The anomalous change of the sound property of electrorheological fluid

The properties of ultrasonic wave propagating in electrorheological (ER) fluid as a function of the intensity of electrical field and the concentration of particles are researched. Three kinds of dielectric particles (BaTiO/sub 3/, SrTiO/sub 3/ and KNbO/sub 3/)-are used as the suspensions particles. The applied electric field is in the range of 200 V to 3000 KV. Experimental results show that the time of flight depends on the kind of dielectric particles and is related to the intensity of electrical field and the concentration of particles. There is a critical intensity of electrical field and an optimization concentration of particles for the largest change of the time of flight to occur. When the intensity of applied electrical field increases to the critical value, the particle chain (or bridged fibrils) form. The stronger the electrical field the smaller the amplitude of ultrasound is, when the intensity of electrical field is larger than the critical value. The experimental system, measurement method, experimental results and discussion are presented.