Combination of direct, half-skip and full-skip TFM to characterize multi-faceted crack

To improve the characterizing accuracy of a vertically extended and multi-faceted crack embedded in a weldment, direct, half-skip and full-skip total focusing method (TFM) are combined to image the crack. The B-scan images of the three modes are obtained and combined to a whole image, and then the extending trend of the crack in vertical direction is made out. Based on the combined image, sizing of crack along the depth direction is given using a basic quantitative method. Results show that the combined TFM in determining the extending trend and estimating the equivalent depth in the vertical direction is feasible for cracks with multi facets. Comparing to the conventional TFM imaging method to size an embedded crack, the combined TFM improved the accuracy of sizing of length in depth direction for a multi-faceted crack.