Response of a Magneto-Rheological Fluid Damper Subjected to Periodic   Forcing in a High Frequency Limit
  We explored vibrations of a single-degree of freedom oscillator with a magneto-rheological damper subjected to kinematic excitations. Using fast and slow scales decoupling procedure we derived an effective damping coefficient in the limit of high frequency excitation. Damping characteristics, as functions of velocity, change considerably especially by terminating the singular non-smoothness points. This effect was more transparent for a larger control parameter which was defined as the product of the excitation amplitude and its frequency. 
Marek Borowiec, Grzegorz Litak, Rafal Kasperek