Nugget quality prediction of resistance spot welding on aluminium alloy based on structureborne acoustic emission signals

The structureborne acoustic emission signals during resistance spot welding on 2024 aluminium alloy were detected in real time and analysed to find the characteristics of signals corresponding to the physical phase of welding process. The curve fitting models were developed based on the acoustic emission count and positive peak of nugget nucleation event. These mathematical models were used to predict the tensile-shear strength of spot weld. The results showed that the physical phases of welding process can be characterised by the acoustic emission signals detected during the resistance spot welding process. The acoustic emission count and the positive peak of nugget nucleation event of resistance spot welding on 2024 aluminium alloy have good relevance to the tensile-shear strength of spot weld, and these correlations were fitted to comply with some functional relationships, which can be used to realise the prediction of the strength of spot weld. It can be concluded that the prediction of weld strength based on the acoustic emission count of nugget nucleation event has good performance, but the prediction of weld strength based on the positive peak of nugget nucleation event is more susceptible to the expulsions and has poor performance when there are expulsions.