This project is supported under NSF's "Small Grants for Exploratory Research (SGER)" Program and jointly by the Structural Systems and Construction Processes and Earthquake Hazard Mitigation Program. The objective of this project is to explore the feasibility and applicability of electrorheological fluids (ER) as a semiactive scheme for vibration control of structures. The approach is to use a simple system whose control parameters, damping and stiffness coefficients, dependent on the ER fluid, are varied in real time through control of the electric field. a multidisciplinary approach is undertaken in which both experimental and analytical tasks will conducted. The analytical model takes into account the nonlinear dynamics of this problem. A nonlinear control scheme will be developed, based on the constructive use of Lyapunov stability theory. Such a controller is efficient in computation time (essential for real time applications) and, in addition, handles nonlinear dynamics. ER materials characterization and response will be measured using the experimental arrangement. One important result of the research, in addition to demonstration the advantages of semiactive control for structural vibration, is that it will provide guidelines for the requirements of suitable ER fluids for such applications. This investigation explores, for the first time, the feasibility of ER scheme for use in controlling the dynamic structural response and assesses its potentials in solving seismic, wind, or machine-induced vibration problems.
