July 28, 2011

Magneto Rheometer

Engineers are increasingly turning to so-called smart fluids to solve complex mechanical problems. One specific type of smart fluid is the magnetorheological fluid (MR fluid) which greatly increases its viscosity to the point of becoming a viscoelastic solid when subjected to a magnetic field. Importantly, the yield stress and viscosity of the fluid when in its active state can be controlled very accurately by varying the magnetic field intensity. CPG has recently developed an MR fluid testing apparatus that integrates with a standard shear rheometer made by TA Instruments.

The MR fixture mounted on a TA Instruments AR-G2 shear rheometer

CPG has developed a hardware and software add-on that enables a current commercial shear rheometer to test magnetorheological fluids across temperature and field strengths relevant for a wide range of industries. The MR fixture leverages existing rheometer hardware and uses a parallel plate geometry in a controlled magnetic field over a wide temperature range while monitoring conventional shear viscosity parameters such as stress, strain and viscosity in steady or dynamic shearing modes. The high power magnet of this instrument provides the ability to characterize magnetorheological fluids through the spectrum of magnetic flux ranging from -1 to +1 Tesla, or more and across a broad temperature range.

The MR fixture is sold through TA Instruments. Contact Cambridge Polymer Group for more details.

Schematic diagram of sample shearing zone of MR fixture