超大型矿砂船典型节点优化设计研究

以两条超大型矿砂船为例,采用节点细化有限元分析方法,对一系列高应力区域进行研究。以双层底局部短纵桁与内底/外底纵骨连接处、槽型横舱壁与纵舱壁相交处、边舱平面横舱壁水平桁趾部等位置为例,对应力集中节点的结构优化方案进行了比较计算,得到的结论对这些区域的节点设计具有一定指导意义。     

基于响应面法的船底纵桁结构优化设计

提出基于响应面法的船体结构优化方法,对一艘76 000 DWT散货船货舱段的双层底纵桁进行优化设计以验证该方法的实用性。在不同板厚尺寸、相同载荷作用下进行纵桁参数的敏度分析,选取适合的参数作为自变量。在计算出最大相当应力、最大剪切应力的基础上,应用响应面法的正交组合设计试验方法,得出该舱段船底纵桁最大应力与结构尺寸的函数表达式。以结构重量最轻为目标函数,在结构强度、规范要求最小厚度的约束条件下,对该舱段的船底纵桁结构厚度进行优化。     

阿芙拉型油船节点优化设计

以2艘Aframax型油船为例,采用节点细化有限元分析法,对高应力区域进行结构分析,以平面横舱壁水平桁、纵横舱壁相交处大肘板趾端为例,对高应力区域的结构优化方案进行比较,得到的结论可为船体结构设计提供参考。     

无顶凳槽形横舱壁附近甲板构件布置及型式优化

针对某MR型油船无顶凳槽形舱壁设计中,舱壁前后一档强框范围内甲板纵骨应力水平高,存在结构安全隐患的问题,基于有限元计算分析,通过多方案对比,探讨甲板结构布置形式对槽形横舱壁上端约束的影响,提出一种优化的甲板短纵桁布置方案及其端部连接型式,既可有效降低舱壁附近甲板纵骨的应力水平,又可解决短纵桁与纵骨连接处的疲劳问题。     

基于遗传算法的潜艇首端耐压平面舱壁构架分级优化研究

探讨了潜艇首端耐压平面舱壁的结构优化设计,针对舱壁结构复杂、设计变量多、取值离散规格化等难点,确定两级优化方案,即先后分别对舱壁内部主构架和肘板进行优化,采用遗传算法作为优化方法,并利用ANSYS程序对舱壁结构进行受力分析.对遗传算法进行了改进,并在此基础上用MATLAB语言编程实现遗传算法操作,同时编程与ANSYS结合起来,完成结构优化设计.经过迭代优化,得到一个优化方案,优化部分的结构重量较初始方案降低了18.39%.     

内压下矩形耐压舱内部结构优化设计

[目的]为有效降低内压下矩形耐压舱板架弯曲应力,[方法]分别提出内压下矩形耐压舱内部平台位置和支柱布局以及尺寸优化设计数学模型。以内部平台垂向位置作为设计变量,极小化横纵舱壁结构的最大弯曲应力,采用遗传算法求解,得到最优的内部平台布置位置,其优化结果接近垂向均布。支柱设计采用分级优化设计方法,先以等刚度支柱位置作为设计变量,极小化顶甲板结构的最大弯曲应力,分别得到不同支柱数量下的最优布局方案;然后依据应力约束条件选取支柱数量及布局,在此基础上进一步以支柱截面尺寸作为设计变量,以基础优化方案的重量作为约束,极小化顶甲板结构的最大弯曲应力,得到不等刚度支柱最优截面尺寸。[结果]其优化结果显示偏中心区域支柱截面积更大。最终优化设计方案较初始方案,横舱壁、纵舱壁和顶甲板弯曲应力分别降低了28.3%,25.7%和13.9%。[结论]本优化设计方法可为类似结构设计提供方法参考和设计借鉴。     

舱壁水平桁材的侧向稳定性

根据舱壁垂直扶强材的侧向稳定性计算方法同样的原理,作出了舱壁水平桁材(包括水平桁及水平扶强材)的侧向稳定性计算公式与计算曲线,可供油轮舱壁(平面舱壁或槽形舱壁)的水平桁或水平扶强材及货船深舱水平桁作强度校核之用。     

