NONCONTACT ULTRASONIC FLAW DETECTION USING A DOPPLER EFFECT

摘要

FIELD: defectoscopy.;SUBSTANCE: invention can be used for non-contact ultrasonic flaw detection using Doppler effect. Essence of the invention consists in the fact that during the relative motion of the contactless acoustic transducer and the controlled article at a given frequency, ultrasonic vibrations are emitted into the article with a beam pattern symmetric in the probing plane with known angles, receiving reflected echo signals, at known speed of movement calculating Doppler frequency shift of echo signals, determining instantaneous frequencies of echo signals received in limits of opposite directed main lobes of the beam pattern of the converter, in direction and values of their change and by mutual time position of groups of echo signals received by said lobes of the beam pattern, presence and position of the defect are determined.;EFFECT: high reliability of detecting defects at considerable scanning speeds (up to 120 km/h and higher).;1 cl, 4 dwg