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为了适应当前的海洋开发需求,海洋工程结构物的大型化已成为必然发展趋势,这使得原有海工建造施工场地的滑道处于临界承载状态,给安全生产带来了巨大隐患。本文针对典型滑道结构,采用有限元参数化建模技术(ANSYS Parametric Design Language,ANSYSAPDL)模拟上部载荷滑块在滑道板上的灵活布置,对滑道强度储备进行分析。研究表明:设计载荷下,滑道板的强度储备较滑道桩体及滑道桩侧土小,滑道强度的控制因素为滑道板强度;改变上部载荷滑块的位置,探索不同位置处滑道极限承载力,提高施工建造过程中滑道利用率。 相似文献
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面板局部屈曲的船体双层板架整体屈曲分析 总被引：1，自引：0，他引：1
首先应用von-Kurman大挠度薄板方程，对有初挠度的船体板进行后屈曲特性分析，以此为基础，导出屈曲后板的减缩有效宽度，进而用减综有效宽度作为双层板架中受压纵杵的带板宽度，将双层板架模型化为四边弹性转角约束的正交异性板，考虑横向剪切变形的影响，提出了一种求解双层板架临界应力的方法。 相似文献
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海上施工栈桥作为一种可以快速装配的施工辅助设施,在跨海大桥建设中得到广泛应用。为研究海上施工栈桥在极端波浪作用下的结构性能,基于波浪增量分析(IWA)理论,提出海上施工栈桥承载性能评估方法。以某在役海上施工栈桥为例,考虑杆件弹塑性和节点局部柔性建立结构非线性分析模型,评估了海上施工栈桥在不同方向极端波浪荷载作用下的结构承载性能及倒塌失效模式。研究表明,随着极端波高逐渐增大,栈桥依次出现首次屈服、塑性铰和倒塌起始三种非线性行为点,结构将依次经历正常使用、可以使用、临近倒塌和倒塌破坏四个承载性能状态;波浪入射方向对于海上施工栈桥的承载性能和倒塌失效模式影响较大;海上施工栈桥的主要薄弱部位位于钢管桩桩底及其与支撑框架下横撑相交的节点处,应在设计中重点关注。 相似文献
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水下生产系统跨接管结构极限承载能力分析 总被引：1，自引：0，他引：1
跨接管是水下生产系统的主要构件之一,水下地形变化易导致跨接管两端承受较大边界位移载荷,对水下生产系统的结构安全性产生不利影响。研究并分析了端部相对位移载荷作用下跨接管结构的极限承载能力及跨接管失效模式的特点,表明整体轴向压缩位移分量是导致跨接管结构发生极限破坏的主要因素。在此基础上考虑了内表面周向裂纹对跨接管极限强度的影响。分析结果表明:当裂纹较小时,因弯管截面的椭圆化和塑性屈服,轴向压缩位移很容易使跨接管发生整体压缩失效;当裂纹较大时,因为裂纹韧带区的高应力效应,跨接管会在整体压缩失效之前达到极限状态;最终失效模式取决于裂纹的位置及大小。 相似文献
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圆弧板透空式防波堤消波性能试验研究 总被引：1，自引：1，他引：0
提出了一种由多层圆弧板组成的新型透空式防波堤结构,并对其在二维规则波浪作用下的消波性能进行了物理模型试验研究。在不同入射波高条件下,对圆弧板和水平板透空结构的消波性能进行了比较分析,探讨了圆弧板间距和层数对圆弧板透空式结构消波性能的影响。研究结果表明,圆弧板透空式结构的消波效果优于水平板式透空结构,在相对宽度为0.2时,可以使透射系数达0.5以下。随着圆弧板间距从0.15 m减小到0.05 m时,消波效果逐步提升,而圆弧板的层数对结构的消波性能也有一定影响。 相似文献
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提出了一种将波浪中倾斜板问题等效化简为波浪中水平板单元组的方法,该方法建立在使用分离变量法求解水工结构边值问题的基础上,并使用伽辽金法精确求解连续边界条件,确定考虑衰减波态的速度势函数,从而求解没水倾斜板结构的消波性能。等效化简法计算精度于边界元法相当,且计算单元数量少、开销低。基于二维线性势波理论,对没水倾斜板式防波堤消波性能分析显示,没水板的倾斜角度、没水深度与板长是结构消波性能的控制因素:没水倾斜板防波堤的消波性能优于没水水平板防波堤的消波性能,随着没水板结构的倾斜角度增大,没水倾斜板结构的波浪透射系数显著减小,且长板优于短板,浅板优于深板;与前人的水槽实验对比显示,相对没水深度与波陡影响结构的消波性能,且波陡造成的波浪破碎贡献了显著的波能消耗。该结论对板式防波堤的结构配置、优化设计有重要意义。 相似文献
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加肋板是机械产品常用的一种结构形式,其目的是为了加强板结构的刚度特性,以降低结构面的振动响应及抑制结构的辐射噪声。然而,对于肋板结构参数对板结构刚度特征的影响规律,却缺乏深入地研究。本文利用有限元方法,分析研究了肋板的高度、宽度、数量及加肋位置等设计参数对板结构刚度影响的规律性。研究表明:肋板的结构参数与板结构的静、动态刚度呈非线性关系,肋板的高度参数对结构刚度的影响最为显著,纵向肋板在板厚2～4倍高度时对静态刚度的增强效果最大,随着肋板的位置逐渐偏离受载中心,肋板对结构刚度的影响逐渐减小。相关研究结果,对广泛采用板式结构形式的机械产品的结构设计具有一定的参考价值。 相似文献
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板格形导管架桩基码头是适用于深水域软土地基的新型港口与海岸工程结构。该结构由预制的板格形导管架及桩基构成,承载特性和破坏模式复杂。假定码头结构发生倾覆失稳时,转动点位于前桩轴线上,且距导管架底面距离为L。除结构的自身重量外,综合考虑板格形导管架与周围土体间的摩擦力、桩侧摩阻力、桩侧水平土抗力等,对结构进行极限状态受力分析,建立基于假想支撑点的稳定性分析模型,并通过强度折减法进行计算,求取安全系数。以天津滨海沿岸水文地质条件为背景,利用ABAQUS有限元分析软件,建立板格形导管架桩基码头三维弹塑性有限元模型进行稳定性分析,并与简化方法进行比较。结果表明,通过简化计算方法得到的安全系数与有限元结果较为吻合。 相似文献
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基于准连续介质方法模拟纳米多晶体Ni中裂纹的扩展 总被引：1，自引：0，他引：1
通过准连续介质方法模拟了纳米多晶体Ni中裂纹的扩展过程.模拟结果显示:裂纹尖端的应力场可以导致晶界分解、层错和变形孪晶的形成等塑性形变;在距离裂纹尖端越远的位置,变形孪晶越少;在裂纹尖端附近相同距离处,层错要远多于变形孪晶.这反映了局部应力的变化以及广义平面层错能对变形孪晶的影响.计算了裂纹尖端附近区域原子级局部静水应力的分布.计算结果表明:裂纹前端晶界处容易产生细微空洞,这些空洞附近为张应力集中区,并可能促使裂纹沿着晶界扩展.模拟结果定性地反映了纳米多晶体Ni中的裂纹扩展过程,并与相关实验结果符合得很好 相似文献
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Offshore pipelines operating under high pressure and temperature are subjected to upheaval buckling. Pipeline behaviour in upheaval buckling depends on a number of factors including the shape of pipeline imperfection, installation stresses, loading types, seabed sediment behaviour and the flexural stiffness of the pipe. Current method of predicting upheaval buckling is based on simplified shapes of pipeline imperfection developed for idealized seabed conditions. To account for the effect of internal pressure, the pressure load is