Dynamic Properties of Laminated Composites with Shape Memory Alloy Long Fibers

Shape memory alloy have unique damping properties due to the internal damping of the martensitic phase. Good mechanical properties and high damping are often simultaneously demanded in technological Applications. SMA yarns or wires can be used as embedded fibers into conventional resins or composites so as to obtain high damping laminated composites with significant potential application in the field of structural vibration control. With regards a future applications, many R&D project have been strongly supported and recently SMA yarns and wires of small diameter have also become commercially available for the design of smart composite structures because can be more easily produced. In the present paper a new SMA-based laminated composite, made of Glass Fiber Reinforced Polymer with unidirectional Ti-Ni alloy long fibers, is proposed. To design SMA reinforcement so as to obtain an optimal passive damping performance of the composite, it is especially important to accurately predict the effect of loading frequency and small strain amplitude on the damping of the SMA material. To take this two effects into account a series of vibration tests are performed onto SMA yarns excited axially and the damping ratio have been identified for strain amplitude in the range of 10-5-10-3 microepsilon and frequencies until 200 Hz. On the basis of the experimental tests, a rheological model of the material has been formulated. The rheological model has been implemented in a user subroutine of the FE Abaqus code. Then a Finite Element analysis of the laminated composite has been used to analytically optimize, the laminated composite with respect to the damping capacity varying the number and the diameter of the embedded yarns.