Shearography-Based Evaluation of Resistance Spot Welds: From In-Process Monitoring to Structural Health Monitoring

This study explores the potential of shearography for both in-process monitoring and structural health monitoring (SHM) of resistance spot welds. For in-process inspection, the method is applied immediately after the welding operation to monitor surface deformation during cooling, allowing a direct correlation between the measured deformation field and weld quality. For SHM applications, existing welds are thermally excited using induction, and their deformation response is analysed. The results demonstrate that shearography enables quantitative correlations between measured deformation gradients and mechanical weld properties such as nugget diameter. Furthermore, the integration of AI-based signal interpretation significantly enhances classification accuracy and robustness, paving the way for an automated, non-destructive 100 % inspection approach suitable for industrial implementation [15,16].