| Abstract Scope |
Resistance spot welding is widely used in automotive applications, yet reliable nondestructive evaluation of thin sheet aluminum spot welds remains challenging due to strong attenuation, geometric constraints, and complex wave interactions. This work presents an ultrasonic imaging approach for characterizing aluminum spot welds with improved spatial and temporal insight into the weld integrity. Ultrasonic data is acquired using a microscopic resolution ultrasonic imaging system, ultrasonic property maps are reconstructed to form images of ultrasonic wave propagation through the weld region. This study will analyze the resistance spot weld region by using amplitude, attenuation, velocity, frequency maps to understand how the ultrasonic wave interacts with the welded region. Furthermore, ultrasonic property maps could have a high probability to identify weld conditions in time and frequency domains to understand shape and size of the weld as well as detailed examination of defects.
The proposed ultrasonic property map framework emphasizes thin-sheet considerations, including plate-mode behavior, limited weld thickness, and sensitivity to nugget geometry and kissing-bond defects. Ultrasonic property maps could reveal distinct scattering and attenuation patterns associated with weld nugget size, lack of fusion, and interfacial discontinuities. Experimental results obtained on aluminum lap-shear spot weld specimens demonstrate that the techniques enhance defect contrast and provides intuitive visualization of weld formation compared to solely time-integrated imaging approaches. Overall, ultrasonic property maps offers a promising avenue for quantitative and interpretable assessment of thin aluminum spot weld quality, with potential for integration into in-line inspection and advanced data-driven evaluation methods. |