OPTIMAL VIBRATION CONTROL OF NITINOL-REINFORCED COMPOSITES

Shape-memory fibers, made of a Nickel-Titanium alloy (NITINOL), are em bedded inside smart composite beams in order to control the dynamic ch aracteristics 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 balan ce between the thermal softening of the composite matrix, the stiffeni ng effect imparted by the activated fibers, and the enhanced damping o f the matrix as it is heated towards its glass transition region. A fi nite element model is developed to model the dynamics of damped NITINO L-reinforced composite beams. The model is utilized to compute the nat ural frequencies, the modal loss factors and the frequency response fu nctions of this class of SMART beams. The frequency responses of the N ITINOL-reinforced beams are compared with those of the unreinforced be ams in order to emphasize the importance of the NITINOL reinforcement and its optimal tuning in significantly attenuating the vibration of t hese beams.