三维建模与分析软件在舰船结构快速评估中的应用

随着计算机软件的快速发展,软件在船舶设计与分析中发挥越来越重要的作用。本文基于船舶三维建模软件Tribon对某舰船进行建模分析,阐述Tribon在船舶建模过程的强大功能;基于MSC.Patran/Nastran对船用结构件进行有限元分析,得出其应力云图和模态分析图,并根据分析结果对船舶结构件进行优化分析。     

基于PCL的散货船直接强度评估系统开发

以MSC/Patran为平台,应用PCL语言开发交互式的散货船强度评估系统。该系统包括参数化建模、载荷计算、施加载荷和结果分析等功能模块,初步实现散货船强度评估的自动化。以实船算例的对比分析验证系统的实用性以及工程有效性,表明该系统可显著提高散货船强度分析的工作效率。     

32 000 DWT运木散货船结构强度有限元分析

为了满足散货船结构共同规范直接强度分析的要求,利用MSC Patran/Nastran和中国船级社开发的CSR计算软件CCS-Tools,对32000DWT运木散货船进行了货舱结构的整体有限元分析、高应力区域细化网格有限元分析和疲劳敏感区域精细网格有限元分析.     

30 000 t级散货船结构强度有限元分析

依据散货船结构共同规范,采用MSC Patran/Nastran、CCS船级社开发的CSR计算软件CCS-Tools和LR船级社的ShipRight SDA 2007.对30000t级散货船进行了货舱结构的整体有限元分析、高应力区域细化网格有限元分析和疲劳敏感区域精细网格有限元分析.并就所遇问题进行探讨.     

基于UG二次开发的船用螺旋桨参数化建模方法与实现

船用螺旋桨的建模方法是将二维初始型值点导入通用CAD软件,通过多步操作得出三维空间数据,完成整个造型过程.这种方法不但操作繁琐,而且效率低.在研究了船用螺旋桨参数化建模方法的基础上,采用对UG进行二次开发的方法,编制出船用螺旋桨参数化建模的功能模块.通过给定船用螺旋桨的主要几何参数,计算出初始型值点,进行坐标变换,将其从平面坐标系还原到空间真实位置.另外给出桨叶叶梢缺失部分数据的NURBS拟合补充方法,并在进行光顺处理后,最终生成船用螺旋桨的三维模型.     

基于UG的系列船用螺旋桨三维建模和数控编程技术研究

螺旋桨是一类复杂的自由曲面零件,根据螺旋桨的主要设计数据和叶切面的投影原理,以VC++和UG的二次开发工具UG/Open Grip为工具开发了船用螺旋桨的参数化建模系统。在此基础上,针对螺旋桨数控编程工作目前存在的问题,将知识工程技术引入螺旋桨的数控编程中,构建了螺旋桨的广义知识库和加工知识模板。运用知识推理进行螺旋桨的加工工艺决策;并且在UG的平台上,通过二次开发技术完成了船用螺旋桨的自动数控编程系统的开发,实现了船用螺旋桨CAD/CAM系统的集成化、自动化和智能化。     

30 000 DWT散货船货舱段结构强度有限元计算

利用MSC Patran/Nastran和英国劳氏船级杜(LR)的ShipRight SDA软件对30000DWT散货船进行货舱段结构强度直接计算,使其满足散货船共同结构规范直接强度分析的要求.利用整体舱段的粗网格模型计算结果,建立于模型划分精细网格进行结构细部疲劳评估.     

典型船舶焊接接头应力集中系数有限元分析

利用MSC/Patran and MSC/Nastran对焊接中常见的对接接头焊趾处的应力集中系数进行有限元建模和计算,在分析有限元计算结果的基础上,提出比较完整的估算焊接接头应力集中系数公式。     

基于OpenGL的螺旋桨几何造型程式化实现

介绍通过螺旋桨设计图纸提供的型值数据等进行螺旋桨三维几何建模的方法.利用VC++6.0编制了适合于各种类型螺旋桨的三维几何建模程序,并借助OpenGL技术实现了三维螺旋桨造型及其尾涡面的显示与人机交互功能,提高了螺旋桨三维几何建模的效率.研究中所进行的对桨叶、尾涡面以及桨毂面元网格的计算也为螺旋桨水动力数值预报提供了基础.     

船体有限元建模属性定义解决方案及软件实现

针对应用MSC.Patran进行船体结构有限元建模时属性创建、编辑,以及管理不便的问题,通过对属性参数进行梳理和分析一些参数自动计算方法,提出针对性的解决方案,开发通用软件工具。     

基于CATIA的舰船轴系自动化建模技术研究

针对传统舰船轴系建模过程复杂、效率低下的问题,研究了基于CATIA的舰船轴系自动化建模技术.分析了CATIA环境下的自动化建模方法,结合舰船轴系轴段的结构特点,研究舰船轴系自动化建模方法;分析了舰船轴系模型的装配关系,研究了CATIA环境下为轴系部件定义装配特征和根据特征进行装配的方法.通过论文的研究,能够为舰船轴系自动化建模提供有效的指导,同时也能为提高舰船轴系设计效率奠定一定的基础.     

