Characteristic analysis of magnetorheological fluid based on different carriers

In order to prepare special MRFs to satisfy the demands of tracked vehicle,two different carrier fluids were used to prepare MRFs.Preparation of MRF,which are based on carrier of special shock absorption fluid and 45# transformer oil,was finished.And characteristics of these samples were tested and analyzed.The results show that Tween-80 and Span-80 can improve the sedimentary stability,and the larger mass fraction can also increase the sedimentary stability.Using 45# transformer oil instead of special shock absorption fluid as a carrier of MRF,the shear yield stress remains nearly constant but the viscosity and the sedimentary stability are reduced.The MRF with diameter of 2.73 μm shows better sedimentary stability than that of the MRF with diameter of 2.30 μm,or 4.02 μm.Stearic acid obviously improves sedimentary stability and off-state viscosity,but has no function on the shear yield stress.In magnetic field of 237 kA/m,the shear yield stress of MRF based on special shock absorption fluid is 18.34 kPa and the shear yield stress of MRF based on 45# transformer oil is 14.26 kPa.     

无毒低污染油基切削液的研究

依据“一剂多用”原则,以油酸、油酸三乙醇胺、苯并三氮唑、三乙醇胺为原料,采用正交试验法优化设计了不含亚硝酸盐、磷、硫、苯酚等有害元素的无毒低污染油基切削液．研究结果表明：该切削液具有优良的润滑性、防锈性和防腐性,具有良好的应用前景．     

Optimizing control of a two-span rotor system with magnetorheological fluid dampers

A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological (MRF) dampers is designed. A finite element model of the MRF damper-rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled (first critical speed region 37%, second critical speed region 42%). To reflect advantages of optimizing strategy presented and validate the intelligent optimization control technology, detailed experiments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.     

交变磁场下盘型磁流变流体阻尼器的动力特性

为了掌握交变磁场对基于剪切方式的盘型磁流变（MR）流体阻尼器动力特性的影响，试验研究了正弦磁场下支承在盘型磁流变流体阻尼器上的柔性转子系统的动力特性.通过测量不同磁场频率和强度下转子系统的运动轨道、振动时间历程和不平衡响应曲线，并与恒定磁场下的结果进行了比较.结果发现，磁场的频率对盘型磁流变流体阻尼器的动力特性有着显著的影响.随着磁场频率的增大，盘型磁流变流体阻尼器抑制转子振动的能力减小.当磁场的频率高于一个临界频率后，转子系统的动力特性与无磁场时的动力特性相同，正弦磁场不能够控制磁流变流体阻尼器的动力特性.磁场强度越大，正弦磁场的临界频率越高.     

传动装置中磁流变液的稳态流动分析

为了了解磁流变液在传动装置中的流动,基于Bingham模型和流体动量方程,分析稳态下传动装置中磁流变液的流动特性。研究结果表明,在同步工况下,传动装置流场中磁流变液未屈服,各点角速度相同;在滑差工况下,随外加磁场的增大和滑差转速的减小,磁流变液逐渐从完全屈服向部分屈服转变;磁流变液完全屈服时,磁流变液角速度随半径呈非线性增加,工作间隙中磁场越强,流场的非线性分布越明显;磁流变液部分屈服时屈服区域随外加磁场的增大而减小,随滑差转速的增大而增大,未屈服区与主动转子相连;稳态下磁流变传动装置传递的转矩随外加磁场的增加而近似呈线性增大,但在相同外加磁场下,传递转矩基本不随滑差转速改变而改变,表现出良好的恒转矩特性。     

Rheological properties of magnetorheological fluid prepared by gelatincarbonyl iron composite particles

1INTRODUCTION Smartmaterialisanimportantbranchofnewmaterial.Smartmaterialincludesthreepartsthat areelectrorheological(magnetorheological)fluids,shapememoryalloy,andelectrostriction(magne tostriction)material.Theresearchofsmartmate rialusuallyinvolvesmaterialscience,mechanics,highpolymerchemistry,andautomaticcontrol,etal.Asoneofthesmartmaterials,electrorheologi cal(magnetorheological)fluidshavebeenrapidly developedinrecentyears.Becausemagnetorheo logicalfluidshavemoreexcellentpropertiestha…     

Rheological properties of magnetorheological fluid prepared by gelatin-carbonyl iron composite particles

Gelatin — carbonyl iron composite particle was prepared by micro emulsion method. The analysis of scanning electron microscope(SEM) shows that the ultrafine particles are spheroids coated by gelatin, and the average sizes of particles are 3 – 10 μm. The specific saturation magnetization σ_s is 130.9 A · m²/kg, coercivity H _c is 0.823 A/m, and residual magnetism r is 4.98 Am²/kg for the composite particles. It is shown that the particles possess properties of soft magnetic. The yield stress of magnetorheological fluid (MRF) with composite particle reaches 70 kPa at 0.5 T magnetic induction. Magnetorheological effects are superior in lower magnetic field intensity and the subsidence stability of the MRF is excellent compared with pure carbonyl iron powder.     

