A nondestructive testing method of ultrasonic defect characterization based upon the separation in time-of-arrival between the reflected pulse and its leading diffracted satellite pulse in the case of a crack-like defect and its lagging scattered satellite pulse in the case of an inclusion-like defect is shown. The angle beam, single probe type, echo ranging technique differentiates the main defect reflection from the satellite pulses of the defect and uses the sequence and magnitude of the separation in time-of-arrival between the pulses to determine the shape and size of the defect. Due to a discovered linear relationship between the ultrasonic delay time and defect size, the time scale of an oscilloscope's screen can be adjusted to read directly in terms of crack depth or inclusion diameter. Beyond the need to recognize returning pulses, the relationship is independent of wave amplitudes and the technique is thus easily utilized and is compatible with many different types of materials to be tested.
George J. Gruber