Seepage Analysis Using the Composite Element Method

Author(s):  
Sheng-hong Chen
2013 ◽  
Vol 838-841 ◽  
pp. 1693-1697
Author(s):  
Gui Sheng Xu ◽  
Jian Qiang Guo

For seepage analysis using Composite Element Method(CEM), the drainage holes are treated as “air sub-elements” with high permeability contained in the conventional rock(soil) element, which is called “composite element”. To ensure the validity and correctness of the calculated results, the “permeability coefficient” of drainage holes and transmissibility coefficient of the interface between rock(soil) and drainage holes are studied and some reasonable suggestions are given. To improve the calculation precision and efficiency of CEM, the p-version adaptive method is studied and the corresponding algorithm of upgrade the hierarchical order and accelerating convergence are implemented in the CEM.


2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Ling Huang ◽  
Zhongrong Lv ◽  
Weihuan Chen ◽  
Jike Liu

An approach based on homotopy iteration algorithm is proposed to identify the crack parameters in beam structures. In the forward problem, a fully open crack model with the composite element method is employed for the vibration analysis. The dynamic responses of the cracked beam in time domain are obtained from the Newmark direct integration method. In the inverse analysis, an identification approach based on homotopy iteration algorithm is studied to identify the location and the depth of a cracked beam. The identification equation is derived by minimizing the error between the calculated acceleration response and the simulated measured one. Newton iterative method with the homotopy equation is employed to track the correct path and improve the convergence of the crack parameters. Two numerical examples are conducted to illustrate the correctness and efficiency of the proposed method. And the effects of the influencing parameters, such as measurement time duration, measurement points, division of the homotopy parameter and measurement noise, are studied.


2011 ◽  
Vol 199-200 ◽  
pp. 835-838
Author(s):  
Xu Bin Lu ◽  
Zhong Rong Lv ◽  
Ji Ke Liu

The composite element method is utilized to discretise a stepped Euler-Bernoulli beam with a crack. The local stiffness reduction due to the crack is introduced by using a simplified crack model. The finite element equation for the forced vibration analysis is obtained using the composite element method (CEM). The forced vibration response of the cracked stepped beam is numerically calculated using Newmark integration method. Numerical results indicate that the position and depth of a crack affects the low and high natural frequencies and modes of a cantilever beam, respectively. And the position of the crack has significant effects on the dynamic responses of the beam.


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