About Influence of Thickness of a Layer of a Contact Liquid on Amplitude Echo Signal the Normal Probe With Different Number of Reflections From a Bottom Surface

Abstract

With use of the analytical description of coefficient of reflection of a bottom signal from area of contact of a sample and the normal probe growing with increase of frequency of fluctuations transmitted and a registered longitudinal wave and thickness of a layer of a contact liquid, computer modeling spectra and pulses of signals of models of direct converters with frequencies 5; 7,5; 10 МГц for number of reflections from a ground surface from 1 up to 3 is carried out. It is established, that with growth of thickness of a layer of a contact liquid and frequency of the probe values of maxima of pulses of the second and third bottom signals concerning a maximum of the first bottom signal are increased. Comparison settlement for model and experimental values for the direct converter frequency 5 MHz (P111-5,0-K6-002) relative maxima of pulses of the second and third bottom signals has shown their provisional conformity for thickness of a layer of a contact liquid of 0,004 mm. The account of factor of reflection of a bottom signal from area of contact of a sample and the probe may be useful at calculation of amplitudes ground echo signals longitudinal waves for samples of metal with the purpose of increase of opportunities of correct interpretation of research by a ultrasonic method of its structure.