ELECTRORHEOLOGICAL MATERIAL BASED ADAPTIVE BEAMS SUBJECTED TO VARIOUSBOUNDARY-CONDITIONS

The semi-active vibration control capabilities of Electrorheological ( ER) material based adaptive beams were investigated in this study. The adaptive nature of such ER beams was achieved by controlling the pre- yield theology of the ER material in response to varying applied elect ric field levels. The cross-sectional configuration of the beams consi dered was based on sandwiching the ER material between elastic face pl ates. A dynamic model of the beam structure based on thin plate theory was developed. The resulting dynamic model was able to predict the st ructural vibration characteristics of the ER adaptive beam. The inform ation determined included natural frequencies, loss factors, and trans verse vibration responses at any location on the beam surface. These v ibration characteristics were determined as functions of excitation fr equency and applied electric field level. Also the beam model was deve loped for generalized boundary conditions. The boundary conditions con sidered in this study were: clamped-clamped, clamped-free, clamped-sim ply supported and simply supported. Variations in the natural frequenc ies, loss factors, and transverse vibration response of the adaptive s tructure were analyzed for the listed boundary conditions. Additionall y, effects of variations of the damping layer thickness of the adaptiv e beam on the structural loss factor was studied. Results were compare d for the boundary conditions studied, and considerable variations in beam vibration responses were observed. As a result, the semi-active c ontrol capabilities of ER material based adaptive beams were theoretic ally illustrated.