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船舶结构的建模及水下振动和辐射噪声的FEM/BEM计算 总被引:25,自引:1,他引:24
船舶动力系统的振动通过壳板向水下辐射噪声的预报一直是非常关键的问题。船舶的声学设计应建立在全船结构声一体化的前提下,本文基于船体与周围声学流体介质的耦合作用,建立了带有浮筏结构的动力装置的整个双层壳体船舶的FEM/BEM数学模型。在理论分析的基础上,利用有限元软件ANSYS建立了水下船舶结构的振动和声场耦合的模型,首先计算在模拟发动机的激励下船舶壳板的振动,并利用边界元软件SYSNOISE,对轻外壳面上的声强进行预报,本文的方法为解决大型复杂结构的耦合声振预报提供了一个典型的实例。 相似文献
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单壳体潜艇敷设声学覆盖层应具有机械噪声、水动力噪声和声目标强度控制的多功能特性,为此需要解决两个基本问题:其一,提高机械噪声低频控制效果;其二,实现覆盖层的多功能兼容性。本文从降低机械激励壳体声辐射角度出发,采用模态叠加法,建立无限大理想水介质中分层梯度声学覆盖层与有限长加肋圆柱壳的声振耦合及声辐射模型,基于声学覆盖层模态传递函数特性,计算分析声学覆盖层分层梯度分布及厚度、层数等参数对加肋圆柱壳辐射噪声影响的特征和规律,给出分层梯度声学覆盖层的特征声阻抗渐变参数分布并与敷设均匀声学覆盖层降噪特性比较。研究结果表明:加肋圆柱壳敷设内层至外层声阻抗逐渐递增,各分层取慢波速的声学覆盖层,具有比均匀声学覆盖层更有效地降低外表面振动位移的特性,可明显增加降噪效果,并扩展低频降噪范围。声学覆盖层的优化应增加声阻抗的内分层失配和外分层适配的效应,有利于降低加肋圆柱壳低频声辐射,并可兼顾降低声目标强度。 相似文献
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[目的]因对于钛合金耐压夹层圆柱壳这种新型耐压结构研究得较少,其芯层拓扑形式有待优化确认,需开展芯层拓扑优化。[方法]首先,选择一个壁厚较大的无加筋圆柱壳作为分析对象,采用ANSYS轴对称单元计算结构的应力;然后,沿圆柱壳厚度方向划分为上、中、下3个区域,将中部区域的结构设为设计变量,并建立其芯层结构形式的两阶段拓扑优化数学模型;最后,基于Matlab建立遗传算法主控程序,针对无加筋圆柱壳芯层的布置,分别仅沿轴向、轴向与径向布置形式两个阶段进行拓扑优化,以验证上述耐压夹层圆柱壳加筋形式的合理性。[结果]优化方案芯层拓扑形式为等间距设置,垂直连接内壳和外壳的肋板。[结论]静水压力载荷下的耐压夹层圆柱壳结构是一种合理的耐压结构形式。 相似文献
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《舰船科学技术》2016,(5)
对于潜艇外壳等外压容器来说,满足稳定性要求至关重要。本文利用Matlab编写改进粒子群算法优化程序,利用Ansys的Apdl语言完成了环肋圆柱壳的参数化建模,以圆柱壳厚度、肋骨尺寸和肋距作为离散设计变量,以稳定性要求作为约束条件,构造了合适的惩罚函数,以质量最轻作为设计目标,实现了基于BP神经网络和粒子群算法的环肋圆柱壳优化设计。在优化过程中,首先采用拉丁超立方体抽样完成了样本点的选取,然后对样本点进行有限元分析,根据有限元分析结果构建BP神经网络代理模型,并探讨了样本点数量对代理模型预测精度的影响,最后采用改进粒子群算法对代理模型进行优化。优化结果表明,对于需要考虑离散变量和复杂非线性约束的结构优化问题,采用BP神经网络和粒子群算法联合优化的方法能够节省大量计算时间,并达到理想的优化效果。 相似文献
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对于潜艇外壳等外压容器来说,满足稳定性要求至关重要。本文利用Matlab编写改进粒子群算法优化程序,利用 Ansys的 Apdl语言完成了环肋圆柱壳的参数化建模,以圆柱壳厚度、肋骨尺寸和肋距作为离散设计变量,以稳定性要求作为约束条件,构造了合适的惩罚函数,以质量最轻作为设计目标,实现了基于 BP神经网络和粒子群算法的环肋圆柱壳优化设计。在优化过程中,首先采用拉丁超立方体抽样完成了样本点的选取,然后对样本点进行有限元分析,根据有限元分析结果构建 BP神经网络代理模型,并探讨了样本点数量对代理模型预测精度的影响,最后采用改进粒子群算法对代理模型进行优化。优化结果表明,对于需要考虑离散变量和复杂非线性约束的结构优化问题,采用 BP神经网络和粒子群算法联合优化的方法能够节省大量计算时间,并达到理想的优化效果。 相似文献
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Soonhung Han Yeon-Seung Lee Young Bok Choi 《Journal of Marine Science and Technology》2012,17(1):1-17
Hydrodynamic optimizations of ship hull forms have been carried out employing parametric curves generated by fairness-optimized B-Spline form parameter curves, labeled as F-Spline. Two functionalities of the parametric geometry models are used in the present study: a constrained transformation function to account for hull form variations and a geometric entity used in full parametric hull