Small delamination detection in carbon fibre reinforced polymer composite beam by NDT and vibration analysis

Fibre reinforced polymer (FRP) composites have been prone to damages such as delamination, debonding, matrix cracking and fibre breakage. In this paper, detailed study has been carried out on determining the presence of small delamination in sub layers of carbon fibre composite beam using various non-destructive tests (NDT) and vibration signal analysis. We have concluded that ultrasonic and X-Ray Diffraction (XRD) tests have found to be more effective in detecting small delamination than X-Ray radiography and thermography tests. In the vibration test, we have observed that the natural frequency decreases and the rate of damping increases in delaminated carbon fibre composite beam as compared to composite beam without delamination. Besides, the fast fourier transform (FFT) results of vibration signal of delaminated beam have clearly shown higher harmonics and side bands. Finally, we have concluded that online vibration test can also be used effectively to detect presence of small delamination in FRP composites.