Roll Motion of a Roro-Ship in Irregular Following Waves

駛上駛下船通常其船型較瘦，但在艏艉水線上方有很大的舷緣外傾。這類船爲了獲得較大的載貨空間一般其船寬—吃水比亦很大。如此之船體構形，當其航行於波浪中時，將會產生相當大之定傾高變化，隨之船體橫搖振幅亦會變得甚大，其運動分析屬強非線性問題。本文針對駛上駛下船在不規則艉浪中考慮參數激振橫搖運動，推導簡化之分析模式。以伏特娜系統來探討非線性參數激振現象，並利用蒙地卡羅模擬分析駛上駛下船最有可能因參數激振而造成之橫搖模式。就實船之數値分析結果顯示，非線性參數激振現象對橫搖運動行爲之評估必須列入考慮。藉由有義波高及波週期等之參數分析顯示，駛上駛下船在實際狀況產生大橫搖角運動之可能性是存在而不可忽視的，其機率端視服勤海域之波浪統計而定。

關鍵字

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並列摘要

A RoRo-ship usually has a fine hull form with large flare at bow and stern. In order to achieve large cargo space, large ratio of the beam to draught are quite common for this kind ship. Such a hull configuration can be subjected to considerable variation of the metacentre height as she sailing in waves. As a consequence the parametric excitation becomes considerably great so that a large roll motion appears. This is a strongly nonlinear problem. A simplified model is formulated in this paper to take account for the parametrically excited roll motion of a RoRo-ship in irregular following waves. The nonlinear parametric excitation is approched by a Volterra system. Monte-Carlo simulations are used to analyse the two most probable roll modes of a RoRo-ship due to the parametric excitation. The numerical result of the studied ship shows that the nonlinear parametric excitation has to be taken into account for the assessment of the roll motion behaviour. The parameter study related to the significant wave height and wave period has shown that a large roll motion can take place to the ship in reality with an non-negligible probability depending upon the wave statistics of the service sea area.

並列關鍵字

roll motion ； parametric excitation ； irregular following waves ； nonlinear GM-variation ； volterra system

國際替代計量

Roll Motion of a Roro-Ship in Irregular Following Waves

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