An extraction method of welding crack acoustic emission signal using harmonic analysis

The actual collected welding crack acoustic emission (AE) signal has the characteristics of multi-sources coexistence and weak feature. An extraction method using harmonic analysis is proposed for separation of welding crack AE signal from the multi-sources ones. The collected AE signal from welding process is synthesized to be the high order reconstruction matrix, the valid harmonic layers are obtained by Singular Value Decomposition (SVD) that decompose and judge the reconstruction matrix. The Fast Fourier Transform (FFT) is adopted to extract the valid harmonic of signal, of which the welding crack AE signals are recombinated. Combined with the welding AE signal test experiment, the proposed extraction method is applied to separate the crack AE signal in the welding heating and cooling process respectively. The results indicate that the proposed method can effectively achieve separation and extraction of the welding crack AE signal, which provides a method for the structure crack detection in the welding process.