Measuring the yield stress of a particulate suspension under high electric fields

Certain classes of particulate suspensions, consisting of semi-conducting, solid particles dispersed in an insulating carrier liquid, show a dramatic increase in flow resistance when placed under an external electric field. These so-called “electro-rheological fluids” have potential application in engineering devices such as tunable vibration damping systems. Under the field, a yield stress is induced in the fluid, and the characterisation of this quantity is essential for the design of many engineering devices. A new method for determining the yield stress is presented, which involves subjecting the sample to a constant shear stress and monitoring its shear rate after a step change in the electric field. It is found that this step field method can reproducibly determine the field-induced yield stress of a suspension of silica particles in silicon oil.     

硅酸铝-淀粉系复合悬浮相电流变流体的流变特性研究

研究了硅酸铝-淀粉系复合悬浮相电流变流体的流变特性,发现其某些流变曲线超出已有流体流变曲线范围,而呈现“V”形,且在高电场强度时这种趋势更为明显。为解释该现象,提出了一种复合粒子的极化模型。     

基于内检测数据的腐蚀管道完整性评价

完整性评价是完整性管理中的重要环节。GB 32167-2015《油气管道完整性管理规定》中建议优先采用内检测数据对管道的完整性进行评价。基于工程实例,对某管线内检测检出缺陷进行分级、分类评价,并根据评价结果制定相应的维修响应策略。结果表明,该管道的内腐蚀较为严重,且集中在5~7点钟方向,可采用预估维修比(ERF)作为缺陷是否需要进行维修响应的判定条件。通过综合分析,所有缺陷ERF均小于1,剩余强度满足要求;应立即响应的缺陷共有6处,可在1 a内计划响应的缺陷共有85处;应在2024年7月13日前再次开展内检测作业。     

电流变流体机械特性振动响应的研究

电流变流体是一种新型的智能材料,在工程中有广泛的应用前景。本文利用自行设计的测试装置通过对测杆振幅、共振频率等参数的测定,研究电场作用下电流变流体刚度及阻尼变化。根据实验研究提出变参数的粘弹阻尼力学模型,描述电流变流体在电场作用下附加阻尼和附加刚度。     

一种新型有机半导体的电流变特性的研究

本文对一种表现出合理电流变效应的新型有机半导体的合成及电流变性质进行了探讨。并用经过改进的旋转粘度计对表征电流变性质的屈服应力、电流密度等随电场强度的变化关系进行了测试。结果表明，这种新型有机半导体粒子可组成高电流变的无水ＥＲ液     

声波反射法测量电流变液参数

电流变(Electrorheological, ER)液是一种新型智能材料,在外部电场作用下其物理特性可调节。文章设计了一种电流变液的声学测量系统,利用声波反射法测量电流变液的反射系数和相位差,根据声阻抗率与弹性模量关系,得到电流变液储能模量、耗能模量和损耗角等参数。实验结果表明：声阻抗率、储能模量和损耗角等参数与所施加外部电场的电压有关,采用电极绝缘漆处理工艺能有效兼顾电流变液对较大剪切应力和快速响应时间的性能要求。     

Development of electrically controlled polishing with dispersion type ER fluid under AC electric field

This paper shows that a dispersion type functional fluid and AC electric field may be used to control the distribution of abrasives in free-abrasive polishing and to improve surface roughness and finishing time. In the case of polishing conductive materials, such as cemented carbide, an AC electric field created by a mono-pole electrode has concentrated abrasives in the polishing area. To obtain a minimum surface roughness, a peak-to-valley voltage of 2 kV at a frequency of 0.8 Hz has been applied. Then the surface roughness of a cemented carbide plate was reduced from 0.65 μm Ra to 0.02 μm Ra in 5 min. But to polish non-conductive materials, such as glass and semiconductors, a multi-layered concentric electrode must be introduced. The surface roughness of borosilicate glass plates has been reduced from 13.5 nm Ra to 7.5 nm Ra in 3 min under the optimum AC electric field gradient of 2 kV/mm and 0.8 Hz frequency.     

基于NI虚拟仪器的电流变网络化测控系统

讨论用NI虚拟仪器构建的电流变网络化远程检测与控制系统，详细地介绍了系统的结构、功能和实现过程。