典型油船槽形舱壁优化和参数化建模研究
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摘要
为了洗舱的方便,在中小型油船的结构设计中,槽形舱壁已经得到了广泛的应用。由于槽形舱壁的重量在空船结构重量中占有不小的比例,所以优化出一组合理的槽形参数,使得该槽形舱壁的结构满足规范的各项强度衡准,且总重量最轻,这对减轻空船结构重量,降低造船成本有一定的实际意义。
在优化的过程中,考虑到工程项目的复杂性,优化程序通常会给出若干种相对较优的方案,以供设计者分析比较。而对每种方案分别建立有限元模型并计算分析,将导致大量的重复性工作,耗费设计者较多的时间与精力。
基于以上两点,本论文以MSC. Patran为开发平台,利用Patran的二次开发工具PCL编制了槽形形状优化和参数化建模程序。该程序包含槽形形状优化模块、参数化建模模块和自动计算分析模块。三个模块之间相对独立但又彼此数据共通。
优化模块以槽形舱壁单位长度的平均重量为目标函数,并依据油船共同规范,从局部抗弯强度、抗剪强度、槽形面板稳定性和总体抗弯强度四个方面定义了槽形形状优化问题的约束条件,建立了该问题的数学模型。根据不同的要求,优化程序可以给出几组优化解,供设计者选择。在优化结果的基础上,结合舱段的其它信息,参数化建模模块被用来快速生成典型油船船舯区域的三舱段模型。自动计算分析模块根据油船共同规范的要求施加载荷与边界条件,并利用Nastran求解位移刚度矩阵,最终得到该组方案下槽形舱壁的应力分布信息。这样一来,结构设计师就可以根据应力结果对各个设计方案进行筛选比较,节约了优化设计过程中结构有限元的建模时间。由于参数化建模模块主要使用了程序参数化方法和基于几何造型的有限元建模法,所以在参数化建模部分,本文主要解决了以下两个关键技术问题：1、如何通过参数描述模型的几何特征；2、如何将几何对象离散为符合规范要求的有限元单元。为此,程序将三舱段模型分为数个子区域,分别创建各个区域的几何外形。并在几何内部和边界添加控制约束,由Patran软件的网格生成器自动划分各几何区域的网格。
最后,本文以三艘原油/成品油船为例,测试了这三个模块的适用性。其中的槽形形状优化模块还应用到其他三个合同项目的槽形结构设计中。通过这些设计实例证明该程序具有较强的工程实用价值。
Corrugated bulkheads have been widely applied in oil tankers because of their advantages in tank cleaning. The weight of corrugated bulkheads takes up a considerable proportion in the hull structure weight. Therefore, an optimum corrugated bulkhead whose strength meets the criteria of rules and total weight is lightest is very important to reduce the light structure weight and shipbuilding cost.
Usually several feasible schemes which will be analyzed and compared by designers are deduced from the results of optimization calculation due to the complicacy of a project. If each finite element model is modeled and analyzed separately, much time is wasted on the reduplicate operations.
To solve these two problems, a program consisting of the optimization module of corrugation form, parametric modeling module and automatic analyzing module is developed with Patran Command Language (PCL) based on MSC. Patran software. These three modules are correspondingly independent to each other, but they are joined together by the same data stream.
A mathematic model is modeled while the average bulkhead weight per unit length is defined as the objective function. According to Common Structure Rules for double hull oil tankers, local bending stress, shear stress, panel bulking stress and total bending stress are considered as four constrains. In terms of different restriction terms, several schemes are presented to designers by the optimization module. On the basis of the optimization solutions, three-cargo-holds models of typical tankers are modeled rapidly by the parametric modeling module thinking of cargos' other information. Loading conditions and boundary conditions are input according to CSR requirements by running the automatic analyzing module. After solving the stiffness matrix by Nastran, the stress distribution on the bulkheads is displayed to structure designers, and helps them to select the fittest corrugated form from several schemes. So, much time of modeling are saved during the structure optimization. The program parametric method and the finite element method (FEM) based on geometries are included in the parametric modeling module. Consequently, two key problems are solved in this paper, one is how to describe the geometry characters by parameters, and the other is how to disperse the geometry to finite elements whose shapes meet the CSR requirements. Therefore, the program divides the three-cargo-holds into several sub models, generates geometries each and creates meshes automatically by mesh generator in Patran by controlling the constraints on boundaries.
