Effect of Spot Weld Indentation on Spot Weld Nugget Characterization

When using the ultrasonic attenuation to size the nugget in the C-scan image, the contribution of indentation to ultrasonic wave attenuation will affect the accuracy of sizing the nugget. This paper studies the effect of the indentation on the sizing of spot weld nugget. First, the impact of indentation is analyzed from a theoretical perspective. Second, using simulation data sets, the effects of indentation on sizing of nugget in C-scan image are studied. Finally, the C-scan imaging and sizing of the spot weld are performed using actual two-dimensional scan data and the estimated size of the nugget is given. The results show that the existence of indentation may result in under sizing of nugget. If the information of the indentation is used, the error of the nugget quantification can be further grasped and understood.