用EIB对变形纱的外观形态和膨松性的测试与探讨

为了对变形纱的外观形态和膨松性进行更好的评价，利用EIB对几种线密度较接近的棉纱、毛纱、低弹丝和空变纱分别进行测试，可以获得纱线的毛羽、丝圈或丝弧的数据、分布情况、形态图及纱线的直径；根据测试得到的数据，利用新建立的表征变形纱膨松性的指标进行比较和评价，得出用这种方法来评价是可行的，且低弹丝的膨松性较高。     

基于反馈线性化的非线性气动伺服系统跟踪控制

针对气动位置伺服系统跟踪控制中系统受压力波动、摩擦力扰动等非线性因素影响较大的特点，提出基于压力反馈线性化、摩擦力补偿的内外双环型控制算法。仿真与实验结果表明，该算法结构简便又宜于实用、跟踪精度较高，控制效果较好。     

Velocity Distribution of Slurry in Horizontal Pipe When Solid Particles Sliding

Based on the laws of momentum conservation and impulse in accelerating process, the distribution on speed of ununiform slurry flow in a horizontal pipe was studied. According to the momentum change of solid particles and conveying liquid of slurry flow during accelerating, and some effect factors, the relationship between the speed of solid particles and the speed of conveying liquid was obtained.When dealing with the friction between sliding solid particles and pipe, it is pivotal to reasonably distribute component of friction to each solid particle. The friction coefficient between solid particles was obtained by forces analysis and theoretic calculation, and can be used to calculate the friction force on every solid particle. The effect of friction on speed of ever), solid particle was investigated through the impulse law. The result is more accurate than that by using uniform friction on solid particles. It is completely new method to use above theory to get solid particles speed distribution, conveying liquid speed distribution and slurry speed distribution.     

滑动支座摩擦效应对连续梁桥地震响应影响

以1座跨度为(55+4×90+55)m的预应力混凝土变截面连续梁桥为研究对象,采用ANSYS软件建立桥梁动力分析模型.选取3条人工地震波作为地震动输入,基于动力非线性分析方法,考虑摩擦效应,分析盆式橡胶支座连续梁桥非固定墩的地震响应和支座的滞回性能,并与未考虑摩擦效应的地震响应进行比较.结果表明:非固定墩处的盆式橡胶支座在地震作用下形成了规则、饱满的滞回曲线,形状近似为矩形;相对未考虑盆式橡胶支座摩擦效应的模型,考虑支座滑动后,固定墩墩底顺桥向弯矩、剪力分别降低了25.91%、27.41%,固定墩墩顶顺桥向位移和非固定墩墩梁相对位移分别降低了26.15%、25.59%;对于多跨长联连续梁桥,滑动支座数量多且反力大,若不考虑滑动支座的摩擦耗能,桥梁结构地震响应结果偏大,抗震设计偏于保守.     

高速水润滑止推轴承的滑移润滑性能研究

建立了多种具有不同滑移区域分布特征的推力瓦数学模型,在考虑流体边界滑移效应、扩展了经典Reynolds方程并设定合理边界条件的基础上,借助MATLAB软件对模型进行数值仿真求解,研究了滑移区域分布方式、面积占比及滑移长度对轴承动压润滑性能的影响。结果表明,在靠近流场入口处沿周向分布滑移区域能显著提升不同转速条件下的推力瓦面承载力;当滑移区域面积占瓦面面积比介于0.3~0.4且滑移长度为1000nm时,轴承推力瓦面具有最优动压润滑性能。     

高温合金轴向超声振动钻削减摩机理

针对高温合金钻削困难、钻削过程中摩擦力大等问题,采用超声振动技术加工.首先,分析了超声振动减摩机理,构建了平均摩擦力与振动参数之间的关系,并得出了平均摩擦力与振幅之间的变化趋势.建立轴向超声振动钻削系统,利用该系统对高温合金进行钻削加工.结果表明:振动振幅对孔壁表面质量的影响符合超声振动钻削的减摩特性.利用优化后的振幅超声振动钻削,与普通钻削相比,切屑形态更加规整,孔壁表面粗糙度值更小,表面质量更好.     

铝锡轴承合金的摩擦磨损机理与性能

铝锡轴承合金对大型载重汽车、坦克、高速汽车、拖拉机等的高速高压柴油机的发展有重要的意义。提高铝锡合金的耐摩擦磨损性能可节省大量能源并延长零件的使用寿命,如何取得具有优良的耐摩擦磨损的铝锡合金成为研究的重点。本文介绍了提高铝锡合金的耐摩擦磨损性能的措施及其影响因素,总结铝锡合金中锡元素含量改变、合金元素的添加、热处理与制备工艺的改变对铝锡合金的显微组织以及耐摩擦磨损性能的影响。     

基于无线传输的内燃机活塞组-缸套摩擦力测量方法

探讨了平均指示有效压力法测量活塞组-缸套摩擦力的原理,给出了活塞组及连杆的惯性力计算方法,利用无线传输方法实现了连杆应力信号的可靠传输,并通过倒拖试验得到了不同转速条件下柴油机活塞组-缸套系统的摩擦力.     

Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.     

数码卷绕的概念和技术

数码卷绕是在精密卷绕的基础上，引入导丝机构的数字控制方式，得到张力更稳定、纱管成形更完善的最新卷绕技术。文章介绍了高速精密数码卷绕技术的概念、实现原理和应用现状。