螺旋桨用高阻尼合金研究

作者研制的ＺＨＧＨ２３１０高阻尼合金，不仅具有螺旋桨材料综合性能，而且还具有较高的阻尼特性。实船试验表明该合金螺桨比铜合金螺旋桨噪声有较大幅度降低。此外，这种合金作为功能材料可用于船舶其他零部件。     

船用螺旋桨的应用与发展趋势

回顾了船用螺旋桨的历史演化过程。对不同船舶工作条件下的一些特种螺旋桨特点进行了分析，重点介绍了几种新型螺旋桨的构造与应用，指出了今后螺旋桨设计的发展方向。     

基于遗传算法的船舶螺旋桨优化设计

船舶螺旋桨的设计主要分为理论法与图谱法,目前,图谱法设计已有成熟的计算程序与之匹配,采用遗传算法搜索进行船舶螺旋桨优化设计是一条新的思路。采用Wageningen B图谱的回归多项式,利用遗传算法的高效、并行、基于适应度函数的搜索法,进行螺旋桨优化设计,将螺旋桨直径、螺距比和盘面比作为设计变量,空泡性能作为约束条件,在保证目标转速的前提下优化船舶航速。经优化设计实例计算表明,遗传算法适用于船舶螺旋桨的优化设计。     

Numerical Calculation of Marine Propeller Hydrodynamic Characteristics in Unsteady Flow by Boundary Element Method

In this paper, a low-order potential based on surface panel method is used for the analysis of marine propellers in unsteady flow.A linear propeller wake model is employed and its geometry is assumed to be independent of the time.The calculation in time domain is carried out from a moment when the rotation of the propeller becomes steady instead of from the moment when the rotation strats from stationary condition.At every time step a linear algebraic equation established on a key blade is solved numerically combined with the Kutta pressure conditon.The calculated results by developed code indicate good convergency and effrctiveness of present algotithm for conventional propellers and highly skewed propellers.     

Fatigue predictions for flexible marine propellers using FSI analysis considering Euler force in the rotating frame

Analysis of flexible marine propellers in terms of their structural response and stress is the key to accurate fatigue prediction. At present, finite element method (FEM) analyses of flexible propellers have been performed as a part of the fluid–structure interaction (FSI) analysis using a numerical method for the flexible structures, which is identical to that used for their rigid counterparts. In this study, the Euler force in a rotating frame is employed as an additional external force on the blades of the marine propeller during the FSI analysis. The Euler force is an inertial force component in the rotating frame due to angular acceleration. Acceleration of the rotating frame arises from large deformations of the propeller due to its flexible characteristics. The angular acceleration of the propeller is obtained for each time step, and the resulting Euler force is accounted for as a body force. The FSI analysis results are compared to experimental results in terms of the structural response, stress, and fatigue. It is clear that the Euler force has a major effect on the fatigue characteristics of the propeller because it amplifies the main response components. In conclusion, incorporating the Euler force in FSI analyses of flexible marine propellers is necessary for adequate prediction of the propeller fatigue.     

Prediction of Hydrodynamic Performance of Marine Propellers by Surface Panel Method

The potential based low order surface panel method is used to predict the hydrodynamic performance of marine propellers. In present method the hyperboloidal quadrilateral panels are employed to avoid the gap between the panels. The influencecoefficients of panels are calculated by Morino's analytical formulations for increasing numerically calculating speed.The pres-sure Kutta condition is satisfied on the trailing edge of propeller blade by Newton-Raphson iterative procedure.Therefore the     

滑行艇半浸式螺旋桨的水动力学特性

Demand for high-speed marine vehicles (HSMVs) is high among both commercial and naval users. It is the duty of the marine vessel’s designer to provide a hull and propulsion system that diminishes drag, improves propulsive efficiency, increases safety and improves maneuverability. From the propulsor side, surface piercing propellers (SPPs) should improve performance. Unlike immersed propellers, behavior of the SPP is affected by depth of immersion, Weber number and shaft inclination angle. This paper uses a practical numerical method to predict the hydrodynamic characteristics of an SPP. The critical advance velocity ratio is derived using the Weber number and pitch ratio in the transition mode, then the potential based boundary element method (BEM) is used on the engaged surfaces. Two models of three and six-bladed SPPs (SPP-1 and SPP-2) were selected and some results are shown.     

Development of a time domain prediction method for hull pressure fluctuation induced by marine propeller sheet cavitation with consideration of scattering effects

Using a time domain acoustic analogy, we develop a method to predict the sound field and hull pressure fluctuation generated by unsteady sheet cavitation on marine propellers. Formulation 1A of Farassat is introduced to enhance theoretical understanding of this work, and it is applied to modeling the scattered sound field created by the fuselage boundary. To express the direct sound field resulting from sheet cavitation, a new solution is studied which considers the Doppler effect and also separately expresses the near and far fields. A small cube model is used to verify the method. Computed acoustic field pressures around the cube are compared with the boundary element method, and the numerical results show good agreement. Finally, the pressure fluctuation on a ship stern model is calculated.     

非均匀船舶尾流中工作的常规和大侧斜船用螺旋桨的水动力和水声计算预报（英文）

Despite their high manufacturing cost and structural deficiencies especially in tip regions, highly skewed propellers are preferred in the marine industry, where underwater noise is a significant design criterion. However, hydrodynamic performances should also be considered before a decision to use these propellers is made. This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case. However, propulsive characteristics are significantly different when propeller-hull interactions take place. Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller. In this study, propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case, which is computationally demanding, an indirect approach was adopted; axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach. A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods, implementing the Ffowcs Williams-Hawkings(FW-H) equation. The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results, experiments, and quasi-continuous method for the open-water case. With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input, simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field. Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theoretical values. Results also show that a highly skewed propeller generates less noise even in noncavitating cases despite a small reduction in hydrodynamic efficiency.