represented using an equivalent temperature. However, the applicability of these idealizations on the prediction of upheaval buckling has not been well-investigated. In this paper, the three-dimensional finite element modelling technique is used to investigate the applicability of idealized shapes and their effects on the upheaval buckling of pipeline for a seabed condition at offshore Newfoundland in Canada. The finite element model is then used to conduct a parametric study to investigate the effects of installation stress, loading types, seabed parameters and the flexural stiffness of the pipe. Finally, a design chart is developed to determine the optimum height of seabed features to manage pipeline stability against upheaval buckling under different temperature and pressure loadings. 相似文献
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Slender piles embedded in soft ground or liquefied soil may buckle under vertical load. In this paper, both small- and large-scale model tests are conducted to investigate the buckling mechanisms of a slender pile and the lateral earth pressure acting on the pile. To observe the buckling of a slender pile, the strain-controlled loading method is adopted to apply a vertical load. When the two ends of a slender pile are hinged, the buckling mechanisms of small- and large-scale model tests are same. It should be noted that this applies only to a system with a small ratio of pile bending stiffness to soil bending stiffness. An applied vertical load increases with an increasing pile head settlement until it reaches the critical buckling load. By further increasing the pile head settlement, the measured load approaches the critical buckling load. In the large-scale model test, the measured lateral earth pressure (i.e., active and passive) acting on the slender pile varies linearly with the lateral pile displacement when the measured range is 3–5?m beneath the ground. A critical buckling calculation method has been adopted to compare with the conventional “m” method. The two-sided earth pressure calculation method can achieve more approximate results with the model test. 相似文献
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海洋油气资源的运输主要通过海底管道进行,管道在工作时受到较大的温度荷载,会产生整体屈曲变形。深海管道设计中常采用人为装置触发一定程度的水平向整体屈曲变形,来释放轴向的温度应力,浮力装置是常用的触发方式之一。本文通过数值模拟研究,分析了不同浮力大小和不同浮力施加范围下,管道水平向整体屈曲的临界屈曲力,得出临界屈曲力随浮力大小和施加范围变化的情况;并研究了不同土体阻力下,浮力装置触发整体屈曲的效果。研究表明,水平向土体阻力较大时,浮力装置触发水平向整体屈曲的效果较好。浮力装置的触发效果对轴向土体阻力不敏感。 相似文献
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Three types of ice loading, which are most commonly present when ice acts on structures, are chosen and simulated for use of fatigue crack propagation tests on offshore structural steel A131. The three types of ice categorized in accordance with the failure modes when acting on structures called crushing ice, bending ice, and buckling ice, respectively. This paper presents an experimental investigation on the fatigue crack propagation behavior of widely used high strength steel A131 for offshore jackets in the loading environment of ice crushing, bending, and buckling. The test results of fatigue crack propagation in steel A131 under these simulated ice loading at temperature 292K. are presented and analyzed in detail in this paper. The amplitude root mean square stress intensity factor is optimized to be the fundamental parameter of fatigue crack propagation for all types of ice loading histories. The results are also compared with constant amplitude fatigue crack propagation conclusions as in wave loa 相似文献
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线性断裂力学中研究裂纹的扩展通常用应力强度因子的断裂准则，但是对复合型裂纹，应力强度因子理论就发生了困难。本文用光弹性方法求得裂纹前缘的应力强度因子，然后用应变能密度因子理论研究了船舶大开口舱口角隅处疲劳裂纹和Ｔ型管节点热点处表面裂纹的扩展规律和方向，得到较好的结果 相似文献
