A Hybrid Model for Characterizing Pre-Yield Properties of MR Fluids

2014 ◽  
Author(s):  
Mehdi Eshaghi ◽  
Ramin Sedaghati ◽  
Subash Rakheja
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Shear Modulus ◽  
Hybrid Model ◽  
Applied Magnetic Field ◽  
Sandwich Beams ◽  
Complex Shear Modulus ◽  
Mr Fluid ◽  
Field Dependent ◽  
Complex Shear

This study aims to present a field dependent phenomenological model to characterize the Magneto-Rheological (MR) fluid in the pre-yield region under varying frequency and applied magnetic field. Systematic analytical and experimental studies are proposed to formulate a hybrid model for representing complex shear modulus of a typical MR fluid (MR 122EG from Lord Corporation) as a function of both applied magnetic field and frequency. Two fully treated MR based sandwich beams with aluminum and copper face layers and MR fluid as the core layer are designed and fabricated. Uniform magnetic flux across the sandwich beam is provided using two permanent magnets. The fabricated MR based sandwich beams are then tested on an electrodynamic shaker under sweep sine excitation and different applied magnetic field to realize the effect of external excitation frequency and applied magnetic field on the stiffness and damping properties of the structure. The finite element model based on classical plate theory is also developed to analyze vibration response of the designed MR based sandwich beams incorporated with MR fluid. Then, by correlating the finite element results with those of the experiment, the frequency and field dependent complex shear modulus of the MR fluid is identified.

Identification of Complex Shear Modulus of MR Layer Placed in Three-Layer Beam – Part 2: Algorithm

2015 ◽  
Vol 759 ◽  
pp. 15-25
Author(s):  
Mateusz Romaszko ◽  
Jacek Snamina ◽  
Sebastian Pakuła
Keyword(s):  
Magnetic Field ◽  
Shear Modulus ◽  
Field Data ◽  
Free Vibrations ◽  
Complex Shear Modulus ◽  
Mr Fluid ◽  
Magnetic Field Data ◽  
Complex Modes ◽  
Complex Shear ◽  
The Magnetic Field

The paper presents the procedure of identification of a complex shear modulus which describes properties of MR fluid in the pre-yield regime as a function of magnetic field. Data necessary for identification were collected basing on measurements of free vibrations of a three-layered cantilever beam at a special laboratory stand. Magnetic field exerting on MR fluid placed in the beam was generated by electromagnet. In the next step, complex modes of beam vibrations for various places of applying the magnetic field and its strength were calculated.

Identification of Complex Shear Modulus of MR Layer Placed in Three-Layer Beam – Part 1: Finite Element

2015 ◽  
Vol 759 ◽  
pp. 1-13 ◽  
Author(s):  
Mateusz Romaszko ◽  
Jacek Snamina
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Fluid Layer ◽  
Efficient Solutions ◽  
The Finite Element Method ◽  
Complex Shear Modulus ◽  
Mr Fluid ◽  
Linear Finite Element ◽  
Stiffness Matrices ◽  
Complex Shear

The paper presents the finite element, which can be used to analyse the vibration of a three–layer beam with magnetorheological (MR) fluid layer. The MR fluid layer was sealed with silicone rubber. On the basis of the analysis of displacements, deformations of each layer has been established. Next, potential and kinetic energy of the three–layer beam were calculated. Because of the complexity of the beam with MR fluid, efficient solutions can be obtained only after discretization of the system. The finite element method was used in the study. For this purpose the mass and stiffness matrices were determined for the proposed linear finite element of two nodes and four degrees of freedom in each node.

CHARACTERIZING THE EFFECT OF TEMPERATURE AND MAGNETIC FIELD STRENGTHS ON THE COMPLEX SHEAR MODULUS PROPERTIES OF MAGNETORHEOLOGICAL (MR) FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1318-1324 ◽  
Author(s):  
W. W. CHOOI ◽  
S. O. OYADIJI
Keyword(s):  
Magnetic Field ◽  
Shear Modulus ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Excitation Frequency ◽  
Effect Of Temperature ◽  
Complex Shear Modulus ◽  
Mr Fluids ◽  
Complex Shear ◽  
Frequency Coverage

When a magnetic field is applied across MR fluids, a yield stress is developed, and their rheological properties can then be categorized into two distinct regimes; pre-yield and post-yield. This paper concerns the viscoelastic behaviour of MR fluids in the pre-yield region. Oscillatory tests were carried out to determine the complex shear modulus properties of MR fluids between the temperature range of -20°C and +50°C. The test results show that the storage modulus and loss modulus increased in value as the excitation frequency was increased from 5Hz to 50Hz. The complex modulus was also found to be influenced by changes in temperature; the higher the temperature, the lower the complex modulus. This is consistent with the behaviour of viscoelastic polymers. The sets of temperature-dependent and frequency-dependent data were subsequently condensed using the method of reduced variables into master curves of complex modulus which effectively extended the frequency coverage of the data at the reference temperature.

SIMULATION OF NONLINEAR MAGNETORHEOLOGICAL PARTICLE-FILLED ELASTOMERS

2013 ◽  
Vol 02 (03n04) ◽  
pp. 1350018
Author(s):  
SHULEI SUN ◽  
XIONGQI PENG ◽  
ZAOYANG GUO
Keyword(s):  
Magnetic Field ◽  
Shear Modulus ◽  
Young’S Modulus ◽  
Applied Magnetic Field ◽  
Smart Materials ◽  
Young's Modulus ◽  
Particle Volume ◽  
Magnetorheological Elastomers ◽  
Maxwell Stress Tensor ◽  
Element Simulation

Polymer matrix filled with ferromagnetic particles is a class of smart materials whose mechanical properties can be changed under different magnetic field. They are usually referred to as magnetorheological elastomers (MREs). A finite element simulation was presented to describe the mechanical behavior of MREs with the nonlinearity of the particle magnetization being incorporated. By introducing the Maxwell stress tensor, a representative volume element (RVE) was proposed to calculate the Young's modulus and shear modulus of MREs due to the applied magnetic field. The influences of the applied magnetic field and the particle volume fractions in the shear modulus and Young's modulus were studied. Results show that the shear modulus increases with the magnitude of the applied magnetic field, while the Young's modulus decreases.

scholarly journals A sensitive dynamic viscometer for measuring the complex shear modulus in a steady shear flow using the method of orthogonal superposition

1995 ◽  
Vol 34 (6) ◽  
pp. 606-621 ◽  
Author(s):  
Jos Zeegers ◽  
Dirk van den Ende ◽  
Cor Blom ◽  
Egbert G. Altena ◽  
Gerrit J. Beukema ◽  
...  
Keyword(s):  
Shear Flow ◽  
Shear Modulus ◽  
Steady Shear ◽  
Complex Shear Modulus ◽  
Complex Shear ◽  
Steady Shear Flow ◽  
Dynamic Viscometer
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