Multi-objective topology and size optimization of high-speed vehicle-passenger catamaran structure by genetic algorithm

Ship structural design has become recently an ever more important and difficult task, because it should always take into account several estimation criteria which are a crucial element of shipyard management, as the hull structural strength is one of the most important factors of overall ship safety, and the total cost of structural materials used for the construction of a ship is a significant part of her total construction cost. Simultaneously, a complete definition of the optimal structural design requires a formulation of size-topology-shape-material optimization task unifying the optimization problems from these four areas and giving an effective solution of this problem. So far, a significant progress towards a solution of this problem has not been achieved. An objective of the underlying paper was to develop an evolutionary algorithm for multi-objective optimization of both topology and scantlings of structural elements of large spatial sections of ships. In the paper an evolutionary algorithm where selection takes place based on the scalar objective function is proposed and applied to solve the problem of structural elements weight and cleaned and painted surface area on a high-speed vehicle-passenger catamaran structure with several design variables, such as plate thickness, scantlings of longitudinal stiffeners and transverse frames, and spacing between longitudinal and transversal members. The results of numerical experiments with the use of the developed algorithm are presented. They show that the proposed genetic algorithm can be an efficient multi-objective optimization tool for simultaneous design of the topology and sizing of ship structures.     

基于有限元法的小水线面双体船结构优化

小水线面双体船结构复杂,需要有效的工具对其进行优化设计,在满足强度刚度要求的情况下控制结构重量.本文利用优化软件Altair.OptiStruct、Msc.Nastran、iSIGHT对一艘小水线面双体船结构进行了尺寸优化、形状优化、和拓扑优化.结构优化基于有限元法完成,以结构重量作为目标函数,结构应力作为约束条件.优化结果表明,通过选择适当的设计变量,能够在结构应力不超过规定上限的条件下使结构重量显著降低并达到最小值.     

基因演算法於船体加强板架之最佳化设计应用

船体结构之最佳化设计是一个复杂非线性的混和离散问题，并且要搜寻到全域的最佳值并不容易。在复杂的设计环境下基因演算法（Genetic Algorithm；GA）却可以搜寻到近似的全域最佳值。本文主要是应用基因演算法对T加强板架（Tee stiffened panel）、平板加强板架（flat-bat stiffened Panel）等常用且最具代表性之船体结构件进行最佳化设计，使结构在满足终极破坡限制（ultimate failure constraints）与耐用破坏限制（serviceability failure constraints）等所有限制条件下，求得最佳目标函数值中各设计变之最佳组合。在过程中并考量不同族群大小、变换机率、突变机率因素对最佳化结果的影响。文中是以制造成本为目标函数，其中同时考量材料成本及劳工成本，且所得之结果与连续性线性规则（Sequential Linear Programming；SLP）最佳化结果作了比较。计算的结果显示基因演算法可以有效地与快速地获得最小重量和最低成本的目标。     

Multi-fidelity optimization of a high-speed foil-assisted semi-planing catamaran for low wake

The wakes of high-speed passenger-only ferries that operated through Rich Passage, on the Seattle-Bremerton ferry route, caused beach erosion and damage to habitat. A task was initiated to design a low-wake high-speed vessel using multi-fidelity CFD based design optimization by using low-fidelity potential flow solvers for initial global design optimization and by using URANS solvers for high-fidelity tuning of the optimized design. This simulation based design process involved a close collaboration between ship designers, and hydrodynamics and CFD specialists, whose collective expertise guided the evolution of the design based on both hydrodynamic and structural aspects. The initial hull shape optimization using potential flow code was carried out by blending three different initial concepts provided by the designers. Subsequently, URANS was used to evaluate the potential flow optimized hull and to further optimize the hull configuration parameters, namely, the centre-of-gravity, demihull spacing, foil location, foil angle and slenderness ratio at different displacement conditions. The URANS based configuration optimization also took into account the far field wakes’ energy spectrum with an objective of reducing the energetic, low frequency far field wakes which are associated with beach flattening on the mixed sand and gravel beaches. Calculation of the far field wake using URANS would require an unfeasibly large domain size; therefore, a Havelock code with a source distribution matching the URANS calculated near field wave elevation was used to propagate the wakes into the far field. The end result of the optimization was a design with significantly reduced far field wake, which is currently being built for experimental testing.     

抗振板壳结构的仿生拓扑优化设计方法

以抗振结构设计为目标,将仿生设计技术应用于板壳结构加强部件的分布设计中,提出了一种简单高效的结构拓扑优化设计方法,以处理具有复杂边界条件的抗振板壳结构的拓扑优化设计.将结构加强部件分布的形成看成和植物根系的成长过程一样,加强部件从给定的"种子"出发,根据一定的成长规则生长、分歧或退化,在体积增量的控制下,形成最优的分布形态.设计结果可作为进一步详细设计的近似优化模型.对一些典型的抗振板壳结构进行了设计,结果表明所提出的方法克服了现有的结构拓扑优化技术的一些局限性,可简单有效地处理复杂结构的设计问题.     

