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The echogram of an ultrasonic pulsed flaw detector with the contact testing technique has been considered as a convolution when a transducer with a protector matching the couplant receives an acoustic pulse emitted by the same transducer through the couplant into the load and reflected from this load and from this transducer. A method is proposed for calculating echograms for products, transducers, and couplants made of any materials with any size of the contact layer, provided that the acoustic impedances of the materials used are known. A method is proposed for compensating interfering reflections for a transducer matched to the couplant. [ABSTRACT FROM AUTHOR]

A procedure for the calculation of the emitted acoustic pulse of a transducer that contains a piezoelectric crystal plate, damper, and protector is experimentally verified. The presence of a protector increases the sensitivity at high resolution (five half-periods of oscillation at the antiresonance frequency of the piezoelectric crystal plate or at the 50% transmission band at frequencies to 6 MHz) in comparison with the sensitivity of a transducer with an undamped piezoelectric crystal plate. The requirements for the materials of the transducer and its geometric dimensions are determined and an example of its manufacturing is given. The relationship that establishes the connection between the effective frequency of the echo pulse with the antiresonance frequency of the piezoelectric element is experimentally determined. The characteristics of known transducers and the proposed one are compared. [ABSTRACT FROM AUTHOR]