共查询到19条相似文献，搜索用时 500 毫秒
1.
基于API BULL2U规范有关圆柱壳体结构稳定性条文,对Spar平台的圆柱型硬舱壳体的骨架布置型式与圆柱壳体结构的稳定性关系进行了初步探讨,编写了圆柱壳体结构稳定性计算分析软件。通过对例题的计算,认为在Spar平台硬舱壳体设置环向加强筋可显著提高第Ⅱ类和第Ⅲ类屈曲的临界应力,但对第Ⅰ类屈曲的临界应力影响不大;当数量超过的临界值时,设置纵向筋可显著提高第Ⅰ类屈曲临界应力,但对第Ⅱ类和第Ⅲ类屈曲模式纵向加强作用有限。 相似文献
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耐压舱设计是水下机器人的核心技术之一,其极限承载力研究是核心中的核心。针对球壳封盖加柱形壳体耐压舱,现行标准对于初始导入缺陷数值的确定往往过于保守,对于耐压舱体数量较多的无人潜水器来说,过大的设计质量是总体设计所无法接受的。首先采用装配体整体建模策略,建立复合屈曲的受力模型,将三大非线性影响因素同时引入到极限承载力研究中,提升了计算精度。然后分别针对确定性缺陷和非确定性缺陷结构开展极限承载力研究。最后,提出以0.23%的初始缺陷导入尺度作为球壳封盖加圆柱壳体的耐压壳体缺陷导入参数,给出了导入尺度的计算方法,并借助水压试验对上述参数的准确性进行验证。 相似文献
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本文研究了海洋平台桩脚在沿长度承受非线性变化的侧向压力作用下的稳定性。采用塑性形变理论,综合考虑了几何非线性及物理非线性对带初始缺陷的环肋管桩壳体的屈曲影响。 相似文献
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本文基于Kármán-Donnell壳体方程,研究了具有涡形几何缺陷的海洋管线在轴力和外压共同作用下的后屈曲问题.文中利用双重尺度摄动法和Fourier展开相结合,导得了管线相应的初始后屈曲系数以及极值载荷与缺陷参数之间的定量关系.通过实例计算得到了一系列曲线图谱,它们描述了一些因素对缺陷敏感度的影响程度. 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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船体板架结构在屈曲约束下的优化问题具有变量多和约束多的特点,且屈曲计算需借助有限元分析,属于大规模耗时优化问题,运用常规优化方法求解需要较高的计算成本。这里提出一种适用于屈曲约束下船体板架快速优化方法,该方法利用板格屈曲利用因子具有局部性的特点,对板格厚度自变量空间进行降维处理;利用板格屈曲利用因子对板格厚度具有单调性的特点,采用牛顿迭代方法求解其达到目标值的板格厚度;同时比较板格在相同重量增量下,加筋叠加板厚与仅加板厚对屈曲利用因子改善程度的大小决定是否加筋;通过两阶段的迭代寻优,快速获得最优的板厚以及防屈曲筋布置方案。某油船双层底优化结果显示,该方法能够在30步之内完成优化计算,优化效率高;优化方案相比原始方案减重达17.63%,绝大部分板格屈曲利用因子取值在0.9～1.0之间,材料得到充分利用。 相似文献
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在深海环境中,海底管线不仅承受较高外压,还会因为海水及运输介质的常年侵蚀而形成腐蚀缺陷,而腐蚀缺陷往往会导致管道的外压承载力下降。基于壳体稳定性理论,建立了含有非对称局部壁厚减薄管道在外压作用下的屈曲压力理论公式。公式具有广泛的适用性,当内、外局部壁厚减薄深度相等时,可用于计算含有对称局部壁厚减薄管道屈曲压力,而当内部或外部缺陷深度为零时,便可用于计算只含外部或者内部腐蚀缺陷的管道屈曲压力。通过有限元分析验证了该公式的正确性,结果表明公式可以准确预测不同缺陷位置及尺寸时管道的屈曲压力。详细研究了局部壁厚减薄缺陷位置、长度和深度等参数对屈曲压力的影响。研究表明,局部腐蚀对管道的屈曲压力产生重要影响,尤其当腐蚀角度和深度较大时,在腐蚀形成初期就会造成管道的承载力急剧下降,并且管道的屈曲压力与缺陷的径向位置有关,腐蚀缺陷位于管道外侧时的屈曲压力明显大于其位于管道内侧时的屈曲压力。 相似文献
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环肋圆柱壳体在水下冲击波作用下的动力弹塑性屈曲 总被引：1，自引：0，他引：1
本文以加肋圆柱壳体为对象建立力学模型，在水下爆炸产生的冲击波作用下，考虑流体与结构的耦合效应，研究加肋圆柱壳体的弹塑性失稳变形量及动力响应特性。数值分析显示出的最终变形形状和压力变化过程与实验资料一致的 相似文献
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基于振动的水下环肋圆柱壳临界载荷的预报具有结构无损的优势。以Flügge壳体理论和基于正交各向异性理论的环肋圆柱壳自由振动方程为基础,运用波传播法得出耦合系统的频率方程,并求出对应外压下的固有频率,通过最小二乘法线性拟合获得临界载荷、外压及固有频率的关系表达式。绘图得知任意边界的同一模态下,水下环肋圆柱壳的固有频率平方与静水压力成正比。结构失稳时,刚度丧失,固有频率降为零,据此求出水下环肋圆柱壳的最小弹性临界载荷。分析了不同边界条件对环肋圆柱壳临界载荷的影响,得知边界约束越强,环肋圆柱壳的临界载荷越大。结果对比表明了本方法的正确性,为水下环肋圆柱壳的固有频率及临界载荷的理论计算提供了一种新的方法。 相似文献
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- The dynamic buckling of elasto-plastic cylindrical shells under axial fluid-solid impact is investigated theoretically. A simplified liquid- gas- structure model is given to approximately imitate the problem. The basic equation of the structure is derived from a minimum principle in dynamics of elasto-plastic continua at finite deformation, and the flow theory of plasticity is employed. The liquid is incompressible and the gas is compressed adiabatically. A number of numerical results are presented and the characteristics of the buckling behavior under fluid-solid impact are illustrated. 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 paper presents a non-linear buckling analysis of ring stiffened cylindrical shells subject to external pressure. The collapse pressure is calculated by assuming failure to occur when the material reaches a plastic stress state defined by the Ilyushin criterion. It is shown in the paper that use of the non-linear theory can reduce the estimated first yield by up to 25% in comparison to the linear buckling analysis used up to now. Comparison of predicted failure loads are in good agreement with the lower bound of test results. 相似文献
