Natural Frequencies and Damping Properties of Hybrid Polymeric Composite Material Reinforced with Nitinol Shape Memory Alloy Wires

In this study, the damping ratio and the natural frequencies of the vibration modes were investigated. Hand lay-up technique was used to prepare the samples, which were formed by stacking the layers within the laminates, that containing epoxy as a matrix reinforced by layers of woven roving carbon fibers and smart shape memory alloy (Nitinol) wires, with different volume fractions. Experimentally, the damping ratio was determined by using half-power bandwidth techniques. The natural frequencies of the vibration modes were calculated by using the equations of the cantilever beam and compared with the experimental results. ANSYS composite Prep-Post (ACP) integrated within ANSYS Workbench software was first used to determine the mode shape and find the natural frequencies of the vibration modes and then compared with the experimental results. The results showed that increasing the number of Nitinol wires leads to increase the values of the bending modulus, the damping ratio of the vibration modes and the natural frequencies of the vibration modes at room temperature (martensite phase). While at austenite phase (55°C), the values of the damping ratio of the vibration modes decreased, and the bending modulus and the natural frequencies increased (higher than martensite phase), this change in natural frequencies values is useful in order to avoid the resonance.