漩流氧枪转炉炼钢熔体的喷溅行为

 转炉冶炼过程金属熔体的喷溅对于转炉反应器的性能有重要影响。氧枪作为氧气射流的产生及控制单元,决定了转炉吹炼过程熔体的喷溅行为。通过水模型试验,研究了漩流氧枪转炉冶炼过程熔体的喷溅,考察了氧枪喷孔扭转角设计及操作参数下熔体喷溅速率和喷溅的空间分布规律,基于此,分析了漩流氧枪对转炉反应器性能的影响。结果表明,相比于传统氧枪吹炼,漩流氧枪吹炼时熔体喷溅速率降低,喷溅高度下降,喷溅在径向空间分布趋于均匀,且随着喷孔扭转角的增大,该分布规律变化更为显著,扭转角大于20°时,喷溅到炉口及炉外的熔体降为零。漩流氧枪吹炼时,喷溅速率及喷溅量在不同径向和高度位置处分布随着顶吹气量的增大而增大,受枪位的影响规律与扭转角有关。     

双曲扭壳屋盖力学性能分析

本文从扁壳的挠度和内力函数混合方程出发,得出了双曲扭壳的双三角级数表示的解析结果,进一步确定了扭率对该扭壳的刚性影响,从而提出关于扭率判别条件的上界和下界,当实际结构的扭率小于判别值的下界时,扭壳可视为矩形平板;当扭率大于判别值的上界时,扭壳可忽略平板效应,视其为无矩状态。对于这两种情况,工程误差不大于百分之一。实际双曲扭壳的屋顶,其扭率在大多数情况下大于判别值的上界。     

纯毛高弹织物的开发

对普通精纺股线实施追加捻工艺以保证足够的退捻力矩,然后采用不同的经纬纱支、不同的捻向配置,试织具有不同经纬密度的纯毛高弹织物.其中,通过控制经纬纱的交织规律和纱线的退捻力矩实现织物的伸长与回缩,通过收缩整理使织物得到高弹性,并对织物进行了弹性伸长率测试.     

Investigation of mode III fracture toughness using an anti-clastic plate bending method

In this paper, results of a mode III (tearing mode) fracture toughness investigation with the method of anti-clastic plate bending (ACPB) or equivalently the plate twist method are reported. A testing device using the ACPB phenomenon was constructed and was used to determine the shear modulus of a number of foams and polymeric materials. In this work, potential applications of this method and the associated testing device were extended to the study of the mode III fracture toughness of various materials. The materials investigated included polymethylmethacrylate (PMMA), polycarbonate (PC), and foams consisting of polyvinylchloride (PVC), polyetherimide (PEI) and polymethacrylimide (PMI), polystyrene (PS-X) and laminated composites including carbon fiber reinforced plastic (CFRP), and glass fiber reinforced plastic (GFRP). Values for the compliance, energy release rate, and fracture toughness of these materials were obtained and the functional dependency of these quantities on the crack length was determined. This work shows that the ACPB method can provide a reliable and yet simple testing method not only for the determination of the shear properties of polymeric and laminated materials, but also for mode III fracture toughness investigations.     

New measuring method for determining alignment parameters in twisted‐nematic and super‐twisted‐nematic cells

Abstract— A new method for determining the thickness, twist angle, and azimuth of the director for a substrate with twisted‐nematic (TN) and super‐twisted‐nematic (STN) liquid‐crystal (LC) cells has been proposed. The measurement was carried out by using an optical system which consisted of a monochromatic light source, polarizer, rotating analyzer, and software programs. The polarization transfer matrix, or Jones matrix, of a TN or an STN LC cell is formulated by the Fourier coefficient of the signal that is modulated by the rotating analyzer. These three alignment parameters are derived directly from components of the Jones matrix. We made a special effort to design the system to ensure accurate, stable, and quick measurement. Thus, the three parameters were determined simultaneously within a few seconds with good reproducibility; e.g., the standard deviation of the twist angle in the TN cell is 0.02° or less.     

股线与单纱捻系数比对粘胶股线性能的影响

为综合反映单纱结构参数对股线性能的影响,采用传统环锭纺纱方式,以粘胶纤维为原料,研究了不同线密度、不同捻度的单纱反向加捻为双股线时,捻系数比对股线强伸性、毛羽、耐磨性能的影响。结果表明:反向加捻的双股纱线存在2个临界捻系数比,分别位于捻系数比为0.7和1.5左右,在这2个捻系数比处股线可获得较高的强力;当捻系数比大于1时,可显著减少股线表面的有害毛羽数;当捻系数比在0～2之间时,捻系数比越大,股线耐磨性越好;综合对比得到捻系数比为1.5时可保证股线综合质量最好。     

短纤维单纱捻度测试方法的研究

测试短纤维单纱捻度的方法目前主要有直接退捻法、1次退捻加捻法和2次退捻加捻法,但这3种方法检测结果有一定的差异.在同一标准大气环境下使用同一台仪器、同一种纱线分别用直接退捻法、1次退捻加捻法和2次退捻加捻法测试短纤维单纱的捻度,通过试验过程及数据结果的分析来比较这3种方法的差异.     

精梳毛纱细度偏差的控制

细度偏差是精梳毛纱评等考核的重要指标之一,为使最终成品细度非常接近客户的要求,增强产品的市场竞争力,关键要确定好精纺机设计细度,同时要控制好细度偏差。文章主要介绍了运用最小二乘法确定毛纱的设计细度及运用平均值一极差控制图对毛纱细度进行有效管理的方法,使精纺机的生产过程达到统计控制状态,及时发现细度异常变化,降低毛纱细度偏差,提高毛纱质量。     

基于旋量理论的装配模型中零件瞬时运动分析

提出一种直接根据装配模型中零件几何信息和空间配置关系分析其零件瞬时运动特性的方法。该方法首先对不同零件CAD模型中面几何方程进行比较得到零件之间的面-面接触关系和类型,并应用旋量理论将面-面相对瞬时运动表示为螺旋;然后,对多个面接触上的螺旋进行交运算,生成零件之间的相对瞬时运动螺旋;最后,根据零件邻接关系图和邻接零件相对运动螺旋,对装配模型中零件整体瞬时可动性和驱动关系进行了分析,给出不相邻零件之间的相对瞬时运动螺旋计算方法和它们之间可驱动性的判断方法。论文通过实例验证了该方法的正确性及有效性。     

涤纶强捻仿真丝织物工艺探讨

涤纶强捻仿真丝产品具有天然真丝般优异的回弹性、悬垂性,手感柔和,且具有真丝产品不可比拟的可打理性和各向高牢度,其问世以来一直深受市场欢迎。本文阐述了涤纶强捻织物从原料选型到成品织染工艺制定原理及对常见问题的应对办法。