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Despite the availability of other transport methods such as land and air transportations, marine transportation is the most preferred and widely used transportation method in the world because of its economical advantages. In service, ships experience cyclic loading. Hence, it can be said that fatigue fracture, which occurs due to cyclic loading, is one of the most critical failure modes for vessels. Accordingly, this makes fatigue failure prevention an important design requirement in naval architecture. In general, a ship structure contains many structural components. Because of this, structural modeling typically relies on Finite Element Analysis (FEA) techniques. It is possible to increase fatigue performance of the ship structures by using FEA in computer aided engineering environment. Even if literature papers as well as rules of classification societies are available to assess effect of fatigue cracks onto the whole ship structure, analytical studies are relatively scarce because of the difficulties of modeling the whole structure and obtaining reliable fatigue life predictions. As a consequence, the objective of this study is to improve fatigue strength of a mercantile vessel against fatigue loads via analytical method. For this purpose, the fatigue life of the mercantile vessel has been investigated. Two different type of fatigue assessment models, namely Coffin-Manson and Morrow Mean stress approaches, were used and the results were compared. In order to accurately determine the fatigue life of the ship, a nonlinear finite element analysis was conducted considering plastic deformations and residual stresses. The results of this study will provide the designer with some guidelines in designing mercantile vessels.

Despite the availability of other transport methods such as land and air, marine transportation is the most preferred and widely used transportation method in the world because of its economical advantages. Due to the economical advantages, ship based studies have gained importance especially in recent years. In order to design safe, ergonomic and at the same time economic ships or vessels, both numerical and experimental methods have to be taken into account. Large-scale structural modeling like the cases in ships, on the other hand, typically relies on Finite Element Analysis (FEA) techniques. With the widespread use of Finite Element Methods (FEM) in the field of Computer Aided Design (CAD) engineering, it is possible to increase the strength of a mercantile vessel shipboard. As a consequence, in this study, the strength of a mercantile vessel shipboard has been investigated under working conditions by using ANSYS package program. The results of this study can provide the designer with some guidelines in designing shipboard of mercantile vessels.