Analytical Modeling of Electrorheological Material Based Adaptive Beams

The use of electrorheological (ER) materials in adaptive structures has received much attention recently. ER adaptive structures are based on controlling the pre-yield rheology of the ER material, which is achieved by applying different electrical fields to the ER material. In this study the dynamic behavior of an ER material based adaptive beam was modeled. Previous modeling efforts were extended towards a more detailed analysis of modal results. The adaptive beams focused on were composed of three layers: an ER material controllable damping layer and surrounding upper and lower elastic plates. A structural model of the assembly in a transverse continuous vibration mode subjected to simply supported boundary conditions was developed and analyzed. It was assumed that each structure was subjected to sinusoidal actuation applied at one or two locations. The model was tested under the conditions of varying forcing frequency from 0-300 Hz, and applied electrical field from 0-3.5 kV/mm. Time domain displacement response, natural frequencies, and loss factors of the structures at varying electric fields and varying damping layer thicknesses were obtained. The analytical results of the adaptive beam were compared with experimental results under the same physical conditions. Qualitative agreement between theory and experimentation resulted. In addition an effort was made to reduce the vibration of the structure by selecting the optimum electrical field which yields minimized vibration for each excitation frequency.