Defect Identification and Sizing by the Ultrasonic Satellite-Pulse Technique

Abstract

<p>Type and size are the most important defect characteristics that need to be determined for reliable prediction of the remaining service lifetime of a defective structure or part. The analytical and supporting experimental results presented in this paper concern a universal ultrasonic defect-identificationand- subsequent-sizing method. The conceived satellite-pulse technique (SPT) is based on the interpretation, in terms of defect types and dimensions, of the separation in time-of-arrival between the specularly-reflected pulse and its tip-diffracted or tangentially-scattered "satellite" contained in the composite defect signal. Several alternate calibration procedures were also developed, any one of which enables the ultrasonic examiner to make the time scale of the oscilloscope read directly in terms of equivalent crack depth or void diameter as appropriate.</p>