(64d) Engineering Magnetic Composites for Improved Shear Behavior through Orthogonal Means

Magnetorheological fluids (MRFs) are fundamentally simple composites of magnetic particles in a non-magnetic carrier fluid that are able to switch between liquid-like and solid-like states depending on the presence of a magnetic field. MRF shear strength is dependent on many factors such as magnetic particle loading, carrier fluid viscosity, fluid hysteresis and aging, and magnetic field strength. While MRFs were first discovered decades ago in the early 20^th century, and some industries show ongoing research efforts in MRFs such as civil infrastructure (earthquake dampers) and automotive/aerospace (shock absorbers) many key challenges have limited there widespread adoption. While the Koh Laboratory is investigating solutions to issues of colloidal and chemical stability, of critical concern is the power that is required to actuate MRFs. While at the lab scale MRFs are often actuated using a permanent magnet, MRFs in practice are actuated by magnetic fields generated by inductor coils, meaning that the magnetic field will be based on the power (current) supplied to the inductor. A strong MRF typically requires a high magnetic field, which means high power. High power requirements will limit the utility of MRFs during environmental disasters (think: power plants going down during earthquakes) or for wearable technologies (joint shock absorbers for prosthetics). Recent work out of the Koh Lab has investigated new classes of inclusions into MRFs based on elastic and immiscible fluidic components to increase shear strength without increasing magnetic field. This opens up MRFs to a broader range of applications while keeping the fluids safe and reliable.