非均匀磁

发布时间：2018-04-02 14:30

本文选题：磁流变液　切入点：剪切应力　出处：《兰州交通大学》2015年硕士论文

【摘要】：磁流变液是智能材料重要分支之一,无磁场时表现为悬浮状牛顿流体,当外磁场存在时,可毫秒级时间内转变为粘稠状的类固体或固体结构,这种可逆转变被称为磁流变效应。磁流变器件就是基于磁流变效应研制的,其中磁流变液剪切特性应用最为广泛。磁流变液剪切特性受到磁场、温度、重力场、剪切速率、软磁颗粒的分散情况、器件结构与材料特性、工作面粗糙度等诸多因素影响。同时磁流变器件工作中不避免的会产生热能从而改变工作温度,这使得磁流变器件多数时间处于磁场、温度复合的环境中。而目前磁流变器件多数是基于静态匀强磁场磁流变液剪切应力模型,并未对磁场、温度的改变所导致的器件失效性进行研究。通过模拟器件失效环境,研究非均匀磁场、温度复合场对磁流变液剪切应力的影响。简单介绍了磁流变液及其特性,回顾国内外磁流变液研究现状及其剪切应力测量装置的发展,着重从磁场、温度角度阐释了静态匀强磁场磁流变液剪切模型的失效性,结合非均匀磁场、温度复合环境,给出了研究目的和研究方法,其意义旨在研究非均匀磁场、温度复合作用对磁流变液剪切应力的影响,为磁流变器件设计与应用提供参考。本文主要进行的工作如下:(1)建立了非均匀磁场作用下磁流变液剪切应力微观模型。考虑非均匀磁场、温度对磁偶极子间相互作用力的影响,指出温度改变磁偶极子热运动,对相互作用力起次要作用;而磁场改变磁偶极子磁化强度等,对相互作用力起决定性作用。非均匀磁场等效为多个均匀磁场的组合,根据安培分子电流假说先求得匀强磁场磁偶极子剪切应力理论公式,再对各个均匀磁场剪切应力进行积分求得非均匀磁场剪切应力公式,得到磁流变液剪切应力的各个影响因素。(2)开发了非均匀磁场、温度复合场磁流变液剪切应力测量装置,主要包括非均匀磁场、温度复合场环境发生装置、剪切装置、机械运动模块和数据采集与处理模块等四个部分。选定提拉法对磁流变液剪切应力进行测量,并用复合的方式搭建非均匀磁场、温度发生装置,通过ANSYS仿真辅助调整磁流变液剪切装置剪切方向,结合单片机部分实现剪切应力的自动测量,完成测量装置整体设计。(3)完成了非均匀磁场、温度复合场空间分布的描述。同一时刻实验装置内磁流变液温度处处相等,不同时刻温度对磁流变液剪切应力的影响进行纵向比较。实验区域内,两个C型电磁铁空间磁感应强度分布不是简单的单个电磁铁磁场的叠加,需要依据磁路定理、ANSYS仿真和数据测量,得出非均匀磁场空间磁感应强度分布的准确描述。(4)完成非均匀磁场、温度复合场作用下磁流变液剪切应力测量,并对实验数据进行分析:相同磁场分布,复合场磁流变液剪切应力测量值与匀强场剪切应力模型计算的理论值存在差异,说明复合场环境匀强场理论的失效性;相同温度下,磁场磁流变液剪切应力随磁感应强度增大而增大;相同磁感应强度下,剪切应力随着温度的上升而下降;磁感应强度场越大,温度上升对磁场影响越大,对剪切应力影响也越大;相比较而言,磁感应强度的上升对剪切应力的影响要大于温度上升的影响。研究不仅验证了实验装置及测量结果的准确性,还对差异性可能产生的原因进行了分析。模拟磁流变元器件的工作环境,通过研究了磁流变器件因磁场、温度改变而产生的失效机制,为磁流变元器件设计研发提供一定的指导意义。
[Abstract]:Magnetorheological fluid is an important branch of the intelligent materials, without magnetic field performance for the suspended Newton fluid, when the external magnetic field exists, can milliseconds into viscous solid or solid structure, the reversible transformation is called magnetorheological effect. The research and development of magnetorheological devices is based on magnetorheological effect. The magnetorheological fluid shear characteristics of the most widely used. The shear properties of magnetorheological fluid by magnetic field, temperature, gravity, shear rate, dispersion of soft magnetic particles, device structure and material properties, effect of surface roughness and other factors. At the same time Mr devices work not avoid generate heat to change work the temperature, which makes the most of the time in the field of magnetorheological devices, the ambient temperature of the composite magnetorheological device mostly static magnetic field of magneto rheological fluid shear stress model based on the magnetic field and temperature is not. The device of changes that lead to failure of failure. Through the environment simulator, research on non uniform magnetic field, the influence of temperature field on composite magneto rheological fluid shear stress. Introduces magnetorheological fluid and its characteristics, reviews the domestic and foreign research status of magnetorheological fluid and shear stress measuring device, mainly from the temperature field, explained the failure of static magnetic field of magneto rheological fluid shear model, combined with the nonuniform magnetic field, the temperature of composite environment, gives the research purpose and research methods, the significance to study the inhomogeneous magnetic field, combined effects of temperature stress of the magnetorheological fluid shear, provides the reference for the design and Application of magnetic rheological device. The main work of this paper is as follows: (1) the establishment of a non-uniform magnetic field of magneto rheological fluid shear stress model. Considering the micro inhomogeneous