Active vibration control of intelligent composite laminate structures incorporating an electro-rheological fluid

This paper addresses an active vibration control of intelligent composite laminate structures containing an electro-rheological (ER) fluid. Firstly, complex shear modulus of the ER fluid itself is obtained as a function of imposed electric fields and excitation frequencies through a rotary oscillation test. By incorporating the measured complex modulus with a conventional sandwich beam theory, elastodynamic properties of the structures are then predicted. Subsequently, an experimental investigation is undertaken in order to identify modal characteristics such as damped natural frequencies, damping ratios, and mode shapes of the structures. As for the validation of the modeling methodology, the comparison between the predicted elastodynamic properties and the measured ones is performed. Characteristics of the ER fluid actuator explicitly representing the relationship between elastodynamic properties and imposed electric fields are also inferred. A control system model is then formulated by combining the actuator characteristics into a phenomenological governing equation of a finite element form. Based on the field-dependent frequency responses of the structures, an active control algorithm for accomplishing desired responses of the tip deflection is established. In addition, in order to validate the proposed control strategy, the measured desired responses by means of an experimental implementation are compared with the predicted ones through the proposed model in the frequency domain. Finally, the effectiveness of the proposed control model for avoiding resonance to variable disturbances is evaluated by presenting the controlled tip deflection of the employed composite structures with respect to control gain in the time domain.