NON-LINEAR ACOUSTIC METHOD FOR DETECTING CRACKS AND THEIR POSITIONS IN STRUCTURE AND DEVICE FOR REALIZATION OF SAID METHOD Russian patent published in 2006 - IPC G01N29/04 

FIELD: technology for detecting local defects in solid bodies by means of ultrasound waves, possible use for finding cracks in sheets, vessels and pipelines.

SUBSTANCE: an ultrasound wave is periodically emitted into structure, serially altering its input angle α_i from minimal necessary to maximal, thus forming a range of researched distances. For each value of input angle α_i current distribution of values of modulation amplitude of ultrasound wave is determined from distance for at least two frequencies of low-frequency vibration, which is excited in structure. From received distributions for each distance only maximal values of modulations amplitudes of ultrasound waves are selected and registered. On basis of the latter presence and dimensions of cracks are estimated. Position of cracks is determined on basis of time delay of expansion of ultrasound wave. In device, control block and electronic assembly for altering input angle of ultrasound wave are mounted, the latter being made in form of acoustic prism with matrix mounted on its surface formed by n ultrasound transformers and commutation block connected thereto. Commutation block is made with possible simultaneous element-wise commutation of m (m<n) ultrasound transformers and is connected to control block and ultrasound scanner. Ultrasound scanner is connected to information processing block, to which control block is also connected. Block for exciting low-frequency oscillations also contains serially connected low frequency generator and vibrator.

EFFECT: improved productiveness of measurements and their trustworthiness due to providing for crack detection in said structures from on place of the area by means of ultrasound wave along all possible routes of area during minimal time.

2 cl, 1 dwg