IN-SITU TIME RESPONSE MEASUREMENT OF THE MICROSPHERES DISPERSED IN ELECTRORHEOLOGICAL FLUIDS

The aggregations of different kinds of microspheres suspended in elect rorheological fluids have been observed in situ upon application of ti me-regulated electric field. It is found that both the initial respons e time and the chain's formation time depend on the conductivity of th e microspheres. Water free, watered, and metal-coated glass microspher es together with SrTiO3 and Cu microspheres were studied. Among them, the water-free glass particle shows the longest initial response (chai n formation) time of 16.7 ms (117.6 ms) under an electric pulse streng th Vp-p of 2.6 kV, while the metal-coated microsphere has the shortest initial response (chain formation) time of 0.5 ms (25.4 ms). The over all trend is that the higher the microsphere's conductivity, the short er the response time and the stronger the particles' interaction under the same external electric field. Moreover, it is found that the aggr egation of the microspheres becomes faster if the applied field streng th is increased.