首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   18篇
  免费   0篇
地球科学   18篇
  2008年   2篇
  2007年   3篇
  2005年   2篇
  2004年   4篇
  2003年   2篇
  2000年   1篇
  1998年   1篇
  1994年   1篇
  1992年   1篇
  1989年   1篇
排序方式: 共有18条查询结果,搜索用时 78 毫秒
1.
1 .IntroductionNondestructiveinspection (NDI)isveryimportantforensuringthereliabilityofoffshorestructuresintheirservicelives (Lauraetal.,1 996 ) .Itiswellknownthatdetectionofflawsinvolvesconsider ablestatisticaluncertainties.Asaresult,theprobabilityofdetection (POD)forallflawsofagivensizehasbeenusedintheliteraturetodefinethecapabilityofaparticularNDItechniqueinagivenen vironment.SincethedataofPODusuallyscatterlargely ,itisdifficulttodeterminewhichmodelfitstheavailabledatabest.Thismodelun…  相似文献   
2.
受损结构余度评估的半概率方法   总被引:3,自引:0,他引:3  
本文给出了一种结构系统余度的度量定义,基于结构系统机构化失效概念和相当可靠性指数。本文提出了对受损结构安全评做的半概率方法。所示算例表明了本方法的有效性。  相似文献   
3.
According to the characteristics of deepwater top tensioned risers, a simplified model is presented to predict the multi-modal response of vortex-induced vibration (VIV) in non-uniform flow based on energy equilibrium theory and the exporimental data from VIV self-excited and forced oscillations of rigid cylinders. The response amplitude of each mode is determined by a balance between the energy fed into the riser over the lock-in regions and the energy dissipated by the fluid damping over the remainders. Compared with the previous prediction models, this method can take fully account of the intrinsic nature of VIV for low mass ratio structures on lock-in regions, added mass and nonlinear fluid damping effect, etc. Moreover, it is the first time to propose the accurate calculating procedure for VIV amplitude correction factor by solving energy equilibrium equation and a closed form solution is presented for the case of a riser of uniform mass and cross-section oscillating in a uniform flow. The predicted values show a reasonable agreement with VIV experiments of riser models in stepped and sheared currents.  相似文献   
4.
Truss Spar平台在风、浪、流的作用下,结构受力十分复杂,准确分析其疲劳强度相当困难。通过建立Truss Spar平台三维有限元模型,利用HydroD软件进行载荷预报、波浪搜索,得到产生最大应力幅响应的最不利浪向和相位角。运用Sestra软件进行整体有限元分析,得到的结果作为桁架管节点细化模型的边界条件,再用Nastran软件进行局部分析求得节点的热点应力,修正壁厚影响。最后根据DNV规范的S-N曲线计算了管节点的疲劳寿命。  相似文献   
5.
随着海洋石油天然气资源的不断开发,海洋结构物得到了广泛的应用。长时间持续工作于海洋环境以及一旦失效代价高昂的特点使得海洋结构物的安全问题倍加瞩目。基于风险的检测和维护将海洋结构物的风险与费用相结合,可以在满足安全要求的前提下合理地降低运营费用,是目前国际上研究领域的热点问题。通过分析基于风险的海洋结构物检测和维护的国内外研究现状,对检测及维护操作过程中的一些关键问题和目前主流的研究方法及应用情况做了概述。最后讨论了海洋结构物检测维护研究中存在的一些问题,提出了今后的研究方向。基于风险的检测和维护将是今后一个值得关注的重要课题。  相似文献   
6.
34万吨级FPSO的中横剖面优化设计   总被引:5,自引:1,他引:4  
以中横剖面的面积最小为目标函数,应用自适应步长随机搜索法,对34万吨级FPSO中横剖面进行了优化设计,并将规范设计结果和优化设计结果进行了比较,优化效果较好。  相似文献   
7.
A framework of risk based inspection and repair planning was presented to optimize for the ship structures subjected to corrosion deterioration. The planning problem was formulated as an optimization problem where the expected lifetime costs were minimized with a eonstraint on the minimum aceeptable rehability index. The safety margins were established for the inspection events, the repair events and the failure events for ship struetures. Moreover, the formulae were derived to calculate failure probabihties and repair probabilities. Based on them, a component subjected to corrosion is investigated for illustration of the process of selecting the optimal inspection and repair strategy. Furthermore, some sensitivity studies were provided. The results show that the optimal inspection instants should take place before the reliability index reaches the minimum acceptable reliability index. The optimal target failure probability is 10^-3. In addition, a balance can be achieved between the risk cost and total expected inspection and repair costs by means of the risk-based optimal inspection and repair method, which is very effective in selecting the optimal inspection and repair strategy.  相似文献   
8.
考虑焊缝影响的管接头有限元分析   总被引:1,自引:0,他引:1  
本文提出了一种用罚单元方法及虚梁法处理海洋平台管状接头分析中弱连接问题的方法。有效地用来考虑焊缝影响的管状接头应力分析。应用本方法对T型管接头进行了数值计算,计算的结果与实验结果相当符合。由于计入了焊缝对结点处应力分布的影响,本法较一般已有的算法更合理。本文还探讨了焊缝形状及尺寸对‘热点’位置及应力集中系数的影响。  相似文献   
9.
本文提出了一种改进的空间梁单元,可以考虑单元两端节点的柔性,用来模拟海洋平台等工程结构的柔性接头特性,用此改进梁单元作海洋平台结构总体分析,不仅简单可行、通用性强,而且有足够的精度,算例结果表明了它的有效性和可靠性。  相似文献   
10.
利用谱分析方法对新型多柱桁架式Spar平台的关键点进行了疲劳寿命分析计算.首先建立平台的有限元计算模型,并在频域内进行动力分析;然后利用热点应力法求出关键点应力传递函数,根据应力传递函数得到每个短期海况的应力谱和应力谱参数;最后采用Miner线性累积损伤准则计算出关键点的疲劳寿命,计算结果表明关键点疲劳寿命符合规范要求.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号