DI AFFERENZA

LLOYD’S REGISTER
LLOYD’S REGISTER ASIA
LLOYD’S REGISTER GROUP LIMITED

RIVISTA

ISOPE International Ocean and Polar Engineering Conference, Rhodes, Greece

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