OPTIMAL VIBRATION CONTROL OF NITINOL-REINFORCED COMPOSITES

Shape-memory fibers, made of a Nickel-Titanium alloy (NITINOL), are embedded inside smart composite beams in order to control the dynamic characteristics and the damped response of these beams when subjected to external excitations. The NITINOL fibers are tuned by adjusting their initial tension and operating temperature to achieve an optimal balance between the thermal softening of the composite matrix, the stiffening effect imparted by the activated fibers, and the enhanced damping of the matrix as it is heated towards its glass transition region. A finite element model is developed to model the dynamics of damped NITINOL-reinforced composite beams. The model is utilized to compute the natural frequencies, the modal loss factors and the frequency response functions of this class of SMART beams. The frequency responses of the NITINOL-reinforced beams are compared with those of the unreinforced beams in order to emphasize the importance of the NITINOL reinforcement and its optimal tuning in significantly attenuating the vibration of these beams.