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采用实验和数值模拟方法研究了一种新型海洋平台管节点在地震载荷下的响应和破坏情况。采用拟静态循环加载模拟地震载荷 ,对真实尺寸的试件进行实验 ,研究局部屈曲和裂纹等对管接点抗震性能的影响。能量分析表明 ,发生在斜支管中的局部屈曲消耗了大部分输入能量。与现在使用的N型管节点相比 ,该新型管节点有较好的抗震性能。采用有限元数值模拟方法分析比较了不同尺寸配置下 ,该型管节点的响应曲线 相似文献
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Shen Huishen
Professor 《中国海洋工程》1996,(4)
- posthuckling analysis is presented for the stilTened cylindrical shell of finite length subjected to combined loading of external liquid pressure and axial compression. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The "smeared stifl'cner" approach is adopted for the stiffencrs. In the analysis a singular perturbation technique is used (o determine the interactive buckling loads and the postbuckling paths. Numerical examples cover the performance of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results arc presented in the dimcnsionless graphical form. 相似文献
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The main objective of the present study is to examine the residual ultimate strength characteristics of steel plates with cracking damages under axial compressive actions through experimental investigations. The present study is a sequel of the author's previous paper (Paik, J.K., Satish Kumar, Y.V., Lee, J.M., 2005. Ultimate strength of cracked plate elements under axial compression or tension. Thin-Walled Structures, 43, 237–272). In contrast to the previous paper which dealt with transverse cracks located in the direction normal to the axial loading direction, the present paper is concerned with longitudinal cracks which are located in parallel to the axial loading direction. Similar to the previous paper, the orientation/location and size of cracks inside the plates are varied for the present experimental investigations. The details of experimental results are documented. The database and insights developed from the present work will be useful for cracking damage-tolerant design of steel-plated structures and also for condition assessment or health monitoring of aging steel-plated structures. 相似文献
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Lateral Global Buckling of Submarine Pipelines Based on the Model of Nonlinear Pipe–Soil Interaction
With the increasing development and utilization of offshore oil and gas resources, global buckling failures of pipelines subjected to high temperature and high pressure are becoming increasingly important. For unburied or semi-buried submarine pipelines, lateral global buckling represents the main form of global buckling. The pipe–soil interaction determines the deformation and stress distribution of buckling pipelines. In this paper, the nonlinear pipe–soil interaction model is introduced into the analysis of pipeline lateral global buckling, a coupling method of PSI elements and the modified RIKS algorithm is proposed to study the lateral global buckling of a pipeline, and the buckling characteristics of submarine pipeline with a single arch symmetric initial imperfection under different pipe–soil interaction models are studied. Research shows that, compared with the ideal elastic–plastic pipe–soil interaction model, when the DNV-RP-F109 model is adopted to simulate the lateral pipe–soil interactions in the lateral global buckling of a pipeline, the buckling amplitude increases, however, the critical buckling force and the initial buckling temperature difference decreases. In the DNV-RP-F109 pipe–soil interaction model, the maximum soil resistance, the residual soil resistance, and the displacement to reach the maximum soil resistance have significant effects on the analysis results of pipeline global buckling. 相似文献