Non-destructive measurement of weld toe radius using Weld Impression Analysis, Laser Scanning Profiling and Structured Light Projection methods

Significant stress concentrations in welded structures typically arise at crack like defects and at weld toes.The geometry of the weld toe is therefore one of the primary geometrical features that control the fatigue life of welded components. This work is focused on evaluating three non-destructive methods to measure the weld toe radius: Weld Impression Analysis (WIA), Laser Scanning Profiling (LSP) and Structured Light Projection (SLP). Measurements were first done on a reference block with five different radii. The accuracy of the three methods was estimated by comparing the results with those measured by cross sectioning the reference block and then using image analysis to determine the radius. Finally the non-destructive methods were employed to measure the weld toe radius for a corner fillet weld. Results show that all three methodspresent precise and accurate values when the cross section of the object being measured is circular. For noncircular cross sections such as a weld toe, the measurements are associated with a larger scatter. WIA seems to be a suitable and economical choice when the aim is just finding the radius. However, SLP is a good method to fast obtain a three-dimensional image of the weld profile, which also makes it more suitable for quality control in production.

Keywords:

Weld toe , Non-destructive methods , Weld Impression Analysis , Laser Scanning Profiling , Structured Light Projection.