form design. The present F-Spline based optimization procedure is applied to two distinct hydrodynamic hull form optimizations: the global shape optimization of an ultra-large container ship and the forebody hull form for the hydrodynamic optimization of an LPG carrier. Improvements of ship performance achieved by the proposed F-Spline procedure are demonstrated through numerical experiments and through correlations with experimental data. The ultra-large containership was built and delivered to the ship owner. The present study validates the effectiveness of the proposed hydrodynamic optimization procedure, ushering in process automation and performance improvement in practical ship design practices. 相似文献
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船型设计是船舶总体设计中一项极其复杂且又重要的内容,船舶的结构设计、性能计算、总布置等都要以船型为依据,因此,如何实现船型参数化设计尤为重要。FRIENDSHIP系统为船型设计提供了基于Feature特征和仿真驱动设计的参数化方法和实现机制。在对船型参数化基本理论———特征参数、特征曲线和曲面生成等进行详细阐述的基础上,以某型船艉部裸船体为例,具体阐述了船型参数化的实现流程,以及以Feature、Curveengine和Meta surface为特征机制的船型参数化的具体步骤。以Feature特征为核心的船型参数化方法不仅能为船型曲面的快速建立提供技术支撑,还可以为性能分析和优化提供基础条件。 相似文献
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基于参数化CAD模型的船型阻力/耐波性一体化设计 总被引:1,自引:0,他引:1
在舰船概念设计阶段,往往需要快速生成阻力和耐波性能兼优的船型。采用基于母型船的船型融合生成方法,实现了参数化船型自动生成。在此基础上,采用iSight优化平台,将参数化船型生成技术与阻力、耐波性计算模型集成,运用多学科设计优化技术实现了船型阻力/耐波性性能一体化设计。优化方法采用多目标遗传算法以获取Pareto前沿。以一艘46 000 DWT油船的型线优化为算例对这个过程进行了具体说明,试验结果表明总阻力降低了3%,验证了这种方法的可行性。 相似文献
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船型几何模型的参数化表达,是船型多学科设计优化的基础。其作用是为各学科分析和优化提供一个统一的几何模型,并根据各学科分析结果自动修改调整船体型线。文中尝试使用Friendship进行船体完全参数化建模,并使用该软件中的feature编程功能编程实现shipflow型值数据的提取;通过改变一系列重要的船型参数实现变换船型几何模型,以获得满足性能需求的船型。最后利用该软件的优化框架,采用切线搜索法 (Tangent Search, TSearch) 完成1300TEU集装箱船的兴波阻力优化,优化球首和前体船体曲面。结果表明,该参数化方法在改进船型水动力性能方面有很好的效果。 相似文献
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基于标准的协同优化算法,针对其对初始点敏感、收敛慢等固有缺陷,将协同优化算法法与混合优化算法及动态松弛法相结合,提出分段动态松弛协同优化算法,并将其应用到船舶机舱结构多目标优化问题中。针对船舶主机舱结构静、动态多学科多目标优化问题,建立主机舱结构的多目标协同优化模型。在Isight优化软件中采用改进的分段动态松弛协同优化算法,对船舶机舱结构进行静、动态多学科多目标协同优化设计,得到优化设计的最优解。优化结果表明,相对于基于遗传算法的协同优化算法,分段动态松弛协同优化算法兼顾了优化的高效性和准确性,对于实际工程中更加复杂的多学科多目标结构优化具有一定的参考价值。 相似文献
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A new weather-routing system that accounts for ship stability based on a real-coded genetic algorithm 总被引:1,自引:0,他引:1
Atsuo Maki Youhei Akimoto Yuichi Nagata Shigenobu Kobayashi Eiichi Kobayashi Shigeaki Shiotani Teruo Ohsawa Naoya Umeda 《Journal of Marine Science and Technology》2011,16(3):311-322
The operation schedule of an oceangoing vessel can be influenced by wave or wind disturbances, and is therefore weather routed.
