This system when used with MR fluid or ER fluid
has an upper hand over both passive and active types.
Example applications include self-coupled dampers based on ER fluid
and piezoelectric ceramic for vibration control, and a flexible sandwiched ER composite for sound transmission control.
An ER fluid usually consists of fine dielectric solid particles suspended in a nonconducting oil phase.
For commercial purposes, an ER fluid should also possess properties such as low off field viscosity, low current consumption, high yield stress in electric fields, and low temperature sensitivity.
When the voltage is turned off, the ER fluid reverts to its liquid state, and the beam becomes flexible again.
ER fluids consist of a suspension of fine polarizable particles, or particles that acquire a positive charge at one end and a negative charge at the other.
In a hydraulic valve using an ER fluid, for example, all that would be needed to stop the flow would be an electric current under the control of a microcomputer.
Similarly, in a clutch, a motor-driven rotor (drive in) would transfer its spin to a drive shaft (drive out) through a thin layer of ER fluid.
A hollow beam filled with ER fluid
and fitted with load-monitoring sensors could respond to changes in load by changing, says, its stiffness and vibrational frequencies.
Many polyaniline derivatives have been reported based upon modification of oxidation state, dopant and polymerization conditions (10), since polyaniline has advantages over the other polymer particles as a polarizable particle for ER fluid
with respect to density, conductivity control, and thermal stability.
Researchers at the Cranfield Institute of Technology in Cranfield, England, already have announced making an ER fluid
containing less than 5 percent water.
Although a number of theoretical analyses and experimental observations have been conducted, the exact mechanism of forming a chainlike structure within an ER fluid
is not yet well understood.