Effect of carbon nanotube reinforcement on the natural frequencies and damping ratios of nanocomposite beams

In this study, the effect of carbon nanotube (CNT) reinforcement on the natural frequencies and damping ratios of nanocomposite beams are examined. Three nanocomposite plates reinforced with different CNT weight ratios (0% neat epoxy-glass fiber composite beam, 0.25%, 0.5%) are produced. Multi Walled Carbon Nanotubes (Purity>96%, outside diameter < 8nm) are mixed into the epoxy resin with an ultrasonic stirrer. The plates also contain glass fibres as an additional reinforcement. Test specimens are cut parallel and perpendicular to the direction of the fibres to obtain two different sets of specimens. Free vibration tests are performed by a wireless accelerometer sensor (WAS), a wireless data acquisition system (WDA) and a PC. Natural frequencies and damping ratios are determined from the acceleration data obtained from the experiments. For both the 0° and 90° specimens an increase in natural frequency is observed. However, while the damping ratio of the 0° specimen increases, the damping ratio of 90° one decreases.