Magnetorheological elastomers — An underestimated class of soft actuator materials

Abstract

In this paper, the results of various investigations on the viscoelastic and magnetic properties of magnetorheological elastomers (MRE) in magnetic fields of variable strength, are reported. These characteristics have a strong influence on the behavior of MRE in various applications such as vibration damping and tunable vibration absorbers. Moreover, the actuation capabilities of MRE with different kinds of deformation in a magnetic field are considered. The degree of deformation depends on the magnetic field strength and its gradient and can reach about 10%. When removing the magnetic field, the MRE body relaxes back to its initial shape. MRE materials can be used for linear actuators, where the MRE body is deformed due to the attraction by a magnetic circuit acting from one side. Such linear actuators may be applied for haptic feedback and pumps. However, ring-shaped MRE bodies can also deform radially around their cylindrical axis, if the magnetic field is oriented correspondingly. This unusual type of deformation allows the realization of a proportional valve, whose opening is controlled by the magnetic field strength. Similar configurations can be used for controllable seals, for locking devices and even for inchworm drives. Various versions of this actuation principle are discussed in the paper.

Design, Fabrication and Analysis of Magnetorheological Soft Gripper

“…Further, the permeability of magnetorheological elastomer is low (for instance in compare to electromagnetic steel). It is worth to point that similar range of permeability for MRE is also found in the work [ 7 ].…”

“…The first one is for instance exploited in the electroactive polymers to create deformation [ 1 , 4 ]. The second one is popular for instance in the ferroelectric polymers [ 1 ], magnetorheological fluids [ 5 , 6 ] and magnetorheological elastomers [ 7 ].…”

Magnetorheological elastomer‐based 4D printed electroactive composite actuators

“…These materials are divided into shape memory polymers (SMPs) [9], shape memory alloys (SMAs) [10], shape memory polymer composites (SMPCs) [11], magneto/electro materials [12], liquid crystal elastomers [13], and hydrogels [14]. Smart materials are space-time dependent and can change over time depending on the external stimuli they are exposed to, such as temperature [15], light [16], pH [17], magnetic field [18], electricity [19], and moisture [20].…”

Magnetorheological Fluid Filled Spring for Variable Stiffness and Damping: Current and Potential Performance

“…Thus, further device development is seen in utilizing magnetorheological elastomer (MRE) instead of MR fluid. Being a solid material in a passive state, MRE will resist buckling of the hollow spring, prevent oil leakage, ease device handling, and potentially enable device additive manufacturing (Böse et al, 2021;Park et al, 2022). A higher range of controllable modulus and research interest to improve this material property will enhance the variable stiffness of the device.…”