Functional behavior of isotropic magnetorheological gels

Abstract

Magnetorheological (MR) gels are a new class of soft polymers whose properties can be controlled using a magnetic field. The functional effectiveness of these gels depends on their magnetic controllability. In this paper, an experimental investigation on the functional behavior of a particular type of magnetorheological gels under dynamic and static shear conditions in the presence of a magnetic field is studied. MR gels are prepared with micron sized polarizable carbonyl iron particles interspersed in a polymer matrix gel. The compliance of this magnetic gel can be varied under the influence of an external magnetic field. Since dynamical mechanical analysis tests are difficult to conduct in the presence of large deformations of the order of 50% and strong magnetic fields, a free decay test apparatus is designed and fabricated for obtaining the magnetic field dependent shearing response under dynamic conditions at room temperature. It is observed that a significant change in the elastic modulus occurs in the gels under a magnetic field in the range of 0.1-0.4 T. However, no significant change in the damping ratio is observed under various magnitudes of magnetic field. It is shown that the increase in shear modulus of this kind of magnetic composite gel could be as high as 59% of the zero field value for a gel prepared with 50% by weight of carbonyl iron particles.

Stretchable polyurethane sponge reinforced magnetorheological material with enhanced mechanical properties

“…Flexible, highly sensitive, quick-responding, and environmentally friendly magnetorheological (MR) materials are highly desired in future generations of shock absorption and noise reduction devices, such as the adaptive tuned vibration absorbers, mass dampers, sensors, actuators, base isolator, etc [1][2][3][4][5]. The MR materials are classified into MR elastomers [6], MR foams [7], MR fluids [8], MR gels [9], and so on. Traditional MR fluids and MR gels are flexible, but have the problems of particle deposition, environmental contamination, sealing, etc [10][11][12].…”

Soft magnetorheological polymer gels with controllable rheological properties

“…Generally, MR gels are regarded as a type of composite consisting of magnetic particles, partially crosslinked polymer gels, and other additives. A variety of polymer gels were tried to serve as the matrix of MR gels and the magnetorheology of these MR polymer gels (MRPGs) was also characterized [2][3][4][5][6][7][8][9][10][11][12][13][14]. The early MR gels presented a liquid-like state in the absence of a magnetic field, which is actually an imitation of MR fluids with higher yield stress and lower particle settling behavior [3][4][5].…”

Magnetic field intensity effect on plane electric capacitor characteristics and viscoelasticity of magnetorheological elastomer

“…MR elastomers can be produced either in the absence or in the presence of the magnetic field. Without magnetic field, an isotropic MR elastomer is produced [17][18][19], while anisotropic MR elastomers are produced in the presence of the magnetic field [20][21][22][23]. These two types of MR elastomers are different from the formation of microparticle chains along the magnetic field lines.…”