Papers by Author: Qing Yuan Meng

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Authors: Wei Zhao, Qing Yuan Meng
Abstract: The adsorption of methane (CH4) molecule on the pristine and Al-doped (4, 8) graphene was investigated via the first-principles calculations. The results demonstrated that, in comparison to the adsorption of a CH4 molecule on the pristine graphene sheet, a relatively stronger adsorption was observed between the CH4 molecule and Al-doped graphene with a shorter adsorption distance, larger binding energy and more charge-transfer from the graphene surface to the CH4 molecule. Therefore, the Al-doped graphene can be expected to be a novel sensor for the detection of CH4 molecules in future applications.
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Authors: Zhi Fu Yang, Qing Yuan Meng, Kang You Zhong
Abstract: The oil well structure is comprised of stratum, concrete sheath and the steel casing. In petroleum engineering, the liquid concrete is usually poured into the annular gap between the well bore and the steel casing to form a concrete sheath. During the solidification process of the concrete, its volume and mechanical parameters may vary with time and the chemical solidification stresses will therefore be generated. At the same time, the concrete sheath is under the loading of the ground stresses and the hydraulic pressure of the drilling fluid in the casing. Nowadays, most of the researchers calculate the stresses distribution of the oil well concrete sheath based on the external loading only and the solidification process is ignored. In this work, an interference fitting algorithm in consideration of the concrete solidification process is proposed and the external loads such as ground stresses and drilling fluid hydraulic pressure in the steel casing are also considered. The calculated results show that the stresses of the concrete sheath are mainly dependent upon the hydraulic pressure of the liquid concrete and the chemical solidification stresses, rather than the external loads. In addition, an experimental facility used to simulate the oil well structure under the ground stresses is designed in this work, and the results of the experiment verified the conclusion mentioned above.
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Authors: Qing Yuan Meng, Yu Fei Gao, Xian Qin
Abstract: Carbon nanotubes (CNTs) is a well thermal transport nano materials, however, the thermal conductivity of CNTs has not been well established, only a few groups had reported experimental data and the existed simulation results ranged widely. Specially, the conclusions in low temperature section and dynamic structures were not very clearly. In this paper, the methods based on phonon scattering theory were applied to explore the thermal transport properties CNTs. The investigation was carried out under the conditions of temperature and axial strain. In the consideration of quantum effect, the thermal conductivity increased linearly with the growth of temperature in low-temperature section, and began to decrease gradually when the temperature exceeded a definite value. If an axial strain was concerned, there was an increasing trend of thermal conductivity as the stretch strain increases. However, after the strain exceeded a particular value the thermal conductivity decreased significantly. In addition, the high frequency phonon peak in PDOS was found to be an important parameter in describing thermal transport properties of dynamic structures.
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Authors: Jian Guang Liu, Zhong Jin Wang, Qing Yuan Meng, Yu Long Zheng
Abstract: Viscous pressure forming (VPF) uses a highly viscous but flowable material as pressure-carrying medium (PCM). Due to the relative low flowability of viscous medium compared with fluid, nonuniform pressure distribution in viscous medium can be used to control and regulate the deformation sequence of the workpiece through controlling the loading mode of viscous medium. In the present study, viscous pressure bulge (VPB) tests with three kinds of loading location of viscous medium (central zone, corner zone and the whole deformation zone) are conducted and the influences of loading location of viscous medium on sheet deformation behavior are investigated via numerical simulations and experiments. It is found that changing the loading location of viscous medium can greatly affect the deformation behavior of sheet metal. When the viscous medium is injected from the die corner zone, a local high pressure formed at the corner zone of sheet metal and a higher limiting dome height and strains are obtained.
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Authors: Ai Bin Li, Qing Yuan Meng, Lin Geng, Guo Jian Cao, Wen Bin You, Yi Wu Yan
Abstract: The effect of temperature on strain softening behavior of composites with small misaligned whiskers is investigated. The results show that the temperature affects the matrix and whisker mechanical behavior and corresponding composite deformation behavior. With increasing temperature, the whisker rotation angle increases, but their breakage decreases. Meanwhile elevating temperature not only reduces the matrix flow stress and work hardening rate, but also decreases load transfer from the matrix to the whiskers and stress induced by the whisker rotation and breakage.It is found that during hot compression, strain softening behavior of composites decreases as temperature increases.
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Authors: Kang You Zhong, Qing Yuan Meng, Zhi Fu Yang
Abstract: The interaction of the shuffle 60° dislocation with a regular chain of hexavacancies was investigated via the molecular dynamics simulation with Stillinger-Weber potential. The results show that an attraction exists between the shuffle 60° dislocation and hexavacany. The attraction energy is dependent obviously upon the hexavacancy concentration. The dislocation can overcome the pinning of vacancies under a critical resolved shear stress, and a linear relationship is found between the critical stress and hexavacancy concentration.
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