Finally, three crude oil/product tankers are modeled to verify the program's applicability. The optimization module of corrugation form is applied on the other three contract designs. The practicability of this program is proved well by these actual design examples.
在优化的过程中,考虑到工程项目的复杂性,优化程序通常会给出若干种相对较优的方案,以供设计者分析比较。而对每种方案分别建立有限元模型并计算分析,将导致大量的重复性工作,耗费设计者较多的时间与精力。
基于以上两点,本论文以MSC. Patran为开发平台,利用Patran的二次开发工具PCL编制了槽形形状优化和参数化建模程序。该程序包含槽形形状优化模块、参数化建模模块和自动计算分析模块。三个模块之间相对独立但又彼此数据共通。
优化模块以槽形舱壁单位长度的平均重量为目标函数,并依据油船共同规范,从局部抗弯强度、抗剪强度、槽形面板稳定性和总体抗弯强度四个方面定义了槽形形状优化问题的约束条件,建立了该问题的数学模型。根据不同的要求,优化程序可以给出几组优化解,供设计者选择。在优化结果的基础上,结合舱段的其它信息,参数化建模模块被用来快速生成典型油船船舯区域的三舱段模型。自动计算分析模块根据油船共同规范的要求施加载荷与边界条件,并利用Nastran求解位移刚度矩阵,最终得到该组方案下槽形舱壁的应力分布信息。这样一来,结构设计师就可以根据应力结果对各个设计方案进行筛选比较,节约了优化设计过程中结构有限元的建模时间。由于参数化建模模块主要使用了程序参数化方法和基于几何造型的有限元建模法,所以在参数化建模部分,本文主要解决了以下两个关键技术问题：1、如何通过参数描述模型的几何特征；2、如何将几何对象离散为符合规范要求的有限元单元。为此,程序将三舱段模型分为数个子区域,分别创建各个区域的几何外形。并在几何内部和边界添加控制约束,由Patran软件的网格生成器自动划分各几何区域的网格。
最后,本文以三艘原油/成品油船为例,测试了这三个模块的适用性。其中的槽形形状优化模块还应用到其他三个合同项目的槽形结构设计中。通过这些设计实例证明该程序具有较强的工程实用价值。
Corrugated bulkheads have been widely applied in oil tankers because of their advantages in tank cleaning. The weight of corrugated bulkheads takes up a considerable proportion in the hull structure weight. Therefore, an optimum corrugated bulkhead whose strength meets the criteria of rules and total weight is lightest is very important to reduce the light structure weight and shipbuilding cost.
Usually several feasible schemes which will be analyzed and compared by designers are deduced from the results of optimization calculation due to the complicacy of a project. If each finite element model is modeled and analyzed separately, much time is wasted on the reduplicate operations.
To solve these two problems, a program consisting of the optimization module of corrugation form, parametric modeling module and automatic analyzing module is developed with Patran Command Language (PCL) based on MSC. Patran software. These three modules are correspondingly independent to each other, but they are joined together by the same data stream.
A mathematic model is modeled while the average bulkhead weight per unit length is defined as the objective function. According to Common Structure Rules for double hull oil tankers, local bending stress, shear stress, panel bulking stress and total bending stress are considered as four constrains. In terms of different restriction terms, several schemes are presented to designers by the optimization module. On the basis of the optimization solutions, three-cargo-holds models of typical tankers are modeled rapidly by the parametric modeling module thinking of cargos' other information. Loading conditions and boundary conditions are input according to CSR requirements by running the automatic analyzing module. After solving the stiffness matrix by Nastran, the stress distribution on the bulkheads is displayed to structure designers, and helps them to select the fittest corrugated form from several schemes. So, much time of modeling are saved during the structure optimization. The program parametric method and the finite element method (FEM) based on geometries are included in the parametric modeling module. Consequently, two key problems are solved in this paper, one is how to describe the geometry characters by parameters, and the other is how to disperse the geometry to finite elements whose shapes meet the CSR requirements. Therefore, the program divides the three-cargo-holds into several sub models, generates geometries each and creates meshes automatically by mesh generator in Patran by controlling the constraints on boundaries.
Finally, three crude oil/product tankers are modeled to verify the program's applicability. The optimization module of corrugation form is applied on the other three contract designs. The practicability of this program is proved well by these actual design examples.
