Selection of the parameters of a probe during immersion ultrasonic inspection

On the possibility of increasing the sensitivity and resolution of an immersion piezoelectric transducer

“…2 and 4b by forming a protector that matches the piezoelectric cell of the transducer and the immersion medium [1][2][3][4][5]. The protector thickness, h, is specified as equal to the ultrasound quarter wavelength at the antiresonance frequency of the piezoelectric cell f PC (frequency f PC ) [5] and has the acoustic resistance [1,16]: (6) In addition, the frequency, f PC , is assumed equal to the effective frequency of the echo pulse, f. How ever, the above ratio is doubtful with respect to the selection of the material and has not been practically confirmation [5].…”

“…The table summarizes the calculated data for three values A 1med , the ratio A 1med /A 1 , and losses in sensitivity (in dB and %) relative to the maximum value as function of Z pr at Z med = 1.5, Z PC = 27, A 1 = 0.0526C (see (4)). It is clear that the maximum amplitude will be if the AI of the protector is calculated by the known formula (6) Z pr = = 6.36 (in this case, A 1med = 0.07276C), which will be A 1med /A 1 = 1.383 (or 2.82 dB).…”

“…Great attention is given to improving the characteristics of immersion ultrasonic transducers (referred to below as ultrasonic transducers) that operate in the pulse mode [1][2][3][4][5]. However, it is difficult to com pare the proposed improvements and, hence, to evaluate the efficiency and expediency of using the trans ducer.…”

“…Two basic characteristics (sensitivity and resolution) are used for ultrasonic inspection methods; it is reasonable to apply them to a transducer, since improvement in the sensitivity and resolution of a trans ducer leads to improving the characteristics of the inspection method. Note that they are often interde pendent, i.e., the improvement of one leads to the proportional deterioration of the other [1][2][3][4][5] and uncertainty arises.…”

An immersion piezoelectric transducer with advanced characteristics

“…Based on the magnitude of f PE that is used during the design, which is taken from an experiment or intuition, one can exactly determine the piezoelectric element and protector thicknesses; however, there is a great probability that one will not only not attain f, but will not enter the admissible (by GOST (State Standard) 26266 90 [2]) ranges of the devia tion of f from the nominal one, as well. The significance of this problem was substantiated in [9][10][11]; it was noted that f is noticeably lower than f PE for the immersion transducer with a protector; therefore, the problem of the determination of the f and f PE frequencies or their interrelation seems to be very significant.…”