基于马氏链样本模拟的潜艇耐压结构系统可靠性计算

潜艇耐压结构主要由耐压船体和耐压液舱组成，是潜艇承受外载的主要结构。在结构可靠性分析中，潜艇耐压结构的可靠性分析属于多个相关模式串联的系统可靠性问题。本文提出了一种适合于结构系统可靠性计算的重要样本法，主要的改进在于根据Metropolis准则，构造马尔可夫链模拟样本，并结合重要抽样技术，计算结构的系统可靠性。潜艇耐压结构的系统可靠性计算的算例表明：该方法具有较好的效率和精度。     

基于MATLAB的潜艇耐压液舱结构优化设计

本文以MATLAB为平台,进行了同心圆和准同心圆式潜艇耐压液舱结构的优化设计。计算结果与有限元计算结果相比偏于安全,两种结构形式的优化结果比较接近,考虑到工程实际,准同心圆式潜艇耐压液舱结构值得推荐。     

潜艇耐压液舱结构破坏原因及加强形式探讨

耐压液舱区域的耐压壳体在外载荷作用下发生破坏,其破坏原因与相邻耐压壳体的受力相关,相邻耐压壳体的变形对其影响往往很大。在吸收现有潜艇耐压液舱结构理论计算方法、有限元分析和试验研究的基础上,对其结构破坏原因及加强形式进行了探讨。     

潜艇耐压圆柱壳结构的可靠性研究

举艇耐压圆柱壳是潜艇承受外载的主要结构,其失效模式多种移样,而且相互关联,因此,潜艇耐压圆柱壳结构的可靠性分析是一个多复杂、相关问题的可靠性分析问题,本文从潜艇耐压圆柱壳的失效模式建立到总体及各种失效模式的可靠性大小计算,建立了一套计算潜艇耐压圆柱壳结构可靠性的分析。编制了潜艇耐压圆柱壳结构的可靠性分析计算机程序,并以具体潜艇耐压圆柱壳结构进行了可靠性分析,从其对耐压圆柱壳的计算结果可以看出,潜艇耐压圆柱壳结构的失效概率并不等于各失效模式的失效概率之和,这不同于Ｆａｕｌｋｎｅｒ做出的求和理论假定。本文的潜艇耐压圆柱壳可靠性分析,为多模态失效的系统可靠性计算开辟了新的途径,对潜艇耐压圆柱壳结构的可靠性设计提供了一定的理论基础。     

潜艇耐压液舱区域有限元应力计算

针对目前潜艇耐压液舱结构应力解析公式精度不高的情况,根据其受力特点建立了同心圆和准同心圆式耐压液舱结构有限元分析的力学模型,编程通过实例计算表明自编有限元程序可靠性很高,可单独作为一个模块取代传统的近似解析法进行应力分析及后续的优化设计。     

同心圆柱壳耐压液舱结构弹塑性有限元应力分析

潜艇耐压液舱结构中某些区域的应力可能会超过材料的屈服极限,为了得出结构进入塑性阶段后应力分布的变化情况,本文利用ANSYS软件对这些结构进行了弹塑性有限元分析.通过实例计算发现,耐压液舱壳板有部分区域进入了塑性,与有限元弹性计算结果相比表明,液舱壳板中应力出现重新分布,应力峰值明显下降,应力分布趋于均匀化.计算结果和结论可供同行们参考.     

漂浮耐压体的有限元分析

潜艇的集体逃生舱是一种新型脱险装置,可有效地提高失事潜艇艇员的自救能力。本文在设计、计算中,采用求解结构的非线性屈曲问题,应用有限元分析软件ANSYS对漂浮耐压体结构进行有限元直接计算。     

一种基于方向概率的潜艇结构可靠性计算方法

潜艇结构可靠性分析属于多个相关模式串联的系统可靠性分析问题，本文通过随机空间的映射变换。将其多个失效模式的失效面统一变换到随机独立的标准正态空间（Gauss空间）内，以利用该空间球坐标沿其径向的x^2分布特性计算总体失效域上的失效概率，由于无须进行模式间相关性的近似分析，因而提高了系统失效概率的计算精度，潜艇两种耐压结构的可靠性分析算例表明，该方法实用性强，操作性好，精度较高，对于有高度非线性失效面方程的可靠性计算问题有很强的适应性。     

