PROCESS DETERMINING PLANAR LACK OF CONTINUITY IN THICK- WALLED ARTICLES BY ULTRASONIC METHOD Russian patent published in 2002 - IPC

FIELD: nondestructive inspection with use of acoustics. SUBSTANCE: increased sensitivity, reliability and efficiency of control are achieved due to placement of two ultrasonic converters on surface of tested article, to entry into article of inclined beam of lateral waves polarized in plane of incidence perpendicular to plane of defect subject to detection at angle of incidence on plane of defect less than third critical angle. Beam of transformed longitudinal waves scattered by defect and reflected from bottom surface of article is received. Amplification, time gating, detection and recording with scanning of signals from defects with amplitude exceeding specified level are carried out. Acoustic axes of converters cross in one point on bottom surface of article. Two converters of lateral and longitudinal waves with parameters identical in pairs to parameters of first two converters are placed on surface of article in addition. Converters are simultaneously and cophaselly excited by electric pulses, signals received by each converter are processed in separate reception-amplification channel where time selection of bottom signals is conducted and time interval for selection of signals from defects is established. Sensitivity of control is tuned up per each position of converters on surface of article in process of scanning and/or per each cycle of radiation of probing signals and reception of echoes. Maximum amplitudes of bottom signals U_l01, U_l02 for longitudinal and U_t01, U_t02 for lateral waves are measured in each reception- amplification channel. If any amplitude is not less than minimum permissible levels of bottom signals over defect-free sections of article then level of reference signal U_ref is computed by certain formulas. Level of test sensitivity U_r is set as share of reference signal. Signals from defects selected during scanning and amplified in each channel are detected, detected signals from outputs of reception-amplification channels are summed up and maximum amplitude U_dmax of summary signal from defect is measured. If U_dmax>U_r, then presence of defect is recorded and cross-section of article in which defect is located is found at moment when signal achieves maximum amplitude while defect is crossed by symmetry plane of acoustic system. EFFECT: increased sensitivity, reliability and efficiency of control. 6 dwg