多工况应力约束下多用途船货舱结构优化

  目的  为提高有限元结构强度校核效率,减少尺寸优化迭代成本,提出散货船双层底纵桁的板缝布置和尺寸优化方法。  方法  首先,基于理论公式论证子模型技术的可靠性,提出双层底纵桁优化设计的多工况筛选方法。然后,以某散货船双层底纵桁为例,对纵桁进行板格划分,以板格厚度为变量、《散货船和油船共同结构规范》（HCSR）的许用应力为约束条件进行尺寸优化,用穷举法列举所有板缝布置方案对优化后的板格厚度进行合并,选出重量最轻的板缝布置优化方案。最后,基于HCSR舱段有限元计算的屈服强度要求,对上述散货船双层底纵桁需加强的区域进行板缝布置优化,在此基础上,采用尺寸优化方法实现满足屈服强度要求的结构尺寸优化。  结果  结果显示,采用提出的基于尺寸优化的板缝布置优化和结构加强方法能减轻优化区域重量 4.9%。  结论  所提方法能有效减少人为有限元加强时的随机性,优化有限元结构加强方案,减轻结构加强重量。     

无横撑、少制荡舱壁的VLCC货舱优化设计

在货舱横向强框架上应用拓扑优化和形状参数优化技术,不仅实现了VLCC纵舱壁垂直桁无横撑设计的目的,而且使货舱区结构重量减轻,建造工艺简化。通过合理布置货舱的横舱壁和纵舱壁,可以在实现制荡舱壁数量和长度最小化的同时,明显减小装载手册所有工况的静水弯矩包络值,从而提高船体的安全性。预计可以降低VLCC货舱区建造成本的5%以上。     

船舶结构优化设计技术研究进展

  目的  为有效降低内压下矩形耐压舱板架弯曲应力,  方法  分别提出内压下矩形耐压舱内部平台位置和支柱布局以及尺寸优化设计数学模型。以内部平台垂向位置作为设计变量,极小化横纵舱壁结构的最大弯曲应力,采用遗传算法求解,得到最优的内部平台布置位置,其优化结果接近垂向均布。支柱设计采用分级优化设计方法,先以等刚度支柱位置作为设计变量,极小化顶甲板结构的最大弯曲应力,分别得到不同支柱数量下的最优布局方案;然后依据应力约束条件选取支柱数量及布局,在此基础上进一步以支柱截面尺寸作为设计变量,以基础优化方案的重量作为约束,极小化顶甲板结构的最大弯曲应力,得到不等刚度支柱最优截面尺寸。  结果  其优化结果显示偏中心区域支柱截面积更大。最终优化设计方案较初始方案,横舱壁、纵舱壁和顶甲板弯曲应力分别降低了28.3%,25.7%和13.9%。  结论  本优化设计方法可为类似结构设计提供方法参考和设计借鉴。     

Least-weight topology and size optimization of high speed vehicle-passenger catamaran structure by genetic algorithm

Selection of the “best” or “optimum” engineering design has always been a major concern of designers. Reduction of hull weight is the most important aim in the structural design of many ship types. But the ability of designers to produce optimal designs of ship structures is severely limited by the calculation techniques available for this task. Complete definition of the optimal structural design requires formulation of size–topology–shape–material optimization task unifying optimization problems from four areas and effective solution of the problem. So far a significant progress towards solution of this problem has not been achieved. In other hand in recent years attempts have been made to apply genetic algorithm (GA) optimization techniques to design of ship structures. An objective of the paper was to create a computer code and investigate a possibility of simultaneous optimization of both topology and scantlings of structural elements of large spatial sections of ships using GA. In the paper GA is applied to solve the problem of weight minimization of a high speed vehicle-passenger catamaran structure with several design variables as dimensions of the plate thickness, longitudinal stiffeners and transverse frames and spacing between longitudinals and transversal members. Results of numerical experiments obtained using the code are presented. They show that GA can be an efficient optimization tool for simultaneous design of topology and sizing high speed craft structures.     

舰船刚性阻振质量复合托板隔振特性优化设计(英文)

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.     

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。     

舰船高传递损失复合托板振动特性优化设计

基于结构动力学优化设计理论,研究了潜艇典型舱段双层圆柱壳舷间高传递损失复合托板结构。通过初步优化,得到隔振效果最优的刚性阻振质量块的最优截面尺寸和布设位置,并将最优参数的刚性阻振质量块等效为相同截面惯性矩的球扁钢。在满足舱段总重量及危险截面结构强度的约束条件下,以舱段非耐压壳体全频域内的平均振动加速度级为目标函数,对高传递损失复合托板的开孔半径和托板角度进行动力学优化设计,得到最优振动特性的复合托板形式。由优化结果得到,在中、高频段内,高传递损失复合托板有明显的降噪作用,舱段非耐压壳体全频域内的平均振动加速度级降低了1.66 dB。     

