含腐蝕效應之雙船散裝貨輪的可靠度分析

Reliability Analysis of a Double Hull Bulk Carrier with Corrosion Effects

Generally, hull structures are made of steel, ho ever the steel ill deteriorate under the environment of the high salt and the high humidity. In order to solve the damage of ship due to corrosion, many experts have developed several kinds of linear and nonlinear ship corrosion model respective by way of material experiment, statistics data and various corrosion models. In general, nonlinear corrosion model can explain the real corrosion process more than linear corrosion model. Therefore, the nonlinear corrosion model is used in present investigation. In this study, the new time variant nonlinear ship corrosion model is proposed and other two kinds of corrosion models are used to evaluate the corrosion effects on ship plates. A double hull bulk carrier is selected as an example to exam the method of FORM and SORM. The reliability indices of the ship structure under various failure modes are studied. In addition, different recoating periods are also considered, the comparison of corrosion reliability between the ship with stationary repair period and the ship without any repair is presented. 大型船體結構通常使用鋼材做為船殼主體，然而鋼材在高鹽份、高濕度的環境下極易發生腐蝕現象；為了解決船舶腐蝕破壞的問題，許多學者專家透過材料實驗、統計數據以及分析腐蝕模型的變化，分別發展出幾種線性或是非線性的船體腐蝕模型。針對一般船舶腐蝕情況，非線性腐蝕模式比起線性腐蝕模式，更能完善的解釋船舶受腐蝕的過程，故本文主要以非線性腐蝕模型做為研究之重點，以應用近幾年最新提出之時變性非線性船體結構腐蝕模型做為主要研究主軸，同時亦比較另外兩種較早開發出的腐蝕模型。文中針對一雙船殼散裝貨輪，以一階可靠度以及二階可靠度的計算方法，比較在不同破壞模式以及不同腐蝕模型下其船體結構的可靠度。除此之外，也考慮不同再塗裝（recoating）週期的情況下，比較定期船殼維修與未經船殼維修之船舶，其兩者之間腐蝕可靠度的變化情況。