Development of novel smart MR-gates for wireless dynamic control of fluid flow

With the current advancements in smart materials, magneto-rheological composites have found many applications in a variety of bio-medical engineering problems. The smart devices encompassed by this study are composed of magnetic and nonmagnetic layers. In these composites, the magnetic or magneto-rheological layers serve as the movement control mechanism whereas the nonmagnetic layers serve to rigidify the composite. The dynamic response of the magneto-rheological fluid or of the magnetic particles inside the composite provides real time controllability during the shape adaptation process. Properly designed smart composites can be utilized in the active control of fluid retention/release inside a custom shaped reservoir or dynamic control of the fluid flow though any type of tube or conduit. Depending on the desired application, the means of activation and deactivation might be different but the general idea remains the same: to use magnetic flux on magneto-rheological or magnetic composite to change its properties, hence allowing dynamic interaction with the fluid environment. In this study two types of smart MR-gate were developed. The first type included mini magnetic elastomers, whereas the second type used mini magneto-rheological sponge composites. These smart MR-gates were employed in fluid flow control in horizontal and inclined closed channels. An 81.3% reduction of the flow rate was accomplished during the flow of water inside a horizontal channel with the thin smart MR-gate T4 when 0.125 T of magnetic flux was applied. This control device had a composite mixture ratio of 62.5%Fe-37.5%Si, a concentration of magnetic particles of 0.015 74 g mm(-3) and a 0.61 mm thickness. A 42.9% increase of the flow rate was established during flow inside a 45 degrees inclined channel with smart MR-gate TH1 with an applied magnetic flux of 0.125 T. This smart gate had a composite mixture ratio of 87.5%Fe-12.5%Si, a thickness of 3.16 mm and a concentration of magnetic particles of 0.004 56 g mm(-3). The experimental results show very close dependence of the fluid flow on the dynamically controlled rigidity of the smart MR-gates. The resistance to bending of these composites increases with higher penetration of magnetic flux through a composite containing a high concentration of magnetic material. Consequently the flow of fluid through a channel can be controlled instantaneously using the novel smart MR-gates designed and developed in this study.