Magnetorheology is the science of the flow behavior of magnetically polarizable materials such as ferrofluids, magnetorheological fluids, and magnetorheological elastomers. These substances are so-called smart materials whose properties (viscosity, modulus, inner structure) significantly change when a magnetic field is applied. Magnetorheological investigations can be carried out with constant or variable magnetic flux density in T (Tesla) or magnetic field strength H (in A/m). Besides their ability to undergo a change in their viscosity through the application of a magnetic field, qualities such as fast response time, reversibility and improved re-dispersibility qualify magnetorheological fluids for applications such as torque or force transmission in valves, braking, and clutch systems, vibration damping, and automotive shock absorbers, as well as in the medical device industry, e.g. for “Smart Magnetix” prosthetic legs.
- Magnetorheological fluids (mr fluids) consist of magnetically polarizable particles which are suspended in a carrier fluid. When a magnetic field is applied, the particles align themselves accordingly, form chain-like superstructures, and the rheological properties often change substantially.
- Compared to mr fluids, ferrofluids have significantly smaller particles. They are made of nanoscale particles suspended in a carrier fluid and can also be activated in a magnetic field.
- Magnetorheological elastomers consist of a polymeric matrix (e.g. silicone rubber) with embedded micro- or nano-sized magnetic particles.