引文
[1]IACS. Common Structure Rules for Double Hull Oil Tankers,2010
[2]Schmit LA. Structural design by systematic synthesis. Proc of Conf on Electronic Computation, ASCE, New York,1960:105-122P
[3]Kavlie D, Kowalik J, Lund S and Moe J. Design optimization using a general nonlinear programming method. European shipbuilding.1966,(4):57-62P
[4]王宏伟,任慧龙,戴仰山.基于遗传算法的油轮中剖面横构件优化设计.哈尔滨工程大学学报.2003,24(1)：14-15页
[5]邱伟强.VLCC结构优化设计研究.上海造船.2006,(4)：13-15页
[6]秦洪德,石丽丽.PSO算法在油船双底结构优化设计中的应用研究.哈尔滨工程大学学报.2010,31(8)：1007-1011页
[7]杜忠仁.货舱槽形舱壁尺度要素优化选择.上海造船.2000,(2)：27-29页
[8]Joe-Ming Yang and Cheng-Neng Hwang. Optimization of corrugated BHD forms by genetic algorithm. Journal of Marine Science and Technology.2001,10(2):146-153P
[9]王绍鸿,秦昌威.使用遗传算法的油船舱壁结构优化设计.中国造船.1996,(1)：39-42页
[10]Sutherland I.E. Sketch Pad, a man-machine graphical communication system. PhD thesis,1963
[11]V. C. Lin, D.C. Gossard, R. A. Light. Variational geometry in computer aided design. Computer Graphics.1981,15(3):171-177P
[12]R.A. Light and D.C. Gossard. Modification of geometric models through variational geometry, CAD.1982,14(4):209-214P
[13]于雁云.船舶与海洋平台三维参数化总体设计设计方法研究.大连理工大学博士学位论文.2009：10-14页
[14]Javier Monedero. Parametric design:a view and some experiences. Automation in Construction.2000,(9):369-377P
[15]Kuang-Hua Chang and Javier Silva. Capturing design intents for CAD-based multidisciplinary design optimization. Proceeding of the 4th world Congress of Structural and Multidisciplinary optimization, Dalian, China:2001:408-409P
[16]隋晓峰.基于几何造型的参数化有限元建模和曲面网格生成方法及实现.大连理工大学硕士学位论文.2002：4
[17]Bennett J A and Botkin M E. Shape optimization of 2-D structure with geometric problem description and adaptive mesh refinement. AIAAJ.1985,23(3):258-464P
[18]Botkin M E. Shape design modeling using fully automatic tree dimension mesh generation. Finite Element in Analysis and Design.1991,(10):165-181P
[19]操安喜.基于ANSYS的船舶结构有限元计算模板的研究与应用.武汉理工大学硕士学位论文.2004
[20]郑玄亮,林焰,陈明,任怀远.基于ANSYS的船舶槽形舱壁有限元建模方法及其程序实现.船舶工程.2007,29(5)：23-26页
[21]曾文源.舰船结构有限元参数化建模与优化研究.哈尔滨工程大学硕士学位论文.2005
[22]林慰,赵成壁.船体舱段三维有限元模型参数化建模方法研究.船海工程.2002,37(1)：7-9页
[23]罗忠卿.大型甲板货船参数化设计与结构屈服屈曲强度直接计算研究.武汉理工大学硕士学位论文,2009
[24]俞铭华,邵雄飞,郭小东.超大型油船舱段结构强度评估平台.江苏科技大学学报,2007.21(5),4-8页
[25]MSC. Patran & MSC. Nastran使用指南.2002：16,31
[26]MSC. Patran PCL Handbook.8
[27]刘惟信.机械最优化设计.第二版.清华大学出版社,1994：1
[28]刑文训,谢金星.现代优化计算方法.清华大学出版社,1998
[29]陈宝林.最优化理论与算法.第二版.清华大学出版社,2005
[30]滕晓青,李润培.槽型舱壁极限强度.船舶力学.2000,(4)：48-56
[31]Paik, J.M. Thayamballi, A.K. and M.S. Chun. Theoretical and Experimental Study on the Ultimate Strength of Corrugated Bulkheads. Journal of Ship Research.1997,41(4): 301-317P
[32]冯国庆,刘相春,任慧龙.基于PCL语言的波浪压力自动加载方法.船舶力学.2006,10(5)：107-112页
[33]MSC. Software. MSC. Acumen Author's Guide.2002
[34]MSC. Software. MSC. Patran User's Manual.2003
[35]MSC. Software. PCL Reference Manual.2001
