低维纳米结构材料的弹性性能研究进展

文章从实验研究、理论分析和数值模拟三个方面分别介绍了目前国内外关于低维纳米结构弹性性能尺寸效应的研究现状,总结了现有的一些研究方法和结论

美国研究生负责任研究行为(RCR)教育计划及启示

介绍了美国负责任研究行为(rCr)教育的发展、教学内容、教育资源及作为美国rCr教育体系的重要组成部分的研究生rCr教育计划,并对美国rCr教育给我国研究生的科研诚信教育的启示进行了讨论

计及Casimir效应时旋转式NEMS致动器的动态稳定性研究

分析了Casimir力对旋转式纳电子机械(NEMS)致动器动态稳定性的影响.计及Casimir效应时,旋转式致动器失稳时的临界倾角和临界电压和结构的几何尺寸有关.外加电压为零时,导出了旋转式致动器在Casimir力作用下发生吸合的临界特征几何尺寸.给出了旋转式致动器的无量纲化运动控制方程,并对它作了定性分析.定性分析表明:该运动方程相应的自治系统在相平面上的平衡点包括中心点、稳定的焦点和不稳定的鞍点;相图呈现周期轨道、同宿轨道以及异宿轨道.另外系统还存在分叉现象

计及casirnir效应时旋转式nems致动器的动态稳定性研究

分析了Casimir力对旋转式纳电子机械(NEMS)致动器动态稳定性的影响．计及Casimir效应时，旋转式致动器失稳时的临界倾角和临界电压和结构的几何尺寸有关．外加电压为零时，导出了旋转式致动器在Casimir力作用下发生吸合的临界特征几何尺寸.给出了旋转式致动器的无量纲化运动控制方程，并对它作了定性分析．定性分析表明：该运动方程相应的自治系统在相平面上的平衡点包括中心点、稳定的焦点和不稳定的鞍点相图呈现周期轨道、同宿轨道以及异宿轨道．另外系统还存在分叉现象

Size- And Temperature-Dependent Thermal Expansion Coefficient Of A Nanofilm

The thermal expansion coefficient (TEC) of an ideal crystal is derived by using a method of Boltzmann statistics. The Morse potential energy function is adopted to show the dependence of the TEC on the temperature. By taking the effects of the surface relaxation and the surface energy into consideration, the dimensionless TEC of a nanofilm is derived. It is shown that with decreasing thickness, the TEC can increase or decrease, depending on the surface relaxation of the nanofilm

The surface- and size-dependent elastic moduli of nanostructures

A theoretical model is presented to investigate the size-dependent elastic moduli of nanostructures with the effects of the surface relaxation surface energy taken into consideration. At nanoscale, due to the large ratios of the surface-to-volume, the surface effects, which include surface relaxation surface energy, etc., can play important roles. Thus, the elastic moduli of nanostructures become surface- and size-dependent. In the research, the three-dimensional continuum model of the nanofilm with the surface effects is investigated. The analytical expressions of five nonzero elastic moduli of the nanofilm are derived, and then the dependence of the elastic moduli is discussed on the surface effects and the characteristic dimensions of nanofilms

Instability Analysis Of Torsional Mems/Nems Actuators Under Capillary Force

The static and dynamic instabilities of a torsional MEMS/NEMS actuator caused by capillary effects are studied, respectively. An instability number, eta, is defined, and the critical gap distance, g(cr), between the mainplate and the substrate is derived. According to the values of eta and g, the instability criteria of the actuator are presented. The dimensionless motion equation of the MEMS/NEMS torsional actuator is derived when it makes nonlinear oscillation under capillary force. The qualitative analysis of the nonlinear equation is made, and the phase portraits are presented on the phase plane. In addition, the bifurcation phenomena in the system are also analyzed. (C) 2008 Elsevier Inc. All rights reserved