ON THE FEATURES OF THE CHARACTERISTICS OF THE SPECTRUM AND PULSE OF THE ECHO SIGNAL DURING ULTRASONIC CONTROL OF METAL THROUGH THE FUSED LAYER BY ANGLE BEAM LONGITUDINAL WAVE PROBES

Based on computer simulation of an echo signal from a side drilled hole type reflector during ultrasonic control of the base metal by an angle beam longitudinal wave probe with nominal frequency of 1.8 MHz through transversal-isotropic elastic layer of constant thickness at different values of the anisotropy parameter, it is shown that with an increase in the anisotropy parameter there is a shift of the signal maximum in the direction of increasing the distance to the reflector, which is associated with an increase in the phase velocity of the quasi-longitudinal wave in the layer, and an increase in the maximum value due to a change in the double transformation coefficient when the longitudinal wave passes from the prism of the probe to the layer and back. For a probe with a frequency of 2.5 MHz, an increase in the anisotropy parameter leads to a decrease in the value of the echo maximum, since the increased increase in the attenuation of the quasi-longitudinal wave in the layer is not compensated by a change in the double transformation coefficient. For different nominal angles of probe (45…60°), a noticeable change in the shapes of frequency spectra and echo pulses at different values of the anisotropy parameter has not been established. The effect of increasing the distance from the control surface to the axis of the cylindrical hole at a constant layer thickness on the change of the amplitude of the echo signal in the calculated range of values of the anisotropy parameter is shown.