A new rational-based optimal design strategy of ship structure based on multi-level analysis and super-element modeling method

A new multi-level analysis method of introducing the super-element modeling method, derived from the multi-level analysis method first proposed by O. F. Hughes, has been proposed in this paper to solve the problem of high time cost in adopting a rational-based optimal design method for ship structural design. Furthermore,the method was verified by its effective application in optimization of the mid-ship section of a container ship. A full 3-D FEM model of a ship,suffering static and quasi-static loads, was used as the analyzing object for evaluating the structural performance of the mid-ship module, including static strength and buckling performance. Research results reveal that this new method could substantially reduce the computational cost of the rational-based optimization problem without decreasing its accuracy, which increases the feasibility and economic efficiency of using a rational-based optimal design method in ship structural design.     

工程结构的拓扑优化设计研究

本文讨论了连续体结构拓扑优化的均匀化方法及其相关理论，分别针对静力问题和特征值问题建立了相应的结构拓扑优化模型。目前有关结构拓扑优化的工程应用研究还很不成熟，尤其在国内尚尾于起步阶段。本文将结构拓扑优化设计理论应用于实际工程结构的概念设计之中，并取得了较好的优化效果。通过对经典算例和某卫星构架子结构的拓扑优化计算，表明本文建立的结构拓扑优化模型能够有效地应用于工程结构的拓扑优化设计，从而为工程结构的结构型式选取提供了有价值的概念设计方案。     

知识工程在船舶结构优化设计中的应用

针对船舶结构设计变量是涉及多种设计和约束条件的离散变量,造成结构优化的高度非线性、多峰性等问题,而且设计过程中需要设计规范和专家经验等知识支持,结合其具有很强的综合性、模糊性等特点,提出了基于知识工程的船舶结构优化设计方法。该方法利用知识工程与结构优化相结合,将获取的设计知识构建知识库应用于船舶结构优化设计,并通过知识工程技术实现参数化结构模型与优化数学模型的相互转化,降低结构优化设计对用户知识水平的要求。水密横舱壁结构的优化设计算例表明,满足约束要求的情况下,其结构重量在优化后比优化前降低了,保证了结构性能合理的同时实现重量最轻的目标;将结构参数化模型和数学优化模型结合在一起,为设计经验少的设计者提供了一种结构设计的捷径;实现了从不同资源中获取知识并应用于优化设计过程,促进设计能力的提高,降低优化设计过程对知识和经验的依赖。     

支持向量机和遗传算法组合策略的VLCC船中结构优化设计(英文)

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.     

船体结构最优风险评估维护计划（英文）

Various structures such as marine structures age over time. In order to always maintain safety conditions, maintenance processes including inspection and repair should be implemented on them. Corrosion and fatigue cracks are two main factors that reduce the ultimate strength of the ship's hull girder over time and thus increase the probability and risk of failure. At the time of inspection,the structural conditions must be checked so that, if necessary, the required repairs can be done on it. The main objective of this paper is to provide optimized maintenance plans of the ship structure based on probabilistic concepts with regard to corrosion and fatigue cracks. Maintenance activities increase the operational costs of ships; therefore, it is advisable to inspect and repair in the optimal times. Optimal maintenance planning of the ship structure can be conducted by formulating and solving a multi-objective optimization problem. The use of risk as a structural performance indicator has become more common in recent years. The objective functions of the optimization problem include minimizing the structure's lifecycle maintenance costs, including inspection and repair costs, and also minimizing the maximum risk of structural failure during the ship's life. In the following,to achieve better responses, reliability index has been added to the problem as the third objective function. The multi-objective optimization problem is solved using genetic algorithms. The proposed risk-based approach is applied to the hull structure of a tanker ship.     

基于正交设计与 BP -GA 算法的船体结构耐撞性能优化设计

船体结构耐撞性优化设计的主要目的是在船舶碰撞研究的基础上对结构进行优化设计,提高船体结构的耐撞性能。基于正交试验设计、BP神经网络和遗传算法,形成了船体结构耐撞性能优化设计方法。提出了一种耐撞性综合指标,并以此指标作为优化的目标函数,以结构质量为约束条件,利用MSC/Dytran有限元软件对船舶碰撞进行数值仿真,完成对某船舷侧结构进行耐撞性优化设计,结果表明优化过后结构耐撞性能有较大提高,这为结构耐撞性能优化设计提供了一种新的思路和方法。     

基于工艺可行性的离散变量结构动力特性设计优化

基于船舶工艺可行性分析,建立了使用自适应模拟退火算法的多工况下船体结构动力特性设计优化模型;并给出了相应的设计流程。模型使用矩阵描述由板材厚度和骨材型号构成的离散变量集合,同时将全体设计变量处理为共享设计变量。将模型应用于某集装箱船艉部结构的动力特性设计优化中,优化后的结构不仅减轻了自重,而且增加了频率储备。实例分析表明该模型能应用于工程结构的实际优化设计。     

