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Reliability Investigation of Sizing Horizontal Planar Discontinuities Using a New Time of Flight Diffraction Technique

The reliability of a new time of flight diffraction technique for finding horizontal planar discontinuities (H-TOFD) has been investigated using “â versus a” probability of detection (POD) evaluation. A finite element model (FEM) was developed to simulate the ultrasonic response from horizontal discontinuities at different depths. Several key variables were also considered to represent the modeling procedure, including removing the unwanted reflections by implementing infinite elements and using equivalent mechanical damping for transducer wedges. Simulated data was then generated for evaluating the “â versus a” statistical model. Based on the statistical model results, all tests were found to fit within the bounds of the POD model, demonstrating the H-TOFD technique is reliable for detecting and sizing horizontal planar discontinuities.


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