In this paper a hybrid process of modeling and optimization, which integrates a support vector machine （SVM） and genetic algorithm （GA）, was introduced to reduce the high time cost in structural optimization of sh...In this paper a hybrid process of modeling and optimization, which integrates a support vector machine （SVM） and genetic algorithm （GA）, was introduced to reduce the high time cost in structural optimization of ships. SVM, which is rooted in statistical learning theory and an approximate implementation of the method of structural risk minimization, can provide a good generalization performance in metamodeling the input-output relationship of real problems and consequently cuts down on high time cost in the analysis of real problems, such as FEM analysis. The GA, as a powerful optimization technique, possesses remarkable advantages for the problems that can hardly be optimized with common gradient-based optimization methods, which makes it suitable for optimizing models built by SVM. Based on the SVM-GA strategy, optimization of structural scantlings in the midship of a very large crude carrier （VLCC） ship was carried out according to the direct strength assessment method in common structural rules （CSR）, which eventually demonstrates the high efficiency of SVM-GA in optimizing the ship structural scantlings under heavy computational complexity. The time cost of this optimization with SVM-GA has been sharply reduced, many more loops have been processed within a small amount of time and the design has been improved remarkably.展开更多
Goal based and limit state design is nowadays a well-established approach in many engineering fields.Ship construction rules started introducing such concepts since early 2000.However,classification societies’rules d...Goal based and limit state design is nowadays a well-established approach in many engineering fields.Ship construction rules started introducing such concepts since early 2000.However,classification societies’rules do not provide hints on how to verify limit states and to determine the structural layout of submerged thin-walled stiffened cylinders,whose most prominent examples are submarines.Rather,they generally offer guidance and prescriptive formulations to assess shell plating and stiffening members.Such marine structures are studied,designed and built up to carry payloads below the sea surface.In the concept-design stage,the maximum operating depth is the governing hull scantling parameter.Main dimensions are determined based on the analysis of operational requirements.This study proposes a practical conceptdesign approach for conceptual submarine design,aimed at obtaining hull structures that maximize the payload capacity in terms of available internal volume by suitably adjusting structural layout and stiffening members’scantling,duly accounting for robustness and construction constraints as well as practical fabrication issues.The proposed scantling process highlights that there is no need of complex algorithms if sound engineering judgment is applied in setting down rationally the hull scantling problem.A systematic approach based on a computer-coded procedure developed on purpose was effectively implemented and satisfactorily applied in design practice.展开更多
基金Supported by the Project of Ministry of Education and Finance (No.200512)the Project of the State Key Laboratory of Ocean Engineering (GKZD010053-10)
文摘In this paper a hybrid process of modeling and optimization, which integrates a support vector machine （SVM） and genetic algorithm （GA）, was introduced to reduce the high time cost in structural optimization of ships. SVM, which is rooted in statistical learning theory and an approximate implementation of the method of structural risk minimization, can provide a good generalization performance in metamodeling the input-output relationship of real problems and consequently cuts down on high time cost in the analysis of real problems, such as FEM analysis. The GA, as a powerful optimization technique, possesses remarkable advantages for the problems that can hardly be optimized with common gradient-based optimization methods, which makes it suitable for optimizing models built by SVM. Based on the SVM-GA strategy, optimization of structural scantlings in the midship of a very large crude carrier （VLCC） ship was carried out according to the direct strength assessment method in common structural rules （CSR）, which eventually demonstrates the high efficiency of SVM-GA in optimizing the ship structural scantlings under heavy computational complexity. The time cost of this optimization with SVM-GA has been sharply reduced, many more loops have been processed within a small amount of time and the design has been improved remarkably.
基金Supported by the Italian Ministry of Defense-Segredifesa,in collaboration with Fincantieri under Grant of the ASAMS(Aspetti specialistici e approccio metodologico per progettazione di sottomarini di ultima generazione)project(2019-2022).
文摘Goal based and limit state design is nowadays a well-established approach in many engineering fields.Ship construction rules started introducing such concepts since early 2000.However,classification societies’rules do not provide hints on how to verify limit states and to determine the structural layout of submerged thin-walled stiffened cylinders,whose most prominent examples are submarines.Rather,they generally offer guidance and prescriptive formulations to assess shell plating and stiffening members.Such marine structures are studied,designed and built up to carry payloads below the sea surface.In the concept-design stage,the maximum operating depth is the governing hull scantling parameter.Main dimensions are determined based on the analysis of operational requirements.This study proposes a practical conceptdesign approach for conceptual submarine design,aimed at obtaining hull structures that maximize the payload capacity in terms of available internal volume by suitably adjusting structural layout and stiffening members’scantling,duly accounting for robustness and construction constraints as well as practical fabrication issues.The proposed scantling process highlights that there is no need of complex algorithms if sound engineering judgment is applied in setting down rationally the hull scantling problem.A systematic approach based on a computer-coded procedure developed on purpose was effectively implemented and satisfactorily applied in design practice.
