In this paper reliability-based optimisation technique was applied to a typical transverse frame in a built SWATH ship (Small Waterplane Area Twin Hull) in order to improve the original design. The transverse frame was idealised by a one-dimensional model by carrying out a series of finite element analysis. The response amplitude operators of primary loads on the ship in regular waves were evaluated by a program, MARCHS, in which a three-dimensional oscillating source distribution method in association with linearised potential theory was used. The extreme values were then calculated by a spectral analysis. In the process of reliability-based optimisation, the structural weight was used as the objective function because SWATH ships are weight sensitive. The reliability indices of all the critical elements were restricted to be greater than 3.0. The linearised plasticity condition was used as the failure criteria of critical sections, and the interaction of bending moment, shear and axial force including the buckling effect was considered in the analysis. It was found that there was potential for reducing the structural weight. The optimum structure is lighter, and at the same time has better safety than the original one.
Towards a rational design of SWATH ships by using reliability-based optimisation
Rationeller Entwurf von SWATH-Schiffen mit Einsatz einer Optimierungsmethode auf Zuverlässigkeitsbasis
1997
6 Seiten, 1 Bild, 3 Tabellen, 17 Quellen
Conference paper
English
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