ACOUSTIC EMISSION METHOD FOR DIAGNOSING STRUCTURE CONDITION Russian patent published in 2001 - IPC

FIELD: quality control. SUBSTANCE: method involves applying sequential multichannel acoustic emission signal impulse wave shape cycle digitizing. The signal arrives from all the channels at discretization period rate approached as much as possible to but not exceeding the resonance half-period of impulses excited by piezoelectric transducers. Its amplitude threshold value being exceeded at least in one channel, digitized impulse shape is saved in memory. The acoustic emission signal impulse shape is digitized by sequentially testing all channels using the same threshold level in each channel in one discretization period. Digitizing cycle is terminated on out of memory space event reached on the main memory unit of analog-to-digital converter unit. Acoustic emission signal arrival time moments and its source coordinates in different channels are calculated using central processor unit of personal computer from digitized acoustic emission signal impulse wave shape. Impulse source risk degree is evaluated. The next new acoustic emission signal impulse wave shape cycle is digitized in parallel with new threshold value equal to 0.5-0.9 times the max amplitude of the preceding acoustic emission signal impulse. The new acoustic emission signal impulse wave shape cycles are digitized with corresponding threshold values. Their parameters are calculated repeatedly until acoustic emission signal impulse amplitudes coming through all channels become less than threshold value in previous cycle. The threshold value is reduced to minimum level after more than one maximum acoustic emission signal impulse propagation time interval is over. EFFECT: high accuracy in determining acoustic emission signal source coordinates; reliable evaluation of risk degree. 2 cl, 1dwg