Π形弯补偿器在LNG船低温管路中的应用分析

LNG船低温管路系统因受外界环境变化、大量频繁船体变形作用及自身巨大工作温差变化的影响,产生复杂的二次应力,容易导致疲劳破坏.通过分析某型LNG船低温管路系统中π形弯的设置对改善管路柔性、降低管路二次应力水平的影响,给出一个适用于该类型管路的π形弯变形补偿器设置原则.     

新型潜艇耐压船体绝缘材料应用研究

根据我国潜艇耐压船体绝缘材料的现状，针对潜艇耐压船体绝缘材料的基本要求，在充分论证的基础上，从工艺配套性筛选试验、实艇模型施工工艺、修补工艺试验等方面，对新型绝缘材料及其在潜艇耐压船体上的施工进行了详细的阐述，提出了新材料在施工中应注意的问题。在大量研究和实践的基础上，给出了一种适合潜艇采用的新型耐压船体绝缘材料。     

潜艇耐压液舱区耐压船体计算方法的探讨

本文采用大曲率梁和弹性基础梁理论，建立舷间耐压液舱区域时辰主船体的微分方程，并求解出其挠度表达式，由此得到耐压船体的强度计算公式，通过数值计算表明结果的正确性。     

耐压液舱区域的耐压船体应力分析研究

本文以耐压液舱区域的耐压船体结构为对象,在轴对称假设的前提下建立力学模型,得到耐压船体结构挠度表达式,推演出壳板强度计算公式.通过计算表明与试验结果是一致的.     

潜艇外部耐压液舱结构型式研究

讨论了潜艇外部耐压液舱可能的结构形式。指出了传统的全实肋板外部耐压液舱、耐压船体壳板应力集中较严重，轴向应力很大。指出了加强液舱南板难以降低耐压船体壳板应力，反过来，加强耐压船体壳板也难以改善液舱壳板的应力状态。指出了液舱壳板加纵骨的全实肋板同心双层圆柱层是一种优良的耐压液舱新型结构型式。     

耐压液舱极限承载能力的影响因素分析与匹配设计北大核心CSCD

[目的]旨在讨论相同的强度储备裕度条件下耐压船体与耐压液舱极限承载能力之间的关系,以获得二者极限承载能力相当的匹配设计。[方法]首先,以典型的外置式耐压液舱为研究对象,在评估耐压液舱初始结构方案稳定性与极限承载能力的基础上,分析液舱壳板厚度、液舱实肋板厚度以及液舱横舱壁结构对耐压液舱极限承载能力的影响;随后,适当调整初始方案,获得耐压船体与耐压液舱强度储备裕度相当的设计方案,并在此基础上讨论耐压船体与耐压液舱极限承载能力之间的关系,进一步加强耐压船体,获得匹配耐压液舱与耐压船体承载能力的方案以及对应的强度裕度。[结果]结果显示,减薄液舱壳板30%、液舱实肋板33.3%及液舱横舱壁30%,其极限承载能力将分别降低16.5%,36.4%和0.17%。[结论]研究表明在相当强度储备裕度条件下,耐压船体的承载能力远低于耐压液舱的承载能力;在耐压液舱壳板的强度储备裕度约为25%、耐压船体壳板的强度储备裕度约为40%时,耐压船体与耐压液舱的极限承载压力大致相同。     

潜艇全实肋板带纵骨式耐压液舱结构应力的板壳有限元公司

本文用有限元方法给出了潜艇全实肋板带纵骨式耐压液舱结构应力分布规律，指出了在这种结构中的应力存在着明显的非轴对称特性，说明了局部加厚耐压船体壳板可明显降低应力集中程度，在耐压船体上加设纵骨对地降低轴向弯曲应力有良好作用。     

耐压液舱结构强度与稳定性

应用有限元方法对纵骨式耐压液舱结构进行系列计算,通过多参数多工况方案对比分析,详细讨论了耐压壳板半径、液舱壳板半径、耐压船体壳板板厚、液舱壳板板厚、相邻实肋板间距、相邻纵骨间距等参数对液舱壳板和耐压船体壳板结构强度和稳定性的影响,研究结果可供潜器耐压液舱结构设计参考,并为进一步完善耐压液舱结构的理论计算方法提供依据.     

