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Atomistic study of anisotropic effect on two-dimensional dynamic crack

Frontiers of Materials Science 2012年第1期6卷 87-96页

作者： Guo-Wu REN Tie-Gang TANG Qin-Zhong LI Institute of Fluid Physics Chinese Academy of Engineering PhysicsMianyang 621900China

We adopt molecular dynamics （MD） method to extensively study the dynamical process during the crack propagation along two crystallographic directions in the two-dimensional close-packed system. The dependence of crack initiation time on the loading rates is investigated in comparison with continuum analysis. By calculating the displacement and stress field, the results are in excellent agreement with the asymptotic continuum solution of low-speed propagating crack. Moreover, the crack-tip velocity is numerically attained and associated with the instability of crack surface morphology, which results from the strongly anisotropic behavior. Further analysis remarkably observes the crack-branching healing process in that the dislocation emission absorbs the concentrated strain energy of crack tip.

关键词： crack anisotropic effect molecular dynamics (MD)

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Propagation of Airy Gaussian vortex beams in uniaxial crystals

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Chinese Physics B 2016年第4期25卷 121-126页

作者：余伟浩赵瑞璜邓富黄加耀陈迟到杨湘波赵燕平邓冬梅 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices South China Normal University CAS Key Laboratory of Geospace Environment University of Science and Technology of ChinaChinese Academy of Sciences (CAS)

The propagation dynamics of the Airy Gaussian vortex beams in uniaxial crystals orthogonal to the optical axis has been investigated analytically and numerically. The propagation expression of the beams has been obtained. The propagation features of the Airy Gaussian vortex beams are shown with changes of the distribution factor and the ratio of the extraordinary refractive index to the ordinary refractive index. The correlations between the ratio and the maximum intensity value during the propagation, and its appearing distance have been investigated.

关键词： Airy Gaussian vortex beams uniaxial crystals anisotropic effect

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Propagation of an Airy–Gaussian beam in uniaxial crystals

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Chinese Physics B 2015年第12期24卷 309-312页

作者：周美玲陈迟到陈波彭喜彭玉莲邓冬梅 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices South China Normal University CAS Key Laboratory of Geospace Environment University of Science&Technology of ChinaChinese Academy of Sciences(CAS)

Under the paraxial approximation, the analytical propagation expression of an Airy–Gaussian beam（Ai GB） in uniaxial crystals orthogonal to the optical axis is investigated. The propagation dynamics of the Ai GB is given for different ratios of the extraordinary index to the ordinary refractive index. It has been found that the continuity and the self-bending effect of Ai GB become weaker when the ratio increases. From the figure of the maximum intensity of Ai GB, one can see that the maximum intensity is not monotone decreasing due to the anisotropic effect of the crystals. The intensity distribution of Ai GB in different distribution factors is shown. The Ai GB converges toward a Gaussian beam as the distribution factor increases.

关键词： Airy–Gaussian beam extraordinary and ordinary refractive index anisotropic effect

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Property comparison of polarons in zinc-blende and wurtzite GaN/AlN quantum wells

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Journal of Semiconductors 2011年第11期32卷 9-13页

作者：朱俊班士良哈斯花 School of Physical Science and Technology Inner Mongolia University Department of Physics College of SciencesInner Mongolia University of Technology

The properties ofpolarons in zinc-blende and wurtzite GaN/AIN quantum wells with Frohlich interaction Hamiltonians are compared in detail. The energy shifts of polarons at ground state due to the interface （IF）, confined （CO） and half-space phonon modes are calculated by a finite-difference computation combined with a modified LLP variational method. It is found that the two Frohlich interaction Hamiltonians are consistent with each other when the anisotropic effect from the z-direction and the x-y plane is neglected. The influence of the anisotropy on the polaron energy shifts due to the IF phonon modes for a smaller well width or due to the CO phonon modes for a moderate well width is obvious. In addition, the built-in electric field has a remarkable effect on the polaron energy shifts contributed by the various phonon modes.

关键词： polaron quantum well anisotropic effect

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Finite element analysis of stress concentrations and failure criteria in composite plates with circular holes

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Frontiers of Mechanical Engineering 2014年第3期9卷 281-294页

作者： Abdelhak KHECHAI Abdelhamid GUETTALA Abdelouahab TATI Laboratory of Civil Engineering University of Biskra Biskra 07000Algeria Laboratory of Energy Engineering and Materials University of BiskraBiskra 07000 Algeria

In this study, the （SCF） in cross-and-angle-ply stress concentration factors laminated composite plates as well as in isotropic plates with single circular holes subjected to uniaxial loading is studied. A quadrilateral finite element of four-node with 32 degrees of freedom at each node, previously developed for the bending and mechanical buckling of laminated composite plates, is used to evaluate the stress distribution in laminated composite plates with central circular holes. Based up on the classical plate theory, the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element. The numerical results obtained by the present element compare favorably with those obtained by the analytic approaches published in literature. It is observed that the obtained results are very close to the reference results, which demonstrates the accuracy of the present element. Additionally, to determine the first ply failure （FPF） of laminated plate, several failure criterions are employed. Finally, to show the effect of E1/E2 ratio on the failure of plates, a number of figures are given for different fiber orientation angles.

关键词： laminated composite plates stress concentration geometric singularity anisotropic effect

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