SU1446561A1 - Ultrasonic method of measuring the sound attenuation factor in material specimens - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to determine the attenuation and velocity of propagation of elastic waves in samples of materials. The purpose of the invention is to improve the accuracy of measuring the attenuation of longitudinal and transverse elastic waves by taking into account the influence on the attenuation of the quality of the processing of the interfaces and the contact pressure on them. For this, an acoustically rigid load made of a waveguide material is placed in a focused acoustic field of an acoustic waveguide and measured at a given pressure of the amplitude of longitudinal and transverse reflected waves at the interfaces: the waveguide is an acoustically rigid load, then instead of an acoustically rigid load a sample is placed in the sound field with an acoustically rigid load having a cavity with a radius of more than four wavelengths and measuring at the same pressure the amplitude of the longitudinal and transverse reflected waves on the face In the section: an acoustically rigid waveguide — the sample and the sample — an acoustically rigid load, and the attenuation coefficient is determined by a formula taking into account the measured amplitudes of the reflected waves. 1 il. WITH/)

Description

The invention relates to non-destructive testing and can be used to determine the attenuation and propagation velocity of elastic waves in samples of materials.

The aim of the invention is to increase the accuracy of measuring the attenuation of longitudinal and transverse elastic waves.

The drawing shows a device that implements the proposed method.

The device consists of a rigid waveguide 1, which is fixed. Emitters 2 and receivers 3 are longitudinal and transverse ultrasonic vibrations, the acoustic axes of which are oriented to the center of the surface of the opposite end of waveguide 1, to which sample 4 is attached, connected to a rigid load 5, made from. The waveguide material t and the sample-side having a closed cavity 6 with a radius of more than four wavelengths.

In the proposed method, the effect on the attenuation of the quality of the processing of the interfaces and the contact pressure on them is affected. For this purpose, an acoustically rigid load made of a waveguide material is placed in a focused acoustic field of an acoustic waveguide and measured at a given pressure of the amplitude of longitudinal and transverse reflected waves at the interfaces: waveguide - acoustically hard load, then instead of an acoustically hard load in the sound field a sample is placed with an acoustically rigid load having a cavity of radius R of more than four wavelengths and is measured at the same pressure P of the amplitude of the longitudinal and transverse reflected waves on the ground The sections of the section: an acoustically rigid waveguide — the sample and the sample — an acoustically rigid load, after which the attenuation coefficients of the longitudinal and transverse waves are determined by the formula

where s

1 1 AI

l, - 1 „1п1А1ГА). S ai

- wavelength of the sample

- accordingly, the amplitudes of the reflected waves at the interfaces of the waveguide - sample, the waveguide - acoustics

50

5 О e 0 d

0

five

The load is rigidly rigid and the sample is acoustically rigid.

The method is carried out in the following manner.

Radiators 2 longitudinal and transverse ultrasonic vibrations alternately excite longitudinal and transverse waves in waveguide 1. The reflected pulses of longitudinal and transverse waves, respectively, are received by receiver 3 of longitudinal and transverse oscillations. In the first case, the sound field is placed an acoustically rigid load 5 with sample 4 and measured at a given pressure P of the amplitude of the longitudinal and transverse reflected waves at the interface of the acoustically rigid waveguide 1 — the acoustically hard load 5. In the second case, a sample is placed in the sound field 4 with an acoustically rigid load 5 and measured at the same pressure as in the first case, the amplitudes of the longitudinal and transverse waves at the interfaces: acoustically rigid waveguide 1 - sample 4 - acoustically rigid load After measuring the amplitudes of the reflected waves, the attenuation coefficients of the longitudinal and transverse waves are determined using the above formula.

Claims (1)

Invention Formula An ultrasonic method for determining the attenuation coefficient of sound in images of a material, which consists in measuring the amplitudes of the reflected sound waves in a sample equipped with a tightly pressed acoustically rigid load and placed in the sound field, taking into account the sound attenuation coefficient that differs from that, in order to improve the measurement accuracy, the sound field is focused on the end of an acoustically rigid waveguide, an acoustically rigid load from a material is successively placed in a focused sound field waveguide and the sample with rigid acoustic load, the cavity having a radius greater than four wavelengths measured and p are the amplitudes of the reflected waves at the interfaces of the waveguide - acoustic - ically w ostka load waveguide - 31446561 the sample and the sample are an acoustically rigid load, and the attenuation coefficient З is determined by the formula , .one. , „Ь, where S is the wavelength of the sample;  one BUT one accordingly, the amplitudes of the reflected waves at the waveguide-waveguide sample interface are acoustically rigid and the sample is acoustically rigid.