The response of electrorheological fluid under oscillatory squeeze flow

The behaviour of an electrorheological fluid under oscillatory squeeze flow is experimentally examined using a new instrument, the Micro-Fourier Rheom eter. Under high voltages a distinct flattening of the waveforms of the tra nsmitted force is observed. The amplitude and harmonic composition are inve stigated as functions of voltage, frequency and amplitude of the input osci llation. and show qualitative agreement with the theoretical hi-viscous mod el for a Bingham-type fluid. Differences in the waveforms indicate that the actual yielding process is considerably more gradual than for a Bingham ma terial. (C) 1999 Elsevier Science B.V. All rights reserved.