No abstract

The measurement of the dielectric spectra of PAnQR based ER fluids under shear and electric fields is discussed and results presented. Data in which either but not both shear or electric fields are present are submitted to analysis in terms of known theories. For flow alone, that analysis provides information on the attenuation of polarization by the uniform shear fields whilst the polarization of quiescent fluids by electric fields may lead to estimates of particles packing within the columns. Permittivity data when both fields are acting is presented, but in the absence of suitable theory, not modelled quantitatively. Empirical correlations are discussed and the conclusion drawn that fibrillation is readily suppressed by even moderate shear rates, although long range dipolar forces still persist to high shear rates.The dc conductance of these fluids have also been measured. This together with permittivity data under ER fluid working conditions has importance in establishing the electrical parameters for any ER fluid. 1.

How electromagnetic waves and dielectric materials interact is a problem that has taxed the mind of humans for many years. One of the early pioneers was, of course, Maxwell, who unified electric and magnetic fields into a simple set of equations. Since then our knowledge has progressed in leaps and bounds, even though it has always lagged behind our curiosity.