递归响应法对磁流变阻尼结构的时滞补偿

控制系统中的时滞现象是影响控制效果的不可忽视的因素。文章采用递归响应法对磁流变阻尼控制系统的算法进行仿真计算,分析在不同情况下递归响应法对磁流变阻尼控制系统的时滞补偿效果,并与主动控制系统进行比较。结果表明,递归响应法对磁流变阻尼控制系统有一定的补偿效果,对主动控制系统效果更加显著。     

Damping of magnetorheological elastomers

The damping property of magnetorheological elastomers(MREs) is characterized by a modified dynamic mechanical-magnetic coupled analyzer.The influence of external magnetic flux density,damping of matrix,content of iron particles,dynamic strain and driving frequency on the MREs’ damping was investigated experimentally.The results indicate that the MREs’ damping property depends on the interfacial slip between the inner particles and the matrix.Different from the general composite materials,the interfacial slip in MRE is affected by the external applied magnetic field.     

水泥砂浆外涂有机硅烷防护效果研究

为了研究外涂有机硅水泥砂浆材料的防护效果,用有机硅涂料对水泥砂浆进行表面涂层处理,并与未涂层水泥砂浆和涂丙烯酸的水泥砂浆相比较,系统研究了改性有机硅涂层对防水抗渗性能、抗碳化性能、抗氯离子渗透等性能的影响。试验结果表明：有机硅外涂水泥砂浆呈现出较好地疏水效果,使用有机硅外涂水泥砂浆的防水抗渗性能大大改善了;与空白组、丙烯酸组相比,涂有有机硅涂层的砂浆的氯离子扩散系数显著降低,约为空白组的1／4,约为丙烯酸组的1／3;随着养护时间的增加,涂有有机硅涂层的试块的碳化程度明显低于空白组和丙烯酸组,而且碳化深度增长速度明显变慢;空白样水泥砂浆密实性较差,表面粗糙多孔,试块结构疏松,而加了硅烷的试块涂料与水泥浆表面粘结紧密,界面区并不明显。为烷氧基有机硅烷作为水泥砂浆防护材料实际工程应用奠定一定的基础。     

Dynamic damping property of magnetorheological elastomer

Magnetorheological elastomer(MRE) is a new kind of smart materials,its dynamic mechanic performances can be controlled by an applied magnetic field.MRE is usually used as a stiffness-changeable spring in the semi-active vibration absorber.In order to get perfect vibration control effect,low dynamic damping of MRE is need.But the dynamic damping of MRE was not studied deeply in the past.The dynamic damping of MRE was studied and analyzed.The influences of different test conditions including test strain amplitude,test frequency and test magnetic field were deeply studied.MRE sample and pure silicone rubber sample were prepared and tested under different conditions.The test results show that the main source of dynamic damping is the friction between iron particles and rubber matrix.And the friction is mainly influenced by the strain amplitude and test magnetic field.     

碳纤维/膨胀石墨协同复合对硅橡胶性能的影响

采用溶液插层法制备了膨胀石墨(expanded graphite,EG)/硅橡胶(VMQ)导热复合材料,利用短切碳纤维(carbonfiber,CF)对复合材料体系进行增强.研究了EG、CF和钛酸酯偶联剂对硅橡胶导热和力学性能的影响.结果表明:短切CF与EG有良好的协同复合作用,一定量的钛酸酯偶联剂可以有效地改善填料与...     

磁流变阻尼器结构改进设计与性能研究

为了研究新型可控流体磁流变液的特性,以及利用磁流变液为流体的阻尼器的阻尼特性。讨论了描述磁流变液的流变模型,即在分析现有磁流变阻尼器结构的基础上,提出了一种改进的阻尼器结构,并对改进结构进行了性能测试．测试结果表明：Herschel-Bulley模型能更好地描述磁流变液的力一速度特性;改进结构的磁流变阻尼器,可使阻尼特性得到提高;在三角波激励情况下,当速度较大时磁流变液存在剪切稀化现象;在正弦波激励情况下,磁流变液存在非线性迟滞现象．     

磁流变液屈服应力计算模型研究

为了改善磁流变液颗粒链模型的准确性,对比分析了经典偶极子模型、局部场偶极子模型及有限元模型的适用范围,提出了一种新型颗粒链计算模型———分裂偶极子模型,并计算了分裂磁偶极矩,得到颗粒间作用力的误差大小.研究表明:颗粒链在外加磁场作用下,其作用力模型可以用两对经典偶极子模型表示;当外加磁场较小时,分裂偶极子模型中心线磁场误差大于20%,此时模型不再适用;当外加磁场为中强磁场时,分裂偶极子模型适用于任意颗粒间距,且其中心线磁场误差小于15%,颗粒间相互作用力误差小于10%,分裂偶极子模型优于经典偶极子模型和局部场偶极子模型.     

