Safety as objective in multicriterial structural optimization

Žanić, Vedran and Kitarović, Stanislav and Prebeg, Pero (2010) Safety as objective in multicriterial structural optimization. = Safety as objective in multicriterial structural optimization. In: ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2010, 6-11.06.2010., Shanghai; China.

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Multicriterial design methodology with safety as one of the design objectives is presented. The aim of the paper is to analyze the influence of safety based design objectives on generated nondominated designs on the Pareto frontier. Possible improvements in nondominated designs are investigated by comparison to ones obtained with the standard design procedure when safety criteria are used as design constraints only. It is assumed that safety based objectives and targets act as attractors, driving nondominated designs along the constant cost/weight contours in design space towards its safer regions. Global safety objectives (for hogging/sagging modes), are based on the maximization of ultimate longitudinal strength in vertical bending calculated via the extended IACS incremental-iterative method. Applied compound safety measures for gross-panel (stiffened panel with associated girders) are based upon 34 failure modes, belonging to serviceability/collapse subsets. Objectives based on the maximization of safety measures are applied together with standard design objectives such as minimization of initial cost and weight. The following problems were solved with different sets of objectives: (a) minimize cost and weight objectives subject to safety constraints (used for reference), (b) only the maximization of local safety measures is added to (a) as additional objectives, (c) only the maximization of global safety measures is added to (a) as additional objectives, (d) maximization of safety measures ad (b) and (c) are added to (a) as additional objectives. For each of the problems (a-d) the developed design procedure is executed. It contains two basic tasks for structural design of realistic (non-academic) problems: (1) multicriterial optimization with topology / geometry design variables; (2) multicriterial optimization of gross-panels with scantling / material design variables. Design procedure steps are executed using a fast and balanced collection of analysis and synthesis modules/methods of the OCTOPUS design system: • Determination of design load sets, • MOGA / MOPSO based generation of nondominated designs for the selected ship structure; • For each design the following analysis blocks are executed: - calculation of ship's primary and racking response fields, - calculation of ship's ultimate longitudinal strength, - calculation of serviceability and collapse safety criteria on the gross-panel level. Comparisons of results, based on generated Pareto hyper-surfaces and on subset of preferred designs, are given for problems (a-d). Insights into the results of optimization process, using 5-D graphics for design and attribute spaces, are also presented. Design problems of modern RoPax and SWATH structures are used in case studies. © 2010 by ASME.

Item Type: Conference or Workshop Item (Lecture)
Keywords (Croatian): Analysis and synthesis; Collapse safety; Design constraints; Design load; Design Methodology; Design objectives; Design problems; Design procedure; Design spaces; Design systems; Following problem; Geometry designs; Global safety; Hyper-surfaces; Initial costs; Local safety; Longitudinal strength; Material designs; Multi-criteria structural optimization; Optimization process; Pareto frontiers; Response fields; Safety constraint; Safety criterion; Safety measures; Ship structure; Standard design; Stiffened panel; Structural safety; Arctic engineering; Bending strength; Civil defense; Failure analysis; Oil tankers; Safety engineering; Shape optimization; Ships; Structural optimization; Structural design
Subjects: TECHNICAL SCIENCE > Shipbuilding
Divisions: 600 Department of Naval Engineering and Marine Technology > 620 Chair of Marine Structures Design
Indexed in Web of Science: Yes
Indexed in Current Contents: No
Citations JCR: 6 (25.10.2017.)
Date Deposited: 15 Apr 2015 11:52
Last Modified: 25 Oct 2017 08:38

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