雙體船在斜浪與橫浪狀況下結構簡化分析方法之研究

The simplified methods for structural analysis of catamaran under quartering and beam sea

施囿丞(You-Chen Shih)

指導教授 ： 李雅榮

共同指導教授 ： 李岳聯(Yueh-Lien Lee)

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202100874

摘要

本研究主要評估雙體船在兩關鍵負荷中船體結構之響應，也就是斜浪狀況下的縱搖連接力矩和橫浪狀況下橫向分裂力造成的橫向彎矩，在驗證負荷之合理性後，依其在負荷中的響應特點建立簡化之分析方法，期能藉此加速雙體船之設計與檢驗期程。
對雙體船而言，一般的分析方法為建立全船有限元素模型，並將計算流體力學軟體計算之負荷加載至全船模型上，此方法雖已經長時間之多方驗證，但耗費之時間與人力成本過大。而船級協會之規範，建議了負荷之公式計算和簡化加載方式，於是首先本研究將已經驗證的規範負荷加載至全船有限元素模型上，並試著從橫跨甲板及胴體沿縱向之位移分布，了解其響應之特性。而根據全船模型在兩種負荷中的結構響應特點，建立兩種簡化計算方法，可以簡易且快速的評估橫跨甲板與胴體連接處之位移與應力。其中一種為簡化的有限元素模型，以梁元素模擬橫跨甲板及胴體，並以剛性元素將兩者連接；另一種為進一步跳過有限元素法，以一般材料力學梁理論公式，經過適當的假設與修正後，直接計算其連接處之位移與應力。最後，以全船模型在橫跨甲板與胴體連接處之位移與應力的計算結果和兩種簡化分析方法做比較，驗證簡化方法的合理及可用性。雖然簡化分析方法之計算精度不如全船有限元素模型，但能大量的減少建立模型與計算之成本，對梁理論簡化分析方法而言，也能夠節省購買商用有限元素法軟體之成本。

關鍵字

雙體船 ； 有限元素法 ； 縱搖連接力矩 ； 橫向分裂力 ； 橫向彎矩

並列摘要

This study aims to use simplified methods to evaluate the response of catamaran under quartering sea and beam sea. When the catamaran is under quartering sea, the waves will induce pitch-connecting moment on the cross-deck. Similarly, when the catamaran is under beam sea, the waves will induce transverse split force on the demihulls and transverse bending moment on the cross-deck at the same time. Based on the response characteristics of the catamaran under two loading conditions, two simplified strength evaluation methods are established and checked by comparing the deflection and the stress of the connection between the cross-deck and the demihulls.
The general strength evaluation procedure of catamaran is establishing the detailed and full ship finite element methods(FEM) model and using computational fluid dynamics(CFD) to calculate the loads and add the load on the full ship model as water pressure. The classification societies have lots of rules for the load value and the simplified ways to load on the full ship FEM model, which have all been verified and validated. The two simplified structure evaluation methods are then established to save calculation time and money. One method is establishing simplified FEM model by using beam elements to simulate the cross-deck and the demihulls, and the other is trying to directly evaluate the strength of the connection between the cross-deck and the demihulls by the basic beam theories and formulas without the using of FEM software.

並列關鍵字

catamaran ； finite element methods ； pitch-connecting moment ； split force ； transverse bending moment

參考文獻

[1] 趙連恩，謝永和，高性能船舶原理與設計，國防工業出版社，北京(2009)

[2] Liang Yun, Alan Bliault, Huan Zong Rong, High Speed Catamarans and Multihulls_ Technology, Performance, and Applications, Springer, New York, (2019)

[3] CR中國驗船中心, Rules for the Construction and Classification of High-speed Craft, (2008)

[4] China Classification Society, Rules for Construction and Classification of Sea-going High-speed Craft, (2015)

[5] BV Classification Society, Hull Structure and Arrangement for the Classification of Cargo Ships less then 65 m and Non Cargo Ships less than 90 m, (2018)