Mechanical Properties of an Er Fluid in Tensile, Compression and Oscillatory Squeeze Tests

Abstract

In this work, the mechanical properties of an anhydrous electrorheological fluid made of carbonaceous particles dispersed in silicone oil were determined in tensile, compression and oscillatory squeeze tests. The mechanical tests were carried out on a Mechanical Testling Machine and the device developed for measuring the ER properties was composed of two parallel steel electrodes between which the ER fluid was placed. The mechanical properties were measured for different DC electric field strengths, velocity and initial gap between the electrodes, and the ERF was tested in two different ways: (a) the fluid was placed between the electrodes (configuration 1) and (b) the electrodes were immersed inside the ERF (configuration 2). The results showed that the ER fluid is more resistant to compression than to tensile, and that the shape of the tensile stress-strain curve and the tensile strength varies with the electric field strength and the initial gap between the electrodes. The compressive stress increased with the increase of the electric field strength and with the decrease of the gap size and upper electrode velocity. In oscillatory test, for both configurations 1 and 2, increasing the oscillation frequency f and the number of cycles N produced a decrease of the damping performance of the ER fluid. Besides this, the damping force of each cycle in oscillatory tests increased with N. The electric field also played an important role on the shape of the hysteresis loop (stress as a function of fluid strain) for both configurations.

Transient response of compressed electrorheological fluid

“…For low mechanical output of ER fluids working in shearing mode, to achieve higher mechanical performance, recently, compression and elongation of ER fluids have been experimentally and theoretically carried out [23][24][25][26][27][28][29][30][31][32]. These investigations indeed show that compression and elongation of ER fluids could bring much higher mechanical outputs than that working in shearing mode.…”

Compression of dispersions to high stress under electric fields: Effects of concentration and dispersing oil

“…They however very importantly recognize and discuss the consideration that the particles are flowing in/out from between the plates of the device during the tests. In a subsequent study, Vieira et al [9] did similar tests on other fluids and with different test configurations but the results were similar. Again, the tests were terminated at low strains.…”

“…Unfortunately it is very difficult to determine quantitatively the proportion of particles pushed out, a parameter which we did not measure but was considered in hindsight. This effect was pointed out in other studies [8,9] but attempts were not made to quantify it or consider it in the analysis of the data.…”

Continuum modelling of viscoelastic behavior under squeezing solicitations of electrorheological fluid

“…Hysteresis loop of stress as a function of strain for a solid electrorheological fluid under an initial electric field E 0 = 1.5 kV/mm [1]. squeeze tests carried out by Vieira et al [1] seems to be the more significant. Fig.…”