With the advancement in the field of morphing and adaptive structures, there has been a tremendous increase in the application of such systems in the civil and aerospace engineering, especially wherever space constraint and variable operational environment demand frequent changes in system configuration. The control of stiffness and hence dynamic response of such deployable structures can be achieved through smart material based actuation mechanisms such as shape memory alloys (SMA), and piezoelectric active fiber composites. Selection of appropriate smart material hinges on the requirements of the speed of actuation, actuator bandwidth, and force requirement. In this work, we study the vibration modes of a bi-morph SMA reinforced composite with controlled current input. The composite consists of two layers of SMA reinforcements with 0° and 90° orientation angles placed orthogonally in alternate plies. The temperatures of these layers are raised through Joule heating, first individually, and then followed by combined actuation, where the current supply is controlled using a programmable DC supply. As the material properties of SMA are temperature dependent, we observe thermal contraction and a resulting increase in laminate stiffness. The change of compliance at multiple step-input current contributes to variation in the natural frequency which is recorded using a 3D laser doppler vibrometer (LDV). This study gives us a deep insight into the application of SMA-based bimorph composites for active damping and vibration control subject to varying temperatures.

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