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.

Simulation and Validation of an Anisotropic Magnetorheological Elastomers Mold with Various Alignment Angles

2018 ◽  
Vol 772 ◽  
pp. 66-70
Author(s):  
Ilham Bagus Wiranto ◽  
Ubaidillah ◽  
Dody Ariawan ◽  
Faishal Harish ◽  
Saiful Amri Mazlan ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Flux Density ◽  
Mold Design ◽  
Magnetorheological Elastomers ◽  
Density Prediction ◽  
Best Value ◽  
The Matrix ◽  
Particle Alignment ◽  
The Difference

In this study, anisotropic magnetorheological elastomers (MREs) mold design with capability of aligning the filler in several angles (0 ̊, 45 ̊, and 90 ̊) were developed. The mold was equipped with electromagnet coil to generate the magnetic flux. The distribution of magnetic flux density in the mold and inside the chamber was investigated by using finite element magnetic analysis. Magnetic flux density of 0.3 T was considered best value to form good particle alignment in the matrix. Moreover, the mold design was fabricated using same material as in the simulation. The magnetic flux density was taken at casing wall and measured by gauss-meter. The data was compared with simulation results. The differences between experimental and simulation is in the range of 6-40 mT. Since the difference is insignificant, it can be said that the data is valid. Finally, the model can be used for further magnetic flux density prediction inside the chamber. In the simulation, it was found that the current needed to generate at least 0.3 T inside the chamber for 0 ̊, 45 ̊, and 90 ̊ are 0.2A, 0.1A, and 3A, respectively.

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.

Solidified microstructure evolution of Mn-Sb near-eutectic alloy under high magnetic field conditions

2009 ◽  
Vol 24 (7) ◽  
pp. 2331-2337 ◽  
Author(s):  
Qiang Wang ◽  
Ao Gao ◽  
Tie Liu ◽  
Feng Liu ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Flux Density ◽  
Volume Fraction ◽  
Primary Phase ◽  
Structure Evolution ◽  
Magnetic Flux Density ◽  
High Magnetic Fields ◽  
Magnetic Field Direction

Mn-90.8 wt%Sb alloys were solidified without and with high magnetic fields to investigate the effects of high magnetic fields on the structure evolution of the alloys. It was found that there were only MnSb/Sb eutectics without any primary phase in the alloy at 0 T, whereas a small amount of primary MnSb dendrites appeared in the MnSb/Sb eutectic matrix when the magnetic flux density was 4.4 T. In magnetic fields of 6.6, 8.8, and 11.5 T, both of two primary phases, i.e., MnSb and Sb, occurred in the matrix. In addition, the volume fraction of these two primary phases increased with increasing magnetic flux density. In magnetic fields of 8.8 and 11.5 T, primary MnSb dendrites aligned parallel to the magnetic field direction and gathered at the edge of the specimens. In contrast, primary Sb dendrites gathered in the center region of the specimens.

Characterization and modeling of hard magnetic particle–based magnetorheological elastomers

2020 ◽  
pp. 1045389X2094256
Author(s):  
Nader Mohseni Ardehali ◽  
Masoud Hemmatian ◽  
Ramin Sedaghati
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Particle ◽  
Excitation Frequency ◽  
Viscoelastic Behavior ◽  
Magnetic Flux Density ◽  
Driving Frequency ◽  
Magnetorheological Elastomers ◽  
Magnetic Poles

Hard magnetic particle–based magnetorheological elastomers are novel magnetoactive materials in which, unlike the soft particle–based magnetorheological elastomers, the particles provide magnetic poles inside the elastomeric medium. Therefore, the stiffness of the hard magnetic particle–based magnetorheological elastomers can be increased or decreased by applying the magnetic field in the same or opposite direction as the magnetic poles, respectively. In the present work, the viscoelastic properties of hard magnetic particle–based magnetorheological elastomers operating in shear mode have been experimentally characterized. For this purpose, hard magnetic particle–based magnetorheological elastomers with 15% volume fraction of NdFeB magnetic particles have been fabricated and then tested under oscillatory shear motion advanced rotational magneto-rheometer to investigate their viscoelastic behavior under varying excitation frequency and magnetic flux density. The influence of the shear strain amplitude and driving frequency is examined under various levels of applied magnetic field ranging from −0.2 to 1.0 T. Finally, a field-dependent phenomenological model has been proposed to predict the variation of storage and loss moduli of hard magnetic particle–based magnetorheological elastomers under varying excitation frequency and applied magnetic flux density. The results show that the proposed model can accurately predict the viscoelastic behavior of hard magnetic particle–based magnetorheological elastomers under various working conditions.

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.

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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