Weld contour measurement of fillet welds by the reverse engineering technique

The external geometry of a fillet weld plays an important role in the strength of the weld. Two factors that influence the external geometry of the fillet weld are weld size and profile. The fillet weld must be made to the weld size and profile as specified in the welding code. An unacceptable profile not only is a defect of the weld but also produces stress risers that reduce the fatigue strength. An insufficient weld that reduces the cross-sectional area of weld throat may cause premature failure. Visual inspection and weld gauges are two of the most widely used simple tools to provide a rapid assessment of the external geometry of the fillet weld. In this study, the reverse engineering technique, in which a laser scanning system integrates with CAD software, is used to provide a more accurate measurement of the weld contour. The weld samples were made of low-carbon steel plates with a T-joint using CO2 welding. The weld volume, weld size, and convexity were determined from the CAD model to evaluate the weld quality. The reverse engineering technique provides a more accurate and efficient method to inspect the external geometry of the fillet weld.