第十四届国际材料强度大会简介

2006年6月5～9日,第十四届国际材料强度大会(14th International Conference on the Strength of Materials,ICSMA 14)在西安古都新世界大酒店举行,会议正式代表322人(其中境外代表200多人),这是该系列国际材料强度大会第一次在中国举办.     

“微／纳系统国际会议（ICMNS2002）”简介

由中国力学学会、中科院力学所非线性力学国家重点实验室(LNM)、香港中文大学和香港科技大学联合主办的“微／纳系统国际会议(ICMNS2002)”于2002年8月ll－14日在云南昆明万恰酒店隆重举行。     

断裂力学中的相似方法

不论是材料的断裂强度还是结构的承载能力均存在着明显的“尺度效应”．本文旨在较全面且系统地总结断裂力学中的相似方法、无量纲数及其断裂力学中有关的尺度率，并给出作者自己对某些问题的看法和认识     

Experimental Investigation of the Velocity Effect on Adhesion Forces with an Atomic Force Microscope

Capillary forces are significantly dominant in adhesive forces measured with an atomic force microscope (AFM) in ambient air, which are always thought to be dependent on water film thickness, relative humidity, and the free energy of water film. We study the nature of the pull-off force on a variety of surfaces as a function of tip velocity. It is found that the capillary forces are of relatively strong dependence on tip velocity. The present experiment is expected to provide a better understanding of the work mechanism of AFM in ambient air.     

端头带有质量块的悬臂梁在冲击载荷下的两种剪切失效模型

剪切失效是强动载荷作用下结构失效的重要模式。本文给出了计及梁的转动惯量时端头带有质量块的悬臂梁结构受到冲击载荷作用后发生剪切失效的无量纲判据。分析表明，在初始速度间断面上是否发生剪切失效取决于质量块初始动能和质量块尺寸与梁厚之比，而与梁的长度无关。梁的转动惯量对于剪切失效具有不可忽略的影响。     

Adhesion elastic contact and hysteresis effect

In this paper, we study the relationship between the pull-off force and the transition parameter (or Tabor number) as well as the variation of the pull-off radius with the transition parameter in the adhesion elastic contact. Hysteresis models are presented to describe the contact radius as a function of external loads in loading and unloading processes. Among these models, we verified the hysteresis model from Johnson－Kendall－Roberts theory, based on which the calculated results are in good agreement with experimental ones.     

Nano-tribological study on a super-hydrophobic film formed on rough aluminium substrates

A novel super-hydrophobic stearic acid (STA) film with a water contact angle of 166^o was prepared by chemical adsorption on aluminum wafer coated with polyethyleneimine (PEI) film. The micro-tribological behavior of the super-hydrophobic STA monolayer was compared with that of the polished and PEI-coated Al surfaces. The effect of relative humidity on the adhesion and friction was investigated as well. It was found that the STA monolayer showed decreased friction, while the adhesive force was greatly decreased by increasing the surface roughness of the Al wafer to reduce the contact area between the atomic force microscope (AFM) tip and the sample surface to be tested. Thus the friction and adhesion of the Al wafer was effectively decreased by generating the STA monolayer, which indicated that it could be feasible and rational to prepare a surface with good adhesion resistance and lubricity by properly controlling the surface morphology and the chemical composition. Both the adhesion and friction decreased as the relative humidity was lowered from 65% to 10%, though the decrease extent became insignificant for the STA monolayer. The project supported by the National Natural Science Foundation of China (50375151, 50323007, 10225209) and the Chinese Academy of Sciences (KJCX-SW-L2)     

Dynamic Behaviour of Nanoscale Electrostatic Actuators

The dynamic behaviour for nanoscale electrostatic actuators is studied. A two parameter mass-spring model is shown to exhibit a bifurcation from the case excluding an equilibrium point to the case including two equilibrium points as the geometrical dimensions of the device are altered. Stability analysis shows that one is a stable Hopf bifurcation point and the other is an unstable saddle point. In addition, we plot the diagram phases, which have periodic orbits around the Hopf point and a homoclinic orbit passing though the unstable saddle point.     

线弹性断裂力学和线弹性动力学中的集中载荷

本文认为线弹性断裂力学（ＬＥＦＭ）中受集中力和集中力偶作用的含裂纹体应力强度因子｀精确解＇的适用范围是值得进一步讨论的问题，并对线弹性动力学中的集中载荷问题进行了讨论     

结构塑性动力响应实验研究的简要综述

讨论和总结了结构塑性动力响应中的相似方法以及进行模化实验所应遵循的原则，对冲击载荷下多种结构塑性动力响应的实验研究进行了简要综述．