Characterisation of plasticity-induced closure--crack flank contact force versus plastic enclave

This paper presents some results from a totally new and powerful fusion between automated, digital photoelastic techniques and mathematical analysis of a crack experiencing closure. In essence, real-time photoelastic stress field data is acquired and fitted to a Muskhelishvili complex potential model of a loaded crack experiencing closure. The fit entails optimisation of multiple variables via a memetic algorithm, which combines a genetic algorithm and a local search. From observations made in this work, it is proposed that the plastic enclave around a crack tip will shield the crack from the full influence of the applied stress field. Furthermore, the effects of this ‘back stress’ are overcome by the applied tensile load in a way that, often, cannot be readily correlated with crack contact length, wake contact force, or with compliance.     

基于AutoCAD2000的图解法确定工艺转角

提出了基于AutoCAD2 0 0 0的图解法求解机械加工过程中工艺转角的问题 ,并针对具体的应用实例给出了圆满的解答 ,并验证了其精度。     

精馏塔静态仿真：Ⅰ.静动态混合数学模型的应用

本文为了克服精馏塔静态仿真不易收敛和初值难以给定等难题，巧妙地利用隐含数值积分方法的特点，将稳态与动态数学模型耦合起来，用以求解高难度的非理想精馏塔静态仿真问题。所得静动态混俣模型大大提高了精馏塔静态仿真的鲁棒性，对于高度非理想精馏塔的仿真尤为有效。通过对某丙烯腈萃取精馏塔的静态仿真，充分证明了这种混合模型化方法的可行性。     

一种新型悬臂棒条筛的设计与应用

介绍了一种新型悬臂棒条筛分机械,论述了其结构、工作原理和技术特性。从理论和实践两方面论证了它的结构、处理能力、筛分效率、返矿率都明显优于普通悬臂棒条筛分机械,可广泛应用于高炉槽下烧结矿的筛分作业。     

保证跌落试件姿态的方法

进行包装件的自由跌落试验时,必须保证试件姿态符合标准规定。笔者在实践中总结出一种保证试件姿态和检验试件姿态误差的具体方法。     

Thermogravimetry and wide angle X-ray diffraction study on the structure of irradiated and thermally treated kodar film

The degradation behaviour of Kodar [poly(1,4-cyclohexylene dimethyl-eneterephthalate)] was investigated in air using thermogravimetry, differential thermal analysis and wide angle X-ray diffraction studies. The rates of crystallization and degradation were influenced by thermal exposure and polychromatic irradiation (Λ > 290 nm) for different time intervals. The crystallinity changes (X_c%) and activation energies (ΔE) for the systems have been determined.     

模块化蓝光光存储性能静态测试系统

蓝光光存储是信息存储领域发展的一个重要方向。测试系统是研究蓝光光存储材料的必备条件，为建立蓝光光存储研究平台，设计和搭建了一套模块化蓝光光存储性能静态测试系统。激光工作波长为406．7nm。系统采用调制解调技术降低系统噪声，提高测量粘度：采用光点移动模式降低对样品尺寸的要求；采用纳米平台提高记录点的反复定位性能。实验结果证明测试系统性能良好，可以满足蓝光光存储性能静态测试要求。     

覆膜滤料的滤尘性能测试方法研究

由于覆膜滤料的结构和性能有别于普通滤料，因而普通滤料的滤尘性能测试方法不完全适用于覆滤料。本文作者在总结实践经验的基础上，提出了在覆膜滤料的滤尘性能测试中应注意的一些问题和应增加的测试项目。     

Comparative study of the electrical properties of diamond films grown by microwave plasma assisted and hot-filament chemical vapor deposition

Schottky diodes were built on different polycrystalline diamond films grown by Microwave Plasma and Hot Filament Chemical Vapor Deposition and their electrical properties were studied. The barrier height increased with the diamond film quality and the corresponding ideality factor decreased. Even though the lower-quality HFCVD film displayed poor rectifying properties, it was found to be much less sensitive to variations in the operating conditions (air vs. vacuum). The activation energies of the films depend on morphological parameters, as preferable grain size or orientation. The bulk conduction also depends on the quality of the deposited films, changing from ohmic to trap-free or shallow trap SCLC and SCLC with an exponential distribution of traps. The hypothesis of using the electrical measurements as an indicator for film quality has been discussed.     

Finite element simulation of the mechanics of flat contact pad fretting fatigue tests

An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area.