CMES-Vol. 93, No. 4, 2013

Open Access

ARTICLE

Sample Size Dependence of Crack-tip Microstructure and Stress Evolutions in Single Crystal Nickel
Wen-Ping Wu^1,2, Zong-Zhuan Yao³
CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.4, pp. 235-252, 2013, DOI:10.3970/cmes.2013.093.235
Abstract The internal microstructure evolution and atomic stress distribution around the crack tip of a pre-cracked single crystal nickel with unequal sample sizes are studied by molecular dynamics (MD) simulation. The simulated results indicate that the crack propagation dynamics and stress distributions around the crack tip are strongly dependent on the microstructure evolution caused by the change of sample size. Unequal sample sizes induce various atomic configurations around the crack tip during the crack propagation. When atomic configuration is invariable around the crack tip, the crack grows rapidly along the crack path, the stress concentration occurs… More >

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ARTICLE

Hyper-Singular Dual Reciprocity Formulation for Potential Problems
C. F. Loeffler¹, R. G. Peixoto²
CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.4, pp. 253-276, 2013, DOI:10.3970/cmes.2013.093.253
Abstract Here is presented a formal deduction for the Dual Reciprocity hypersingular boundary integral equation for application to two dimensional potential problems. The theoretical and numerical derivations are presented in detail, and some simple test problems are included to verify the accuracy of the proposed formulation. Due to its simplicity, Poisson’s Equation is used as a basis for the mathematical formulations and operational procedures related to the body force term, but the methodology can easily be extended to other more elaborate classes of potential problems. Poles are inserted internally to improve the interpolation within the domain, More >

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ARTICLE

Approximate Stationary Solution for Beam-Beam Interaction Models with Parametric Poisson White Noise
Xiaokui Yue¹, Yong Xu², Jianping Yuan¹
CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.4, pp. 277-291, 2013, DOI:10.3970/cmes.2013.093.277
Abstract In this paper, a stochastic averaging method is derived for a class of non-linear stochastic systems under parametrical Poisson white noise excitation, which may be used to model the beam-beam interaction models in particle accelerators. The averaged Generalized Fokker-Planck equation is derived and the approximate stationary solution of the averaged Generalized Fokker-Planck equation is solved by using perturbation method. The present method applied in this paper can reduce the dimensions of stochastic ODE from 2n to n, which simplify the complex stochastic ODE, and then the analytical stationary solutions can be obtained. An example is More >

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ARTICLE

A Benchmark Problem for Comparison of Vibration-Based Crack Identification Methods
Bing Li^1,2, Zhengjia He¹
CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.4, pp. 293-316, 2013, DOI:10.3970/cmes.2013.093.293
Abstract The vibration-based crack identification problem insists of finding a measured vibration parameter from a complete crack-detection-database constructed by numerical simulation. It is one of the classical optimization problems. Many intelligence methods, such as neural network (NN), genetic algorithm (GA), determinant transformation (DT), and frequency contour (FC) etc., have been extensively employed as optimization tools to achieve this task. The aim of this paper is to propose a benchmark problem to compare these extensive-used optimization methods in terms of crack identification precision and computational time. The merit and demerits for each method are discussed. The results More >

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