Rheologcal behavior of ER fluids can be controlled by changing electric field. ER effects come from aligning dielectric particles or molecular chains. These unique characteristics can be applied to the control of local microstructures and mechanical properties of products.

Structure variation of ER fluids under electric field and shear.

What's Electro Rheological Fluids?

Electro Rheological Fluids can be changed Rheological behavior reversibly under an electric field or not. ER

Kind of Electro Rheological Fluids

Electro Rheological Fluids are categorized in "Suspension-type ER fluids", "Blended-type ER fluids" and "Homogeneous-type ER fluids".
Suspension-type ER consist of dispersed particle and insulating oil.
We may describe Blended-type ER fluids that dispersed ferroelectric polymer or polymeric liquid crystal in insulating oil.
Homogeneous ER fluids is only consist of ferroelectric polymer.

suspention-type ER

blended-type ER

Homegeneous-type ER

Mechanism of ER effect

Suspension-type ER fluid

On applying an electric field to the suspension-type ER fluid, dispersed particles polarize and form many chains (clusters) bridging electrodes.
These chains (clusters) prevent the fluid form flow under shear,which causes electrically induced shear stress.


Blended-type ER fluid

Ferroelectric polymer or polymeric liquid crystal form droplets in insulating oil.
When electric field applying,droplets form columns between electrodes.
Change in shear viscosity caused by change in these two different phase ( droplets and insulating oil)ratio that bound electrodes.