摩托车磁流变阻尼器设计研究

为了进行摩托车磁流变阻尼器的研究,选择剪切阀式作为摩托车磁流变阻尼器的工作模式,推导了基于平行结构的Bingham模型阻尼器阻尼力的计算表达式,设计制作了单出杆磁流变阻尼器,并对其阻尼特性进行了实验研究.实验表明:实验结果与理论分析结果相吻合,其设计原理和分析方法是正确可行的;该磁流变阻尼器有较好的可控性,能满足摩托车的使用要求.     

Control effect of fluid entry pressure on hydrocarbon accumulation

The micromigration of oil-drive-water and gas-drive-water in oil and gas fields was studied, by using core slices and micro-experimental technology, and the migration processes and characteristics of oil and gas in pores and throats were observed, as well as entry pressures of oil/gas migration. Research shows that entry pressures of both oil-drive-water and gas-drive-water increase obviously as porosity decreases, and the statistical regularity observes the power function variation. However, there is a complex changing relationship between porosity and different entry pressure values of the two replacement processes, forming three curve sections, each representing a different accumulation significance. When the porosity is over 10%–12%, the difference between oil-drive-water and gas-drive-water entry pressures is small. Both oil and gas can migrate and accumulate in this kind of reservoir. The probabilities of oil and gas reservoir formation are nearly equal, forming conventional oil/gas pools. When porosity is between 5% and 10%–12%, the difference between the two is obvious, which indicates that this kind of reservoir can seal oil, but can also be a reservoir for gas, easily forming unconventional hydrocarbon pools (deep-basin gas pools). When porosity is less than 5%, the difference is indistinct and the entry capillary pressures show the same sealing function for oil and gas. In this condition, both oil and gas pools are difficult to form. Experimental results give a rational explanation for the difference of accumulation probability between deep-basin gas and deep-basin oil, and also for the mechanism of tight sand acting as cap rock.     

Applications of fluid substitution effect analysis on seismic interpretation

The root mean square(RMS) difference of time-lapse seismic amplitudes is routinely used to identify the substituted fluid type in a reservoir during oil field production and recovery. By a time-lapse seismic method, we study the effects of fluid substitution in a physical model, which is an analogy of the three-dimensional inhomogeneous reservoir. For a weak inhomogeneous medium, gas/oil substitution results in positive anomalies in the reservoir layers, and negative anomalies below the bottom of the reservoir layers; while water/oil substitution causes only weak variations in the reservoir layers, but positive anomalies below the bottom of the reservoir layers. For the strong inhomogeneous medium, no matter what kind of fluid substitution(gas/oil or water/oil), there are significant anomalies in seismic amplitude difference attributes both in and below the reservoir layers. Therefore, for weak inhomogeneous media, such as tight sandstone or thin interbedded layers, the RMS amplitude difference attributes can be used to monitor fluid changes and predict the drilling direction; for inhomogeneous medium with karst carves or fractures, it is difficult to accurately determine the distribution of fluids with the RMS amplitude difference attributes.     

Autoregressive trispectrum and its slices analysis of magnetorheological damping device

A combined magnetorheological damper combined with rubber spring and magnetorheological damper is addressed.This type of damping device has inherited the merits of rubber spring and the magnetorheological damper.The test damping device is made up of combined magnetorheological damper,amplitude controller,signal collecting device,computer software for dynamic analysis,etc.When a zeromean and non-Gaussian white noise interfere with the device,a time series autoregressive(AR) model is conducted by using the sampled experimental data.Trispectrum and its slices analysis are emerging as a new powerful technique in signal processing,which is put forward for investigating the dynamic characteristics of the magnetorheological vibrant device.The present of trispectrum and its slices analysis change with the variation of controllable working magnetic field of the damper correspondingly.It is indicated that AR trispectrum and its slices analysis methods are feasible and effective for investigation of magnetorheological vibrant device.     

用均匀设计法制备性能优良的磁流变液

对磁流变液组成材料的选取及相互间的配比关系进行了研究．利用均匀设计配方设计来制备磁流变液,从而通过较少的试验获得了高屈服强度、低沉降性能的优良磁流变液,并分析了不同组分对磁流变液各方面性能的影响．     

基于结构扭转反应控制的MR阻尼器位置研究

提出采用磁流变阻尼器MR控制钢筋混凝土框架—剪力墙偏心结构的扭转反应,并分析影响因素及规律。采用Matlab/Simulink工具进行数值仿真实验,分析MR阻尼器的控制策略、MR阻尼器数量以及竖向布置、水平布置等因素对偏心结构扭转反应控制效果的影响。结果表明:MR阻尼器能够有效控制偏心结构的扭转反应,其中半主动控制策略可以取得较稳定的控制效果,MR阻尼器数量和位置对结构扭转反应的控制效果具有较大影响。