恒定磁场阻垢除垢的分子动力学模拟

磁场的阻垢除垢机理研究不足阻碍了该法的实际应用。为了进一步认识恒定磁场的阻垢除垢机理,研究了不同磁感应强度、不同温度下的阻垢除垢效果。建立模型A和模型B,其中模型A是含少量钙离子和碳酸根离-子的水溶液,模型B是包含方解石(110)晶面与水接触的混合体系。用分子动力学软件Material Explorer 5.0研究在改变磁感应强度和体系温度下,模型A、B分别表现出的阻垢除垢效果。结果表明:对于模型A,只有温度323 K时,磁场的作用下才能表现出阻垢效果,而且磁感应强度与模型温度的不同组合会导致3种趋势:阻垢、促垢、无变化。对于模型B,在磁感应强度与温度改变多次组合后,并未发现有导致水垢被溶解的情形。由此可得恒定磁场的除垢效果缺乏机理的支撑。     

Matter Timed

At best, the ageing of materials is regarded as lending a patina to historic buildings. In reality, however, materials often age disgracefully and unevenly, requiring a high level of maintenance and refurbishment. What if materials could be engineered and integrated into buildings not only to enhance but to heal? Martina Decker , Assistant Professor in the College of Architecture and Design at the New Jersey Institute of Technology (NJIT), looks at pioneering research that is being undertaken into performative, time-dependent materials.     

机床外防护选材的探讨与分析

对机床外防护的选材进行了探讨与分析,通过对机床外防护结构的研究,利用CAE仿真分析软件分析了材料的受力情况,达到合理使用板材的目的,从而使外防护的设计制造更加合理经济。     

Effect on crystalline structure of AISI M2 steel using tungsten–thorium electrode through MRR,EWR, and surface finish

To investigate on the crystalline structure of AISI M2 steel by using tungsten–thorium electrode in electrical discharge machining (EDM) process was studied. Furthermore, the investigation were carried out for finding the value of material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR) of tool steel material depending upon three variable input process parameters. On the basis of weight loss, the value of MRR and EWR were calculated at optimized process parameter. Subsequently, surface topography of the processed material were examined through different characterization techniques like scanning electron microscopy (SEM), Optical surface profiler (OSP) and Atomic force microscopy (AFM), respectively. In XRD study, broadening of the peak was observed which confirmed the change in material properties due to the homogeneous dispersion of the particles inside the matrix. Lowest surface roughness and MRR of 0.001208 mg/min was obtained. Minimum surface roughness was obtained 1.12 μm and 2.18427 nm by OSP and AFM study, respectively. Also, minimum EWR was found as 0.013986 mg/min.     

基于CEL方法的Al/Mg搅拌摩擦焊温度场及材料混合流动研究

本文基于耦合欧拉-拉格朗日(CEL)方法建立5A06铝合金与AZ31B镁合金对接搅拌摩擦焊（FSW）的全热力耦合数值模型,并结合试验测试对Al/Mg异种金属FSW过程的温度场及材料混合流动特征进行研究。数值模拟所得特征点的温度循环曲线、焊缝表面形貌以及横截面上异种材料的混合分布状态均与试验结果吻合良好。在此基础上,采用质点追踪法对材料混合流动行为进行了深入分析。结果显示,高温区集中分布在轴肩下方区域,返回侧(Mg侧)温度较低温度梯度较大。焊缝区上表面材料熔合线偏向于前进侧(Al侧)。搅拌针附近材料流动剧烈,前进侧和返回侧的大部分材料都较均匀地沉积于搅拌针后方。前进侧与返回侧材料在水平和竖直方向上的交叉混合流动,最终形成了两种材料“咬合式”的界面特征。     

阻燃聚丙烯的研究进展

基于聚丙烯的热分解机理,依照材料设计的思路,总结并概括出阻燃聚丙烯的开发已从最开始的单纯的配比添加向深层次的材料设计转变的研究方向。重点概括并论述了当前阻燃聚丙烯材料的开发设计思路,并举例分析了三种层面上的阻燃聚丙烯的国内外的研发进展及其不足。     

硬度检测在压力容器定期检验中的应用

按照《压力容器定期检验规则》的规定,对有材质劣化倾向或有焊缝硬度要求的压力容器,在定期检验时应进行硬度检测。对压力容器硬度检测的作用、时机、部位、评定、注意事项进行了分析与阐述。     

金属塑性成形可靠性判断准则

通过拉伸实验,研究了塑性变形时,各种应力-应变状态下的判断稳定性的通用关系式.讨论了非硬化材料在平面和空间应力状态下的塑性变形产生稳定性的可能性.