Analysis of wavelet de-noising for porosity inspection in carbon fiber reinforced composite

The theory of wavelet denoising were studied in this paper. Daubechies wavelet, Symlet wavelet and Coiflets wavelets were used to de-noise the ultrasonic signals of carbon fiber reinforced composite. The results show that the de-noising results of different wavelets for the same signal are different, but they conform to a certain rule; the de-noising results of different signals also conform to a certain rule for the same wavelets. The relationship between ultrasonic attenuation and porosity was compared for original signals and de-noised signals, and the relationship for de-noised signals turned out to be closer to parabola relationship.