PARAMETER-ESTIMATION AND DAMPING PERFORMANCE OF ELECTRORHEOLOGICAL DAMPERS

Electro-rheological (ER) fluid is a kind of smart material with bright prospects for industrial applications. Its viscosity can be changed i nstantaneously by changing the intensity of an imposed electric field. In this paper two types of ER dampers, the MP one with multi-electrod e plates and the SP one with sliding electrode plates, are designed. E xperiments involving sinusoidal excitations and random excitations sho w that they are very effective in vibration control for excitation fre quencies below 100 Hz, but are less or no longer effective for excitat ion frequencies over 100 Hz. It is the large viscous damping of the ER damper that suppresses the vibration in the lower frequency bands. Ho wever, ER fluid may change from liquid to a solid-like structure due t o the high intensity of an imposed electric field, which causes the ra pid rise of Coulomb frictions, but too large Coulomb friction will inc rease the response of the ER damper in the higher frequency bands. The MP damper has a broader varying range of damping than the SP one. Und er high electric field intensity, the damping and stiffness of ER damp ers change considerably, exhibiting strong non-linearity. The natural frequency of an ER damper shifts with the varying electric field due t o changing stiffness. The viscous friction force and Coulomb friction force of an ER damper are estimated by a recursive least-square algori thm. The change in stiffness has been considered in the estimation. Th e estimated results agree very well with the experimental results. (C) 1997 Academic Press Limited.