[36]MSC. Software. Nastran Reference Manual.2001
[2]Schmit LA. Structural design by systematic synthesis. Proc of Conf on Electronic Computation, ASCE, New York,1960:105-122P
[3]Kavlie D, Kowalik J, Lund S and Moe J. Design optimization using a general nonlinear programming method. European shipbuilding.1966,(4):57-62P
[4]王宏伟,任慧龙,戴仰山.基于遗传算法的油轮中剖面横构件优化设计.哈尔滨工程大学学报.2003,24(1)：14-15页
[5]邱伟强.VLCC结构优化设计研究.上海造船.2006,(4)：13-15页
[6]秦洪德,石丽丽.PSO算法在油船双底结构优化设计中的应用研究.哈尔滨工程大学学报.2010,31(8)：1007-1011页
[7]杜忠仁.货舱槽形舱壁尺度要素优化选择.上海造船.2000,(2)：27-29页
[8]Joe-Ming Yang and Cheng-Neng Hwang. Optimization of corrugated BHD forms by genetic algorithm. Journal of Marine Science and Technology.2001,10(2):146-153P
[9]王绍鸿,秦昌威.使用遗传算法的油船舱壁结构优化设计.中国造船.1996,(1)：39-42页
[10]Sutherland I.E. Sketch Pad, a man-machine graphical communication system. PhD thesis,1963
[11]V. C. Lin, D.C. Gossard, R. A. Light. Variational geometry in computer aided design. Computer Graphics.1981,15(3):171-177P
[12]R.A. Light and D.C. Gossard. Modification of geometric models through variational geometry, CAD.1982,14(4):209-214P
[13]于雁云.船舶与海洋平台三维参数化总体设计设计方法研究.大连理工大学博士学位论文.2009：10-14页
[14]Javier Monedero. Parametric design:a view and some experiences. Automation in Construction.2000,(9):369-377P
[15]Kuang-Hua Chang and Javier Silva. Capturing design intents for CAD-based multidisciplinary design optimization. Proceeding of the 4th world Congress of Structural and Multidisciplinary optimization, Dalian, China:2001:408-409P
[16]隋晓峰.基于几何造型的参数化有限元建模和曲面网格生成方法及实现.大连理工大学硕士学位论文.2002：4
[17]Bennett J A and Botkin M E. Shape optimization of 2-D structure with geometric problem description and adaptive mesh refinement. AIAAJ.1985,23(3):258-464P
[18]Botkin M E. Shape design modeling using fully automatic tree dimension mesh generation. Finite Element in Analysis and Design.1991,(10):165-181P
[19]操安喜.基于ANSYS的船舶结构有限元计算模板的研究与应用.武汉理工大学硕士学位论文.2004
[20]郑玄亮,林焰,陈明,任怀远.基于ANSYS的船舶槽形舱壁有限元建模方法及其程序实现.船舶工程.2007,29(5)：23-26页
[21]曾文源.舰船结构有限元参数化建模与优化研究.哈尔滨工程大学硕士学位论文.2005
[22]林慰,赵成壁.船体舱段三维有限元模型参数化建模方法研究.船海工程.2002,37(1)：7-9页
[23]罗忠卿.大型甲板货船参数化设计与结构屈服屈曲强度直接计算研究.武汉理工大学硕士学位论文,2009
[24]俞铭华,邵雄飞,郭小东.超大型油船舱段结构强度评估平台.江苏科技大学学报,2007.21(5),4-8页
[25]MSC. Patran & MSC. Nastran使用指南.2002：16,31
[26]MSC. Patran PCL Handbook.8
[27]刘惟信.机械最优化设计.第二版.清华大学出版社,1994：1
[28]刑文训,谢金星.现代优化计算方法.清华大学出版社,1998
[29]陈宝林.最优化理论与算法.第二版.清华大学出版社,2005
[30]滕晓青,李润培.槽型舱壁极限强度.船舶力学.2000,(4)：48-56
[31]Paik, J.M. Thayamballi, A.K. and M.S. Chun. Theoretical and Experimental Study on the Ultimate Strength of Corrugated Bulkheads. Journal of Ship Research.1997,41(4): 301-317P
[32]冯国庆,刘相春,任慧龙.基于PCL语言的波浪压力自动加载方法.船舶力学.2006,10(5)：107-112页
[33]MSC. Software. MSC. Acumen Author's Guide.2002
[34]MSC. Software. MSC. Patran User's Manual.2003
[35]MSC. Software. PCL Reference Manual.2001
[36]MSC. Software. Nastran Reference Manual.2001