Development of an Ultrasonic Linear Phased Array System for Real-time Quality Monitoring of Resistance Spot Welds

This thesis presents research in the development of using an ultrasonic linear phased array transducer for real-time quality monitoring of resistance spot welds. Existing in-line systems use a single element transducer installed inside the welding electrode which capture the entire welding process. The single element system can very accurately determine the quality of a spot weld by acquiring A-scans through the center of the heat affected zone during welding. The linear phased array system being presented extends on the existing single element system utilizing a 24 element linear array transducer. By having 24 elements, the setup presented has the capability to inspect an entire line through the heat affected zone. This system makes it possible to measure the nugget diameter and detect potential voids inside the weld nugget, thus potentially improving in-line, non-destructive evaluation of spot welds