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1.
流体饱和多孔介质中波传播问题的有限元分析   总被引:4,自引:1,他引:3  
采用基于混合物理论的多孔介质模型,给出流体饱和两相多孔介质波动问题的有限元分析方法· 采用罚方法导出的有限元动力方程,时间积分可采用显式和隐式积分两种方案· 用编制的有限元程序分析了一维柱体在跃阶载荷和脉冲载荷作用下的波传播问题,得到该两种瞬态载荷作用下固体和流体相位移、速度以及固体相有效应力和孔隙压力随时间的变化关系,并对波的传播现象进行了分析· 所得结果与理论相吻合·  相似文献
2.
饱和土中球面波的传播   总被引:3,自引:0,他引:3  
本文采用工程上通用的土力学模型,利用Laplace变换求解了饱和土中球面波的传播问题,对一种特殊情形下的均匀受压球形空腔得到了解析解,并与弹性单相介质中均匀受压球形空腔进行了对比,以考察流体对饱和土体动力响应的影响·本文为分析地下结构动力响应提供了一种有效的方法,有重要的工程应用价值  相似文献
3.
电磁波在三相土介质中的传播   总被引:1,自引:0,他引:1  
研究电磁波(EM波)在土中的传播特性,必须获得如介电常数和磁导率等基本电磁参数.在麦克斯韦方程组的基础上,提出了等效模型来计算土体介电常数.利用该模型的计算结果与实测数据符号很好,可以为利用电磁波法测量土体含水量,土体的CT分析以及土工环境监测奠定理论基础。  相似文献
4.
Numerical dispersion of two-dimensional finite elements was studied. The outcome of the dispersion study was verified by the numerical and analytical solutions to the longitudinal impact of two long cylindrical bars. In accordance with the results of the dispersion analysis it was demonstrated that the quadratic elements showed better accuracy than the linear ones.  相似文献
5.
Here, we solve the time-dependent acoustic and elastic wave equations using the discontinuous Galerkin method for spatial discretization and the low-storage Runge-Kutta and Crank-Nicolson methods for time integration. The aim of the present paper is to study how to choose the order of polynomial basis functions for each element in the computational mesh to obtain a predetermined relative error. In this work, the formula 2p+1≈κhk, which connects the polynomial basis order p, mesh parameter h, wave number k, and free parameter κ, is studied. The aim is to obtain a simple selection method for the order of the basis functions so that a relatively constant error level of the solution can be achieved. The method is examined using numerical experiments. The results of the experiments indicate that this method is a promising approach for approximating the degree of the basis functions for an arbitrarily sized element. However, in certain model problems we show the failure of the proposed selection scheme. In such a case, the method provides an initial basis for a more general p-adaptive discontinuous Galerkin method.  相似文献
6.
Mindlin板条中弹性波传播问题的分析   总被引:1,自引:0,他引:1  
基于Mindlin弹性厚板理论,采用Hamilton状态空间求解方法,研究了板条横向两侧为自由边界条件下的弹性:波传播问题,给出了问题的分析解,以及各种振动模态和波传播模的存在性.采用本征函数展开法给出了条形板中导波模的频散方程,并与直接根据Mindlin提出的解获得的频散关系进行了比较,通过比较发现:在短波时,频散曲线相差较大,即前几阶低频模式有一定差别。根据Hamilton体系得到的截止频率高一些,长波时频散曲线几乎相同,即高频模式无差别。  相似文献
7.
The wave propagation at large distances from a source of disturbance (isolated harmonic electric charge or body force of fixed frequency) in an infinite piezoelectric medium belonging to classes (6), (6 m m) or ceramic (α m) and (6 2 2) is discussed by means of asymptotic evaluation (at large distances) of Fourier integrals. Numerical results are given for the (6 m m) crystal class using the constants of cadmium selenide crystal.  相似文献
8.
The wave propagation at large distances from a source of disturbance (isolated harmonic electric charge or body force of fixed frequency) in an infinite piezoelectric medium belonging to classes (6), (6 m m) or ceramic (α m) and (6 2 2) is discussed by means of asymptotic evaluation (at large distances) of Fourier integrals. Numerical results are given for the (6 m m) crystal class using the constants of cadmium selenide crystal.  相似文献
9.
The boundary element method (BEM) has been recognized by its unique feature of requiring neither internal cells nor their associated domain integrals in the computation. The method preserves its elegance for transient problems by means of a certain time-stepping scheme that initiates the time integration always from the initial time. Unfortunately, this time-marching scheme becomes rather difficult to apply, because the computation time and storage requirement grow dramatically with the increasing number of time steps. This paper shows that a reduction of one half of the computation time as well as the storage requirement can be achieved by an efficient truncation scheme for two-dimensional transient wave propagation problems. In particular, a guiding parameter for the determination of the truncation limit is proposed, and the overall measure of the error with respect to the truncation guide parameter is established.  相似文献
10.
The effect of liquid on the propagation of waves in a micropolar elastic layer with stretch has been investigated. The frequency and wave velocity equations for symmetric and antisymmetric vibrations are derived. Propagation of monochromatic waves in a micropolar elastic layer with stretch is discussed. Results of this analysis reduce to those without stretch.  相似文献
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