Experimental study of sound transmission loss in electrorheological fluids under DC voltage

The electrorheological (ER) liquids possess the ability to
change their physical properties like the apparent viscosity and modulus of
elasticity which is related to stiffness under influence of external electric
field. They serve successfully in the field of semi-active/active vibration
control - as well as in many other areas. The STL was investigated for various
kinds of ER suspensions in the frequency range from 100 Hz to 2 kHz. An
influence of the electric field density on the STL was different for normal and
tangential sound wave propagation. In both cases the STL decreases with the
increasing electric field density. Those properties can be potentially useful in
sound propagation control applications.