潜艇耐压液舱的研究现状和发展趋势

对潜艇耐压液舱的研究现状进行综述。通过分析外置式耐压液舱的研究方法和途径,展望内置式耐压液舱结构设计、计算、优化等方向研究的发展趋势。     

带纵骨实肋板式耐压液舱壳板强度计算方法研究

本文把耐压液舱结构看成一弹性整体，先对其进行整体求解，然后再对耐压液舱壳板按具有初始膜应力的混合边界问题求解。结果表明：在弹性范围内，本文方法计算值与有限元计算值及实验值吻合较好；在弹塑性范围内，本文对耐压液舱壳板边界约束的处理比文献「１」方法更符合弹塑性状态时其边界约束的真实状况。     

大型结构系统可靠性分析方法研究

结构系统的可靠性评估是结构设计的一个重要研究内容,而极限状态函数的建立是进行可靠性评估的基础.但是,大型结构系统的极限状态函数极为复杂,响应面法用简单的多项式进行模拟的精度较低,导致误差较大.文章提出用神经网络替代多项式来拟合复杂的极限状态函数,形成所谓的神经网络响应面.然后,基于塑性极限理论,文中提出了不依赖于失效模式的极限状态函数表达形式及采用ICP对该极限状态函数进行计算的方法.最后,依照拟合得到的神经网络响应面,给出了大型结构系统失效概率的方法.通过两个算例计算并和其它方法进行比较,表明该方法的计算精度较高,而计算时间大大降低.     

复合材料船体结构可靠性分析

本文综合考虑了复合材料本身及外载的多处不确定因素，首次对复合材料船全校 强度、可靠性问题进行了较全面的研究，考虑了多种失效模式并对复合材料结构本身的各随机变量的分布规律进行了统计分析。给出了一硬壳式下班钢艇的实例计算并分析了各种参数对船体结构可靠性的影响，得到了一些很有实际应用价值的结论。     

在ANSYS中开发用响应面法求解结构可靠度的专用程序

ANSYS用于对结构作概率分析,可求得复杂结构的可靠度.但ANSYS采用的随机变量分布类型中无极值型分布,而工程结构所承受的实际载荷大多为极值型分布.为处理此类情形,该文用ANSYS自带的二次开发工具APDL语言开发了用响应面法求解结构可靠度的专用程序.与ANSYS的另一开发工具UPDFs相比,文中开发的程序完全独立于ANSYS核心程序,不用对其修改,不会影响其稳定性,故适用范围更广.为了方便使用,文中用VB程序编制了输入随机变量的类型及控制参数的交互界面,并自动生成可用于ANSYS以Batch mode方式运行所需的控制文件.对于计算中各随机变量相应设计点的变动过程,特别是非正态变量在验算点处的当量正态化,用AutoCAD中Visual LISP语言编制了相应的显示程序,部分实现了计算过程的可视化.     

载人潜水器耐压球壳的多目标优化设计

采用基于响应面(RSM)近似模型和遗传算法(GA)对某深海载人潜水器耐压球壳进行多目标优化设计。首先建立深海载人潜水器耐压球壳的结构优化模型,通过试验设计(DOE)获得设计目标的响应特性,拟合得到响应面近似模型,最后采用Pareto遗传算法对响应面模型进行多目标优化求解,得到潜水器耐压球壳的优化设计方案。     

Strength reliability analysis of stiffened cylindrical shells considering failure correlation

The stiffened cylindrical shell is commonly used for thepressure hull of submersibles and the legs of offshore platforms.There are various failure modes because of uncertainty with thestructural size and material properties, uncertainty of the calculationmodel and machining errors. Correlations among failure modesmust be considered with the structural reliability of stiffenedcylindrical shells. However, the traditional method cannot considerthe correlations effectively. The aim of this study is to present amethod of reliability analysis for stiffened cylindrical shells whichconsiders the correlations among failure modes. Firstly, the jointfailure probability calculation formula of two related failure modesis derived through use of the 2D joint probability density function.Secondly, the full probability formula of the tandem structuralsystem is given with consideration to the correlations among failuremodes. At last, the accuracy of the system reliability calculation isverified through use of the Monte Carlo simulation. Result of theanalysis shows the failure probability of stiffened cylindrical shellscan be gained through adding the failure probability of each mode.     