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Wu Lianyuan Hu Gangyi Professor Shanghai Jiaotong University Shanghai Engineer Wuhan Ship Development & Design Institute Wuhan 《中国海洋工程》1994,(2)
-This paper adopts approximate formulas for residual stresses caused by cold bending for plates with stress-strain curve form a = K n. A typical distribution of the longitudinal residual stress due to welding is also assumed. The effects of residual stress due to cold bending and welding on plastic buckling of axially compressed cylindrical shells are studied by the finite element method. 相似文献
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Carl T. F. Ross Andrew P. F. Little Leonidas Chasapides Jeff Banks Daniele Attanasio 《Ocean Engineering》2004,31(2):239-252
The paper reports on the buckling of three ring-stiffened prolate domes under external hydrostatic pressure. The study was partly theoretical and partly experimental, where in the case of the latter, the finite element was used. Comparison between experiment and theory was good. The effect of ring stiffening the domes was to increase their buckling resistances by factors varying from 4.43 to 5.72. 相似文献
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Results of a numerical and experimental study into buckling performance of multi-segment pressure hull subjected to uniform hydrostatic pressure are discussed. Constituents of multi-segment configurations are bowed-out cylindrical shells with, and without flanges. Details about five collapse tests of laboratory scale mild steel, CNC machined models are given. Segments were about 200 mm diameter, 100 mm long and had uniform wall thickness of 3 mm. Experimental collapse pressures were in the range from 12 to 20 MPa. Numerical collapse pressures agreed well with those obtained during experiments. 相似文献
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The paper describes experimental tests carried out on three ring-stiffened cones that were tested to destruction under external hydrostatic pressure. The cones were carefully machined from EN1A Steel. All three cones failed by plastic non-symmetric bifurcation buckling in a mode commonly known as general instability. In this mode the entire ring-shell combination buckles bodily.The paper also provides a design chart using the results obtained from these three vessels, together with the results of six other vessels obtained from other tests. The design chart allows the possibility of obtaining a plastic knock down factor, so that the theoretical buckling pressures, based on elastic theory, can be divided by the plastic knockdown factor, to give the predicted buckling pressure. This method can also be used for the design of full-scale vessels. 相似文献
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为提高耐压柱壳设计效率,设计了耐压柱壳参数化分析流程。研究了有限元分析所涉及的材料属性、载荷施加、边界条件设置等内容,确定了采用弧长法分析耐压柱壳稳定性。利用Python语言对于ABAQUS软件进行了二次开发,利用Isight软件实现了ABAQUS的集成,实现了耐压柱壳有限元分析模型的网格自动划分、自动分析计算等。选择样本点进行参数化分析,利用响应面模型对于样本点进行了拟合,得到了具有较高拟合精度、满足工程需要的近似模型,进行了设计变量的灵敏度分析。研究结果表明:参数化分析流程可实现耐压柱壳的自动分析、近似模型及灵敏度分析,可降低耐压柱壳分析难度,均可提高耐压柱壳设计效率。 相似文献