高温高应变率下AM60B镁合金力学性能及失效行为

为了研究镁合金在高温、高应变速率下的变形行为及失效机制,采用分离式Hopkinson压杆在应变速率为1 600~4 500 s^-1、温度为27~150 ℃范围内,对真空压铸AM60B镁合金进行了动态压缩实验,并采用金相显微镜和扫描电子显微镜对压缩后的组织进行了观察.结果表明:在所测试的应变范围内,随着应变率的提高,应力-应变曲线均呈现上升趋势,且最大应变也随之增加,表现出正应变率强化效应.在150 ℃时真空压铸AM60B镁合金变形能力最好; 50 ℃时断裂强度最高.真空压铸AM60B镁合金在高温及高应变率下的断裂方式为以解理断裂为主并伴有韧性断裂的混合断裂方式.当变形温度低于150 ℃时,真空压铸AM60B镁合金在高应变率压缩下的变形机制主要是滑移.     

基于dsPIC的转差频率矢量控制在电梯控制中的应用

介绍了一款结合单片机控制特点和数字信号处理器（DSP）高速运算优点的新型芯片——dsPIC30F6010。阐述了异步电动机转差频率矢量控制策略，给出了dsPIC30F6010在电梯变频调速系统中的应用实例，并对系统进行了仿真。     

滑模施工技术在仓筒结构中的应用

结合工程实例,介绍了仓中仓库壁滑模施工中的滑升装置及组装、滑升程序,以及在施工过程中混凝土的控制措施.     

小型CPL用高性能烧结毛细芯的研制

采用粉浆浇注工艺和氢气还原烧结工艺研制小型CPL用烧结镍毛细芯，通过优选粉浆液固比、添加剂的种类与数量、浆料pH值等参数制备了符合设计要求的烧结毛细芯。测试了毛细芯孔径、孔隙分布特征、孔径分布、孔隙度、渗透率等性能参数，分析了烧结气氛、温度、时间对毛细芯性能的影响。试验结果表明，研制的毛细芯孔隙度在68％以上，孔隙尺寸约4μm，渗透系数在10^-12～10^-13m^2之间。     

关于球罐球片包装架的结构分析

球片包装架是球罐产品包装及运输过程中必需的结构件，然而在实际使用过程中，包装架系列过于安全。从而产生材料消耗较大、铁路运输成本升高等因素。用力学方法，通过对包装架进行合理的受力分析和计算，并以此为理论根据，本着安全、合理及高效的原则，可以降低包装架主体构件——承重梁(槽钢)型号，或增加包装架承重量的方式，对球片包装架构件进行重新设计，从而可以节省材料,增加效益。     

A fast integral approach for drag force calculation due to oscillatory slip stokes flows

In this paper, we describe an efficient numerical method for modelling oscillatory incompressible slip Stokes flows in three dimensions. The efficiency is achieved by employing an integral approach combined with an accelerated boundary‐element‐method (BEM) solver. First the integral representations for slip flows with two different slip models are formulated. The resulting integral equations are then solved using the BEM combined with the precorrected‐FFT accelerated technique. 3D numerical codes have been developed based on the method described above. These codes are then used to calculate the drag forces on oscillating objects immersed in an unbounded slip flow. Three objects are considered, namely a sphere, a pair of plates and a comb structure. The simulated drag forces on these objects obtained from the two slip models are compared. In the sphere case, the simulated results are also compared with the analytical solutions for both the steady‐state case and the no‐slip oscillatory case and are found to be in good agreement. In addition, qualitative comparison of the simulation results with the experimental results in the plate problem is also presented in this paper. Copyright © 2004 John Wiley & Sons, Ltd.     

钢绞线混凝土黏结性能试验与锚固长度分析

为研究较大直径钢绞线与混凝土间的黏结锚固问题并提出合理锚固长度,针对15.2、17.8、21.6mm三类公称直径的高强低松弛钢绞线,以混凝土保护层厚度、体积配箍率及埋置长度为基本参数,完成了32个钢绞线的中心及偏心拔出试验.试验结果表明,不同参数水平条件下拉拔试件的破坏可分为两类,一是较薄保护层厚度与较小体积配箍率的少量试件劈裂破坏;二是在绝大部分试件中出现的表面未开裂但钢绞线拔出的破坏.结合破坏特征及拉拔力-滑移关系曲线,揭示了钢绞线混凝土间的黏结破坏机制,并以拉拔力-滑移曲线的峰值为破坏标志,提出了分别考虑3个参数影响的钢绞线混凝土黏结强度计算方法;结合本文试验结果,引入近似概率法,确定了满足相应可靠指标要求的钢绞线锚固长度设计值,可为装配式公共建筑结构中采用的大型先张预制预应力混凝土构件的设计提供技术支持.     

基于MSP430的肌电假手系统设计

在对人体表面肌电信号研究的基础上,设计出一种肌电假手系统,其中包括肌电信号采集调理系统和假手控制系统。肌电信号经信号调理电路放大、滤波、陷波后,由低功耗的MSP430F149单片机进行A/D转换、特征计算。单片机结合肌电信号与触滑觉传感器反馈的信息来控制电机转向与转速,从而控制假手做出相应动作。通过实际采集的肌电信号在示波器上显示的波形与假手的动作进行对比,说明系统设计是合理有效的。     

Forward and Backward Slip Models in MAS Rolling Process and Its OnLine Application

Based on the MAS rolling process in plate mill, the mathematical models of forward and backward slips of the wedges at plate head and tail were derived. According to the new model, the difference between the forward slip of the wedge and that of the normal part of the plate is obviously very small. The deviation is less than 25% in general. Thus, in actual application, the forward slip of normal part of the plate can be used to calculate the length of rolled plate instead of the derived model. The rationality of this simplified method was confirmed with the application in Shougang 3 500 mm plate mill. The test results showed that the wedges of plate head and tail are symmetrical. The plate width deviation is greatly decreased by using the MAS method.     

Low Cycle Fatigue Behavior and Deformation Mecha-nism of TWIP Steel

Low cycle fatigue behavior of TWIP （twinning induced plasticity） steel was investigated in axial symmetric tension-compression cyclic loading pattern. Fracture surfaces and microstructures were examined by optical, scanning electron and transmission electron microscopes. It was found that the fatigue life at the strain amplitude of 0.4 % is up to 15 000 cycles, which is much longer than TRIP780 and HSLAS00 steels. The strain hardening and softening features are significant until the strain amplitude comes to 1.25 ~. Persistent slip bands and tiny mechanical twinning layers were observed after fatigue deformation. Deformation mechanism of TWIP steel at low cycle fatigue process is not only twinning, but a complex of both twinning and persistent slip bands.