遗传算法的改进及其在超大型油船结构优化中的应用

遗传算法是一种基于适者生存理念的随机搜索算法,它具有极强的全局搜索能力,且不需要知道问题的导数信息.然而,简单遗传算法局部搜索能力差以及易于早熟.文章编制了一种基于实数编码的适用于连续型变量的遗传算法,比较适合于多峰函数的全局寻优,且对之略作改进,也可用于离散型变量优化.采用大量经典数学测试函数对该遗传算法的优化能力进行测试,取得了很好的优化结果.在此基础上,选用经典10杆桁架结构对该算法的寻优能力进行了验证.最后,以一艘超大型油船的典型中横剖面作为研究对象,选取396个设计变量,所有变量在优化过程中都进行了离散化处理,应用JTP规范[1]作为校核依据,采用该遗传算法进行优化设计.经过优化后,船中剖面面积下降了2.6%.     

Rule-based optimization of midship structures

A rule-based overall design methodology for midship structures of small inland waterways vessels is presented. It is shown how the designer, under conflicting requirements, can select the optimum design by using a combined objective function with priority factors assigned to individual design criteria. The concept of optimization, in large-scale structural design problems, is extended to the local members (the stiffening elements) of the ship structure, so that the stiffeners can be specified by their actual dimensions instead of section moduli. The effects of price-structure (labour rate to material price ratio) and the choice of type of stiffener on design are investigated. Standard sections and optimized fabricated sections are taken as the alternative options for selecting the stiffeners. Conversion of exact mathematical optimum solutions into production-oriented designs is also demonstrated in a series of practical applications of the proposed method.     

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.     

潜艇外部耐压液舱结构型式研究

  目的  为了简化建造工艺和减轻液舱结构重量,对外置式耐压液舱实肋板结构进行拓扑优化和开孔尺寸优化设计。  方法  首先,利用Hyperworks/Optistruct对外置式耐压液舱整体模型进行结构应力分析。然后,在拓扑优化中,除与液舱壳板和耐压船体壳板相连的约100 mm长条状范围外,以实肋板其他范围内的单元密度为设计变量;以与实肋板相连的液舱壳板和船体壳板上结构的典型应力及实肋板体积分数为约束,以实肋板上最大Mises应力最小化为目标,针对满载和空舱两种工况,利用商用软件Hyperworks/Optistruct对实肋板结构进行拓扑优化。最后,基于Matlab和ANSYS联合优化,以实肋板上von Mises应力和剪应力为约束,以相应结构重量极小化为目标,对实肋板开孔进行尺寸优化,从而得到精细化开孔方案。  结果  拓扑优化结果表明,外置式耐压液舱实肋板开减轻孔应集中在中、下部。开孔尺寸优化结果表明,相比初始方案,实肋板剪应力增加38%,其他关注区域应力相当时,内部实肋板上结构重量可降低19%。  结论  两类优化设计均表明,外置式耐压液舱实肋板开减轻孔应集中在中下部,且从下到上开孔面积应逐渐减小。     

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.     

Assessment of IACS-CSR implicit safety levels for buckling strength of stiffened panels for double hull tankers

The present study aims at applying structural reliability methods to assess the implicit safety levels of the buckling strength requirements for longitudinal stiffened panels implemented in the IACS Common Structural Rules (CSR) for double hull oil tankers. The buckling strength requirements considered are used in the initial stage of the hull girder scantlings’ design to control the buckling capacity of longitudinal stiffened panels subjected to the compressive loads induced by the hull girder vertical bending. The following buckling collapse failure modes are explicitly considered in the design formulation: uniaxial buckling of the plating between stiffeners, column buckling of stiffeners with attached plating and lateral-torsional buckling or tripping of stiffeners.The paper presents the procedure used to assess the implicit safety levels of the strength requirements for the three buckling collapse failure modes above mentioned, which includes the optimization of the scantlings of the plate panels and longitudinal stiffeners in order to reflect the minimum strength required by the formulation. A first order reliability formulation is adopted, and stochastic models proposed in the literature are used to quantify the uncertainty in the relevant design variables. A sample of five oil tankers representative of the range of application of the IACS-CSR design rules is considered. The effect of corrosion in the implicit safety levels is quantified based on the three corrosion levels of the Net Thickness Approach (NTA) adopted in the design rules. Sensitivity analyses are also performed to quantify the relative contribution or importance of each design random variable to the implicit safety levels.