Test Method for Rheological Behaviors of Magnetorheological Grease Based on Coaxial Cylinder Shear Mode and Rheometer

2011 ◽  
Vol 291-294 ◽  
pp. 1929-1934
Author(s):  
Li Juan Fu ◽  
Chang Rong Liao ◽  
Jian Zuo Ma
Keyword(s):  
Shear Stress ◽  
Angular Velocity ◽  
Magnetic Flux ◽  
Flux Density ◽  
Coaxial Cylinder ◽  
Approximate Algorithm ◽  
Magnetic Flux Density ◽  
Shear Mode ◽  
Rheological Behaviors ◽  
Test Methodology

A test methodology for rheological behaviors of MR greases based on double rotational coaxial cylinder shear mode is presented in this paper. Both flow velocity profiles and shear stress profiles of MR greases in shear channels are analytically explored. The theory relationship between shear stress acted on MR greases and transmission torques is established, an approximate algorithm is put forwarded to acquire nominal shear stresses by transmission torques. On the basis of differential equation and its rational boundary conditions from stress equilibrium of MR greases micro-unit, an approximate corresponding algorithm is worked out for nominal shear strain rates by rotor angular velocities. The relationship between average value of magnetic flux density in annular channels and excitation electrical currents are experimentally obtained. Based on test methodology above-mentioned, a rheometer is fabricated and modulated, in which torque sensor, angular velocity sensor and ampere meter are respectively used to test transmission torque, angular velocity and electrical current. Rheological parameters of MR grease from the rheometer, whose shear rate is more than 2000 1/s and magnetic flux density acting on MR greases exceed 0.6T, are in good agreement with those from test conduced by commercial theological rheometer.

A novel bi-directional shear mode magneto-rheological elastomer vibration isolator

2020 ◽  
Vol 31 (17) ◽  
pp. 2002-2019 ◽  
Author(s):  
Amir Jalali ◽  
Hashem Dianati ◽  
Mahmood Norouzi ◽  
Hossein Vatandoost ◽  
Mojtaba Ghatee
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Excitation Frequency ◽  
Magnetic Flux Density ◽  
Shear Mode ◽  
Vibration Isolator ◽  
Horizontal Shear ◽  
Shear Modes ◽  
Magneto Rheological ◽  
Mechanical Devices

In this article, a novel bi-directional shear mode magneto-rheological elastomer–based vibration isolator has been designed, fabricated, and characterized to improve the dynamic response and identification of this class of “intellectual” mechanical devices. A heuristic embodiment has been realized in order to design such an isolator wherein both the vertical and horizontal directions can be operated only in the shear mode not only individually but also simultaneously. Two fixtures have been designed for performing the characterization of the magneto-mechanical behavior of the proposed magneto-rheological elastomer isolator in the vertical and horizontal shear modes under wide ranges of strain amplitude (4%–32%), excitation frequency (1–8 Hz), and magnetic flux density (0–220 mT). Experimental results revealed maximum relative magneto-rheological effects of 35% and 27 % in the vertical and horizontal shear modes, respectively. Furthermore, basic mathematical models of single-degree-of-freedom systems, employing the magneto-rheological elastomer–based isolator in the vertical and horizontal shear modes, have been established. The proposed magneto-rheological elastomer isolator in the vertical mode exhibited natural frequency shift of 6.1% by a small increment in the magnetic flux density which approves the potential of the proposed bi-directional shear mode magneto-rheological elastomer–based vibration isolator for vibration control applications, such as seat suspension systems.

scholarly journals The Influence of Additives on the Rheological and Sedimentary Properties of Magnetorheological Fluid

2021 ◽  
Vol 7 ◽  
Author(s):  
Xiangcheng Zhang ◽  
Xiaotong Liu ◽  
Xiaohui Ruan ◽  
Jun Zhao ◽  
Xinglong Gong
Keyword(s):  
Shear Stress ◽  
Magnetic Flux ◽  
Stearic Acid ◽  
Flux Density ◽  
Carbonyl Iron ◽  
Mass Fraction ◽  
Iron Particle ◽  
Magnetorheological Fluid ◽  
Magnetic Flux Density ◽  
Carbonyl Iron Particle

In this research, the influence of additives on the rheological and sedimentary properties of the magnetorheological fluid (MRF) was tested and analyzed. The additives were stearic acid, sodium dodecyl sulfate (SDS), and their mixture, respectively. The MRF was composed of carbonyl iron particle, silicone oil, liquid paraffin, graphite particle, bentonite, stearic acid, and SDS. The results indicated that the rheological properties of the MRF were mainly influenced by the mass fraction of carbonyl iron particle. When the mass fractions of carbonyl iron particle and additive were the same, the shear stress of MRF with stearic acid was larger than that of MRF with SDS, and the maximum increment was 73.81%. When the mass fraction of carbonyl iron particle was 40–50%, the shear stress of MRF increased firstly and then decreased with the increase of the external magnetic flux density. When the mass fraction of carbonyl iron particle was 60–70%, the shear stress of MRF increased firstly and then was stable with the increase of the external magnetic flux density. The results indicated that the sedimentary property of MRF with the mixture was better than that of MRF with the stearic acid and SDS. The settling rate of MRF with the mixture increased 91.53% compared to other additives.

Static and Dynamic Characterization of Magnetorheological Elastomers Under Shear Mode Operation

2018 ◽  
Author(s):  
Ashkan Dargahi ◽  
Ramin Sedaghati ◽  
Subhash Rakheja
Keyword(s):  
Magnetic Flux ◽  
Shear Strain ◽  
Flux Density ◽  
Volume Fraction ◽  
Dynamic Properties ◽  
Magnetic Flux Density ◽  
Shear Mode ◽  
Iron Particles ◽  
Magnetorheological Elastomers ◽  
Mode Operation

Static and dynamic properties of six magnetorheological elastomers (MRE) with iron particles volume fraction ranging from 12.5% to 40% were experimentally characterized under shear mode operation. The experiments were designed on the basis of standardized methods defined in ISO-1827 and ISO-4664. The static shear stress-shear strain data obtained under strains up to 30% were used to quantify absolute and relative MR effects of the MREs as functions of magnetic flux density in the 0 to 450 mT range. The MRE specimen with highest iron particles fraction and a softening agent revealed greatest MR effect. The dynamic characteristics of this MRE specimen were then evaluated under harmonic excitations in the 0.1–50 Hz frequency range with shear strain amplitude and magnetic flux density ranging from 2.5 to 20%, and 0 to 450 mT, respectively. The data were then utilized to evaluate elastic and loss shear moduli of the specimen.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

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