潜器耐压液舱结构有限元分析

应用有限元方法对纵骨式耐压液舱结构进行系列计算,通过多参数多工况方案对比分析,详细讨论了耐压壳板半径、液舱壳板半径、耐压船体壳板板厚、液舱壳板板厚、相邻实肋板间距、相邻纵骨间距等参数对液舱壳板和耐压船体壳板结构强度和稳定性的影响,研究结果可供潜器耐压液舱结构设计参考,并为进一步完善耐压液舱结构的理论计算方法提供依据。     

水下充气运输船的设想

本文设想给水下运输船货舱充气,以平衡舷外水压,使货舱壳体由原来的承受外压变为承受内压,可避免在外压情况下危险的失稳条件,使之由坚厚的耐压船体改为轻薄的非耐压船体,因而有可能简化在水下船体上开大舱口的强度保证问题。同时能减轻船体重量,提高     

Stress concentration factors at welds in pipelines and tanks subjected to internal pressure and axial force

In this paper, analytical expressions for stress concentration factors in pipes subjected to internal pressure and axial force are derived for a number of design cases based on classical shell theory. The effect of fabrication tolerances in simple butt welds is assessed. Analyses based on classical mechanics are compared with results from axisymmetric finite element analyses for verification of the presented methodology. Stress concentration factors are presented for circumferential butt welds in pipes welded together from pipes with different thicknesses, welds at buckling arrestors, welds at flanged connections in pipelines, and welds at ring stiffeners on the inside and the outside of the pipes. It also includes stress concentration factors at end closures in pipes for gas storage. Larger pipes are fabricated from plates with a longitudinal weld. This fabrication process introduces out-of-roundness in the pipes. The actual out-of-roundness is a function of internal pressure. An analytical expression for the bending stress in the pipe wall due to this out-of-roundness is presented. The derived stress concentration factors can be used together with a hot spot stress S–N curve for calculation of fatigue damage.     

大型LNG船玻璃钢压载水管道应力校核方法

玻璃钢管作为大型液化天然气(LNG)船压载水管道,在其应用过程中易出现部分管道破裂以及管道支架损坏的问题,针对该问题,以某大型LNG船为例,采用管道应力分析软件CAESARII建立压载水系统玻璃钢管道有限元模型。根据实际建造营运方式,考虑船舶运动加速度、船体变形、温度和压力等载荷,确定能覆盖所有建造运营条件的载荷工况。采用ISO 14692标准作为大型LNG船玻璃钢压载水管应力校核设计的标准,分析压载水管道的应力水平以及作用在管道支架上的负荷,对应力超标处的管道进行优化布置,对承受大负荷的管道支架进行结构加强设计。实船应用结果表明,该方法的应用效果良好,可推广到其他类型船舶的玻璃钢压载水管道系统的设计中。     

薄膜型LNG船交变温度载荷下疲劳分析

海上环境引起的船体外板温度昼夜交替变化及装卸载会造成薄膜型LNG船温度应力交替变化。采用综合温度折算法确定船体外板典型昼夜温度,并针对薄膜型LNG船温度场分析建立三舱段有限元模型及底边舱折角区域精细模型,采用子模型法计算出各典型温度下的结构温度应力。研究结果表明底边舱折角处温度应力与船体外板水线面上下的温度差异呈良好的线性关系,船体外板温度的日周期性变化及装卸载引起的温度交变应力对船体结构疲劳强度影响不大。     

钢带软管内压和弯曲研究

复合材料管已成为管道发展的热点和趋势。文中对钢带软管在同时受到内压和弯曲组合载荷作用下的力学性能进行了研究。基于建立的钢带软管的环向和径向力学平衡方程,提出了不同弯曲半径下该种类型管道的爆破压力理论计算方法。文中还进行了有限元数值模拟,并与理论计算结果对比分析,分析结果表明文中提出的爆破压力计算方法可作为此类管在同时受到内压及弯曲组合载荷作用下的通用算法,为解决此类工程问题提供重要参考。     

基于Midas/Civil的大体积混凝土温度应力计算及其防裂技术措施

广东南澳大桥工程(三标段)东引桥浅水区E34～E39承台为大体积混凝土结构(7.1 m×6.4 m×2.5 m)。基于Midas/Civil2010有限元分析软件对该承台建立大体积混凝土水化热数字分析模型。对无冷却水管和有冷却水管的混凝土内部分别进行温度应力计算,并将计算结果指导于现场施工。应用实例证明,这些技术措施可有效避免混凝土贯穿裂缝的产生,保证大体积混凝土的施工质量。     

