Detection of arc characteristics and weld forming quality of aluminum alloy DP-MIG welding using AE signal through resonance demodulation

Acoustic emission (AE) signals are generated during aluminum alloy double-pulse melt inert-gas (DP-MIG) welding, which contains physical information related to arc stability and weld forming quality. In this paper, the AE signal test platform of aluminum alloy DP-MIG welding is constructed. An adaptive resonance demodulation method for AE signals in unknown frequency bands is proposed, which is applied for the AE signals of the six groups different welding process parameters. The time-domain waveform and frequency spectrum of the acquired AE envelope signals are consistent with that of the arc current. Hilbert-Huang transform (HHT) is performed on the envelope signal to obtain a time–frequency diagram. The signal energy changes periodically along the time scale, and the frequency distribution ranges from 0 to 2000 Hz. The segmental entropy of the AE signal is calculated to evaluate the welding seam forming quality. The calculated entropy values of 0.6, 0.9 and 1 mean that the welding seam is formed well, the values of 1.6 and 1.9 mean that the welding seam is poor. The research provides a new and effective method for realizing the quality monitoring of aluminum alloy DP-MIG welding process.