Abstract
To enhance the yield shear stress of magnetorheological (MR) fluids is
an important task. Since thick columns have a yield stress much higher
than a single-chain structure, we enhance the yield stress of an MR
fluids by changing the microstructure of MR fluids. Immediately after
a magnetic field is applied, we compress the MR fluid along the field
direction. SEM images show that the particle chains are pushed
together to form thick columns. The shear force measured after the
compression indicates that the yield stress can reach as high as
800 kPa under a moderate magnetic field, while the same MR fluid has a
yield stress of 80 kPa without compression. This enhanced yield stress
increases with the magnetic field and compression pressure and has an
upper limit well above 800 kPa. The method is also applicable to
electrorheological fluids.