潜艇结构的失效模式及影响分析

在结构系统可靠性分析或系统安全分析中，主要是要对系统的失效模式有较深刻的理解。而FMEA（失效模式及影响分析）方法虽然简单，却很实用，能够透彻地理解系统的安全性要求，同时也为结构系统的风险分析（PRA）打下基础。本文对潜艇结构的失效模式与影响分析作了初步研究。     

RSM-FORM 的改进与环肋圆柱壳结构的可靠性计算(英文)

文章在用有限元法对结构进行强度计算和分析的基础上,应用RSM确定了环肋圆柱壳结构强度失效的功能函数;在对相关可靠度理论进行研究的基础上,将RSM与FORM相结合,对FORM进行了改进,解决了当量正态化和参数独立化问题,保留了功能函数的二次项,使计算精度满足实际工程的需要;最后用RSM-FORM对环肋圆柱壳结构强度的可靠性进行了计算分析,计算结果表明,RSM-FORM具有较好的计算精度。     

A simplified method for reliability- and integrity-based design of engineering systems and its application to offshore mooring systems

This paper presents a simplified method for the reliability- and the integrity-based optimal design of engineering systems and its application to offshore mooring systems. The design of structural systems is transitioning from the conventional methods, which are based on factors of safety, to more advanced methods, which require calculation of the failure probability of the designed system for each project. Using factors of safety to account for the uncertainties in the capacity (strength) or demands can lead to systems with different reliabilities. This is because the number and arrangement of components in each system and the correlation of their responses could be different, which could affect the system reliability. The generic factors of safety that are specified at the component level do not account for such differences. Still, using factors of safety, as a measure of system safety, is preferred by many engineers because of the simplicity in their application. The aim of this paper is to provide a simplified method for design of engineering systems that directly involves the system annual failure probability as a measure of system safety, concerning system strength limit state. In this method, using results of conventional deterministic analysis, the optimality factors for an integrity-based optimal design are used instead of generic safety factors to assure the system safety. The optimality factors, which estimate the necessary change in average component capacities, are computed especially for each component and a target system annual probability of system failure using regression models that estimate the effect of short and long term extreme events on structural response. Because in practice, it is convenient to use the return period as a measure to quantify the likelihood of extreme events, the regression model in this paper is a relationship between the component demands and the annual probability density function corresponding to every return period. This method accounts for the uncertainties in the environmental loads and structural capacities, and identifies the target mean capacity of each component for maximizing its integrity and meeting the reliability requirement. In addition, because various failure modes in a structural system can lead to different consequences (including damage costs), a method is introduced to compute optimality factors for designated failure modes. By calculating the probability of system failure, this method can be used for risk-based decision-making that considers the failure costs and consequences. The proposed method can also be used on existing structures to identify the riskiest components as part of inspection and improvement planning. The proposed method is discussed and illustrated considering offshore mooring systems. However, the method is general and applicable also to other engineering systems. In the case study of this paper, the method is first used to quantify the reliability of a mooring system, then this design is revised to meet the DNV recommended annual probability of failure and for maximizing system integrity as well as for a designated failure mode in which the anchor chains are the first components to fail in the system.     

结构模糊可靠性分析

结构破坏准则实际上是带有模糊性的，要合理判断结构强度必须依靠模糊概率方法。本文采用基于模糊判决的限界搜索法，给出了计算结构模糊可靠性清晰解的方法。以受集中力的两端刚固梁和船首底板砰击强度为例进行了数值计算，并讨论了容差变化对模糊可靠度指标的影响。     

船体梁与加筋板极限强度可靠性设计

本文应用结构可靠性分析方法,分别以船体梁和船体纵向加筋板极限承载能力为失效模式,对船体结构进行了安全评估和可靠性设计。应用所开发的新的改进可靠性计算方法,计算了基本物理量的不确定性对船体结构极限强度函数统计特征的影响,同时结合所开发的用于直接估算船体梁和加筋板极限强度的荛用计算方法,确定出不同船体结构的失效概率和设计目标安全指数,推导了局部安全因子,可以进行船体结构的可靠性设计与再评估。