An Integrated framework for conceptual design stage structural optimisation of RoRo&RoPax vessels

Abstract

Optimization generally involve picking the optimum solution to a problem considering all the factors or design variables. HOLISHIP (HOLIstic optimisation of SHIP design and operation for life-cycle) is a European Union research project which is a system based approach aimed at developing optimized designs for the future, structure of which is divided into clusters and into several work packages (WP). Structural optimization of RoRo & RoPax vessels pose several challenges due to the unique design features of these type of vessels. This Thesis work concentrates on structural optimization of midship section transverse frame of RoRo & RoPax hulls for minimum weight thus achieving reduction of lightship weight which is one of the major technical requirements during conceptual design phase as part of WP4&WP7 of HOLISHIP project. Rule based tool called ‘STEEL’ by Bureau Veritas is used for the structural & load modeling and further structural analysis of the transverse frame and then optimization loop is established using ‘modeFRONTIER’ and ‘CAESES’ tools to study effect of different design variables. Also the structural optimization loop involving STEEL tool is to couple with a parametric hull in order to enable study of coupled structural analysis for different parametric hull variations. Structural weight is kept as the objective to minimize and design constraints are considered as per applicable Bureau Veritas rules for classification of steel ships. Then surrogate models are generated to replace the optimization loop using Response surface methodology and results obtained with different algorithms like polynomial regression, artificial neural networks etc. are studied further which would reduce complexity associated compared to conventional direct methods