Effect of fiber orientation in uni-directional glass epoxy laminate using acoustic emission monitoring

Acoustic emission （AE） can be used for in situ structural health monitoring of the composite laminates. One of the main issues of AE is to characterize different damage mechanisms from the detected AE signals. In the present work, pure resin and GFRP composites laminates with different stacking sequences such as 0°, 90°, angle ply[±45°], cross-ply [0°/90°] are used to trigger different failure mechanisms when subjected to tensile test with AE monitoring. The study of failure mechanisms is facilitated by the choice of different oriented specimens in which one or two such mechanisms predominate. Range of peak frequencies in each orientation is investigated using FFT analysis. Fast Fourier Transform （FFT） enabled calculating the frequency content of each damage mechanism. Randomly selected hits from each range of peak frequencies for the specimens with different orientations subjected to tensile test with AE monitoring are analyzed using short time FFT （STFFT） analysis. STFFT analysis is used to highlight the possible failure mechanism associated with each signal. The predominance of failure modes in each orientation is useful in the study of discrimination of failure modes in composite laminates from AE data.