SU1698741A1

SU1698741A1 - Method of determining the acoustic waves absorption coefficient

Info

Publication number: SU1698741A1
Application number: SU894749822A
Authority: SU
Inventors: Анатолий Сергеевич Рубанов; Валерий Михайлович Добрянский; Олег Петрович Приходько
Original assignee: Белорусский институт механизации сельского хозяйства
Priority date: 1989-10-17
Filing date: 1989-10-17
Publication date: 1991-12-15

Abstract

Изобретение относитс к неразрушающему контролю. Целью изобретени вл етс повышение чувствительности и точности. Излучают первым преобразователем в исследуемую среду акустические волны, принимают прошедшие через среду акустические волны вторым преобразователем, измер ют амплитуду прин того сигнала при условии образовани квазисто чей волны между преобразовател ми и ее максимума на втором преобразователе, излучают акустические волны вторым преобразователем, принимают этим же преобразователем прошедшие волны при условии максимума амплитуды квазисто чей волны на втором преобразователе, измер ют амплитуду прин того сигнала. Определ ют искомый параметр с учетом измеренных амплитуд.This invention relates to non-destructive testing. The aim of the invention is to increase the sensitivity and accuracy. Acoustic waves are emitted by the first transducer into the medium under study, the acoustic waves transmitted through the medium are transmitted by the second transducer, the amplitude of the received signal is measured under the condition that a quasi-wave between the transducers and its maximum at the second transducer is generated, the second transducer is emitted The transmitted waves, subject to the maximum amplitude of the quasi-optical wave at the second transducer, measure the amplitude of the received signal. The desired parameter is determined based on the measured amplitudes.

Description

Изобретение относитс к неразрушающему контролю и может быть использовано при ультразвуковом контроле.This invention relates to non-destructive testing and can be used with ultrasonic testing.

Цель изобретени - повышение чувствительности и точности.The purpose of the invention is to increase the sensitivity and accuracy.

Способ определени коэффициента поглощени акустических волн осуществл ют следующим образом.The method for determining the absorption coefficient of acoustic waves is carried out as follows.

Излучают первым электроакустическим преобразователем гармонические акустические волны в исследуемую среду, принимают вторым электроакустическим преобразователем прошедшие через исследуемую среду акустические волны, измер ют амплитуду Јpi прин того сигнала при рассто нии L между преобразовател ми и частотео аку- стических волн, выбранными из услови The first electroacoustic transducer is emitted by harmonic acoustic waves into the medium under study, and the second electroacoustic transducer is received by acoustic waves passing through the medium under study, the amplitude Јpi of the received signal is measured at a distance L between the transducers and the frequency of acoustic waves selected from the condition

2лгп, (1) 2lgp, (1)

где п 1, 2, 3...; V -; скорость акустических волн в исследуемой среде; 5i и дг - фазы комплексных коэффициентов отражени акустических волн от первого и второго преобразователей соответственно. Излучают акустические волны той же частоты вторым преобразователем. Принимают этим же преобразователем прошедшие через исследуемую среду акустические волны, измер ют амплитуду ЈР2 прин того сигнала при выполнении услови (1) при di 62 0, п Г2 1, п 2k + 1, где к 0,1,2..., п и п - модули комплексных коэффициентов отражени акустических волн от первого и второго преобразователей соответственно. Определ ют коэффициент а поглощени акустических волн по формулеwhere n 1, 2, 3 ...; V -; the speed of acoustic waves in the studied medium; 5i and dg are the phases of the complex reflection coefficients of the acoustic waves from the first and second transducers, respectively. Acoustic waves of the same frequency are emitted by the second transducer. Acoustic waves transmitted through the medium under study are received by the same transducer, and the amplitude V2 of the received signal is measured when condition (1) is satisfied at di 62 0, n G2 1, n 2k + 1, where k 0,1,2 ..., p and n are the modules of the complex reflection coefficients of the acoustic waves from the first and second transducers, respectively. The absorption coefficient of acoustic waves is determined by the formula

a iardi;|(lH-iu, . (2)a iardi; | (lH-iu,. (2)

L1 §02 |р1 L1 §02 | р1

юYu

где |jbi и Јо2 - амплитуды сигналов акустических волн, излучаемых первым и вторым преобразовател ми соответственно.where | jbi and 2о2 are the amplitudes of the acoustic wave signals emitted by the first and second transducers, respectively.

Способ определени коэффициента поглощени акустических волн наиболее эф- фективен в области сильного поглощени этих волн средой.The method for determining the absorption coefficient of acoustic waves is most effective in the region of strong absorption of these waves by the medium.

Claims

The invention The method for determining the absorption coefficient of acoustic waves, which consists in emitting a harmonic acoustic wave into a test medium by a first electroacoustic transducer, receives a passive acoustic wave transmitted through the test medium by a second electroacoustic transducer between converters selected from the condition:

l k-ai-u -2 p, where n 1,2,3 ....,;

V is the velocity of acoustic waves in the medium under study;

a) their frequency;

5i and fc are the phases of the complex reflection coefficients of the acoustic waves from the first and second transducers, respectively,

and determining the desired parameter with regard to the measured value, characterized in that, in order to increase sensitivity and accuracy, acoustic waves are additionally emitted by the second transducer, the acoustic waves passing through the medium under test are received by the second transducer, and the amplitude of the received signal is measured when the conditions are met

5i - 62 - 0, n rz 1, n 2k + 1, where k 0,1,2 ...;

P and G2 are the absolute values of the complex reflection coefficients of the acoustic waves from the first and second transducers, respectively, and take it into account when determining the desired parameter.