Combination of direct, half-skip and full-skip TFM to characterize defect(II)

To improve the accuracy of defect quantification, especially for those defects with a certain extension length, the ultrasonic echo information returned from different regions of defects is explored and combined. Indications of different defect areas are identified and extracted from three different B-scan images obtained by three total focusing method (TFM) modes. Then the different defect areas are combined in a hybrid TFM image to characterize the defect. Simulation is done for defect with extension in vertical direction to prove the validity of the method. For the experiment, a defect buried in the test block invisibly is characterized to further verify the feasibility of the method. Results show that the hybrid TFM is feasible in determining the extension trend and it can give more information in characterizing defects.