大型全集装箱船总体设计中有关问题的探讨

作者结合对3500 TEU集装箱船型技术论证对第三代以上大型集装箱船总体设计作了分析探讨,对设计中的箱型、平均箱重、船型,舱內列层数、稳性、航速、技术指标等主要问题发表了自己的见解,并提供了大型集装箱船的设计流程及计算公式供设计参考。     

虚拟仿真技术在溢油回收装置结构性能评估和轻量化设计中的应用

针对传统设计方法依靠经验开展设计的缺陷,提出了基于虚拟仿真技术的结构性能评估和优化设计方法.针对某溢油回收船溢油回收装置,利用虚拟仿真技术对其结构性能进行评估,并利用拓扑优化技术开展溢油回收装置结构的轻量化设计,实现以仿真来驱动设计,以期为虚拟仿真技术在船舶设计特别是溢油回收船溢油回收装置设计中的应用提供参考.     

浅谈船用薄板焊接变形的控制

为了减轻结构质量、提高舰船性能,舰船上层建筑等部位普遍采用薄板焊接结构,而薄板变形将严重影响焊接质量和舰船外观。文中论述了薄板焊接变形的成因、设计与工艺控制方法,这些方法的使用将为优化薄板变形的控制工艺提供帮助。     

Influence of different topological variants on optimized structural scantlings of passenger ship

For a multi-deck ships with extensive superstructures (such as passenger and cruise ships, RoPax, mega yachts, etc.) the global structural response can be particularly complex. The influence of the superstructure to the primary strength for those multi-deck ships must be considered from an early design phase. Main global topological parameters (e.g. size of side openings, position and stiffness of longitudinal and transverse bulkheads, etc.) have dominant influence on the shape of hull girder stress distributions over the ship height. The Taguchi concepts and techniques (FFE, orthogonal arrays, ANOVA, etc.) could be used to systematically study influence of multiple topological parameters on the global structural response obtained by FEM analysis. It also enables rational identification of the most dominant parameters and provide designer with the near-optimal level of each topological parameter for the defined design objective. It has been demonstrated how different topological variants can lead to different optimal structural scantlings w. r.t chosen design objectives (mass, VCG, etc.), using simplified full ship 3D FE model of passenger ship as an example. Structural design software MAESTRO and in-house developed framework for the design support system DeMak – OCTOPUS Designer were used as a structural optimization tool. This paper aim to extend the standard scantling optimization by introducing topological aspects as a first STEP in overall optimization procedure.     

一种船舶结构优化的实用方法

本文针对船舶结构优化设计中普遍存在的混合离散变量的现象，应用一种简便而实用的估化新方法－模拟退火算法直接获得最优解，而需地离散散现象进行了“规格化”后处理，以舱口盖和槽形舱壁的结构优化为例，详细讨论了模拟退火过程中冷却过程进度表优化质量及效率的影响。     

大型集装箱船绑扎桥结构优化设计

为有效降低大型集装箱船的空船重量,针对绑扎桥结构轻量化设计进行研究。以某14500TEU集装箱船为研究对象,根据船级社规范要求针对结构设计方案进行有限元计算分析,依次从剪力墙布置、立柱设置和局部尺寸优化等三个层次对原始方案进行优化设计。研究结果表明,优化方案在满足船级社规范要求、保证堆重指标的同时有效降低了绑扎桥的结构重量。本文的设计思路和优化方法可以为今后大型集装箱船绑扎桥的结构设计提供一定参考。     

舰船刚性阻振质量基座振动特性优化设计

基于结构动力学优化设计理论,研究了舰船刚性阻振质量基座结构形式的设计方法。在满足基座舱段总重量限制的约束条件下,分别建立了刚性阻振质量布置及截面尺寸优化设计模型,并进行了以基座舱段耐压壳体振动加速度为目标函数的动力学优化设计。通过优化分析,得到了在给定约束条件下减振效果最佳的刚性阻振质量截面尺寸和布置。研究结果表明,刚性阻振质量基座中阻振质量高度越大,基座舱段耐压壳体平均振动加速度级就越小。通过优化设计可以找到满足要求的结构,分析得到目标函数随设计变量的变化趋势,并对此优化方法的有效性进行验证。     

吃水受限内河船舶航行性能综合优化的分层并行混沌算法

船舶航行性能综合优化设计分析是一项非常重要的工作。基于分层思想、并行算法和混沌算法,建立了吃水受限内河船舶性能综合优化的数学模型,设计了一种求解此类问题的基于敏感变量分段的分层并行混沌复合算法。编制了界面友好的VC＋＋软件。对于吃水受限内河船舶快速性和操纵性综合优化问题,进行了遗传算法、混沌算法、并行混沌算法和分层并行混沌算法的大量优化计算,结果表明：该复合算法计算可靠、效率高;为吃水受限内河大型船舶综合优良船型设计奠定了良好基础。