The weather-routing problem is considered to be a multimodal function problem. Therefore, in the present research, the real-coded
genetic algorithm technique (an evolutionary calculation technique) is applied to globally search for the optimum route. Additionally,
to avoid maritime accidents due to parametric rolling, this route optimization method takes into account the risk of parametric
rolling as one of its objective functions. Numerical verification is carried out for three kinds of objective functions with
different weight ratios between fuel efficiency and ship safety in parametric rolling. As a result, it is numerically confirmed
that the relation between economics and ship safety is a trade-off, and the safer route is not necessarily the most economical.
Considering its robustness, the proposed method appears to be a powerful practical tool by choosing the most appropriate weights
for economics and ship safety. 相似文献
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构建船舶与海洋工程数字化性能平台促进科技自主创新 总被引:4,自引:0,他引:4
作为对船舶设计基础共性技术研发的一种思考,提出构建“船舶与海洋工程数字化性能平台”的设想。这一性能平台是以信息化、数字化为核心,以虚拟技术、网络协同、远程交互技术为手段,开放式和加盟式一体化的综合集成系统。在这种数字化性能平台上,运用计算流体动力学方法,可以全面地对船舶的安全性能、综合航行性能和海洋工程结构物的流体动力特性进行预报、评估和优化,成为新型舰船、新型海洋平台和海洋结构物研究开发的重要工具和手段,促进船型开发和设计的自主创新。 相似文献
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A new method for ship finite element method (FEM) preprocessing is presented as well as its program development. The method
is applicable for all kinds of ships at different levels, such as a whole ship, cargo hold parts or detailed structures. The
3D parametric technique is used when creating ship structures, which improves the modeling efficiency greatly and makes the
model easy to modify. A 3D geometric constraint solver is developed to solve the constraint system of the parametric model.
A meshing procedure is presented to automatically convert the parametric structure model into a finite element model, by which
high quality mesh is generated in the stress concentrated area. It also becomes possible to create finite element models for
different levels from the same structure model. Using this method, the engineers avoid much of the complex and laborious work
of FEM preprocessing, which consumes a very significant amount of time in finite element analysis, and can pay more attention
to post-processing. This method has proved to be practical and highly efficient by several engineering trials.
This work is sponsored by “Liaoning BaiQianWan Talents Program”. 相似文献
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Underwater cylindrical shell structures have been found a wide of application in many engineering fields, such as the element of marine, oil platforms, etc. The coupled vibration analysis is a hot issue for these underwater structures. The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths. In this study, an acoustic finite element method was used to evaluate the underwater structures. Taken the hydrostatic pressure into account in terms of initial stress stiffness, an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation. By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function, the validity of present analysis was checked. Finally, test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis. The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion, and the characteristics of sound radiation change with water depth. Furthermore, the analysis methods and the results are of significant reference value for studies of other complicated submarine structures. 相似文献