engleski

Multi-objective Optimization of Ship Structural Topology and Scantlings

The decision support problem formulation for ship structures based upon coordinated multi-criteria structural optimization is presented. Problem identification implies reduction of design variables, design criteria (serviceability, ultimate strength) and relative measures of design quality (cost, weight, reliability, redundancy and robustness measures) to ones with dominant effect on the design quality. Relative quality measures (enabling correct ordering of design variants) are used as objectives in building of the preference structure needed in generation of the non-dominated Pareto frontier. The developed design system includes specially developed, fast and balanced collection of analysis and synthesis modules/methods. Analysis modules: (1) automated data generation for the structural FEM model from general arrangement plans, (2) descriptor based determination of the minimal scantlings, (3) design oriented FEM calculation of primary response in bending and warping torsion, (4) calculation of the transverse structure/bulkhead response, (5) the library of structural serviceability and ultimate strength criteria on panel (macro-element) level, (6) calculation of system reliability measure using modules (3-5) in beta-unzipping and branch and bound procedures, (7) robustness measure calculation using module (5) and theory of experiments (FFE) on panel level, (8) ultimate strength calculation for structure level (3, 5). Synthesis modules include: (9) design support problem formulation (selection of variables, constraints, definition of objectives based on relative quality measures), (10) calculation of the sensitivity of the structural response w.r.t. design variables based on the modules 3 and 5, (11) global level optimization, (12) optimization for local coordinated subsystems using sequential application of FFE. Additional modules are developed for the designer-model interaction with graphic presentation of model (loading, response, adequacy factors, etc.) and insight into multilevel optimization process with 5-D graphic presentation of designs in the design / attribute spaces. Application of the developed design environment to the structural design of modern multi-deck ship will be presented as practical example.

Ship structural design; design environment; topology optimization; multi-criteria optimization

nije evidentirano