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针对近海结构单桩基础在动力荷载作用下发生复杂的水-桩-土相互作用问题,建立了三维水-桩-土全耦合动力有限元分析模型。土体、桩和水体分别采用实体单元和声学单元模拟,土体截断边界采用滚轴边界条件、水体截断边界采用无反射吸收边界条件,并确定了合理的截断边界位置;以全耦合分析模型计算结果为参考解,系统研究了四种动荷载作用下水-桩不耦合(两者界面自由)和水-土不耦合(两者界面自由)对桩体和海床表面位移和动水压力响应的影响,揭示了不同水深和桩体半径变化下不考虑两种相互作用的影响规律。 相似文献
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针对水-柱体动力相互作用问题,提出一种用于模拟无限域水体的圆柱形高精度时域人工边界条件。首先,基于三维可压缩水体的波动方程和边界条件,采用分离变量法建立了时空全局的精确人工边界条件;然后,将其动力刚度表示为外域模型和波导模型人工边界条件动力刚度的嵌套形式;之后,应用时间局部化方法得到时间局部的高精度人工边界条件;最后,离散高精度人工边界条件,并将其与近场有限元方程耦合,形成一种能够采用显式时间积分方法求解的时间二阶常微分方程组。数值算例表明:提出的三维圆柱形高精度人工边界条件精确、高效、稳定。 相似文献
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建立了一种可以同时考虑流-固耦合与桩-土-结构相互作用的渡槽结构水平地震响应的有限元计算模型,该模型通过等效线性化方法考虑土体非线性,以自由场计算结果为依据,确定黏-弹性人工边界的参数及进行相应的地震动输入。建立了渡槽结构拟动力试验模型的整体有限元计算模型,进行了试验地震波作用下的有限元仿真计算,并与拟动力试验结果进行了比较,计算结果与试验结果基本一致,说明了文中建立的有限元计算模型的有效性。同时,拟动力试验及有限元计算结果表明,水体对渡槽结构地震响应有一定影响,有水工况时,结构的基频降低,可能较无水工况与输入地震波能量主频段偏离更远,从而起到一定的减震作用。 相似文献
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在坝-库水动力流固耦合分析中,比例边界有限元方法(SBFEM)仅需对流固交界面进行离散,就可以模拟半无限域库水,节省了节点自由度个数,具有较高效率。但采用数值方法处理动水压力时得到的附加质量阵为满阵,进行大规模的面板坝弹塑性动力分析时用于求解方程的时间较多。该文根据动水压力附加质量阵的物理意义与分布特点,提出了一种基于FEM-SBFEM的坝与库水的动力耦合简化计算方法,仅需提供一个保留系数β(0 ≤ β ≤ 1.0)即可实现不同程度的动水压力附加质量阵化简,简单易行;将其应用在面板坝与库水的动力弹塑性耦合计算中,建议了β的取值范围,在保证具有良好精度的前提下大幅提高了计算效率。 相似文献
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土,结构相互作用问题的边界元,有限元耦合法 总被引:3,自引:0,他引:3
本文简要介绍了土、结构相互作用边界元、有限元耦合法的发展;着重对近年来应用边界元、有限元耦合法解动力相互作用问题的代表性的研究工作做了介绍,对边界元、有限元耦合法的几个问题的进展进行了综合评述,最后提出了作者对几个问题的见解。 相似文献
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将人工边界设置在半无穷层单元和内部有限元区域的交界面上,建立了半无穷层单元的刚度矩阵后,得到了边界节点的动力平衡方程。任意给定激励圆频率,将边界节点系统的动力平衡方程转化为特征值方程。求解特征值方程得出边界节点系统的特征值和特征模态,利用模态叠加原理得到体现左半无穷层单元和右半无穷层单元对内部有限元区域作用的边界矩阵,这就是该文的一致边界。将其与内部有限元区域的刚度矩阵进行组装来模拟无穷远域介质对波的传播作用。最后用数值算例来说明一致边界的精确性和可行性。 相似文献
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利用有限元与边界元耦合法对三维无界区域中直立圆柱所受的波浪力进行进行计算,把整个求解区域分成内域或外域两部分,在内域采用有限元法,对外域采用边界元法,数值计算的结果与理论解吻合良好,表明该方法有效。 相似文献
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A coupling extended multiscale finite element method for dynamic analysis of heterogeneous saturated porous media
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Hui Li Hongwu Zhang Yonggang Zheng 《International journal for numerical methods in engineering》2015,104(1):18-47
A coupling extended multiscale finite element method (CEMsFEM) is developed for the dynamic analysis of heterogeneous saturated porous media. The coupling numerical base functions are constructed by a unified method with an equivalent stiffness matrix. To improve the computational accuracy, an additional coupling term that could reflect the interaction of the deformations among different directions is introduced into the numerical base functions. In addition, a kind of multi‐node coarse element is adopted to describe the complex high‐order deformation on the boundary of the coarse element for the two‐dimensional dynamic problem. The coarse element tests show that the coupling numerical base functions could not only take account of the interaction of the solid skeleton and the pore fluid but also consider the effect of the inertial force in the dynamic problems. On the other hand, based on the static balance condition of the coarse element, an improved downscaling technique is proposed to directly obtain the satisfying microscopic solutions in the CEMsFEM. Both one‐dimensional and two‐dimensional numerical examples of the heterogeneous saturated porous media are carried out, and the results verify the validity and the efficiency of the CEMsFEM by comparing with the conventional finite element method. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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M. Cemal Genes 《Engineering Analysis with Boundary Elements》2012,36(5):845-857
An algorithm for a parallelized coupled model based on finite element method (FEM), boundary element method (BEM), and scaled boundary FEM (SBFEM) for harmonic and transient dynamic response of large-scale 2D structures embedded in or on layered soil media is presented. The BEM and SBFEM are used for modelling the dynamic response of the unbounded media. The standard FEM is used for modelling the finite region and the embedded structure. The objective of the development of this parallelized coupled model is to use the power of high performance computing, and to take into account the advantages and evade the disadvantages of the above mentioned numerical methods for modelling of the unbounded media in soil-structure interaction (SSI) systems. The development of the parallel algorithm for this model is essential for solving arbitrarily shaped large-scale SSI problems, which cannot be solved within reasonable elapsed times by a serial algorithm. The efficiency of the proposed parallel algorithm and the validity of the coupled model are shown by means of three numerical examples, indicating the excellent accuracy and applicability of the parallel algorithm with considerable time-savings in large-scale problems. 相似文献
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根据线性势波理论,分析了水中截断圆柱体作水平简谐运动时结构周围的辐射波浪。利用分离变量法,分别得到了含有未知常数的三个流体子域速度势的简谐表达形式,并采用一个较为简单的匹配方法使其在流体子域的共同边界上满足压力和法向速度的连续条件。于是求解得到了速度势,进而可得到由等效附加质量和附加阻尼表示的柱体侧面上的动水力。不仅能考虑自由表面波对动水压力的影响,也适用于位于任意水深处的截断圆柱体。实例分析表明,该方法具有较高的计算精度;同时对于截断圆柱体,采用Morison方程中的动水附加惯性力项会高估柱体侧面上的动水力。 相似文献
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Y. K. XUE D. T. GETHIN C. H. LIM 《International journal for numerical methods in engineering》1996,39(15):2531-2554
This paper presents a numerical routine to compute the contact characteristics of elastomer layered cylinders lubricated by isoviscous liquids. The indentation of the elastic layer is calculated from boundary integral equations which are solved by linear and quadratic boundary element methods for a finite plane model and a circular representation of the junction. The hydrodynamic equation is also transformed into a boundary integral equation and solved by Simpson's rule. Some factors which possibly affect numerical accuracy are examined. Examples for finite plane and circular layer are analysed with reference to parameters for printing press roller contact, in which results are obtained for the indentation, film thickness and liquid pressure, as well as internal stresses through the simultaneous solution of the elasticity and hydrodynamic equations. The results show that high precision is easily achieved and the method is efficient for such layered problems. 相似文献