magnetic field and temperature on the interaction between the magnetic dipole The influence of temperature change, pointed out that the magnetic dipole thermal motion plays a minor role on the interaction and change of magnetic dipole magnetic field; magnetization, plays a decisive role in the interaction. The non-uniform magnetic field is equivalent to a uniform magnetic field, according to a molecular current hypothesis to obtain the magnetic field of magnetic dipole shear stress theory formula then, the uniform magnetic field shear stress were obtained by integrating the non-uniform magnetic field shear stress formula factors by magnetorheological fluid shear stress. (2) developed a non uniform magnetic field, temperature field of composite force measuring device of magnetorheological fluid shear, including non-uniform magnetic field, the temperature field of composite environment device, cutting device, four parts mechanical motion module and data acquisition and processing module. The selected Czochralski method of magnetorheological fluid shear stress were measured, and the complex was built by way of Non uniform magnetic field generating device, temperature, through the ANSYS simulation aided adjustment of magnetorheological fluid shear device shear direction, automatic measurement based on single chip implementation of the shear stress, the overall design is completed. The measuring device (3) completed the non-uniform magnetic field distribution, temperature field of composite space description. At the same time in the magneto rheological experimental device the temperature of the liquid equal everywhere, compare the effect of different time temperature of the magnetorheological fluid shear stress. The experimental region, a superposition of two C type electromagnet spatial distribution of magnetic induction intensity is not a simple single electromagnet magnetic field, according to magnetic circuit theorem, ANSYS simulation and measurement data, the inhomogeneous magnetic field spatial distribution of magnetic induction intensity accurate description. (4) non uniform magnetic field, the temperature field of composite magnetorheological fluid shear stress measurement and analysis of the experimental data: the same magnetic field distribution, magnetic field of composite Fluid shear stress measurements and uniform shear force field difference model to calculate the theoretical value, indicating that the composite field uniform magnetic field theory of failure; under the same temperature, the magnetic rheological fluid shear stress increases with the increase of magnetic induction intensity; the same magnetic induction intensity, shear stress decreased with the increase of temperature field; magnetic induction intensity increases, the temperature rise of the influence of magnetic field on the stress, the greater the impact on shear; in comparison, higher magnetic induction intensity of shear stress is greater than the impact of temperature rise. The accuracy of research not only verified the experimental device and measurement results. The reason for the different possible are analyzed. Simulation of magneto rheological components of the working environment, through the study of magnetorheological devices due to the magnetic field, temperature change failure mechanism, provide for magnetorheological components design research The guiding significance.

【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB381

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