Ultrasonic wave propagation diffraction

Non-destructive methods include holographic interferometry, resistance transducers, stress-sensitive covers, and other similar techniques. In practice, the following physical methods of non-destructive monitoring of residual stresses are commonly used X-ray diffraction, measurement of dielectric properties, and ultrasonic control. The main purpose of these methods is to monitor the structural transformations or distortions taking place as a result of residual stresses and local deformations. However, the application of methods such as X-ray diffraction to measure distortions in unit cel dimensions, ultrasonics to measure elastic wave propagation velocities, etc., all encounter numerous experimental problems. Therefore, in ordinary laboratory conditions only quantitative estimations of residual stresses can be obtained. 

Time-of-flight diffraction (TOFD) systems measure the time required for an ultrasonic wave to reach a flaw and return to the transducer. Defect depth and visualization of defect regions can be obtained with this technique. Incident ultrasonic energy propagates differently within a material as follows ... 

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