共查询到19条相似文献,搜索用时 125 毫秒
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针对在设计地震动基础上构建平面半空间自由场的问题,在综合考虑水平向与竖直向设计地震动基础上获得平面半空间自由场,实现了将设计地震动与以任意角度组合入射的P波、SV波构成的自由场相联系。首先在已有成果的基础上,研究了以任意角度入射情况下P波及其反射波、SV波及其反射波对水平向和竖直向设计地震动的贡献;然后在假设入射P波、SV波与两向设计地震动具有相同频率组成的基础上,获得了以特定角度组合入射条件下P波、SV波的频谱和相位信息;进而通过傅里叶逆变换获得入射P波、SV波的时间序列;最后依据P波、SV波及其反射波在平面半空间的传播情况获得自由场条件下平面半空间内任意点的水平向和竖直向地震动。该文所采用的波场构建方法可实现对包含任意频谱和相位信息的两向设计地震动所对应的平面半空间自由场的构建,所获得的斜入射P波和SV波也具有各自的频谱和相位信息。最终得到的平面半空间自由场任意点水平向和竖直向地震动时间序列具有非一致性;根据入射P波、SV波结合地基边界条件确定的空间点地震动时间序列可用于结构的非一致地震动输入。 相似文献
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《工程力学》2004,(6)
第一期目录平面与空间钢框架结构的简化柱梁模型 .................................... 邵永松,刘洪波,谢礼立,张耀春 (001)板壳非线性分析的新理论新方法 .................................................................. 秦 荣 (009)位于弹性半空间上的理想流体层动力反应——平面 SV 波入射 ........................ 王进廷,张楚汉,金 峰 (015)一种改进的基于频率测量的结构损伤识别方法 .............................................. 谢 峻,韩大建 (021)方形断面高层建筑的气动阻尼研究 ...................................… 相似文献
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地震波斜入射下水下地基场地地震动输入问题,是涉及水层、饱和多孔介质和基岩三种不同性质介质耦合的复杂问题,目前理论成果还很匮乏。该文在现有的成层饱和多孔介质平面波斜入射的一维化时域方法的基础上,建立了水下地基场地的一维化时域计算方法。该计算方法依据Snell定理,将地震波斜入射下水层波动的空间二维问题转化为简单的一维问题,通过考虑水层与饱和多孔介质层交界面、不同饱和多孔介质交界面以及基岩与饱和多孔介质层交界面的边界条件,将已有的成层饱和土的一维化有限元方程与水层的一维化有限元方程组装,采用单相弹性介质精确人工边界条件模拟基岩半空间的波动辐射和输入特征,形成了水下地基场地的整体有限元方程,借助于中心差分法和Newmark法相结合的时步积分法,推导了地震波斜入射下水下地基场地各节点动力响应时程的显式表达式。通过与傅里叶变换得到的理论解和现有的文献进行了对比,初步验证了该文时域算法的有效性和精度,为地震波斜入射下水下地基场地地震动输入提供了一种新型高效的研究方法。 相似文献
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非连续弹性圆柱实心桩屏障对弹性波的隔离 总被引:9,自引:0,他引:9
采用波函数展开法和Graf加法定理,根据桩土界面处位移和应力连续的边界条件,得到了非连续弹性圆柱实心桩屏障对入射平面P波和SH波散射系数的理论解,通过引入无量纲位移,即屏障后某处土体内由入射波和散射波引起的总的纵向位移和水平位移与未设屏障时由入射平面P波和SH波在该处土体内单独引起的位移幅值的比值,根据求得的散射系数的理论解,绘制了平面P波和SH波单独入射情况下,弹性圆柱实心桩屏障后不同位置的无量纲位移、不同剪切模量的弹性圆柱实心桩屏障后的无量纲位移等值线和透射系数随桩间距的变化曲线,通过研究这些图件进而分析了屏障后不同位置、剪切模量、桩间距和入射频率对非连续弹性圆柱实心桩屏障的隔离效果的影响,为非连续弹性屏障的隔振设计提供了理论依据. 相似文献
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在作者给出层状饱和场地三维精确动力刚度矩阵和层状饱和半空间中移动荷载动力格林函数基础上,采用间接边界元方法在频域内求解了层状流体饱和场地中沉积谷地对斜入射平面P1波的三维散射问题。该方法的特点在于虚拟移动均布荷载和斜线孔隙水压可以直接施加在沉积与层状饱和半空间交界面而不存在奇异性。该文通过与已有结果的比较验证了方法的正确性,并以均匀饱和半空间和弹性基岩上单一饱和土层中沉积谷地为例进行了数值计算分析。研究表明,沉积谷地对平面P1波的三维散射与二维散射之间存在本质差别,入射角度、孔隙率、饱和土层刚度和饱和土层厚度等参数对沉积谷地附近动力响应有着显著影响。 相似文献
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《振动工程学报》2019,(6)
基于势流理论及Biot多孔介质模型,分析了海水-饱和海床-弹性基岩体系在平面P-SV波入射情形下的动态响应。根据理想流体、饱和海床及弹性基岩之间的界面连续条件,运用Thomson-Haskell传递矩阵方法可得出饱和海床及其上覆海水层的稳态响应,并得到瞬态响应。通过算例验证了该方法的可行性以及所编程序的正确性。进一步分析了入射角度、海水层厚度对自由场响应的影响。结果表明,P-SV波入射时,入射角度和海水层对饱和土表面的响应具有较大影响,在确定海底地震动设计中不可忽视。对于地震波入射时,复杂海底地形的地震反应,以及海水-海床-结构相互作用分析,该方法可为其提供自由场输入。 相似文献
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基于复变函数理论和保角映射方法,采用波函数展开法及多级坐标变换技术,解析求解了半无限空间中空沟对平面SH波和平面P波的隔振问题。首先,通过设虚源法和大圆弧假定法分别给出了平面SH波和平面P波入射半无限空间时的散射场。然后由空沟边界及大圆弧边界处的应力自由边界条件建立无穷阶线性方程组,并通过对该方程组的求解给出了空沟对平面SH波和平面P波散射的解析解答。最后,参数分析了激励频率、空沟深度等因素对隔振效果的影响规律。结果表明,空沟对平面SH波和平面P波的隔振效果随着入射波频率的增大而增大,随着空沟深度增大而增大。 相似文献
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流固耦合问题的描述方法及分类简化准则 总被引:4,自引:0,他引:4
在流固耦合的工程实际问题中的大多数情况下,弹性薄壁构件的变形为几何非线性,再加上流体方程的非线性,将导致流体和弹性体相互作用界面上的强非线性。在界面上便可以结合拉格朗日法和欧拉法建立方程和接触条件。其方法主要有单一拉格朗日法、单一欧拉法、相容拉格朗日-欧拉法和任意拉格朗日-欧拉法四种方法。引入描述弹性体变形特征的数值m、n、k和描述流体运动特征的数值λ、ν,可将流固耦合问题进行分类。在流体弹性力学理论的基础上,介绍了流固耦合问题界面相互作用的描述方法,并根据诺沃日洛夫BB(НовожиловВВ)在非线性弹性力学中,从几何非线性方面对弹性力学问题的分类方法出发,对流体弹性力学中的流固耦合问题进行分类,由此,可为按类别对运动学条件、动力学条件及界面上的接触条件进行相应的简化提供可靠的依据。 相似文献
