АНАЛІЗ ПАРАМЕТРІВ МОДЕЛІ ПРОХОДЖЕННЯ УЛЬТРАЗВУКОВИХ ХВИЛЬ ЧЕРЕЗ ЗАНУРЕНУ У РІДИНУ ПЛАСТИНУ

Abstract

The physical-mathematical model of the fall of an ultrasonic wave falling on the surface of a plate immersed in a liquid has been considered. The parameters of the model are the angle of incidence of the ultrasonic wave, the reflection and transparency coefficients for the incident wave and the thickness of the plate.This model is a theoretical basis for the practical implementation of the immersion method for measuring the velocities of propagation of longitudinal and transverse waves in samples of different materials. According to the experimental results of the propagation velocities of the longitudinal and transverse waves, the Poisson’s ratio of the material is determined. The materials of a typical plate are polymers that have different Poisson ratio in sign and magnitude. If the angle of incidence does not exceed the corners of the total internal reflection on the boundary of the liquid – solid for the longitudinal and transverse waves propagation in the plate, then the reflection and transparency coefficients are the real numbers. In this case, the squares of the modules of these quantities are the reflection and transparency coefficients of the energy of the wave. For the incident ultrasonic wave, reflection and transparency coefficients are calculated, depending on the angle of the incidence, the thickness of the plate and the material of the plate The analysis of the obtained results shows that the functional dependences of the energy coefficients of reflection and transparency are clearly expressed maxima and minima at different angles and plate thickness. For this purpose, the conditions for full reflection for incident waves and transparency for a transverse wave at critical angles of incidence are analyzed. The critical angles of fall of an ultrasonic wave from a liquid are calculated, under which in a plate only a transverse wave propagates. Determined thickness of the plate for polymeric materials, in which there is a complete reflection and full passage of the incident wave.