ABSTRACT
Pure loss of stability is a kind of stability failure mode, which vulnerability criteria are agreed in general by International Maritime Organization (IMO) in the second generation intact stability criteria. Currently different parameters to modify ship hull forms are used to obtain better and more safety designs. For the sake of efficient optimization a reasonable parameter select method is required. For providing some guideline on ship safety design, firstly, a series of transformed hulls are designed on the basis lines of the standard model C11 containership with the optimization method according to Lackenby transformations, and all the sample hulls are calculated on the pure loss of stability failure modes. Secondly, the criteria values are calculated through different parametric variations, the effects of which are evaluated for the vulnerability criteria. Finally, the problem of inconsistency between the levels of vulnerability criteria is discussed with design parameter‗s transformation. The weight factors of different parameters are obtained through regression analysis for the vulnerability criteria, which could be used for ship safety design optimization for the vulnerability criteria for pure loss of stability, which would promote the application of the second generation intact stability criteria.
Pure loss of stability is a failure mode due to restoring variation when a large wave is overtaking the ship and the time of exposure to the crest of the large wave is long enough, which vulnerability criteria are agreed in general by International Maritime Organization (IMO) in the second generation intact stability criteria. Especially for containerships and RORO ships, initial metacnetric height(GM) is generally much bigger, that could be strongly changed because of the small transform of the hull modeled lines or a little of heel angle. Some ships that fully satisfy the 2008 IS Code, may be susceptible to different modes of stability failures.
The stability criteria should be assessed at the design stage, but single parametric variation may not be appreciable for satisfy pure loss of stability criteria owing to diversification of the design parameters. The researches on design optimization for ship stability are few. In this paper total of 80 projects are obtained based on physical programming according to Lackenby transformations in view of a pattern form C11 containership.