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V. S. Ahn J. D. Achenbach Z. L. Li J. O. Kim 《Research in Nondestructive Evaluation》1991,3(4):183-200
A numerical model is presented to calculate V(z) curves for a line-focus acoustic microscope and the specimen configuration of a thin isotropic elastic layer deposited on an isotropic elastic substrate. In this model, a Gaussian beam which is tracked through the lens into the coupling fluid, interacts with the thin-layer/substrate system. The numerical approach is based on the solution of singular integral equations by the boundary element method. The system of singular integral equations follows from the conditions at the interface of the coupling fluid and the thin layer and the interface of the thin layer and the substrate. An electrochemical reciprocity relation is used to express the voltage at the terminals of the microscope's transducer in terms of the calculated incident and back-scattered fields. V(z) curves are presented for various layer thicknesses and various combinations of the elastic constants of the layer and the substrate. The oscillations of the V(z) curves are related to the modes of wave propagation in a thin layer in contact with a solid half-space on one side and a fluid half-space on the other side. Calculated V(z) curves have also been compared with experimentally obtained curves, and good agreement is observed. 相似文献
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Effects of a fluid layer at a micropolar orthotropic elastic solid interface to a moving point load have been studied. After
using the Fourier transform an eigen value approach has been employed to solve the problem. The displacement, microrotation
and stress components for a micropolar orthotropic elastic solid so obtained in the physical domain are computed numerically
by applying the numerical inversion technique. Micropolarity and anisotropy effects along with that of the depth of the fluid
layer on various expressions have been depicted graphically for a particular model. Some special cases of interest have been
presented 相似文献
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A.J. Willson 《International Journal of Engineering Science》1978,16(7):459-473
The propagation of waves of small amplitude at the interface between an elastic half-space and a fluid half-space is investigated. The effects of an explosive line-source embedded in the elastic medium are studied, consideration being given to both dilatational and distortional cases, and a similar investigation is made for a compressive line-source in the fluid. The exact solutions for the displacement field are obtained. It is shown that for fluids of relatively low density, the interfacial waves are of two kinds. The relative efficiencies of the three sources for the launching of these waves are shown explicitly. 相似文献
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预应力钢-混凝土组合梁作为一种新型的横向承重构件,在工程中得到了广泛的使用,准确计算其抗弯承载能力是工程上最为基本也是最重要的要求。该文以弹性分析理论为基础,推导了考虑交界面相对滑移和预应力增量的预应力组合梁弹性承载能力和挠度计算公式;以完全协同作用和平截面假定为前提,采用简化的塑性理论,推导了考虑预应力增量的极限抗弯承载能力计算公式。公式能够反映预应力组合梁的受力特点,计算结果与试验值吻合良好,满足工程精度。 相似文献
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Thérèse Lévy 《International Journal of Engineering Science》1979,17(9):1005-1014
