| Summary: | 碩士 === 國防大學理工學院 === 造船及海洋工程碩士班 === 100 === When the longitudinal length of the superstructure of a warship is more than one tenth of that of the hull, the reaction of the gravity and external forces may result in longitudinal stress transfer from the hull to the superstructure. Therefore, a stress concentration appears in the weak continuity part of the superstructure. This study aims to build up a finite element model of a warship by using finite element software to simulate the stress reduction effect via installing a single or more expansion joints on the superstructure. The stress and stress distribution in the main hull and in the superstructure were calculated in accordance with the Der Norske Veritas Rules about a ship's longitudinal bending moment and load.
Simulation results show that the high stress part originally existed in the superstructure exhibits lower stress values after installations of the expansion joint. The stress concentration area also transfers to the bottom of the expansion joint to which the main deck is connected. The stress distribution of the whole ship was affected by the length of the superstructure and the location where the expansion joint was installed. Furthermore, the strength of the main deck at which the expansion joint was installed may influence the stress value to a different extent. Thus, there is a need to carry out a complete assessment in relation to the structural property of the whole ship as well as the place of installations of the expansion joints before using them to reduce the stress of the superstructure. After cautious consideration, the stress of the superstructure may be effectively reduced so that the possibility of material cracks resulting from the stress concentration may be lowered. As a result, the goal for conserving budget and increasing the appropriate rate of the warship may be achieved.
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