Better method for detecting friction welding defect

Pseudo bonding often occurs in friction welding and greatly reduces the strength of friction weld. Traditional detection method finds it very difficult to detect pseudo bonding reliably as the signal's SNR (signal-to-noise ratio) is very low. This paper aims at providing a better detection method that can raise the SNR of the detection signal. Our better method includes two ways of utilizing wavelet transform: (1) translation invariant wavelet transform; (2) soft thresholding wavelet transform. Simulation experiments show that using translation invariant wavelet transform can give somewhat higher SNR of detection signal than that obtained by using soft thresholding wavelet transform, so that our better method can detect pseudo bonding reliably.