This project involved looking at variations in stiffener and frame spacings, plate thicknesses, use of centreline pillars, and use of aluminium in some decks. Weight savings after the proposed modifications were about 7-8% of the original steel weight. The prototype had been designed according to Classification society rules.

 

Midship model   Critical panels   Critical frames   Stresses in’worst case’ frame

 

Results for a loadcase with larger frame spacing. Actual values of weights and savings are the property of our client, and confidential.

 

Midship section, new frame spacing   Critical panels   Critical frames

 

Results from the use of aluminium structure in some decks. Not surprisingly, this alternative, which was not used in production, gave even larger weight savings.

 

New midship section, aluminium / aluminum decks   Another aluminium / aluminum mid-section   Critical panels   Critical frames

 

An important feature of the optimisation process is to include production-related limitations in the final analysis. Panels, sub-modules or sections must have 'standard' stiffener spacings and make use of profiles and plates commonly available to the builder. The result is marginally less than 'optimum', but practical nevertheless.

 

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