A theory is developed for the propagation of waves in a porous elastic solid containing a compressible viscous fluid using a homogenization process. The matrix is a lattice of periodically distributed gaps of arbitrary shape, the period of the lattice being small compared with the wave length. The present treatment is concerned with materials where fluid and solid are of comparable densities. Two cases are considered: the situation in which the pores are connected and that in which they are not. When pores are closed, the bulk medium behaves like an elastic medium; when they are connected, the fluid filtration and the bulk deformation are coupled. Boundary conditions, for macroscopic variables, at the interface between such a porous medium and the adjacent free flow are given. 相似文献
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D. Pino Muñoz J. Bruchon S. Drapier F. Valdivieso 《International journal for numerical methods in engineering》2013,93(9):919-941
A numerical method for simulating fluid–elastic solid interaction with surface tension is presented. A level set method is used to capture the interface between the solid bodies and the incompressible surrounding fluid, within an Eulerian approach. The mixed velocity–pressure variational formulation is established for the global coupled mechanical problem and discretized using a continuous linear approximation in both velocity and pressure. Three ways are investigated to reduce the spurious oscillations of the pressure that appear at the fluid–solid interface. First, two stabilized finite element methods are used: the MINI‐element and the algebraic subgrid method. Second, the surface integral corresponding to the surface tension term is treated either by the continuum surface force technique or by a surface local reconstruction algorithm. Finally, besides the direct evaluation method proposed by Bruchon et al., an alternative method is proposed to avoid the explicit computation of the surface curvature, which may be a source of difficulty. These different issues are addressed through various numerical examples, such as the two incompressible fluid flow, the elastic inclusion embedded into a Newtonian fluid, or the study of a granular packing. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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S. Santhanam 《International Journal of Fracture》1993,60(1):65-77
Disking is a process designed to cut brittle plates and rods. In axisymmetric disking, a pre-cracked cylindrical rod is placed in an elastic, annular sheath and the composite is subjected to biaxial fluid pressure. At a critical pressure the crack runs across the circular section of the rod producing a clean cut. A linear elastic fracture mechanics analysis is used to develop a fracture criterion for the process. A concentric circular cylinders model is assumed with perfect bonding at the interface. The flaw that initiates fracture in the rod is modeled as an annular crack perpendicular to the interface with one crack tip at the interface. The problem is formulated as a singular integral equation of the first kind with a Cauchy type kernel. The stress intensity factors are determined as a function of crack size and shear moduli. 相似文献