Soft magnetorheological elastomers as new actuators for valves

The actuation behavior of soft silicone-based magnetorheological elastomers in magnetic fields of variable strength was investigated. An inhomogeneous magnetic field gives rise to a reversible actuation effect, which is the result of the competition between magnetic and elastic forces in the material. Magnetorheological elastomers are capable of performing more pronounced deformations than known rigid actuator materials. In this article, the actuation behavior of magnetorheological elastomer ring-shaped bodies in a valve-type device for the control of an air flow is demonstrated. For this purpose, magnetorheological elastomer rings with different Shore hardness were prepared and used in the valve. In addition to the common isotropic magnetorheological elastomer samples, rings with an anisotropic arrangement of the magnetic particles were also prepared. The actuation of these anisotropic magnetorheological elastomers was compared with that of the isotropic samples. Based on simulations, the inhomogeneity of the magnetic field at the magnetorheological elastomer material which is required for the actuation could be strongly affected by the shape in the design of the magnetic yoke. In this study, the closing characteristics of the valve with different yoke shapes and magnetorheological elastomer materials were evaluated by measuring the dependence of the air flow rate on the magnetic field strength. It is demonstrated that the air flow through the valve can be controlled by the current in the field-generating coil, which yields the base for a new type of magnetic valve.