摘要:

A method of measuring the viscoelastic properties of an electrorheological fluid (corn starch in mineral oil) using oscillatory flow in a thin rectangular tubular channel is described. The channel is formed by two conducting plates separated by insulators on two edges, and an electric field is established using the plates as electrodes. The tube is attached to a viscoelasticity analyzer that produces the desired oscillatory flow over a wide range of amplitudes at a selected frequency. The amplitude and phase of the pressure drop and volume flow are measured, from which the three fundamental parameters−shear stress, shear rate, and shear strain−are calculated at the channel walls [G. B. Thurston, J. Appl. Phys.30, 1885–1860 (1959)]. Mineral oil containing starch at concentrations from 1 to 10 g % were measured at 2 Hz with field strengths from 0 to 1829 V/mm. The shear rate dependence of the viscosity and elasticity vary with the electric field strength. The microstructure yields at a stress level which is identified in the elastic component of the shear stress. Plots of the viscous and elastic stress vs strain show that at low field strengths the microstructure degrades at strains<0.1, but at high field strengths, it degrades near unit strain. With higher starch concentrations, viscoelastic dilatancy is evident at high field strengths and high strains.

ISSN:0148-6055    

DOI:10.1122/1.550233

出版商:The Society of Rheology    

年代:1991

数据来源: AIP

摘要:

An electrorheological (ER) material composed of aluminosilicate particles in paraffin oil is studied for its response to sinusoidally oscillating shear strains of frequencies in the range of 300–400 rad/s. The response of the material is linear viscoelastic when subjected to electric fields in the range of 0.0–3.0 kV/mm. The linear viscoelastic parameters−shear loss modulus, shear storage modulus, and loss tangent−were calculated and related to the strength of the field applied to the material. The moduli were found to increase with increasing applied field and the loss tangent decreased with increasing applied field. Finally, a nonlinear data correlator program was used to simulate the ER material’s shear loss modulus as a function of frequency when modeling the ER material using the constitutive equations for a three‐parameter solid.

ISSN:0148-6055    

DOI:10.1122/1.550239

出版商:The Society of Rheology    

年代:1991

数据来源: AIP