焊接残余应力对深潜器耐压球壳承载能力的影响

耐压球壳通常采用焊接方式将两个半球壳连接成整球,在焊缝处产生的接近材料屈服强度的焊接残余应力对球壳的承载能力有多大的影响,是否需要做焊后消除残余应力处理,将直接影响球壳的安全性和生产成本。而现有对球壳极限强度计算,无论是理论计算还是数值计算,均只考虑了球壳初始缺陷中的几何缺陷对球壳极限强度的影响。该文将在现有的耐压壳极限强度设计公式基础上,采用数值计算的方法对耐压球壳的焊接过程进行数值模拟,得到焊后球壳的焊接残余应力分布,并在此基础上考虑残余应力对球壳极限强度的影响,结果表明,对于大潜深厚球壳,焊接残余应力对耐压球壳承载能力影响不显著,为大深度潜器耐压球罐是否需做焊后消除残余应力处理提供了一定的参考依据。     

双壳型船体结构稳态温度场和温度应力

用简化解析方法和有限元数值方法,分析了双壳型船体货舱区域在运载高温液货时的稳态温度场;根据船体结构的温度分布,用有限元法计算了其温度应力,同时与货物压力、海水静动压力、总纵弯矩等载荷作用下的结构应力做了比较。研究结果表明：在货舱结构温度场分析中用简化分析方法和有限元数值方法所得的计算结果相当一致;高温液货大幅度增加船体结构的纵向应力和横向应力,同时加剧结构不连续处的应力集中;槽型舱壁可以有效地释放     

Modelling upheaval buckling in marine buried pipelines by coupling the shear stresses and soft soil stiffness

Buried marine pipelines employed in the Oil & Gas industry are subjected to pressure and temperature gradients, which cand produce local high compression loads leading to the onset of upheaval buckling failure. Upheaval buckling occurs when the localized stresses across the pipeline are high enough to induce constant deformation due to the low soil restriction in the upward direction. Therefore, models to predict upheaval buckling in buried marine pipes caused by high pressure and high temperature (HP/HT) and soil stiffness have been developed based on Euler-Bernoulli beam theory (EBT). However, this theory does not consider stresses and strains due to shear stresses which can play an important role in upheaval buckling failure. Therefore, in this work an analytical model that takes into account Engesser-Timoshenko beam theory (TBT) and considers the shear effects on pipelines was developed to predict upheaval buckling in buried marine pipelines. Furthermore, equations that govern vertical buckling of buried pipelines considering a plastic soil with initial imperfection were considered. Analytical results were compared with finite element models of buried pipeline and other models reported in the literature, and it was observed that analytical results fall in the range of those reposted in the literature. It was also observed that the incorporation of shear stresses in buried marine pipelines has low effect on upheaval buckling onset and propagation, but the soil stiffness has a strong influence on upheaval failure in buried marine pipelines.     

FEM-based evaluation of friction and initial imperfections effects on sandwich pipes local buckling

Sandwich pipes have been studied as one option to overcome the high pressure problems in deep and ultra-deep waters. They have become a possible alternative solution for submarine infrastructure due to its thermal insulation capacity. This contribute to preventing the pipeline from clogging due to the difference in temperature between reservoir fluids and water at the bottom of the sea. The pipelines in ultra-deepwater are continually exposed to severe operating conditions, such as the effect of high levels of external pressure that can cause local deformation or even collapse of the pipe. Thus, a greater understanding of the mechanical behavior of sandwich pipes is required. This paper presents a FEM-based evaluation of friction and initial imperfection effects on sandwich pipes local buckling. The non-linear evaluation was carried out in FEM of local buckling of two sandwich pipes, with polypropylene and cement as filled annular material. The influence of initial imperfections and the degree of friction, between the annular material and the steel pipes, as well as geometric variations of the pipe were considered. The numerical simulations results indicate a capacity to withstand ultra-deep waters collapsing pressures, around 3000 m, either for polypropylene or cement filled annular material model. In addition, the results indicate that the collapse pressure is inversely proportional to the increase in annular thickness and directly proportional to the decrease in friction which have an impact and contribution on the carrying capacity of the sandwich pipe. Further research will consider a design of experiments analysis of reported effects for different diameter-to-thickness ratios.     

焊接初始缺陷对船体梁极限弯矩的影响

对焊接初始缺陷于船体梁极限弯矩的影响进行了研究.采用热传递分析得到焊接结构的温度场,进而采用热弹塑性分析得到结构的焊接残余应力和焊接变形.将得到的焊接变形及残余应力作为结构的初始缺陷,对船体梁的极限弯矩进行了比较计算.结果表明,焊接初始缺陷对船体梁极限弯矩的影响不宜忽略,热传递及热弹塑性分析的方法可较好地模拟船体梁极限弯矩分析中的焊接初始缺陷.